Research On Real-Time Power Regulating System For Wind Farm Based On Hybrid Energy Storage System

The integration of wind farm into power system is an effective way of utilizing wind energy. As the wind speed varies irregularly, the real-time power from wind farm fluctuates at random. The fluctuant wind power will bring a series of negative impacts to the power grid. Regulating the fluctuant wind power to be stable and controllable is one of the keys to the stable operation of wind integrated power system. This paper focuses on the hybrid energy storage technique and the real-time power regulating system for wind farm.Firstly, this paper conducts an analysis on the fluctuation characteristics of real-time wind speed on the foundation of the turbulence model. According to those characteristics, the power fluctuation from wind farm is decomposed into steady power fluctuation and peak power fluctuation. The properties of the decomposed wind power fluctuation are discussed. Furthermore, this paper handles a research on the battery-supercapacitor hybrid energy storage system. The results show that the battery-supercapacitor hybrid system obtains the performance of high power density, high energy density and long cycle life. Consequently, that hybrid system is applicable to the real-time power regulation of wind farm and helpful to reduce the investment cost. Based on the decomposition of wind power fluctuation, a capacity configuration method for the battery-supercapacitor hybrid system is proposed.Then, this paper develops an active-parallel hybrid energy storage system (APHESS) which is composed of a battery, a supercapacitor and two charge-discharge controllers. A theoretical analysis and a simulation verification are carried out on the topology feature and operation mechanism of APHESS. By the reasonable design on the structure of APHESS, the energy storage element can be managed to aborb and release energy fastly as the precise power value. Besides, the whole charging-discharging power of APHESS can be allocated flexibly between the battery and supercapacitor. Thus, APHESS lays foundation for making battery and supercapacitor adjust all the fluctuant power from wind farm in real time according to their energy storage merits.Furthermore, this paper conducts a study on the real-time power regulating system for wind farm based on APHESS. According to the energy storage merits of battery and supercapacitor, energy management rules for suppressing fluctuant wind power are devised and then established into a control information base. As for the operation of the power regulating system, this paper proposes a double-layer control model equipped with the control information base. The simulation study shows that the battery and supercapacitor can be made to balance different kinds of power fluctuation respectively by establishing the control information base reasonably. As a result, their energy storage merits are fully utilized and the service life of APHESS can be prolonged. In addition, the simulation study demonstrates that the double-layer control model contributes to simplifying the control logic in the course of regulating the irregular wind power fluctuation. By that control model, the power regulating system succeeds in controlling the real-time power from wind farm to be stable.Finally, an experimental system is developed, which is composed of a wind turbine and the real-time power regulating system for wind farm. The experimental results indicate that the power regulating system is able to exchange power with the wind power system rapidly and precisely under the government of the double-layer control model. As a consequence, the real-time wind power is regulated to track the reference value stably and the power quality of wind power system is improved. It can be concluded that the achievements of this paper could lay technique foundation for the stable combined operation of wind farm with power grid according to the dispatching plan.