In this paper, an active support control strategy based on the third-order model of synchronous generator is proposed for battery energy storage system in renewable energy systems. The control strategy converts grid-connected inverters of energy storage system into synchronous voltage sources with excitation and speed control systems, which provides necessary inertia and damping characteristics for grid-connected renewable energy sources. The difference coefficient σbattery% of the BESS is defined by the power-frequency proportional coefficient Km and the damping coefficient D. By setting the difference coefficient σbattery%, it is possible to control the frequency modulation depth of the BESS to participate in the primary frequency response of renewable power generation system. The output power for primary frequency response of the synchronous generator is reduced, and the steady frequency deviation of the system after primary frequency modulation can be reduced. Therefore, the frequency stability of the renewable energy systems for power generation are improved.
Keywords BESS, active-supporting control, primary frequency response