- Email: [email protected]
The Ontario Hydro Data Acquisition and Computer System
THE O:-lTARIO HYDRO DATA ACQU ISITION AND COMPUTER SYSTEM
J . W. Shell ey , Pr oject Manager Ont a ri o Hydro DA CS Pr oj ect System Monitoring Divi s ion Rockwell International 3311 Eas t La Palma Ave nue Anahe im , Californi a 92803 U. S . A.
A.J. Harris, System Operation Engineer Ontario Hydro 620 University Avenue Toronto, Ontario, Canada M5G lX6
area contains about 77 generating stations, 202 transformer s tations, 769 distribution stations and over 14,000 mile s of major transmission lines . The primary demand in the winter of 1974 and 1975 was about 14,000 ~N supp lied from installed and purchased resources amounting to 18,470 MW. There are tie lines, mo s tly bidirectional, with adjacent utiliti es including the Power Authority of the ' State of New York, Detroit Edison, Niagara Mohawk, Hydro Quebec, Great Lakes and Manitoba Hydro. Exports up to 2,150 MW of interruptible power have been recorded which is about 15 percent of Ontario's own peak load demand.
ABSTRACT A l ar ge Canadian e l ec trical utility is nearing completion of a data acquisiti on and computer system for the real time monitoring of the operation of its bulk powe r system . It will be capabl e of accessing e~uipment status and electrical quantities from up to 200 transfor me r and generating stations every two seconds. 'rhe project invol ves an auxiliary power subsystem, a comJ?uter s ubsy s tem, a data a cquisi tion master sta tion and remote terminal unit s , power system in s trumentation and control equipment, a cOITUr,unications network, security application p rogra.-ns s ubsys tem, produc tion and control app li cat ion programs subsystem and the man/mach ine subsystem. The f,aper outlines the management organization deve l oped to imp l e::lent the project.
The power system outlined above is operated as an integrated multi-tiered organization comprised of generating and transformer stations, Regional operating centres and the System Control Centre located in Toronto . The function of System Control is twofold. Firstly, it directs the operation of the tran smission, switching and transformation o f the bulk power sys t em (115 kV and higher). Secondly, it dir e ct s the economic scheduling and loadi ng of generating facilities and the imp l ementation of transactions with other systems. To ac comp lish these purposes, a number of operating facilitie s have been provided over the year s prior to DACS including: about eighty t e lemetered quantities from across Ontario and neighbouring systems; breaker status display of three major stations; an IBN 1800 digital computer used for load frequency control and monitoring of a small group of system operating limits ; and an extensive dedicated voice co~-nunication system linki ng Sys tem Control with Regional operating sentres, major stations and neighbouring systems.
TEXT El ectrica l energ y demands doub l e every ten i-'ear s in Ontario. Althoug h t his stateme nt i s an a pproximation, it i s a fact that has been demonstra te·" ove r recent years and is expected t o continue t hr oug h the nineteen-seventies and into the nineteen -eig ht ie s . The p lanned l ll , OOO !negawatt expansion of On tario Hyd r o 3e ne rati ns fac il itie s over t he next ten years vlill be e:qu i valer.t te t he senerating fa cilities Hydro has built in the past sixty yea r s. Pot un.i.que to Ontario Hydro, pO"A'er systerr groKth ir.troduces complexities in syster-. operatior. . The cesign of the Data i·. cq uis i tion and COnli)uter System (DACS) has aCCOl fl....'l.10aa t
e....:
t :le
needs for moderniz ing t he
sys ter" Control Centre t o cope wi to curr en t prcble.ns ar,d the expansio n planned for Ontar io Hydro .
As t he power s ys tem has grown in size and complexity, it has become increasingly difficult for a power control s upervisor to always p re d ict and avoid situations in which portions of the ne two rk may be stressed beyond operating limits. The limits thems elves
1, fe" s ta ti stics may :)rov i ce a better unc.er s t and':'ns of Ontario Hydr o . An are a of 25 0 t h o~£and ssuare miles, e::t ending more than a thousa"c. ::liles e ast and >.-est, is ill ustrateJ by the map i n Figure 1. This
112
have become more cOl,lp lex which increases the difficulty of monitoring effectively . Following disturbances, information for prompt operating analysis and decision making has been obtained from a limited amount of telernetered data and oral corrununication with operators in the power syst~~. As a result a requirement was established to obtain a more secure and reliable pm.,er system operation by the gatherin~ of a large a~ount of network data into a single loca t ion where it can periodically undergo real time and p red ictive computer analysis through study of load flows , circuit and station anomalies and equipment capabilities. In addition , flol'ls , voltage and equip~ent status should be available to the pocler control supervisors by means of a wall diagram and CRT displays at a l l times . The DACS system t hus evolved.
The ~rincipal functi on of ~he DnCS compute r syster.1 is performed by two linivac l~ode l 11 06 processors connected by hardware and software into a ~ultiF roc esso r configuration. Its modular struc ture permits the addition of systems components to fulfill the growth requirements. As shown in F igure 2, the two p rocessors share a common memory and common periphe rals. Dedicated to each CPU is a computer operator's control console, a remote ~'atch terminal, a data acquisition interface and dn interface unit to t he clisplay equipment. Man/t:ach in e
From mid 1971 through 1 972 , engineering planning and design efforts for DACS were directed towards the ~reparation of system specifications and selection of companies to implement the specified system. Implementation of the system follovled with completion scheduled for 1 975. The total DACS Project involves a building addition at the Richview System Control Centre, an auxiliary pm'ler subsystem, computer subsystem and system software , a data acquisition master station and remote tenninal units (RTU ' s), power system instrumentation and control equipment , communications network subsystem, security application Jirogram subsystem, production and control application program subsystem and the man-machine subsystem to p rovide the interface between the power system operators and the i nformation .
The man/machine subsystem, Figure 3 , consists of two computer interface units, seven display generators, each capable of driving four multi-colour cathode ray tubes (CRT ' s), five operating consoles, one training console and one progral'nrner' s console - all having CRT's , switch matrices and special function keys . Also included are two hard copy p rinters for reproduction of CR'2.' images , four data loggers and a 10 by 30 foot dynamic wall diagra"ll of the power systel,1. The wall diagra~, data loggers and switch matrices are driven by master s t ation equipment , whereas the other functions depend upon the 1 1 06 computer. The man/macnine subsyster.·, has been designed with some p ractical redundancies "Jhich exemplify the approach used t h roughou t the DACS to enhance system availability.
Figure 2 is a simplified block d i ag ram of the DACS showing the major hardware units and their data flow interfaces. I n jtially RTU 's are to be located at 8 4 remote s ite locations throughout Ontario and connected to the pmler system instruments and control equipment . At these stations, measurements of powe r system q uantiti es and status are saJe . The data acquisition subsystem samples analogue and status (switch and breaker pos ition) da ta every two seconds by re ques ti ng the re,llote terminal units to read the instruIT,entation . This data is transmitted d igitall y to the master station at the system Control Centre where it is converted into engineering un its and entered into the co~puter memory as an organized data base. Data base i n forma tion is then processed by t he application or man/ machine programs and made available to the power system control supervisors by colour CRT, wall diagram, graphic meter and p~'inter output.
The \\'a ll d iag ram uses t wo tYges of indicator, illurr.inated annunciators and r"Le ters. Tl:e illwei nateJ annunc id tors are used to identify stations where breaker operat ions have occurred and to sho\v line--2 nc status . In all cases , re<...~uEdant lam:-Js c:.nd lamp dr ivers a.re u sed . The intensity of t he dua l lamp configuration is such t ha t lo ss of one l arr,p i s virtually unnoticeable to an observer . A special l aIn", test turns Ol'! only one lar:1p of each 2air at a time for visual identification of failures . The wall diagran meters are comr:rised of both analog or dig ital devices . These are not redundant so should one of them fail, ti1e power system cc·ntrol supe rvisor will be required to obtain the informatiol'! from a cOl'!sole CRT d isplay. ,'10 data is lost, only the ~eans of obtaining the data is changed . There a.re four typers and t·,vo high-speed printers loc ated in various areas of the
113
(
/
1
Manitoba
!
Minnesota
Quebec
WisconSIn
Generating station s
Partial
In
Undef
~i
operatIOn operation constructIOn HydraulIC
Thermal Nuclear
••
()
IJ
o o
~9,an
-\ '~
'-
Heavy water plants
•
<) MIChigan
Routes of main power flow
Power connections
New York
FIGURE I
THE ONTARIO HYDRO GEOGRAPHICALLY MASTER STATION ( M S)
RTU/CNS
COMPUTER SUBSYSTE M ( C S)
EACH 0 G HAS 4 C RT ' S ANO
1 "(YB OA R D
• 7 CONSOLES
_ 20C Rl 'S
. 2 HARO COpy .
L OS CO NTROL L ER
WA L L O I A GR AM
LOS CONT ROL L ER
~ T U -
RE M O T E
eNS -
CO MIIiI U N I C AT IO N$
I/O B -
' /0 BuS
l.OS 1/ F
-
C Pu -
DO
-
C RT -
LOC AL
TER M I NA L
UN. T
NE T wORK
SYST E'"
S W I TC ~
OUT P U T
$V ST EM
I NlE RFA C E
CE NTRA L OI$Pl .6,Y C ATH OD E
PROC ESS I N G U N t T
GENER AT OR RAY
TUB E
(T .... )
FIGURE 2 - SIMPLIFIED BLOCK DIAGRAM OF DACS SYSTEM
114
PR I NTER S 4 LOGGERS
System Control Centre. The normal procedure for requesting a typed report includes speci fying the typer to be used . The user would simply direct any desired printouts to another typer if the one he normally uses i s not functioning . For logs that are output automatically, the computer software provides an alternate device list I.hich it will use to redirect toe output .
Each console has two types of keyboards . One , the display editor, provides the basic capability of entering data into the computer subsystem via CRT displays. Loss of this keyboard for data entry would necessitate using another console for data entry . The power system control supervisors responsible for secure operation have three consoles available for their use and the power system control supervisor responsible for economic dispatch have two consoles. The second keyboard , the switch matrix , is used to quickly call any of 1,200 poss ible CRT displays or application programs . If this keyboard fai l s, call up of displays or application programs may be accomplished using the display editor keys.
'l'here are tIVO bJ ack and v,hi te hardcopy printers for use in obtaining printed copies of CRT displays . If the control room hard copy p rinter fails, outputs will be d irected to the training room hardcopy printer . However , if only the training room hdrdcopy printer fails, it is asslli~ed that the training user can tolerate loss of the uevice while it is being repaired .
Single failures at a console will not cause loss of any capability due to alternate capabilities available on that console. But if a console should be disabled, a second console will be capable of providing identical capabilities as there are few unique features on any console in the Control Centre .
Information for display on the seven consoles initially passes through an interface controller/multiplexer. This device is dual and is associated with a switch panel which allows the computer to select the interface controller/multiplexer to be used for each of eight display generator channels . This selection may also be made manually .
Data Acquisition The data acquisition subsystem , interconnected by t he communication network, provides the capability for gathering of digital data to form a power system data base within the computer subsystem located at the System Control Centre. It provides the information link between the Control Centre and power system electrical instrumentation equipment at facilities throughout Ontario. The data acquisition subsystem also provides the capability for the computer subsystem to communicate with certain segments of the man/mach i ne subsystem . It consists of a master station located at the System Control Centre , remote terminal units (RTU's) located at power facilities (generating stations, transformer stations and sIVitching stations) and the communications network consisting of Ontario Hydro olmed microwave and leased Bell Canada facilities .
The input data paths to the seven display generators are dual by virtue of the interface controller/multiplexer arrangement. Each display generator has four video output ci1annels for a total of twenty- eight video channels. These channels are connected to the twenty-six CRT ' s and two hard copy printers in an interleaved arrangement so that the CRT's on one console are not all driven from one display generator. Using this feature, no more than two CRT ' s on any console will be connected to the same display generator. There is no switching redundancy on the console between the display generators and the displays . Since any picture may be displayed on any CRT , if a display generator video output channel fails , the power system control supervisor can direct the desired picture to appear on one of the remaining three CRT's on his console. If common logic in a displdY generator fails such that all four video outputs are d isabled, the impact on anyone console will be minimal. A modular video patch panel of the plug - jack type is provided which will allow any CRT to be connected to any display generator video channel . Complete flexibility in connecting display generators to consoles is provided by manually repatching the video channels as desired.
The data acquisition subsystem operation is controlled by a compu t e r subsystem specifying data selection and routing through the master station . A poll/response technique is used to control digital data comm~.lI1ication betIVeen the master stations and RTU's. Communication consists of a number of party lines, each VIi th two 2,400 baud routes that are geographically separated and inuependent. Address design capability is provided for from one to thirty RTU's per party line. Each RTU interfaces with two co~~unications circuits through independent r,lodems . The master station can accommodate one hundred corununications circuits . The RTU provides for various combinations of analogue and
The loss of a CRT itself on a console may be compensated for by the user selecting one of the other three CRT's on his console for the picture display .
115
discrete signal interfaces with electrical in strumentation equipment. The basic data accluisi tion subsyste"; is desigr.ed such that it i s eXfandable to accommodate 200 RTU's with an average of 20 analogue data points, 50 eiscrete input po ints and 20 control output poin ts pe r RTU.
Supervisory Sununary Request Read Addressed Point Acknowledge/Reset Continuous Read System Snapshot Store Disable Security Check and Echo Freeze Transfer Trip Close Select Scan Alerted Points Stepwise Raise and Lower Time Duration Raise and Lower
l\ snapshot conm~anc1 is transmi tted on anyone or ;:lore (usually all) of the conununication cnannels. The receipt of the snapshot conunand by an RTU i.nstructs it to refresh the data in ti'!c snar·shot memory . The rr,aster station issues this command to all of the conununications channels within ten milliseconds.
After a tir~e sufficient for the RTU' s to refresh the data in the snapshot memory, about 15 milliseconds, the master station issues to the RTU's the requests for data. The RTU's transfer from the snapshot memory, the re ques ted data to the master station. Data contained in snapshot memory of the ETU is held there until overwritten by a new value in response to a snapshot conunand. If no response is received from an RTU within the norClal time taken to receive the response, the master station recognizes this no response conJitior. and may be programmed to reissue t~e request. The master station also recognizes vlheti,er or not data sent to it is new data or data previously transmitted.
The message is received, checked for probability of error and decoded. The reply from the RTU to the master station contains the synch code, RTU identification, point addresses and information requested by the command. There are four specific response formats that may comprise the RTU reply allowing for the variations in the type and quantity of information from an RTU for any particular scan. Since DACS is primarily a data gathering and processing system, the status registers, accumulators (counters) and analog-to-digital converter are the principle RTU-to-power system interfaces. In the DACS application, control of power system elements is not envisaged in the future except as required for use in automatic generation control.
The multiplex and control portion of the master station consists of three Nova minicomputers, asscciated buffers and watchdog timer and I/O bus switches. Two of the computers are active with the third in standby such t.hat anyone may serve as a backup unit for the other two in the system.
Power system instrumentation and control eq~ipments are the source of signal which are wired to terminal patch racks located adjacent to the RTU at the power station. The signals are patched to the appropriate input channel of the RTU. The "discrete", or contact closure, instrument signal is sensed by the recognition of the absence or presence of a 48 V DC supplied by an RTU instrument power supply. The accumulator signals are similarly 48 V DC from the RTU instrument power supply but are inputted to a counter for registering the times the signal changes state to 9999 counts. The counters (accumulators) are reset upon conunand.
I . cOI~·,puter subsystem interface unit is
providec'1. for each of the three Nova minicom~uters. The interface unit operates as a buffer providir.g the Univac 1106 multiprocessor ",.ith i::itialization control over the highspeed data transfer. The effective transfer rdte ef ·t he Univac/i~ova interface is 1 00,000 v..'ords (3(' bit) :..;e r second. The irlterface ~ni t, on acceptin(J a programrcec output from the Nova, generates an interrupt to the 1106. Eac i1 ir~t e rface Uilit lit ay be accessed by t\,lO 11 (:6 I/O channels, but not simul tar.eously. The adJress structure of the interface unit a1lolo;s 'Jf to seven units to be connected to a sin
The analogue signals, representing quantitative values such as power, potential or position, are presented as -5, 0, +5 volt DC variations at the analogue-to-digital converter. The A~C provides an eleven-bit plus sign binary output with a conversion rate of 2,000 signals per second.
Figc:.re " is an RTlJ simplifiEd block diagra.':l. The cor('.[!1Clnd, an addressed rr;essa'JE to the RTU
AUXILIARY POWER SUPPLY
fror:1 tf:e r~,aster station, may conta in these i nstructions .
Consistent v:i th the power system security role assigned to the DACS, the system must remain functional with the loss of power in
116
the system which it serves. This is accomplished by an auxiliary powe r supply, Figure 5. The function c. l elemp.nts of Dl'.CS at the System Control CeLtre have been designated to function from two power busses such that continued operation, although degraded, is sustained if either, but not both, of toe busses should lose power . Both ousses may, however, be powered from t.he ' sane source if so elected . The vrinciple power sources provided are called "uninterruptable" as a brief loss of J?ower to some DACS equipr:>.ent is catastrophic to its fu nc tion. The uninterruptable feature is accomplished by rectification and inversion 0: the primary l'.e with batteries sustaining the load for t he period the AC primary is lost. A failure in the components of the uninterruptable pOl,'er supVly is sensed t o operate an automatic bYVass . l'ianual bypass is also provided. The pr imilry AC i s normally provided by one, or both, station services ....·hi ch are appropriately fed by isolatable major power system transmission lines to the station. In the event that a ll external station power has been discontinued from these transmission lines, the critical equipment fo r continued Control Cer.tre and DACS operation is supported by either of t\~O 600 k\~ standby diesel units. Figure 5 illustrates the redundancy and crossswi tching provided for maintainir.g System Control Centre pov.'er. It should be noted that critical to extended DACS operation is recovering power to the equipment air conditioning within about 50 minutes . The equipment air conditioning is dependent upon the primary 600 VAC , eitl:e r from a standhy diesel or station service. THE SCFT\'IAkE SYSTE1·j The approach to development and ii:1ple"lenta tion of the extensive DACS software syseem ha~ been (1) develoJ?ment: the analysis 2.Pc. organization of the specific functional requirements into development tasks ar.d (:C) integration: t he proyressive asse;;-.bly of the individual functions that ,.,.ere developed int.o the total system . The task divisions for tlle software system are sho\-JTl in Figure 6. The DACS functior.al or "system" soft\,'are was defined by requirements sJ?ecificaticr.s in tr.e same manner as the hard\vare system at the level of the "executive" and "data base management", etc, to allol-l pregress to be made during development cy separate groups of analysts working with a reasonable degree of independence. Interfac e control docu.-:-,entatien was prepared and rr.aintainec as ':he guiC:elines for controllinq the interaction between the subsystems.
117
The software integration followed the basic sequence of (1) ~xecutive, (2) Data Base, (3) :·!an/::achir.e, (<1) Data Acquisition, (5) Perfornance l·~or.i tor ing and (6) Applications . However , this sequence was not held rigid ar.d req uired considerable iteration. The unique feature s of the DlICS software system are pr incipally in t he area of a pplications. 11 detailed discussion of the DACS software characteristics must wait for a paper specifically dedicated to t his vast topic . THE DACS PROJr:CT The DACS systerr, development activity was established by Ontario Hydro to be controllec! by the DACS Project l1anageF.,e nt Department under the surveillance of the DlIC5 Steering Commi ttee. 'rhe activities requireC: by the nature of the project did not clearly fall into the recognized responsibilities or discip li nes of anyone of Ontario Hydro's existing Divisions. The Steerinc; Committee Vias established consistir.g of the three Division Directors that were most closely associated \-li ti: the Dl'.CS Project \,'ork, the use of the DACS system and the gro ....·th of the :?o....·er syster.l. The rianager of the ne ....·lyfermed DACS Department ....'as also included on the cornmi ttec whic.h was chaired by the Chief Engineer. The administrative home for the DACS Project. Department "'as the St ations Project Division , the Power System Operations Division vias represented as the user and final custoner and the System Planning Divi~;ion as a r:-ajor advisor . Although snall by comparisOl, with many of Ontario Hydro's ;::>rojects, the Dl,CS Project \'Jas recognized as the first of tl-.is magnitul~e in this field of techno.lo(j}' , therefore, fir~t-hand experience for ~roject ma n.::lgerr,ent leadersh i p \'ic.S not available in its imElediate stdff. A conSUlting C\CjrE:e,uent was r:\ade \·:ith F:.o ckv:ell International' s ~ystem ~';onitoring i: : ivi~: ior to p rovide t h is ca.pability . A composite star f for ;"iroject iranagc::;en t, resuire~ents definition, procurecent and system integration ",'as formec.1 of Systerr l!onitorinq Division and On tario i[Yl~rc errploy€e!=-~
about 25/75 percent con[,osi tion respective ly. Principal !larGh"are and soft\·.are supl.).liers in tl:e project h'c re F&t! Systerr;s Company Si.7Crry I
Univac, l.ydin Con trols (for!'lall y ;'-,onitor Systems) and System DevelopLen:: Corlocration . Application rrcg rar.l soft\,,"are is by Ontario Hydro staff .
bei~g
develo.?el.!
In the early days o~ the project , the total task was analyzed and segr1er.ted into smaller elements which could he well-;::efined by product , budget and schedule. These elenents becaJ,~e knOlvT! as \/Or}: pacl:ages anc1 eacr v:as tracked a~d nana0ed as a sut-~roject ~y having its requir e:1lcn ts sLJecificatior.s,
,
separate contract section, statement of work, budget and schedule. The system integration task was defined as the combining of these work package products. Figure 6 depicts the work breakdown into the various work p ackages. Each work package was required to be managed; therefore, the work breakdown structure formed the basis for the project staff organization. A supervisor was given the responsibility for each group of work pacakages as shown. In addition to the three supervisors, a Senior project Engineer with a small staff was established for overall schedule and budgetary control and to provide a centre for change control, which included the introduction of new tasks resulting from power system changes . The Project office also maintained the DACS Information Li s t which provided the basic power system instrumentation requir e me n t s .
I .. :>cr .. s
"' ...'
2 · ~"O G"A ""' AB .
SE
, ~ :;£O!" : E '"
[
' ~ "( T
Cl " "
~ " ~ ... ,"
:: .. s
FIGURE 4 ~ RTU
J ' C :> "''' :)ll £''
SIMPLIFIED BLOCK DIAGRAM
scheduling also followed the work breakdown structure. A simplified PERT schedule was formulated for each work package and for their integration. The events were tracked and a tab was produced monthly or on request in several instances. A DACS Project s tatu s review was held monthly and required participation by all contractors. At the time of this writing, the Project status may be summarized as under budget, behind the original schedule about eight months and high in quality. In August 1975, when the DACS system is expected to be p laced in service, the DACS system should meet all performance objectives initially specified.
COMPUTER ROOM
I SET TO ·
-----i I I
~ .MS
}
, F
3 2 I I
SYSTEM CONSOLES PRODUCTION CONSOLES TRAINING CONSOLE PROGRAMMERS CONSOLE (2 C RT S)
2 HARD COPY PRINTERS( I CRT EACH)
"0 ,
DIGITAL FREQ. METERS NOT LINE LOADS METERS
cs
FIGURE 5- THE AUXILIARY POWER SYSTEM DIAGRAM
.MS
" "02
0{ MS I/O BUS sw 1110 5 6 NO 6
/--=-SY:..:S-,-T::;EM=---I~ SYSTEM
~
PRODUCT ION ~
/---"TO,,',,-'""',,,".o.G-I~ "ETRICES
® CV
SERIAL DATA
{
OPTICALLY COUPLED SERIAL OAT4
FIGURE 3 - DACS MAN/MACHINE SUBSYSTEM
118
J . W. Shell ey , Pr oject Manager Ont a ri o Hydro DA CS Pr oj ect System Monitoring Divi s ion Rockwell International 3311 Eas t La Palma Ave nue Anahe im , Californi a 92803 U. S . A.
A.J. Harris, System Operation Engineer Ontario Hydro 620 University Avenue Toronto, Ontario, Canada M5G lX6
area contains about 77 generating stations, 202 transformer s tations, 769 distribution stations and over 14,000 mile s of major transmission lines . The primary demand in the winter of 1974 and 1975 was about 14,000 ~N supp lied from installed and purchased resources amounting to 18,470 MW. There are tie lines, mo s tly bidirectional, with adjacent utiliti es including the Power Authority of the ' State of New York, Detroit Edison, Niagara Mohawk, Hydro Quebec, Great Lakes and Manitoba Hydro. Exports up to 2,150 MW of interruptible power have been recorded which is about 15 percent of Ontario's own peak load demand.
ABSTRACT A l ar ge Canadian e l ec trical utility is nearing completion of a data acquisiti on and computer system for the real time monitoring of the operation of its bulk powe r system . It will be capabl e of accessing e~uipment status and electrical quantities from up to 200 transfor me r and generating stations every two seconds. 'rhe project invol ves an auxiliary power subsystem, a comJ?uter s ubsy s tem, a data a cquisi tion master sta tion and remote terminal unit s , power system in s trumentation and control equipment, a cOITUr,unications network, security application p rogra.-ns s ubsys tem, produc tion and control app li cat ion programs subsystem and the man/mach ine subsystem. The f,aper outlines the management organization deve l oped to imp l e::lent the project.
The power system outlined above is operated as an integrated multi-tiered organization comprised of generating and transformer stations, Regional operating centres and the System Control Centre located in Toronto . The function of System Control is twofold. Firstly, it directs the operation of the tran smission, switching and transformation o f the bulk power sys t em (115 kV and higher). Secondly, it dir e ct s the economic scheduling and loadi ng of generating facilities and the imp l ementation of transactions with other systems. To ac comp lish these purposes, a number of operating facilitie s have been provided over the year s prior to DACS including: about eighty t e lemetered quantities from across Ontario and neighbouring systems; breaker status display of three major stations; an IBN 1800 digital computer used for load frequency control and monitoring of a small group of system operating limits ; and an extensive dedicated voice co~-nunication system linki ng Sys tem Control with Regional operating sentres, major stations and neighbouring systems.
TEXT El ectrica l energ y demands doub l e every ten i-'ear s in Ontario. Althoug h t his stateme nt i s an a pproximation, it i s a fact that has been demonstra te·" ove r recent years and is expected t o continue t hr oug h the nineteen-seventies and into the nineteen -eig ht ie s . The p lanned l ll , OOO !negawatt expansion of On tario Hyd r o 3e ne rati ns fac il itie s over t he next ten years vlill be e:qu i valer.t te t he senerating fa cilities Hydro has built in the past sixty yea r s. Pot un.i.que to Ontario Hydro, pO"A'er systerr groKth ir.troduces complexities in syster-. operatior. . The cesign of the Data i·. cq uis i tion and COnli)uter System (DACS) has aCCOl fl....'l.10aa t
e....:
t :le
needs for moderniz ing t he
sys ter" Control Centre t o cope wi to curr en t prcble.ns ar,d the expansio n planned for Ontar io Hydro .
As t he power s ys tem has grown in size and complexity, it has become increasingly difficult for a power control s upervisor to always p re d ict and avoid situations in which portions of the ne two rk may be stressed beyond operating limits. The limits thems elves
1, fe" s ta ti stics may :)rov i ce a better unc.er s t and':'ns of Ontario Hydr o . An are a of 25 0 t h o~£and ssuare miles, e::t ending more than a thousa"c. ::liles e ast and >.-est, is ill ustrateJ by the map i n Figure 1. This
112
have become more cOl,lp lex which increases the difficulty of monitoring effectively . Following disturbances, information for prompt operating analysis and decision making has been obtained from a limited amount of telernetered data and oral corrununication with operators in the power syst~~. As a result a requirement was established to obtain a more secure and reliable pm.,er system operation by the gatherin~ of a large a~ount of network data into a single loca t ion where it can periodically undergo real time and p red ictive computer analysis through study of load flows , circuit and station anomalies and equipment capabilities. In addition , flol'ls , voltage and equip~ent status should be available to the pocler control supervisors by means of a wall diagram and CRT displays at a l l times . The DACS system t hus evolved.
The ~rincipal functi on of ~he DnCS compute r syster.1 is performed by two linivac l~ode l 11 06 processors connected by hardware and software into a ~ultiF roc esso r configuration. Its modular struc ture permits the addition of systems components to fulfill the growth requirements. As shown in F igure 2, the two p rocessors share a common memory and common periphe rals. Dedicated to each CPU is a computer operator's control console, a remote ~'atch terminal, a data acquisition interface and dn interface unit to t he clisplay equipment. Man/t:ach in e
From mid 1971 through 1 972 , engineering planning and design efforts for DACS were directed towards the ~reparation of system specifications and selection of companies to implement the specified system. Implementation of the system follovled with completion scheduled for 1 975. The total DACS Project involves a building addition at the Richview System Control Centre, an auxiliary pm'ler subsystem, computer subsystem and system software , a data acquisition master station and remote tenninal units (RTU ' s), power system instrumentation and control equipment , communications network subsystem, security application Jirogram subsystem, production and control application program subsystem and the man-machine subsystem to p rovide the interface between the power system operators and the i nformation .
The man/machine subsystem, Figure 3 , consists of two computer interface units, seven display generators, each capable of driving four multi-colour cathode ray tubes (CRT ' s), five operating consoles, one training console and one progral'nrner' s console - all having CRT's , switch matrices and special function keys . Also included are two hard copy p rinters for reproduction of CR'2.' images , four data loggers and a 10 by 30 foot dynamic wall diagra"ll of the power systel,1. The wall diagra~, data loggers and switch matrices are driven by master s t ation equipment , whereas the other functions depend upon the 1 1 06 computer. The man/macnine subsyster.·, has been designed with some p ractical redundancies "Jhich exemplify the approach used t h roughou t the DACS to enhance system availability.
Figure 2 is a simplified block d i ag ram of the DACS showing the major hardware units and their data flow interfaces. I n jtially RTU 's are to be located at 8 4 remote s ite locations throughout Ontario and connected to the pmler system instruments and control equipment . At these stations, measurements of powe r system q uantiti es and status are saJe . The data acquisition subsystem samples analogue and status (switch and breaker pos ition) da ta every two seconds by re ques ti ng the re,llote terminal units to read the instruIT,entation . This data is transmitted d igitall y to the master station at the system Control Centre where it is converted into engineering un its and entered into the co~puter memory as an organized data base. Data base i n forma tion is then processed by t he application or man/ machine programs and made available to the power system control supervisors by colour CRT, wall diagram, graphic meter and p~'inter output.
The \\'a ll d iag ram uses t wo tYges of indicator, illurr.inated annunciators and r"Le ters. Tl:e illwei nateJ annunc id tors are used to identify stations where breaker operat ions have occurred and to sho\v line--2 nc status . In all cases , re<...~uEdant lam:-Js c:.nd lamp dr ivers a.re u sed . The intensity of t he dua l lamp configuration is such t ha t lo ss of one l arr,p i s virtually unnoticeable to an observer . A special l aIn", test turns Ol'! only one lar:1p of each 2air at a time for visual identification of failures . The wall diagran meters are comr:rised of both analog or dig ital devices . These are not redundant so should one of them fail, ti1e power system cc·ntrol supe rvisor will be required to obtain the informatiol'! from a cOl'!sole CRT d isplay. ,'10 data is lost, only the ~eans of obtaining the data is changed . There a.re four typers and t·,vo high-speed printers loc ated in various areas of the
113
(
/
1
Manitoba
!
Minnesota
Quebec
WisconSIn
Generating station s
Partial
In
Undef
~i
operatIOn operation constructIOn HydraulIC
Thermal Nuclear
••
()
IJ
o o
~9,an
-\ '~
'-
Heavy water plants
•
<) MIChigan
Routes of main power flow
Power connections
New York
FIGURE I
THE ONTARIO HYDRO GEOGRAPHICALLY MASTER STATION ( M S)
RTU/CNS
COMPUTER SUBSYSTE M ( C S)
EACH 0 G HAS 4 C RT ' S ANO
1 "(YB OA R D
• 7 CONSOLES
_ 20C Rl 'S
. 2 HARO COpy .
L OS CO NTROL L ER
WA L L O I A GR AM
LOS CONT ROL L ER
~ T U -
RE M O T E
eNS -
CO MIIiI U N I C AT IO N$
I/O B -
' /0 BuS
l.OS 1/ F
-
C Pu -
DO
-
C RT -
LOC AL
TER M I NA L
UN. T
NE T wORK
SYST E'"
S W I TC ~
OUT P U T
$V ST EM
I NlE RFA C E
CE NTRA L OI$Pl .6,Y C ATH OD E
PROC ESS I N G U N t T
GENER AT OR RAY
TUB E
(T .... )
FIGURE 2 - SIMPLIFIED BLOCK DIAGRAM OF DACS SYSTEM
114
PR I NTER S 4 LOGGERS
System Control Centre. The normal procedure for requesting a typed report includes speci fying the typer to be used . The user would simply direct any desired printouts to another typer if the one he normally uses i s not functioning . For logs that are output automatically, the computer software provides an alternate device list I.hich it will use to redirect toe output .
Each console has two types of keyboards . One , the display editor, provides the basic capability of entering data into the computer subsystem via CRT displays. Loss of this keyboard for data entry would necessitate using another console for data entry . The power system control supervisors responsible for secure operation have three consoles available for their use and the power system control supervisor responsible for economic dispatch have two consoles. The second keyboard , the switch matrix , is used to quickly call any of 1,200 poss ible CRT displays or application programs . If this keyboard fai l s, call up of displays or application programs may be accomplished using the display editor keys.
'l'here are tIVO bJ ack and v,hi te hardcopy printers for use in obtaining printed copies of CRT displays . If the control room hard copy p rinter fails, outputs will be d irected to the training room hardcopy printer . However , if only the training room hdrdcopy printer fails, it is asslli~ed that the training user can tolerate loss of the uevice while it is being repaired .
Single failures at a console will not cause loss of any capability due to alternate capabilities available on that console. But if a console should be disabled, a second console will be capable of providing identical capabilities as there are few unique features on any console in the Control Centre .
Information for display on the seven consoles initially passes through an interface controller/multiplexer. This device is dual and is associated with a switch panel which allows the computer to select the interface controller/multiplexer to be used for each of eight display generator channels . This selection may also be made manually .
Data Acquisition The data acquisition subsystem , interconnected by t he communication network, provides the capability for gathering of digital data to form a power system data base within the computer subsystem located at the System Control Centre. It provides the information link between the Control Centre and power system electrical instrumentation equipment at facilities throughout Ontario. The data acquisition subsystem also provides the capability for the computer subsystem to communicate with certain segments of the man/mach i ne subsystem . It consists of a master station located at the System Control Centre , remote terminal units (RTU's) located at power facilities (generating stations, transformer stations and sIVitching stations) and the communications network consisting of Ontario Hydro olmed microwave and leased Bell Canada facilities .
The input data paths to the seven display generators are dual by virtue of the interface controller/multiplexer arrangement. Each display generator has four video output ci1annels for a total of twenty- eight video channels. These channels are connected to the twenty-six CRT ' s and two hard copy printers in an interleaved arrangement so that the CRT's on one console are not all driven from one display generator. Using this feature, no more than two CRT ' s on any console will be connected to the same display generator. There is no switching redundancy on the console between the display generators and the displays . Since any picture may be displayed on any CRT , if a display generator video output channel fails , the power system control supervisor can direct the desired picture to appear on one of the remaining three CRT's on his console. If common logic in a displdY generator fails such that all four video outputs are d isabled, the impact on anyone console will be minimal. A modular video patch panel of the plug - jack type is provided which will allow any CRT to be connected to any display generator video channel . Complete flexibility in connecting display generators to consoles is provided by manually repatching the video channels as desired.
The data acquisition subsystem operation is controlled by a compu t e r subsystem specifying data selection and routing through the master station . A poll/response technique is used to control digital data comm~.lI1ication betIVeen the master stations and RTU's. Communication consists of a number of party lines, each VIi th two 2,400 baud routes that are geographically separated and inuependent. Address design capability is provided for from one to thirty RTU's per party line. Each RTU interfaces with two co~~unications circuits through independent r,lodems . The master station can accommodate one hundred corununications circuits . The RTU provides for various combinations of analogue and
The loss of a CRT itself on a console may be compensated for by the user selecting one of the other three CRT's on his console for the picture display .
115
discrete signal interfaces with electrical in strumentation equipment. The basic data accluisi tion subsyste"; is desigr.ed such that it i s eXfandable to accommodate 200 RTU's with an average of 20 analogue data points, 50 eiscrete input po ints and 20 control output poin ts pe r RTU.
Supervisory Sununary Request Read Addressed Point Acknowledge/Reset Continuous Read System Snapshot Store Disable Security Check and Echo Freeze Transfer Trip Close Select Scan Alerted Points Stepwise Raise and Lower Time Duration Raise and Lower
l\ snapshot conm~anc1 is transmi tted on anyone or ;:lore (usually all) of the conununication cnannels. The receipt of the snapshot conunand by an RTU i.nstructs it to refresh the data in ti'!c snar·shot memory . The rr,aster station issues this command to all of the conununications channels within ten milliseconds.
After a tir~e sufficient for the RTU' s to refresh the data in the snapshot memory, about 15 milliseconds, the master station issues to the RTU's the requests for data. The RTU's transfer from the snapshot memory, the re ques ted data to the master station. Data contained in snapshot memory of the ETU is held there until overwritten by a new value in response to a snapshot conunand. If no response is received from an RTU within the norClal time taken to receive the response, the master station recognizes this no response conJitior. and may be programmed to reissue t~e request. The master station also recognizes vlheti,er or not data sent to it is new data or data previously transmitted.
The message is received, checked for probability of error and decoded. The reply from the RTU to the master station contains the synch code, RTU identification, point addresses and information requested by the command. There are four specific response formats that may comprise the RTU reply allowing for the variations in the type and quantity of information from an RTU for any particular scan. Since DACS is primarily a data gathering and processing system, the status registers, accumulators (counters) and analog-to-digital converter are the principle RTU-to-power system interfaces. In the DACS application, control of power system elements is not envisaged in the future except as required for use in automatic generation control.
The multiplex and control portion of the master station consists of three Nova minicomputers, asscciated buffers and watchdog timer and I/O bus switches. Two of the computers are active with the third in standby such t.hat anyone may serve as a backup unit for the other two in the system.
Power system instrumentation and control eq~ipments are the source of signal which are wired to terminal patch racks located adjacent to the RTU at the power station. The signals are patched to the appropriate input channel of the RTU. The "discrete", or contact closure, instrument signal is sensed by the recognition of the absence or presence of a 48 V DC supplied by an RTU instrument power supply. The accumulator signals are similarly 48 V DC from the RTU instrument power supply but are inputted to a counter for registering the times the signal changes state to 9999 counts. The counters (accumulators) are reset upon conunand.
I . cOI~·,puter subsystem interface unit is
providec'1. for each of the three Nova minicom~uters. The interface unit operates as a buffer providir.g the Univac 1106 multiprocessor ",.ith i::itialization control over the highspeed data transfer. The effective transfer rdte ef ·t he Univac/i~ova interface is 1 00,000 v..'ords (3(' bit) :..;e r second. The irlterface ~ni t, on acceptin(J a programrcec output from the Nova, generates an interrupt to the 1106. Eac i1 ir~t e rface Uilit lit ay be accessed by t\,lO 11 (:6 I/O channels, but not simul tar.eously. The adJress structure of the interface unit a1lolo;s 'Jf to seven units to be connected to a sin
The analogue signals, representing quantitative values such as power, potential or position, are presented as -5, 0, +5 volt DC variations at the analogue-to-digital converter. The A~C provides an eleven-bit plus sign binary output with a conversion rate of 2,000 signals per second.
Figc:.re " is an RTlJ simplifiEd block diagra.':l. The cor('.[!1Clnd, an addressed rr;essa'JE to the RTU
AUXILIARY POWER SUPPLY
fror:1 tf:e r~,aster station, may conta in these i nstructions .
Consistent v:i th the power system security role assigned to the DACS, the system must remain functional with the loss of power in
116
the system which it serves. This is accomplished by an auxiliary powe r supply, Figure 5. The function c. l elemp.nts of Dl'.CS at the System Control CeLtre have been designated to function from two power busses such that continued operation, although degraded, is sustained if either, but not both, of toe busses should lose power . Both ousses may, however, be powered from t.he ' sane source if so elected . The vrinciple power sources provided are called "uninterruptable" as a brief loss of J?ower to some DACS equipr:>.ent is catastrophic to its fu nc tion. The uninterruptable feature is accomplished by rectification and inversion 0: the primary l'.e with batteries sustaining the load for t he period the AC primary is lost. A failure in the components of the uninterruptable pOl,'er supVly is sensed t o operate an automatic bYVass . l'ianual bypass is also provided. The pr imilry AC i s normally provided by one, or both, station services ....·hi ch are appropriately fed by isolatable major power system transmission lines to the station. In the event that a ll external station power has been discontinued from these transmission lines, the critical equipment fo r continued Control Cer.tre and DACS operation is supported by either of t\~O 600 k\~ standby diesel units. Figure 5 illustrates the redundancy and crossswi tching provided for maintainir.g System Control Centre pov.'er. It should be noted that critical to extended DACS operation is recovering power to the equipment air conditioning within about 50 minutes . The equipment air conditioning is dependent upon the primary 600 VAC , eitl:e r from a standhy diesel or station service. THE SCFT\'IAkE SYSTE1·j The approach to development and ii:1ple"lenta tion of the extensive DACS software syseem ha~ been (1) develoJ?ment: the analysis 2.Pc. organization of the specific functional requirements into development tasks ar.d (:C) integration: t he proyressive asse;;-.bly of the individual functions that ,.,.ere developed int.o the total system . The task divisions for tlle software system are sho\-JTl in Figure 6. The DACS functior.al or "system" soft\,'are was defined by requirements sJ?ecificaticr.s in tr.e same manner as the hard\vare system at the level of the "executive" and "data base management", etc, to allol-l pregress to be made during development cy separate groups of analysts working with a reasonable degree of independence. Interfac e control docu.-:-,entatien was prepared and rr.aintainec as ':he guiC:elines for controllinq the interaction between the subsystems.
117
The software integration followed the basic sequence of (1) ~xecutive, (2) Data Base, (3) :·!an/::achir.e, (<1) Data Acquisition, (5) Perfornance l·~or.i tor ing and (6) Applications . However , this sequence was not held rigid ar.d req uired considerable iteration. The unique feature s of the DlICS software system are pr incipally in t he area of a pplications. 11 detailed discussion of the DACS software characteristics must wait for a paper specifically dedicated to t his vast topic . THE DACS PROJr:CT The DACS systerr, development activity was established by Ontario Hydro to be controllec! by the DACS Project l1anageF.,e nt Department under the surveillance of the DlIC5 Steering Commi ttee. 'rhe activities requireC: by the nature of the project did not clearly fall into the recognized responsibilities or discip li nes of anyone of Ontario Hydro's existing Divisions. The Steerinc; Committee Vias established consistir.g of the three Division Directors that were most closely associated \-li ti: the Dl'.CS Project \,'ork, the use of the DACS system and the gro ....·th of the :?o....·er syster.l. The rianager of the ne ....·lyfermed DACS Department ....'as also included on the cornmi ttec whic.h was chaired by the Chief Engineer. The administrative home for the DACS Project. Department "'as the St ations Project Division , the Power System Operations Division vias represented as the user and final custoner and the System Planning Divi~;ion as a r:-ajor advisor . Although snall by comparisOl, with many of Ontario Hydro's ;::>rojects, the Dl,CS Project \'Jas recognized as the first of tl-.is magnitul~e in this field of techno.lo(j}' , therefore, fir~t-hand experience for ~roject ma n.::lgerr,ent leadersh i p \'ic.S not available in its imElediate stdff. A conSUlting C\CjrE:e,uent was r:\ade \·:ith F:.o ckv:ell International' s ~ystem ~';onitoring i: : ivi~: ior to p rovide t h is ca.pability . A composite star f for ;"iroject iranagc::;en t, resuire~ents definition, procurecent and system integration ",'as formec.1 of Systerr l!onitorinq Division and On tario i[Yl~rc errploy€e!=-~
about 25/75 percent con[,osi tion respective ly. Principal !larGh"are and soft\·.are supl.).liers in tl:e project h'c re F&t! Systerr;s Company Si.7Crry I
Univac, l.ydin Con trols (for!'lall y ;'-,onitor Systems) and System DevelopLen:: Corlocration . Application rrcg rar.l soft\,,"are is by Ontario Hydro staff .
bei~g
develo.?el.!
In the early days o~ the project , the total task was analyzed and segr1er.ted into smaller elements which could he well-;::efined by product , budget and schedule. These elenents becaJ,~e knOlvT! as \/Or}: pacl:ages anc1 eacr v:as tracked a~d nana0ed as a sut-~roject ~y having its requir e:1lcn ts sLJecificatior.s,
,
separate contract section, statement of work, budget and schedule. The system integration task was defined as the combining of these work package products. Figure 6 depicts the work breakdown into the various work p ackages. Each work package was required to be managed; therefore, the work breakdown structure formed the basis for the project staff organization. A supervisor was given the responsibility for each group of work pacakages as shown. In addition to the three supervisors, a Senior project Engineer with a small staff was established for overall schedule and budgetary control and to provide a centre for change control, which included the introduction of new tasks resulting from power system changes . The Project office also maintained the DACS Information Li s t which provided the basic power system instrumentation requir e me n t s .
I .. :>cr .. s
"' ...'
2 · ~"O G"A ""' AB .
SE
, ~ :;£O!" : E '"
[
' ~ "( T
Cl " "
~ " ~ ... ,"
:: .. s
FIGURE 4 ~ RTU
J ' C :> "''' :)ll £''
SIMPLIFIED BLOCK DIAGRAM
scheduling also followed the work breakdown structure. A simplified PERT schedule was formulated for each work package and for their integration. The events were tracked and a tab was produced monthly or on request in several instances. A DACS Project s tatu s review was held monthly and required participation by all contractors. At the time of this writing, the Project status may be summarized as under budget, behind the original schedule about eight months and high in quality. In August 1975, when the DACS system is expected to be p laced in service, the DACS system should meet all performance objectives initially specified.
COMPUTER ROOM
I SET TO ·
-----i I I
~ .MS
}
, F
3 2 I I
SYSTEM CONSOLES PRODUCTION CONSOLES TRAINING CONSOLE PROGRAMMERS CONSOLE (2 C RT S)
2 HARD COPY PRINTERS( I CRT EACH)
"0 ,
DIGITAL FREQ. METERS NOT LINE LOADS METERS
cs
FIGURE 5- THE AUXILIARY POWER SYSTEM DIAGRAM
.MS
" "02
0{ MS I/O BUS sw 1110 5 6 NO 6
/--=-SY:..:S-,-T::;EM=---I~ SYSTEM
~
PRODUCT ION ~
/---"TO,,',,-'""',,,".o.G-I~ "ETRICES
® CV
SERIAL DATA
{
OPTICALLY COUPLED SERIAL OAT4
FIGURE 3 - DACS MAN/MACHINE SUBSYSTEM
118