Research On Active Power Dispatch And Control Method Of Wind Power Systems

With wind power increasing, power grid dispatch will face new difficulties and pressure. Existing dispatch method is based on that generators can be controlled well and load can be forecasted exactly. When wind power is interconnected to power grid, two issues appear. One is that the power output of wind power is random and intermittent. Then the forecasting for the power output of wind power is not exact. The other is that wind power is dispersed and autonomous. Then it can not be controlled well. So it is necessary to research on the dispatch and control method of wind power integrated power system.This dissertation researches on the problems addressed above from the point of how to make traditional generators cooperate with wind generators, how to bridge to existing dispatch, how to adapt to different automation level of power system, how to consider the system operating demand, and so on. Then this dissertation presents two detailed strategies for active power dispatch and control of wind power integrated power system and a new method of active power wind power load sharing. The presented strategies and method make dispatch and control technologies of wind power integrated power systems abundant.Firstly, this dissertation researches on the dispatch method for wind farms interconnected to transmission system and presents a two-layer strategy for wind power system dispatch and control. This strategy can revise pre-dispatch scheme for traditional generators in online dispatch time scale and trace the fluctuation of real-time power output by regulating the Automation Generation Control(AGC) generators related to wind generators in AGC time scale. The key of dispatching and regulating active power of wind power is how to make reasonable cooperation with traditional generators. In the strategy, the adjusting factors for revising traditional generating scheme and load distribution factors for regulating the AGC generators related to wind generators are calculated by the electrical dissecting information of paths among wind generators, related traditional generators and their loads. Example shows that traditional generators can trace the fluctuation and variation of loads and wind power well by using this method.Secondly, this dissertation researches on the active wind power dispatch and regulation strategy for wind farms interconnected to distribution system dispersedly and presents a strategy for decentralized autonomous regulation of distributed wind power considering the system frequency regulation demand. This strategy can make fully autonomous wind power become limitedly autonomous considering the system frequency regulation demand. Then regulation regions of wind generators are divided into interconnection region, normal region, abnormal region, urgent region and clearing region in the strategy. Further, three new regulation modes are proposed, abnormal step-regulation, urgent step-regulation and fault step-regulation. Example shows that the method can make wind generators regulate their outputs actively in order to support the system according to the system frequency regulation demand.At last, a new method of active wind power load sharing in distribution system based on the active wind power grid codes is presented. Feeder terminal unit(FTU) is the control unit of the method. The qualifications for active wind power load sharing are judged considering not only"Law for Renewable Energy in People's Republic of China", but also economic benefits for operators of wind power. And they are judged according to the system frequency and the rate of wind power installation volume. If it is qualified, FTU makes the scheme for active wind power load sharing and sends the instruction to wind generators in the feeder. In the detail, different load sharing schemes are made for different automation levels, one according to rating active power output of wind generators for low automation level and the other according to active power flow distribution for high automation level. Example shows that the method is feasible and both of the schemes can meet the system operation demand well.This research work is supported by the National Nature Science Foundation of China under Grant 50477008, the Research Fund 20040213031 for the Doctoral Program of Higher Education of China and the Heilongjiang Nature Science Foundation of China under Grant E0326.