Inter-Area Oscillation Damping Control Design Considering Impact of Variable Latencies

It is ubiquitously accepted that system latency causes a serious problem in an oscillatory stability, especially when it involves with the centralized damping controllers using wide-area input signals. Previously, the latency was assumed to be constant in the centralized controller design and nonlinear time simulation. However, variable latencies, which vary area-to-area depending on the distances between stabilizing devices and control center, inevitably occur in large power systems. Thus, the damping performance may be deteriorated when variable latencies are ignored in the control design. This paper presents an inter-area oscillation damping controller design considering the impact of variable latencies. Selection of suitable stabilizing devices and input signal is conducted by taking variable latencies into account. Stability studies are carried out in IEEE 50-machine 145-bus to analyze an influence of variable latencies on the oscillation damping and the signal selection. The proposed damping controller can achieve desired damping performance as well as robustness against variable latencies, various operating conditions, and severe disturbances.