Adaptive Automatic Generation Control for Improved Stability of Power Systems with Utility-Scale Photovoltaic Plants

Stability problems arise when large utility-scale solar photovoltaic (PV) plants are integrated into bulk power systems. The intermittent nature of solar radiation results in PV power generation variations, which must be compensated by the conventional power plants (synchronous generators) to regulate the frequency of the power system by balancing generation-load. The compensation involves generation dispatch changes of the synchronous generators. The PV plant variations and synchronous generators' dispatch changes could give rise to electromechanical oscillations (EMOs) in the power system. Severe EMOs can lead to power system instability, and this can be avoided by intelligently modulating the rate of change of dispatch of the synchronous generators during PV plant output variations. The intelligent modulation of the rate of change of dispatch can be implemented via an adaptive automatic generation control (A-AGC). This paper presents the development of an A-AGC based on an EMO index derived from phasor measurement units to ensure the stability of the power system. Typical results are presented to illustrate the operation and performance of A-AGC during PV power variations.