- Email: [email protected]
Analysis on the impact of large-scale wind power accessing the power grid on Inner Mongolia grid
Available online at www.sciencedirect.com
Systems Engineering Procedia
Systems Engineering Procedia 00 (2011) 000–000
Systems Engineering Procedia 3 (2012) 36 – 41
www.elsevier.com/locate/procedia
The 2nd International Conference on Complexity Science & Information Engineering
Analysis on the impact of large-scale wind power accessing the power grid on Inner Mongolia grid Gaoqiang Zhao, Jianxun Qi, Sen Guo a* North China Electric Power University, Changping District, Beijing 102206, China
Abstract With the adjustment of energy structure and the development of wind power accessing the power grid in China, largescale wind power will certainly have a significant impact on the power grid. For the large-scale wind power accessing the power grid in Inner Mongolia, a quantitative study has been done from two aspects which are ancillary facilities of wind power project accessing to power grid and the average price and cost of purchasing electricity for power Grid Corporation. The result shows: firstly, large-scale wind power accessing the power grid will not only increase the transmission line, but also increases the grid construction cost; secondly, large-scale wind power accessing the power grid will increase the average price and cost of purchasing electricity for power Grid Corporation. The analysis on the impact of large-scale wind power accessing the power grid on Inner Mongolia grid can provide some references for policy-makers and researchers.
©©2011 Elsevier Ltd. Ltd.Selection Selectionand andpeer-review peer-review under responsibility of Desheng Dash 2011Published Published by by Elsevier under responsibility of Desheng Dash Wu Wu. Keywords: wind power engineering; power grid; Ancillary facilities; Inner Mongolia grid
1. Introduction In recent years, with the shortage of energy supply and the adjustment of energy structure in China, renewable energy is developing rapidly. As a kind of renewable energy, wind power has the potential of large-scale commercial development with the advantage of huge reserves and mature technology. At the end of the year 2010, the new installed capacity of wind power in China has reached to 16 million kW, and the cumulative installed capacity has reached to 41.827 million kW. The installed capacity of wind power in China is the largest one in the world after surpassing the installed capacity of United States in 2010. Inner Mongolia locates in the northern border of China where wind energy resource is rich. Large wind farms that can be developed mainly locate in rich areas of wind energy resource, including the cities of Alashan, Bayannur, Baotou, Wulanchabu, XilinGol and Chifeng, where the average wind speed reaches to 5.0~6.5m/s and the reserve of wind energy resource amounts to 732 million kW. Inner Mongolia power grid is managed by Inner Mongolia Electric Power Company. The area of electricity supply contains the whole area of Inner Mongolia except Chifeng and Tongliao. Until to December 10, 2009, the installed
* Corresponding author. Tel.: +86 15811424568; fax: +86 10 80796904. E-mail address: [email protected].
2211-3819 © 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of Desheng Dash Wu. doi:10.1016/j.sepro.2011.11.005
Gaoqiang Zhao et al. / Systems Engineering Procedia 3 (2012) 36 – 41
capacity of wind power accessing the power grid had reached to 3.98 million kW, which accounted for 22 percentage of the maximum load of power generation. Until to December 10, 2009, the generation capacity of wind power amounted to 5.27 billion KWh. There are some researches on wind power accessing the power grid. Ref. [1] analyzed the integration of renewable power in Ontario (Canada), and found that the combination of solar and wind within locations and amongst two locations produces less variability in power production than when each resource is produced on its own. Ref. [2] described the considerations and the results of the investigation on short-term voltage stability carried out on a large wind power network model that is similar to a part of the Danish power grid, and a distinction was made between local wind turbines that may trip and those in a large wind farm subject to the Grid Specifications of the transmission system operator (TSO) that must ride through the grid faults. Based on an actual regional power grid in China, Ref. [3] presented a detailed simulation analysis of the impact of large scale wind farm on voltage stability (dynamic voltage stability) of power system under a short-circuit fault performed by PSCAD/EMTDC, and factors influencing voltage stability of the local grid interconnected with the wind farm were also analyzed. Appropriate modeling and simulation techniques were discussed for studying the voltage fluctuation and harmonic distortion in a network to which variable speed wind turbines are connected in Ref. [4], and the result showed the voltage fluctuation and harmonic problems can be minimized with the proposed power electronics interface and control system while the wind energy conversion system captures the maximum power from the wind as wind speed varies. Ref. [5] showed that wind integration required significant changes in grid planning and operations, continued technical evolution in the design and operation of wind turbines, further adoption and implementation of wind forecasting in the control room, and incorporation of market and policy initiatives to encourage more flexible generation. Ref. [6] studied the generation expansion planning of the power system incorporating large-scale wind power in the environment of electricity market, also proposed the concept of the environment-friendly coefficient and established the environment benefits model of the units. This paper takes Inner Mongolia grid for example, and analyzes quantitatively the impact of large-scale wind power accessing the power grid from two aspects which are ancillary facilities of wind power project accessing to power grid and the average price and cost of purchasing electricity for power Grid Corporation. 2. Ancillary facilities of wind power project accessing to power grid 2.1. Transformation equipment and transmission line In the year of 2009, Inner Mongolia grid put a 500KV substation into operation, namely, Qianlishan substation, and expanded three substations. At this year, Inner Mongolia grid also put two 220KV substations into operation, and expanded four substations. Inner Mongolia grid added to transformer capacity of 4110MVA.To the end of 2009, Inner Mongolia grid build two 500KV lines, and the new line length added to 162.395KM with the growth rate of 4.9%; build thirty-six 220KV lines, and the new line length added to 1311.458KM with the growth rate of 13.38%. At that year, the large-scale wind power accessing the power grid in Inner Mongolia increased the length of transmission line by 625.864 km. The large-scale wind power accessing the power grid will certainly increase the length of transmission line. 2.2. Power grid construction cost Large-scale wind power accessing the power grid will promote the power grid construction, and the cost of power grid construction will surely increase. Taking the wind power project as representative, the increased cost of power grid construction caused by large-scale wind power accessing the power grid can be calculated in the following.
37
38
Gaoqiang Zhao et al. / Systems Engineering Procedia 3 (2012) 36 – 41
The power grid corporation recovers the construction funds by way of acquiring wind power farm. The profit of Power Grid Corporation acquiring wind power farm can be calculated in formula (1). Yw = Rw − CPw = ps × Qsw − pw × Q pw
（1）
Suppose: = Qsw Q pw (1 − r )
= Yw Q pw [ ps (1 − r ) − pw ]
（2） （3）
where r represents the average line loss rate; Yw represents the profit of power grid corporation acquiring wind power farm; Rw represents the profit of power grid corporation selling wind power; CPw represents the cost of power grid corporation acquiring wind power farm; ps represents the sales price per unit; Qsw represents the selling wind power of power grid corporation; pw represents the electricity price into grid of wind power per unit; Q pw represents the purchasing wind power of power grid corporation. Suppose that the construction fund recovered by the power grid corporation equals for each year. The recovering cost of the power grid corporation for each year consists of two parts: one is the annually equal recovering cost converted by one-time construction investment, including construction cost, equipment cost, and project management cost; another is annual producing maintenance cost, including salary and additional salary cost, equipment operating cost and operating cost. According to the calculation method of matching annual funding, we can get formula (4).
D = P ( A / P, i, n) − F ( A / F , i, n)
（4）
where D represents the expected investment recovery cost; P represents construction investment costs; F represents the residual value; ( A / P, i, n) represents the recovery coefficient of equal allotment capital; ( A / F , i, n) represents the recovery coefficient of equal allotment sinking fund, n is the recovery period, i represents the interest rate. According to formula (3) and (4), the increased cost of power grid construction caused by large-scale wind power accessing the power grid can be calculated in formula (5). E2 = D + C − Yw = P( A / P, i, n) − F ( A / F , i, n) + C − Q pw [ p s(1 − r ) − pw ]
（5）
where C represents the producing maintenance cost. Until to the year of 2008, the project investment for wind power accessing power grid and ancillary facilities accessing to power grid nearly cost 40 billion Yuan in China, and the capacity of wind power accessing to power grid amounted to 16 million kW. For Inner Mongolia, the capacity of wind power accessing to power grid amounted to 3.74 million kW, and the power generation amounted to 3.74 billion KWh. By analogy, the project investment for wind power accessing power grid and ancillary facilities accessing to power grid nearly cost 9.35 billion Yuan in Inner Mongolia. In the year of 2008, the average line loss rate of Inner Mongolia grid was 4.97%. According to the benchmark price of thermal power with desulfurization, the wind power price purchased by Inner Mongolia grid was 0.2749 Yuan, and the selling price per unit was 0.3578 Yuan. If not consider the residual value and producing maintenance cost, we can get formula (6). （6） E2 = D − Yw = P(a / p )in − Q pw[ ps (1 − r ) − pw ] The increased cost of power grid construction caused by large-scale wind power accessing the power grid is related with the average investment recovery period. When the interest rate is 6%, and the average investment recovery period equals to 10, 15, 20, 25, 30, respectively, we can calculate the increased cost
39
Gaoqiang Zhao et al. / Systems Engineering Procedia 3 (2012) 36 – 41
of power grid construction caused by large-scale wind power accessing the power grid, just as shown in Table.1. Table.1. Grid construction cost under different investment recovery period Average investment recovery period(Year)
10
15
20
25
30
( A / P, i , n)
0.1359
0.1030
0.0872
0.0782
0.0726
D （109 Yuan）
14.3897
9.6305
8.1532
7.3117
6.7881
9
YW （10 Yuan）
2.4364
2.4354
2.4354
2.4354
2.4354
9 E2 （10 Yuan）
11.9533
7.1951
5.7178
4.8763
4.3527
From Table.1, we can see that the grid construction cost will increasingly grow with large-scale wind power accessing the power grid. When the average investment recovery period changes from 10 to 30, the increased cost of power grid construction caused by large-scale wind power accessing the power grid will decrease from 11.9533 ×109 Yuan to 4.3527 ×109 Yuan, correspondingly. 3. Average price and cost of purchasing electricity for grid 3.1. Average price of purchasing electricity for grid In the year of 2008, there are a lot of large-scale wind powers accessing the power grid in Inner Mongolia. The average prices of purchasing electricity for Inner Mongolia grid from the year of 2007 to 2009 are shown in Table.2. Table.2. The average prices of purchasing electricity for Inner Mongolia grid Year
Region
Average price of
Growth rate
2007
Western Inner Mongolia Eastern Inner Mongolia
292.25
0.35
2008
Western Inner Mongolia
322.10
22.58
Eastern Inner Mongolia
313.95
7.43
2009
Western Inner Mongolia
335.64
5.24
Eastern Inner Mongolia
334.15
6.43
purchasing electricity
（%）
262.76
2.63
As shown in Table.2, the average price of purchasing electricity for Inner Mongolia grid has increased significantly from 2007 to 2009 with large-scale wind powers accessing the power grid in 2008. For Western Inner Mongolia, the average price of purchasing electricity has grown 27.736% in 2009 compared with that in 2007. For Eastern Inner Mongolia, the average price of purchasing electricity has grown 14.337% in 2009 compared with that in 2007. Large-scale wind powers accessing the power grid will have a huge impact on the average price of purchasing electricity for Inner Mongolia grid, especially larger on that in Western Inner Mongolia. 3.2. Purchasing electricity cost for grid To promote renewable energy development and power generation, relevant policies require that wind power should access to grid, and this will lead to the utilization hours of thermal power declining and the cost of grid purchasing electricity increasing. The purchasing electricity cost for grid can be calculated by formula (7). CP = pg • Qg
（7）
40
Gaoqiang Zhao et al. / Systems Engineering Procedia 3 (2012) 36 – 41
Where CP represents the purchasing electricity cost for grid, Yuan; pg represents the purchasing electricity price per unit, Yuan/KWh; Qg represents electricity purchasing, KWh. Consider that power Grid Corporation doesn’t acquire wind power, and the power generation of wind power replaces by that of thermal power plant, and the price of thermal power per unit accessing the power grid equals to the average price of the power grid purchasing the thermal power generation. So, the purchasing electricity cost for grid caused by large-scale wind powers accessing the power grid can be calculated in formula (8). E1 = Qgw • pgw − Qgw • pgt = Qgw ( pgw − pgt )
（8）
where E1 represents the increased purchasing electricity cost for grid, Yuan; Qgw represents the purchasing wind power generation, KWh; pgw represents the purchasing wind power price per unit, Yuan/KWh; pgt represents the purchasing thermal power price per unit, Yuan/KWh. The purchasing wind power price per unit of Inner Mongolia Grid Corporation is represented by the western Inner Mongolia benchmark price of thermal power with desulfurization in 2008, i.e. 0.2749 Yuan/KWh; the purchasing thermal power price per unit is represented by the purchasing electricity price per unit of Inner Mongolia Grid Corporation in 2008, i.e. 0.2659 Yuan/KWh; the purchasing wind power generation amounted to 3.74 billion KWh. According to formula (8), we can get E1 = Qgw ( pgw − pgt ) = 37.4 × (0.2749 − 0.2659) = 33.66(million Yuan)
Gaoqiang Zhao et al. / Systems Engineering Procedia 3 (2012) 36 – 41
From above, large-scale wind powers accessing the power grid will have a huge impact on the purchasing electricity cost for Inner Mongolia grid which amounted to 33.66 million Yuan in 2008. 4. Conclusion This paper quantitatively analyses the impact of large-scale wind power accessing the power grid on Inner Mongolia grid from two aspects which are ancillary facilities of wind power project accessing to power grid and the average price and cost of purchasing electricity for Inner Mongolia Grid Corporation, and some conclusions can be drawn in the following: • From the aspect of ancillary facilities of wind power project accessing to power grid, the grid construction cost will increasingly grow with large-scale wind power accessing the power grid. When the average investment recovery period changes from 10 to 30, the increased cost of power grid construction caused by large-scale wind power accessing the power grid will decrease from 11.9533 ×109 Yuan to 4.3527 ×109 Yuan, correspondingly. • From the aspect of average price and cost of purchasing electricity for grid, large-scale wind powers accessing the power grid will have a huge impact on the average price of purchasing electricity for Inner Mongolia grid, especially larger on that in Western Inner Mongolia. Large-scale wind powers accessing the power grid also increases the purchasing electricity cost for Inner Mongolia grid which amounted to 33.66 million Yuan in 2008. Acknowledgements The authors want to gratefully acknowledge the helpful comments and suggestions of the reviewers and the colleagues and students of North China Electric Power University for the measurements of this paper. References [1] E. Troncoso, M. Newborough. Solar and wind resource complementarity: Advancing options for renewable electricity integration in Ontario, Canada. Applied Energy 2011;87:1-15. [2] Vladislav Akhmatov. System stability of large wind power networks: A Danish study case. International Journal of Electrical Power & Energy Systems 2006;28:48-57. [3] Zengqiang Mi, Haifeng Tian, Yang Yu, et al. Study on voltage stability of power grid with large scale wind farm interconnected. In: 2009 International Conference on Sustainable Power Generation and Supply.2009:1-6. [4] Chen, Z., Spooner, E.. Grid power quality with variable speed wind turbines. IEEE Transactions on Energy Conversion 2001;16:148-154. [5] Jennifer DeCesaro, Kevin Porter, Michael Milligan. Wind energy and power system operations: A review of wind integration studies to date. The Electricity Journal 2009;22:34-43. [6] Yuan, J.D., Yuan, T. J. and Yao, Q. Study of generation expansion planning of the power system incorporating large-scale wind power in the environment of electricity market, Power System Protection and Control 2011;39:22-26. (In Chinese).
41
Systems Engineering Procedia
Systems Engineering Procedia 00 (2011) 000–000
Systems Engineering Procedia 3 (2012) 36 – 41
www.elsevier.com/locate/procedia
The 2nd International Conference on Complexity Science & Information Engineering
Analysis on the impact of large-scale wind power accessing the power grid on Inner Mongolia grid Gaoqiang Zhao, Jianxun Qi, Sen Guo a* North China Electric Power University, Changping District, Beijing 102206, China
Abstract With the adjustment of energy structure and the development of wind power accessing the power grid in China, largescale wind power will certainly have a significant impact on the power grid. For the large-scale wind power accessing the power grid in Inner Mongolia, a quantitative study has been done from two aspects which are ancillary facilities of wind power project accessing to power grid and the average price and cost of purchasing electricity for power Grid Corporation. The result shows: firstly, large-scale wind power accessing the power grid will not only increase the transmission line, but also increases the grid construction cost; secondly, large-scale wind power accessing the power grid will increase the average price and cost of purchasing electricity for power Grid Corporation. The analysis on the impact of large-scale wind power accessing the power grid on Inner Mongolia grid can provide some references for policy-makers and researchers.
©©2011 Elsevier Ltd. Ltd.Selection Selectionand andpeer-review peer-review under responsibility of Desheng Dash 2011Published Published by by Elsevier under responsibility of Desheng Dash Wu Wu. Keywords: wind power engineering; power grid; Ancillary facilities; Inner Mongolia grid
1. Introduction In recent years, with the shortage of energy supply and the adjustment of energy structure in China, renewable energy is developing rapidly. As a kind of renewable energy, wind power has the potential of large-scale commercial development with the advantage of huge reserves and mature technology. At the end of the year 2010, the new installed capacity of wind power in China has reached to 16 million kW, and the cumulative installed capacity has reached to 41.827 million kW. The installed capacity of wind power in China is the largest one in the world after surpassing the installed capacity of United States in 2010. Inner Mongolia locates in the northern border of China where wind energy resource is rich. Large wind farms that can be developed mainly locate in rich areas of wind energy resource, including the cities of Alashan, Bayannur, Baotou, Wulanchabu, XilinGol and Chifeng, where the average wind speed reaches to 5.0~6.5m/s and the reserve of wind energy resource amounts to 732 million kW. Inner Mongolia power grid is managed by Inner Mongolia Electric Power Company. The area of electricity supply contains the whole area of Inner Mongolia except Chifeng and Tongliao. Until to December 10, 2009, the installed
* Corresponding author. Tel.: +86 15811424568; fax: +86 10 80796904. E-mail address: [email protected].
2211-3819 © 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of Desheng Dash Wu. doi:10.1016/j.sepro.2011.11.005
Gaoqiang Zhao et al. / Systems Engineering Procedia 3 (2012) 36 – 41
capacity of wind power accessing the power grid had reached to 3.98 million kW, which accounted for 22 percentage of the maximum load of power generation. Until to December 10, 2009, the generation capacity of wind power amounted to 5.27 billion KWh. There are some researches on wind power accessing the power grid. Ref. [1] analyzed the integration of renewable power in Ontario (Canada), and found that the combination of solar and wind within locations and amongst two locations produces less variability in power production than when each resource is produced on its own. Ref. [2] described the considerations and the results of the investigation on short-term voltage stability carried out on a large wind power network model that is similar to a part of the Danish power grid, and a distinction was made between local wind turbines that may trip and those in a large wind farm subject to the Grid Specifications of the transmission system operator (TSO) that must ride through the grid faults. Based on an actual regional power grid in China, Ref. [3] presented a detailed simulation analysis of the impact of large scale wind farm on voltage stability (dynamic voltage stability) of power system under a short-circuit fault performed by PSCAD/EMTDC, and factors influencing voltage stability of the local grid interconnected with the wind farm were also analyzed. Appropriate modeling and simulation techniques were discussed for studying the voltage fluctuation and harmonic distortion in a network to which variable speed wind turbines are connected in Ref. [4], and the result showed the voltage fluctuation and harmonic problems can be minimized with the proposed power electronics interface and control system while the wind energy conversion system captures the maximum power from the wind as wind speed varies. Ref. [5] showed that wind integration required significant changes in grid planning and operations, continued technical evolution in the design and operation of wind turbines, further adoption and implementation of wind forecasting in the control room, and incorporation of market and policy initiatives to encourage more flexible generation. Ref. [6] studied the generation expansion planning of the power system incorporating large-scale wind power in the environment of electricity market, also proposed the concept of the environment-friendly coefficient and established the environment benefits model of the units. This paper takes Inner Mongolia grid for example, and analyzes quantitatively the impact of large-scale wind power accessing the power grid from two aspects which are ancillary facilities of wind power project accessing to power grid and the average price and cost of purchasing electricity for power Grid Corporation. 2. Ancillary facilities of wind power project accessing to power grid 2.1. Transformation equipment and transmission line In the year of 2009, Inner Mongolia grid put a 500KV substation into operation, namely, Qianlishan substation, and expanded three substations. At this year, Inner Mongolia grid also put two 220KV substations into operation, and expanded four substations. Inner Mongolia grid added to transformer capacity of 4110MVA.To the end of 2009, Inner Mongolia grid build two 500KV lines, and the new line length added to 162.395KM with the growth rate of 4.9%; build thirty-six 220KV lines, and the new line length added to 1311.458KM with the growth rate of 13.38%. At that year, the large-scale wind power accessing the power grid in Inner Mongolia increased the length of transmission line by 625.864 km. The large-scale wind power accessing the power grid will certainly increase the length of transmission line. 2.2. Power grid construction cost Large-scale wind power accessing the power grid will promote the power grid construction, and the cost of power grid construction will surely increase. Taking the wind power project as representative, the increased cost of power grid construction caused by large-scale wind power accessing the power grid can be calculated in the following.
37
38
Gaoqiang Zhao et al. / Systems Engineering Procedia 3 (2012) 36 – 41
The power grid corporation recovers the construction funds by way of acquiring wind power farm. The profit of Power Grid Corporation acquiring wind power farm can be calculated in formula (1). Yw = Rw − CPw = ps × Qsw − pw × Q pw
（1）
Suppose: = Qsw Q pw (1 − r )
= Yw Q pw [ ps (1 − r ) − pw ]
（2） （3）
where r represents the average line loss rate; Yw represents the profit of power grid corporation acquiring wind power farm; Rw represents the profit of power grid corporation selling wind power; CPw represents the cost of power grid corporation acquiring wind power farm; ps represents the sales price per unit; Qsw represents the selling wind power of power grid corporation; pw represents the electricity price into grid of wind power per unit; Q pw represents the purchasing wind power of power grid corporation. Suppose that the construction fund recovered by the power grid corporation equals for each year. The recovering cost of the power grid corporation for each year consists of two parts: one is the annually equal recovering cost converted by one-time construction investment, including construction cost, equipment cost, and project management cost; another is annual producing maintenance cost, including salary and additional salary cost, equipment operating cost and operating cost. According to the calculation method of matching annual funding, we can get formula (4).
D = P ( A / P, i, n) − F ( A / F , i, n)
（4）
where D represents the expected investment recovery cost; P represents construction investment costs; F represents the residual value; ( A / P, i, n) represents the recovery coefficient of equal allotment capital; ( A / F , i, n) represents the recovery coefficient of equal allotment sinking fund, n is the recovery period, i represents the interest rate. According to formula (3) and (4), the increased cost of power grid construction caused by large-scale wind power accessing the power grid can be calculated in formula (5). E2 = D + C − Yw = P( A / P, i, n) − F ( A / F , i, n) + C − Q pw [ p s(1 − r ) − pw ]
（5）
where C represents the producing maintenance cost. Until to the year of 2008, the project investment for wind power accessing power grid and ancillary facilities accessing to power grid nearly cost 40 billion Yuan in China, and the capacity of wind power accessing to power grid amounted to 16 million kW. For Inner Mongolia, the capacity of wind power accessing to power grid amounted to 3.74 million kW, and the power generation amounted to 3.74 billion KWh. By analogy, the project investment for wind power accessing power grid and ancillary facilities accessing to power grid nearly cost 9.35 billion Yuan in Inner Mongolia. In the year of 2008, the average line loss rate of Inner Mongolia grid was 4.97%. According to the benchmark price of thermal power with desulfurization, the wind power price purchased by Inner Mongolia grid was 0.2749 Yuan, and the selling price per unit was 0.3578 Yuan. If not consider the residual value and producing maintenance cost, we can get formula (6). （6） E2 = D − Yw = P(a / p )in − Q pw[ ps (1 − r ) − pw ] The increased cost of power grid construction caused by large-scale wind power accessing the power grid is related with the average investment recovery period. When the interest rate is 6%, and the average investment recovery period equals to 10, 15, 20, 25, 30, respectively, we can calculate the increased cost
39
Gaoqiang Zhao et al. / Systems Engineering Procedia 3 (2012) 36 – 41
of power grid construction caused by large-scale wind power accessing the power grid, just as shown in Table.1. Table.1. Grid construction cost under different investment recovery period Average investment recovery period(Year)
10
15
20
25
30
( A / P, i , n)
0.1359
0.1030
0.0872
0.0782
0.0726
D （109 Yuan）
14.3897
9.6305
8.1532
7.3117
6.7881
9
YW （10 Yuan）
2.4364
2.4354
2.4354
2.4354
2.4354
9 E2 （10 Yuan）
11.9533
7.1951
5.7178
4.8763
4.3527
From Table.1, we can see that the grid construction cost will increasingly grow with large-scale wind power accessing the power grid. When the average investment recovery period changes from 10 to 30, the increased cost of power grid construction caused by large-scale wind power accessing the power grid will decrease from 11.9533 ×109 Yuan to 4.3527 ×109 Yuan, correspondingly. 3. Average price and cost of purchasing electricity for grid 3.1. Average price of purchasing electricity for grid In the year of 2008, there are a lot of large-scale wind powers accessing the power grid in Inner Mongolia. The average prices of purchasing electricity for Inner Mongolia grid from the year of 2007 to 2009 are shown in Table.2. Table.2. The average prices of purchasing electricity for Inner Mongolia grid Year
Region
Average price of
Growth rate
2007
Western Inner Mongolia Eastern Inner Mongolia
292.25
0.35
2008
Western Inner Mongolia
322.10
22.58
Eastern Inner Mongolia
313.95
7.43
2009
Western Inner Mongolia
335.64
5.24
Eastern Inner Mongolia
334.15
6.43
purchasing electricity
（%）
262.76
2.63
As shown in Table.2, the average price of purchasing electricity for Inner Mongolia grid has increased significantly from 2007 to 2009 with large-scale wind powers accessing the power grid in 2008. For Western Inner Mongolia, the average price of purchasing electricity has grown 27.736% in 2009 compared with that in 2007. For Eastern Inner Mongolia, the average price of purchasing electricity has grown 14.337% in 2009 compared with that in 2007. Large-scale wind powers accessing the power grid will have a huge impact on the average price of purchasing electricity for Inner Mongolia grid, especially larger on that in Western Inner Mongolia. 3.2. Purchasing electricity cost for grid To promote renewable energy development and power generation, relevant policies require that wind power should access to grid, and this will lead to the utilization hours of thermal power declining and the cost of grid purchasing electricity increasing. The purchasing electricity cost for grid can be calculated by formula (7). CP = pg • Qg
（7）
40
Gaoqiang Zhao et al. / Systems Engineering Procedia 3 (2012) 36 – 41
Where CP represents the purchasing electricity cost for grid, Yuan; pg represents the purchasing electricity price per unit, Yuan/KWh; Qg represents electricity purchasing, KWh. Consider that power Grid Corporation doesn’t acquire wind power, and the power generation of wind power replaces by that of thermal power plant, and the price of thermal power per unit accessing the power grid equals to the average price of the power grid purchasing the thermal power generation. So, the purchasing electricity cost for grid caused by large-scale wind powers accessing the power grid can be calculated in formula (8). E1 = Qgw • pgw − Qgw • pgt = Qgw ( pgw − pgt )
（8）
where E1 represents the increased purchasing electricity cost for grid, Yuan; Qgw represents the purchasing wind power generation, KWh; pgw represents the purchasing wind power price per unit, Yuan/KWh; pgt represents the purchasing thermal power price per unit, Yuan/KWh. The purchasing wind power price per unit of Inner Mongolia Grid Corporation is represented by the western Inner Mongolia benchmark price of thermal power with desulfurization in 2008, i.e. 0.2749 Yuan/KWh; the purchasing thermal power price per unit is represented by the purchasing electricity price per unit of Inner Mongolia Grid Corporation in 2008, i.e. 0.2659 Yuan/KWh; the purchasing wind power generation amounted to 3.74 billion KWh. According to formula (8), we can get E1 = Qgw ( pgw − pgt ) = 37.4 × (0.2749 − 0.2659) = 33.66(million Yuan)
Gaoqiang Zhao et al. / Systems Engineering Procedia 3 (2012) 36 – 41
From above, large-scale wind powers accessing the power grid will have a huge impact on the purchasing electricity cost for Inner Mongolia grid which amounted to 33.66 million Yuan in 2008. 4. Conclusion This paper quantitatively analyses the impact of large-scale wind power accessing the power grid on Inner Mongolia grid from two aspects which are ancillary facilities of wind power project accessing to power grid and the average price and cost of purchasing electricity for Inner Mongolia Grid Corporation, and some conclusions can be drawn in the following: • From the aspect of ancillary facilities of wind power project accessing to power grid, the grid construction cost will increasingly grow with large-scale wind power accessing the power grid. When the average investment recovery period changes from 10 to 30, the increased cost of power grid construction caused by large-scale wind power accessing the power grid will decrease from 11.9533 ×109 Yuan to 4.3527 ×109 Yuan, correspondingly. • From the aspect of average price and cost of purchasing electricity for grid, large-scale wind powers accessing the power grid will have a huge impact on the average price of purchasing electricity for Inner Mongolia grid, especially larger on that in Western Inner Mongolia. Large-scale wind powers accessing the power grid also increases the purchasing electricity cost for Inner Mongolia grid which amounted to 33.66 million Yuan in 2008. Acknowledgements The authors want to gratefully acknowledge the helpful comments and suggestions of the reviewers and the colleagues and students of North China Electric Power University for the measurements of this paper. References [1] E. Troncoso, M. Newborough. Solar and wind resource complementarity: Advancing options for renewable electricity integration in Ontario, Canada. Applied Energy 2011;87:1-15. [2] Vladislav Akhmatov. System stability of large wind power networks: A Danish study case. International Journal of Electrical Power & Energy Systems 2006;28:48-57. [3] Zengqiang Mi, Haifeng Tian, Yang Yu, et al. Study on voltage stability of power grid with large scale wind farm interconnected. In: 2009 International Conference on Sustainable Power Generation and Supply.2009:1-6. [4] Chen, Z., Spooner, E.. Grid power quality with variable speed wind turbines. IEEE Transactions on Energy Conversion 2001;16:148-154. [5] Jennifer DeCesaro, Kevin Porter, Michael Milligan. Wind energy and power system operations: A review of wind integration studies to date. The Electricity Journal 2009;22:34-43. [6] Yuan, J.D., Yuan, T. J. and Yao, Q. Study of generation expansion planning of the power system incorporating large-scale wind power in the environment of electricity market, Power System Protection and Control 2011;39:22-26. (In Chinese).
41