A WAMS based adaptive load shedding control strategy using a novel index of transient voltage stability

Frequency stability and voltage stability have mutual influence on each other. Conventional load shedding control strategies generally apply Underfrequency Load Shedding (UFLS) and Undervoltage Load Shedding (UVLS) respectively without considering time-space distribution characters of voltages and dynamics of induction motors. Based on the two-node model of the power system, this paper analyses the influence of induction motors´ slip on both the voltage stability and the load stability, thus presenting a novel comprehensive R-index composed of slip increment and voltage drop to measure the voltage instability degree effectively. Based on Wide Area Measurement System (WAMS), this paper provides a new adaptive load shedding control strategy by using the novel R-index to decide locations and the amount of load shedding. Moreover, the new control strategy provides two load shedding schemes which activate at all nodes or selected partial nodes, respectively. The effectiveness and superiority of the control strategy, compared with the conventional one´s, are verified by simulations on the IEEE 39-bus system.