Virtual Inertia And Damping Control For Photovoltaic And Energy Storage System

The increasing penetration of static electricity generating units,such as photovoltaic and batteries in power system will bring new challenges to dynamic frequency stability.The mechanical inertia of the electric power system must be reduced,and the damping of the system will also be affected.In order to guarantee the dynamic stability of the system frequency,this paper studies the virtual inertia control and damping control of the optical storage system,and effectively solves the problem of the dynamic stability of the static power generation unit.The main results obtained are as follows:(1)The differences of the virtual inertia,the nature inertia of synchronous generators are discussed.According to the charge and discharge principle of the battery,the definition of the virtual moment of inertia of the battery and the equivalent calculation method are given to establish the dynamic relationship between the system frequency and the stored energy.(2)According to the relationship between the virtual moment of inertia of the battery,it is proposed that the inertial response can be obtained by adjusting the working current of the battery.At the same time,by detecting the state of charge of the battery,the inertial area is determined.Thus through the coordination of battery and photovoltaic,the excessive charging and discharging caused by the inertia control is avoided.(3)The control principle of active power and reactive power increasing system damping is analyzed.Then on the basis of grid connected power control of photovoltaic energy storage system,a novel additional active and reactive power modulation is proposed.It also can make the joint system have the ability to inject active and reactive power,so as to improve the damping characteristic of the system.(4)A typical power system based on photovoltaic and storage system is used to validate the proposed control strategy.For lack of inertia of the system,the battery can invoke its own stored energy,virtualizing the controllable inertial response.When the oscillation occurs,the battery can be coordinated with the control of photovoltaic to provide fast and effective active and reactive power support.