Multi-objective Coordinated Control Of Reactive Compensation Devices Among Multiple Substations

Reactive power compensation device can provide strong voltage support for along-distance transmission system. Different to the separate compensation control mode usedwidely in500kV transformer substations currently, the multi-objective reactive powercoordination control model was presented in this paper to overcome the drawback thatreactive power compensation devices lack coordination and have high active power loss. Inthis model, the minimum bus voltage deviation and total loss of reactive power compensationdevices were taken as objective functions by bringing the lower-voltage reactors andcapacitors into the SVC control system and considering the reactive power compensationdevices interaction between different transformer substations.The reactive power coordinated control was actually a multi-objective mixed-integernonlinear programming problem，the difficulty lay in how to deal with the discrete controlvariables and how to find uniformly distributedpareto front.Due to the different sensitivity ofcontrol variables in control model and lack of the local search ability, control variablesweredivided into sensitive variables and non-sensitive variables, and then, the improved NSGA-IIalgorithm with secondary search ability waspresented and applied to solve the two-stationmulti-objective reactive power coordinated control model. In addition, In order topreferablysolve more stations reactive power coordinated control model, with bigger variabledimensions and slower convergence, this paper proposed a hybrid algorithm with paralleltechnology, by combining the NSGA-II algorithm, NBI method and GAMS software. Themethod combining the characteristics of the rapidity and reliability of NBI-GAMS method,and the advantages of NSGA-II algorithm’s dealing with discrete variables.The improved NSGA-II algorithm and the hybrid algorithm were applied in a largepower grid. The superiority ofmodel and algorithm was validatedfrom quality ofPareto front,coordinated control effect and comparison with otheralgorithms. The analysis results showthat the improved NSGA-II algorithm can effectively solve the two-station reactive powercoordinated control problem by reducing the total loss of devicesand voltage deviation. Formore stations, the hybrid algorithm with multi-agent parallel technology can quicklyfound thePareto front with uniform distribution and better distribution range. The comparison ofdifferent models and the algorithm performance analysis also verify the effectiveness of thereactive power coordinated control model andhybrid algorithmproposed in this paper.