Optimization And Effect Evaluation Of Geomagnetically Induced Current Suppression Measures

Geomagnetically induced current(GIC)caused by geomagnetic storms poses a threat to the stable operation of power grids.Aiming at the problems of traditional schemes and the unity of effect evaluation indicators,optimization algorithm is used to optimize the configuration schemes and evaluation indicators based on transient processes are proposed to evaluate its suppression effect.The main research contents of this paper are as follows:Taking the GIC-Benchmark test case as an example,the GICs of the grid under uniform electric fields of different amplitudes are modeled and calculated.The allowable direct current limits of each substation are calculated and determined.Using the grid GIC values and the direct current limits to determining the layout of the traditional schemes and the constraint conditions of the optimization algorithm.According to the GI C of each substation,four traditional layout schemes are determined,and the suppression effect and the problems of the capacitor device and the resistance device on the GIC is analyzed.It is necessary to use an optimization algorithm to optimize the installation method of the suppression measures.Taking the GIC of the neutral point of each substation is lower than the limit as the constraint condition,the minimum number of suppression devices and the minimum total GICs of the entire network as the objective functions.The shortcomings of the ordinary multi-objective discrete particle swarm optimization(MODPSO)are analyzed.By modifying the inertia weight,the improved MODPSO algorithm is used to optimize the configuration of the suppression measures.The resistance schemes and the resistance-capacitance hybrid schemes are considered respectively.The results show that under the same electric field strength,the suppression effect of the latter is better than the former.The dynamic simulation model of the GIC-Benchmark test case is established on the Powerworld Simulator platform.The change laws of the reactive power output of the generators and the bus voltage in the power grid under the action of the changing electric field arc studied.And four evaluation indicators based on the transient responsc are proposed,making use of the generator reactive power output,bus voltage offset,voltage transient drop duration and the GIC work of transformer winding branchs jointly evaluate the effect ot the optimization measures.The results show that the use of the resistance optimization scheme and the resistance-capacitance hybrid optimization scheme based on the improved MODPSO algorithm can improve the transient process caused by the GIC disturbance to a certain extent,reduce the reactive power output of the generator,increase the voltage level,shorten the transient state process time and reduce the GIC work.The effectiveness of the two optimization schemes from a transient perspective are verified,and the comparison shows that the resistance-capacitance hybrid optimization scheme is more effective.