Quantitative Evaluation Method of Voltage Stability of UHV AC Power Network under Geomagnetic Storm
Xin Wenkai1, Wang Zezhong1, Liu Chunming2, Li Yuyan1
1. Beijing Key Laboratory of High Voltage and EMC North China Electric Power University Beijing 102206 China; 2. School of Electrical and Electronic Engineering North China Electric Power University Beijing 102206 China
Abstract：Geomagnetic storm is a low probability and high risk natural disaster that threatens the security of power grid. During a geomagnetic storm, an induced electric field is generated on the ground surface. Under its action, geomagnetic induced currents will be generated in the circuit formed by the transmission line, the earth and the neutral point of the transformer. When GIC flows through the transformer, it will cause saturation of the core and consume a large amount of reactive power. This increase in reactive power loss (GIC-Q) is linear with GIC flowing through the neutral point of the transformer, which is usually calculated by the k-value method. GIC-Q will cause voltage fluctuation of the power grid. With the expansion of the scale of UHV AC power grid in China, geomagnetic storms are increasingly threatening the voltage stability of UHV AC power grid. In order to accurately evaluate the impact of geomagnetic storms on voltage stability of power systems, this paper establishes an analysis model applicable to the influence of reactive power disturbances derived during geomagnetic storms on voltage stability. Through equivalent transformation of lines, it is suitable for the analysis of voltage stability of multi input line nodes in multi voltage level power networks. Then, the voltage instability index LGIC is proposed through the voltage stability analysis model, which avoids the problems of difficult to accurately select the step size and complex calculation when calculating the voltage collapse point by the conventional continuous power flow method, and makes it easy to determine the weak point of voltage stability and the load margin when the power grid is attacked by geomagnetic storms.This index can indicate the distance between the current operating point and the voltage collapse point during land acquisition magnetic storm. The closer the LGIC is to 1, the closer the node operating point is to the voltage collapse point. This index has the advantages of less information, simple calculation, clear physical meaning and easy realization. To quantitatively evaluate the impact of geomagnetic storms on the voltage stability of the grid, first calculate the GIC value of each substation transformer based on the amplitude of the ground induced electric field when the geomagnetic storm occurs, and then substitute the calculated GIC value and electrical parameters into the GIC-Q voltage stability analysis model of the node. From the given operating state of the grid, the PV curve expression is obtained by mathematical theory analysis and the voltage collapse point is calculated. For UHV grid, the active load margin from the current operating point to the voltage collapse point reflects the capacity of the current grid to withstand load and fault disturbance and maintain voltage stability, and can be used as an index to judge the voltage stability to a certain extent. Since voltage collapse occurs at the node with the weakest voltage stability and then spreads to the whole grid, it is necessary to develop voltage instability indicators to measure the sensitivity of each node to geomagnetic storms, so as to quickly screen out weak points of voltage stability, give warning signals, and take pre disaster preventive measures to avoid large-scale power outages caused by voltage collapse.In order to prevent voltage drop or even voltage collapse caused by geomagnetic storm, it is necessary to take measures at the weak point of voltage to reduce the LGIC of this node. On the one hand, the load active power and equivalent line length at this point can be changed by transferring load and increasing the number of parallel UHV lines to reduce the LGIC value. On the other hand, measures such as capacitor isolation and resistance isolation at the neutral point of the transformer can be taken to adjust the GIC flow path to reduce the impact of geomagnetic storms on voltage stability, but this method needs to consider the increase of LGIC value in other substations caused by the change of GIC flow path.
辛文凯, 王泽忠, 刘春明, 李宇妍. 地磁暴影响下特高压交流电网电压稳定性量化评估方法[J]. 电工技术学报, 2023, 38(21): 5771-5780.
Xin Wenkai, Wang Zezhong, Liu Chunming, Li Yuyan. Quantitative Evaluation Method of Voltage Stability of UHV AC Power Network under Geomagnetic Storm. Transactions of China Electrotechnical Society, 2023, 38(21): 5771-5780.
[1] 刘春明, 王红梅, 王璇. 多次磁暴下特高压电网GIC统计规律研究[J]. 中国电机工程学报, 2019, 39(15): 4606-4615. Liu Chunming, Wang Hongmei, Wang Xuan.Statistical analysis of geomagnetically induced currents in UHV power grids under multiple geomagnetic storms[J]. Proceedings of the CSEE, 2019, 39(15): 4606-4615. [2] Zanetti L J.Review of North American Electric Reliability Corporation (NERC) interim report: effects of geomagnetic disturbances on the bulk power system february 2012[J]. Space Weather the International Journal of Research & Applications, 2013, 11(1): 335-336. [3] Kappenman J G.Geomagnetic storms and their impact on power systems[J]. Power Engineering Review, 1996, 16(5): 5-10. [4] Wik M, Viljanen A, Pirjola R, et al.Calculation of geomagnetically induced currents in the 400 kV power grid in southern Sweden[J]. Space Weather-the International Journal of Research & Applications, 2008, 6(S07005): 1-11. [5] 李冰, 王泽忠, 刘恪, 等. 特高压变压器直流偏磁对绕组电流的影响[J]. 电工技术学报, 2020, 35(7): 1422-1431. Li Bing, Wang Zezhong, Liu Ke, et al.Research on winding current of UHV transformer under DC-bias[J]. Transactions of China Electrotechnical Society, 2020, 35(7): 1422-1431. [6] 王泽忠, 李明洋, 宣梦真, 等. 单相四柱式变压器直流偏磁下的温升试验及仿真分析[J]. 电工技术学报, 2021, 36(5): 1006-1013. Wang Zezhong, Li Mingyang, Xuan Mengzhen, et al.Temperature rise test and simulation of single- phase four-column transformer under DC-bias[J]. Transactions of China Electrotechnical Society, 2021, 36(5): 1006-1013. [7] 李冰, 王泽忠, 刘海波, 等. 直流偏磁下500 kV单相变压器振动噪声的试验研究[J]. 电工技术学报, 2021, 36(13): 2801-2811. Li Bing, WangZezhong, Liu Ke, et al. Research on winding current of UHV transformer under DC-bias[J]. Transactions of China Electrotechnical Society, 2021, 36(13): 2801-2811. [8] 刘连光, 秦晓培, 葛小宁. 基于U-I曲线的单相自耦变GIC无功损耗算法[J]. 电力自动化设备, 2015, 35(12):55-59. Liu Lianguang, Qin Xiaopei, Ge Xiaoning.GIC reactive power loss calculation based on U-I curve for single-phase autotransformer[J]. Electric Power Automation Equipment, 2015, 35(12): 55-59. [9] 刘连光, 钱晨, 朱溪, 等. 应用K值算法的甘肃电网GIC-Q扰动计算[J]. 电网技术, 2016, 40(8): 2370-2375. Liu Lianguang, Qian Chen, Zhu Xi, et al.Calculation of geomagnetically induced currents reactive power loss disturbance in Gansu grid with parameter K[J]. Power System Technology, 2016, 40(8): 2370-2375. [10] 刘连光, 钱晨, 秦晓培. 考虑500 kV影响的特高压电网GIC-Q扰动计算[J]. 中国科学: 技术科学, 2016, 46(11): 1146-1156. Liu Lianguang, Qian Chen, Qin Xiaopei.Calculation of geomagnetically induced currents reactive power loss disturbance in China’s UHV power grid considering the influence of 500 kV power grid[J]. Sci Sin Tech, 2016, 46(11): 1146-1156. [11] Gerin-Lajoie L, Haddadi A, Rezaei-Zare A, et al.Simultaneous DC and AC simulation of GMD impacts in a power systemin[C]//International Conference on Power Systems Transient(IPST), Perpignan, France, 2019: 1-6. [12] Shetye K S, Overbye T J.Parametric steady-state voltage stability assessment of power systems using benchmark scenarios of geomagnetic disturbances[C]// Power and Energy Conference at Illinois (PECI), Champaign, America, 2015: 1-7. [13] Risto Pirjola.Calculation of geomagnetically induced currents (GIC) in a high-voltage electric power transmission system and estimation of effects of overhead shield wires on GIC modeling[J]. Journal of Atmospheric and Solar-Terrestrial Physics, 2007, 69(12): 1305-1311. [14] 郑宽. 大电网地磁感应电流影响因素及建模方法研究[D]. 北京: 华北电力大学, 2014. [15] 刘春明. 中低纬电网地磁感应电流及其评估方法研究[D]. 北京: 华北电力大学, 2009. [16] 秦晓辉, 郭强, 周勤勇, 等. 一种无功平衡与临界潮流快速分析方法及其在特高压可控高抗需求分析中的应用[J]. 中国电机工程学报, 2013, 33(19): 14, 102-110. Qin Xiaohui, Guo Qiang, Zhou Qinyong, et al. Fast analysis method of reactive power balancing and critical power flow and application to study controllable shunt reactors requirement in UHV grid[J]. Proceedings of the CSEE, 2013, 33(19): 14, 102-110. [17] 王泽忠, 黄天超. 变压器地磁感应电流-无功功率动态关系分析[J]. 电工技术学报, 2021, 36(9): 1948-1955. Wang Zezhong, Huang Tianchao.Analysis of geomagnetically induction current-reactive power dynamic relationship of transformer[J]. Transactions of China Electrotechnical Society, 2021, 36(9): 1948-1955. [18] 刘连光, 朱溪, 王泽忠, 等. 基于K值法的单相四柱式特高压主体变的GIC-Q损耗计算[J]. 高电压技术, 2017, 43(7): 2340-2348. Liu Lianguang, Zhu Xi, Wang Zezhong, et al.Calculation for reactive power loss of single-phase four limbs UHV main transformer due to geom-agnetically induced currents with parameter K[J]. High Voltage Engineering, 2017, 43(7): 2340-2348. [19] Blake S P, Gallagher P T, McCauley J, et al. Geomagnetically induced currents in the Irish power network during geomagnetic storms[J]. Space Weather, 2016, 14(12): 1-48. [20] Viljanen Ari, Pirjola Risto.Influence of spatial variations of the geoelectric field on geomagnetically induced currents[J]. Journal of Space Weather and Space Climate, 2017, 7(A22): 1-10.
2023, Vol. 38 
