An Emergency Control Strategy for Isolated Power System of Three-Phase Inverter and Diesel-Engine Generator Operating in Parallel

In the isolated power system of renewable energy power generation inverter and diesel-engine generator operating in parallel, the generator usually runs in the voltage and rotate speed droop control mode, and the three-phase inverter runs in the constant power-control mode. In this case, a sudden load change will be completely undertaken by the generator, which may lead to its overload or reverse power. In order to solve this problem, this paper has proposed an emergency control strategy based on the detection of the rate of system frequency change. In emergency conditions, the strategy can be used to automatically adjust the inverter output power to deal with the aforementioned overload or reverse power and prevent the system from shedding load and avoid protective actions of the generator. Thus, the power-supply capacity and continuity of the system are guaranteed, and its safety and stability are also improved. Time-domain simulations and experiments show that the proposed strategy is feasible and effective.