考虑负荷频率刚性特征的一种新型低频减载实现方案

A novel under-frequency load-shedding implementation scheme considering load frequency-rigidity characteristics

电力负荷的多样性及组合的复杂性决定了难以用微观的具体模型去描述其特征,但是事物的特征一般却可宏观定性描述。提出了一种基于负荷宏观频率刚性的新型低频减载实现方案。该策略在负荷频率调节效应检测的基础上辨识出负荷的频率刚性大小,并基于此实现低频减载的策略优化。在系统出现功率缺额、频率持续降低时,应优先切除频率调节效应系数小、频率刚性强的负荷,而保留频率调节效应系数大的负荷。如此,在频率继续下降时,通过负荷自身的频率调节效应,可减少从系统吸收的功率;而在频率恢复阶段,频率在不断上升恢复时,优先减载频率调节效应系数大、频率刚性弱的负荷,而保留频率调节效应系数小的负荷。通过此减载方案可尽可能减少负荷的损失,同时充分利用负荷的频率调节效应实现系统频率的恢复,尽可能防止系统频率崩溃的发生。

Practice shows that the diversity and complexity of the load make it difficult to describe the load characteristics by using any detailed models, however, they can be described macroseopically. A novel under-frequency loadshedding （UFLS） strategy considering macro-frequency rigidity of the load is proposed. Based on the frequency regulation effects, the strategy identifies the frequency rigidity of loads and optimizes the UFLA strategy. When the system frequency decreases continuously due to lack of active power, the loads with lower frequency regulation effect coefficients and large frequeney rigidity should be shed firstly, which will reduce the active power drawn from the system thanks to the frequency regulation effect of the loads as the frequency continues to decrease. During the restoration period, the loads with higher frequency regulation effect coefficients and small frequency rigidity ought to be shed firstly. In this way, the load loss can be minimized, and the frequency regulation effect coefficient of the load can be fully used to restore system frequency and prevent frequency collapse.