Optimal Dispatch for Smooth Voltage Fluctuation of EHV and UHV Power Grid During Geomagnetic Storms Based on Magnetohydrodynamics Model and Model Predictive Control Method
Xin Wenkai1, Wang Zezhong1, Liu Chunming2, Wang Guyue1
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 storms originate from the geomagnetic disturbances (GMD) caused by the intense solar activity, and the GMD will induce geomagnetic induction currents (GIC) when it is applied to the grid. As the geomagnetic storms caused by solar activity occur almost at the same time around the world, the reactive power disturbance caused by geomagnetic storms has the characteristics of sudden and mass occurrence in the whole grid. The extra-high voltage (EHV) and the ultra-high voltage (UHV) power grids are more vulnerable to geomagnetic storms due to their special electrical characteristics, which can cause voltage fluctuations in the whole grid and even lead to voltage collapse and catastrophic consequences of large-scale power outages. The traditional methods generally use the method of connecting resistors or capacitors in series at the neutral point of the transformer, but these methods are not fully adapted to smoothing the voltage fluctuations of the grid. In recent years, with the development of theories related to geophysics and space weather, the three-dimensional magnetohydrodynamics (MHD) model has been able to predict the GMD of geomagnetic storms more accurately. This paper proposes an optimal dispatch based on the MHD model to smooth out voltage fluctuations in EHV and UHV grids during geomagnetic storms. The EHV and UHV grids achieve voltage control by adjusting the injected power from the EHV grids to the UHV grids. In this paper, the sequence of injected power change amount of controllable pilot nodes is calculated from the voltage-power sensitivity factor. To cope with the adverse effects caused by forecast errors, rolling optimization is performed in certain steps, and only control commands for the current optimization period are sent each time, instead of all periods. And comparing the difference between the phasor measurement unit (PMU) measured reactive power increment and the historical predicted value, and correcting the predicted value of the MHD model in the current optimization period. By this way, a feedback mechanism is formed through rolling optimization and feedback correction to improve the effectiveness of optimal dispatch. Compared with traditional methods, the proposed method is safer and more economical as no new equipment is required. Through the simulation analysis and verification of the Eastern China EHV and UHV power grids, the following conclusions are obtained: (1)The proposed optimal dispatch scheduling coordinates the active and reactive resources in the EHV and UHV grids, effectively suppressing voltage fluctuations during geomagnetic storms, reducing the severity of voltage fluctuations and smoothing the trend of voltage fluctuations. (2)At the time of geomagnetic storm sudden commencement (SSC), the sudden and mass reactive disturbances tend to exceed the substation reactive power margin causing reactive power imbalance and voltage dip. By reducing active power injection, the system voltage stability can be improved and secondary disasters of geomagnetic storm such as voltage collapse can be prevented. (3)The nodes at the corners or ends of the grid topology are the "weak points" of reactive power imbalance, and the reactive power reserves at these substations should be increased appropriately in the planning and design stage to improve the grid's ability to cope with geomagnetic storms.
辛文凯, 王泽忠, 刘春明, 王古玥. 基于磁流体力学模型与模型预测控制的地磁暴期间超高压、特高压电网电压波动平抑优化调度[J]. 电工技术学报, 2024, 39(13): 4003-4014.
Xin Wenkai, Wang Zezhong, Liu Chunming, Wang Guyue. Optimal Dispatch for Smooth Voltage Fluctuation of EHV and UHV Power Grid During Geomagnetic Storms Based on Magnetohydrodynamics Model and Model Predictive Control Method. Transactions of China Electrotechnical Society, 2024, 39(13): 4003-4014.
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2024, Vol. 39 
