考虑无功控制特性的交直流电网双解耦潮流计算方法

Double-Decoupled Power Flow Calculation for AC/DC Hybrid Power System Considering Reactive Power Control Characteristics

直流换流站的无功控制策略直接影响交直流电网之间的无功功率交换和电压运行情况,而现有潮流计算方法由于忽略交直流电网之间的无功电压作用,导致计算结果的准确性较低。为此,提出一种考虑直流换流站无功控制特性的交直流电网双解耦潮流计算方法。首先对交直流系统进行功率解耦,交流系统潮流计算时将直流等效为恒功率节点,进而根据交流侧母线电压结果计算换流变压器的分接头;然后将交流系统潮流方程进行PQ解耦,建立包含直流无功控制策略、直流侧潮流方程以及交流系统无功功率约束的无功优化模型,采用内点法求解得到电网电压和直流控制变量的准确解;最后以4回直流接入下的江苏电网为例进行仿真计算,结果证明了所提算法的有效性。

The reactive power control characteristics, neglected by existed power flow methods, has an important influence on the reactive power exchange and the voltage characteristic of AC/DC hybrid power system. For the purpose of improving the accuracy of the power flow calculation, this paper proposed a double- decoupled method with HVDC reactive power control characteristics. At the beginning, AC and DC system are been decoupled, then AC power flow calculation is processed while HVDC systems are treated as constant power buses. Based on AC voltage results of HVDC converter station, transformers tap is got by corresponding formulas. In the next stage, reactive power optimal model, containing HVDC reactive power control strategy and AC grid reactive power balance equations, are established after decoupling the PQ balance equation of AC grid system. Interior point method is used to solve the above problem. In the end, Jiangsu power grid with 4 HVDC connected is tested by the double-decoupled power flow calculation algorithm and results shows the correctness.