协调经济性及事故评级的紧急减负荷控制优化方法

Coordinated Emergency Load Shedding Control Optimization Algorithm for Economic Cost and Accident Assessment

系统失去大功率电源后,要保持暂态稳定并过渡到新的稳态运行点,此时有可能需要补充一定量的减负荷控制,以消除断面超供、备用不足、频率偏低等问题。为降低减负荷控制的经济代价,同时使各负荷中心事故评级尽量均衡,提出了协调经济性及事故评级的紧急减负荷控制优化方法。首先,进行计及电网频率变化的增广潮流计算,并据此分析减负荷控制对系统静态运行点、频率及备用水平的影响;接着,以归一化的经济代价及减负荷率均衡性指标的加权和为目标函数,在考虑电压、支路潮流、频率偏移等约束的基础上,构建紧急减负荷控制优化问题的数学模型;然后,引入罚函数,将其转化为仅含潮流等式约束的优化问题,并应用改进粒子群算法求出最优减负荷率;最后,以IEEE 10机39节点系统为例,分析了失去大功率电源后受端系统的减负荷协调优化控制。结果表明,与常见的最小经济代价及等切负荷率控制方案相比,协调优化控制不仅经济代价较小,且事故评级相对均衡,具有较好的综合性能。

If system remains transiently stable and transits to a new steady state after loss of bulk power source, supplemented load shedding may be needed to eliminate tie line overload, reserve deficiency or low frequency. To reduce economic cost and balance accident assessments of different load centers, a coordinated emergency load shedding optimization algorithm for economic cost and accident assessment was proposed in this paper. Firstly, frequency deviation and system reserve were studied through augmented power flow calculation. Then, weighted sum of normalized economy cost and balance index was taken as objective function. Emergency load shedding optimization problem was modeled with constraints of voltage, tie line power flow and system frequency taken into account. Penalty functions were introduced to transfer it to an optimization problem with only augmented power flow equation constrains. Improved particle swarm optimization algorithm was utilized to solve optimized load shedding ratio of each load. Finally, this algorithm was applied in IEEE 10-generator 39-bus test system. When a bulk power source was lost, the coordinated load emergency control scheme was designed for receiving end system. In comparison with minimum cost and equal load shedding ratios control schemes, the results showed that the coordinated control strategy can reach compromise between economic cost and balance of accident assessments with good performance.