考虑发电机励磁电流限制的改进连续潮流算法

An Improved Continuation Power Flow Algorithm Considering Generator Excitation Current Limit

连续潮流法是静态电压稳定分析中强有力的方法和工具。常规的连续潮流程序中,使用发电机无功出力最大值Qmax近似表征其无功出力限制。在实际系统中,发电机的无功出力受制于励磁电流的调节能力。从稳态角度出发,提出了使用发电机内电势Eq近似表征无功出力限制的处理方法,建立了考虑励磁电流限制的静态电压稳定分析模型,并提出改进的连续潮流算法。该算法在考虑发电机无功出力最大值Qmax的基础上,将无功出力达到最大值的节点视为有功、内电势恒定(P-Eq)节点。该节点根据有功出力、功角值以及机端电压对校正环节中的无功出力进行修正,更好地模拟了发电机在励磁电流限制下的无功特性。IEEE-30节点系统仿真结果证明了该方法的可行性和实用性。

Continuation power flow （CPF） is a powerful analytical method and tool in static voltage stability analysis. In conventional CPF programs the maximum of reactive power output of generator is utilized to characterize the limit of its reactive power output. In actual power systems, reactive power output of generator is enslaved to the regulating ability of excitation current. In the viewpoint of steady state, a method to approximately characterize the generator reactive power output limit by generator internal EMF is proposed and a static voltage stability analysis model, in which the limit of excitation current is taken into account, is built, and an improved CPF algorithm is put forward. On the basis of considering the maximum of reactive power output of generator, the proposed improved algorithm regards the node, where the reactive power output reaches its maximum, as the node with constant active power and internal EMF. At this node, according to active power output, angle value and terminal voltage of generator the reactive power output is modified by correction step in the improved algorithm, thus the reactive power characteristic of generator under the excitation current limit can be simulated better. Simulation results of IEEE 30-bus system show that the proposed method is feasible and practicable.