考虑负荷特性的解列后受端电网频率控制策略

Frequency Control Strategy After Receiving-End Power Grid Splitting Considering Load Characteristics

当大规模互联系统发生主动解列后,受端电网将出现有功功率不足、频率大幅下降的问题,需要采取切负荷措施保证受端电网的频率稳定。首先,建立了以最小切负荷代价为目标,综合考虑暂态功角稳定约束、节点电压约束、频率稳定约束、负荷电压-频率特性以及调速器一次调频作用,制定紧急控制策略的数学模型。其次,由电网主动解列的特征,简化模型中的大规模微分方程组约束,将解列后局部电网中同调运行的发电机等值为惯性中心系下的一台发电机,从而降低模型的复杂度,极大地提升了求解速度。最后,基于隐式梯形法将微分方程约束差分化并采用内点法求解最优频率控制方案。以IEEE9节点算例、广东电网实际数据计算频率控制策略,并在PSD-BPA中对该控制方案进行仿真验证。仿真结果表明,所得频率控制策略不仅能保证主动解列后受端电网的频率电压稳定,还可以提高紧急控制方案的经济性,验证了所提频率控制模型的有效性。

After active splitting of large-scale interconnected power system,unbalanced power in receiving-end local power grid might arise,resulting in decrease of frequency.Load shedding measure should be taken to ensure stability of local power grid.Firstly,an optimal frequency control model is proposed,considering constraints of transient angle stability,frequency stability and nodal voltage,and voltage and frequency characteristic of load and generator’s primary frequency regulation effect.Then,equivalent generator under inertia center is built and the large-scale differential algebraic equation constraints are simplified.Complexity in solving the problem is thus reduced.Therefore,model solving speed is improved significantly.Differential constraints are differenced with implicit trapezoidal integration method,and the optimization model is solved with interior point method.Finally,frequency stability control strategy of IEEE case 9 and Guangdong power grid is calculated.The load shedding scheme is verified in PSD-BPA.Simulation results show that frequency and voltage stability of the receiving-end local power grid is ensured after active splitting of the power system.Besides,economic efficiency of the control scheme is improved.Validity of the proposed optimization model is thus confirmed.