Research of an active and reactive power coordinated control method for photovoltaic inverters to improve power system transient stability

In recent years, the installed capacity of photovoltaic (PV) power keeps increasing rapidly. However, the typical control objective of the PV system is to provide as much active power to the system as possible, ignoring the reactive operating characteristics of PV inverters. On this basis, an active and reactive power coordinated control method of PV system suitable for electromechanical transient stability analysis is proposed in this paper. Firstly, the mathematical model for PV inverters is established. Then, a novel active and reactive power coordinated control method based on an improved double-loop control scheme is proposed, according to the steady-state active and reactive power operating limits of PV inverters. The voltage control loop is to get active and reactive current component references, combining the maximum active power point tracking under present solar irradiation and reactive power controlling under system voltage requirements; the current loop realizes the active power and reactive power coordinated control. Finally, the effectiveness of the proposed control method on power system transient stability is tested, based on the IEEE standard test system. Simulation results show that the proposed coordinated control method for photovoltaic inverters is helpful in improving the angle stability and voltage stability of power systems.