Research On Coordinated Secondary Voltage Control Algorithm Considering Reactive Power Coupling Among Multiple Zones

Secondary voltage control, which can maintain power system voltage level and enhancevoltage stability, is the most important part in AVC system. While most of secondary voltagecontrol algorithms do not consider reactive power coupling among controlled zones. However,with development of power system, reactive power interaction among control zones will beincreased and cannot be neglected any more. It is necessary to study a new method ofsecondary voltage control considering reactive interaction among control zones.To eliminate the reactive power coupling among controlled zones in coordinatedsecondary voltage control (CSVC), a novel CSVC method considering reactive powercoupling based on the centralized control structure of AVC system in China is proposed.Reactive regulations of controlled generators outside are introduced into objective andconstraints of the original quadratic model to establish a new CSVC model consideringreactive power coupling among multiple correlated zones. In this model, control strategies ofCSVC in all zones are interactive, and reactive regulation of controlled generators outside thezone is unknown, therefore this quadratic programming model cannot be solvedindependently. In order to solve this problem, the CSVC model considering reactive powercoupling among multiple correlated zones can be described as Cournot model according tonon-cooperative game theory. And the Nash equilibrium means the best control strategy inCSVC which can keep each controlled zone running independent and solve the coordinationproblem among zones well. Based on interior-point algorithm, the best response functions ofeach controlled zone are constructed, and the Nash equilibrium, the solution of Cournotmodel, can be found by an algorithm to solve all the best response functions.Computational results on IEEE39-bus and a real provincial power system illustrate thatcontrol oscillation caused by the reactive power coupling among zones is effectivelyattenuated, which proves that this new method can solve coordination problems amongcontrolled zones satisfactorily.