Study Of Control Strategy For Wind-PV-ES Hybrid Power System

Facing the problem of the increasing in global fossil fuel costs, the limitation of reserves and increasingly serious environmental crisis, renewable subject to a high degree of common concern governments and peoples. Wind and solar energy has caught people’s attention as an inexhaustible wealth among the renewable energy in the earth or its surface, and accordingly has widely used by people. As one of the main ways of using solar and wind energy, PV and wind power technology continues to mature. Due to the randomness, intermittent and instability of wind and solar energy, in order to fully enhance the energy conversion efficiency and energy efficiency, the wind-PV-ES hybrid generation system based on wind power and PV power generation was born in the last century. In the wind-PV-ES hybrid generation technology, the control strategy is a very important factor in the overall efficiency of power generation.Establish a system diagram about wind-PV-ES hybrid power system, and give the the power control scheme in wind power systems, PV power system and energy storage system individually, the grid-current control method and the ESS control strategy, on the basis of the overview and the analysis of the working principles over wind power, PV power generation and energy storage systems.(1). PV/wind hybrid system OverviewIntroduce the PV/wind hybrid system. And the wind power systems, PV systems were outlined. The wind power principle is revealed briefly, the exhaustive description about composition and classification of wind power generation system are fully displayed and last select the double-fed wind power generation system as the wind power generation unit of the wind-PV-ES hybrid power system; The power generation principle in PV system are deeply described, and the classification and PV cells and power generation systems are briefly introduced.(2). ESS peak-shaving/valley-filling and power controlBriefly introduce four-control mode in energy storage system: Tracking Program power mode; smooth power output mode; System FM mode; ESS peak-shaving/valley-filling mode. And describes the principles of various control regulation methods, and ESS peak-shaving/valley-filling principle of energy storage systems. Analyze of the battery charge/discharge model and present the algorithm implementation ofcontrol strategy batteries.The selection criteria and classification in ESS are mainly introduced,and select the scenery storage batteries as energy storage unit in wind-PV-ES hybrid power system.Describes the role of energy storage systems peak-shaving/valley-filling in wind-PV-ES hybrid power system. Show the corresponding power control strategies based on the research of the overall power control strategy of the wind-PV-ES hybrid power system. The detailed analysis of active control and reactive power control in wind-PV-ES hybrid power system are presented based on the block diagrams of the control strategies. The control strategies in wind power subsystems, PV subsystem and power storage subsystems are given individually, as well as the thorough analysis of corresponding control strategies figure, and the battery charge and discharge control strategy are given at last.(3). Grid inverter-current control and dead-bandwidth controlHave a research on control strategy of grid-current and dead-bandwidth of DC / AC inverter in wind-PV-ES hybrid power system. Study the DC current and instability existing in wind-PV-ES hybrid power system. The quasi-PR controller(QPR) having harmonic compensation and more practical instead PR controller, improve the DC control strategies of the traditional PI and PR to apply to the three-phase grid-connected inverter DC control; Design new controller to control steady-state error in grid current with adding the ratio and the phase compensator to traditional PR controller to correct the amplitude and phase of PR controller, and the results proves that theoretical analysis of the effect is good. Then modify the traditional controller, give a new control strategy based on the original control strategy, apply new control strategy to dead-bandwidth control, and the three controllers were simulated in dual-loop control system.