Scenery Storage Energy Storage Unit In The System Of Smooth Control Method Research

With the incremental capacity and total power supply proportion of wind power and solar power, it has been more and more significant that wind power and solar power make the voltage and frequency of the grid fluctuate frequently, due to the intermittency and randomness of the wind and solar energy. Wind-Solar-Battery Hybrid Power System (WSBHPS) with energy storage system has been proposed to improve the power quality as a possible solution. To smooth the output power of the WSBHPS, the control strategy of energy storage system is studied in depth.Based on the impact on the stability of the grid, which has been researched in depth when the WSBHPS connects to the grid, the necessities to smooth control the output power are analyzed. And the solutions are proposed to smooth the output power of the WSBHPS:solving the long-term fluctuations problem of the grid-connected WSBHPS’s power by peak load shifting between wind power and solar power; solving the short-term fluctuations problem of the power by the smooth control of the energy storage system.First, to inhibit the wind and solar power fluctuations caused by the fluctuations of wind and solar energy, an energy allocation strategy is proposed. The strategy is studied to prevent the voltage flicker caused by stopping or re-starting many wind turbines or PV modules frequently at the same time, and inhibit the power fluctuation caused by the mismatch between the setting power reference and regulation capability of wind turbines and PV modules. The energy allocation strategy makes the wind power and solar power complementary in time and space, to achieve the goal of inhibition of long-term fluctuations by peak load shifting between wind power and solar power.Second, the distributed control architecture consisted of the energy storage system controller and the energy storage unit controller is proposed to smooth the output power of WSBHPS. In energy storage system controller, the power restraint strategy and power allocation strategy are studied to calculate the charge or discharge setting power of each energy storage unit. In energy storage unit controller, a harmonic suppression strategy is researched to improve the power quality problem caused by the dead-time effect of the bidirectional converter.Based on the above research works, the simulation between the energy allocation strategy and the average allocation strategy show that the power fluctuation result of the former is smaller than that of the latter and the power result of the former is closer to the setting power than that of the latter. And the harmonic suppression strategy simulation results show that the strategy is helpful to improve the power quality. Last, the maximum power variation in10min and in lmin results show that the proposed energy allocation strategy and the energy storage smooth control method with harmonic suppression strategy are effective to inhibite the output power fluctuations.