The Research Of Wind Power Grid-connected Operation Control And Frequency Regulation

In now days, fossil energy is being exhausted and environment is polluted,so the development and use of renewable energy are imposed great significance to sustainable development. Wind power by virtue of its rich resources, easy development and cost-effective advantages, has attracted more and more attention. Because wind energy has uncertainty and random fluctuation, the wind power generator output power has great fluctuation,along with the rapid increase of grid-connected wind capacity, the grid frequency regulation will become more difficult because of wind power fluctuations. Therefore, it is necessary to study the method to solve this problem. In this article, the author makes an attempt to study this problem from two aspects. One is the variable speed wind turbine power output smoothing and the other is frequency control.Firstly, The basic principle of wind power is then analyzed, wind speed, and the rotating mechanism, wind turbine generator mathematical model, at the same time,is also constructed.On this basis, we build windpower grid connecteing model, and study the impact of wind generator to the distribution network is studied.Secondly, The paper investigates the contribution of doubly fed induction generator(DFIG) to system inertial response and frequency regulation. The influence of auxiliary loop parameters on the inertial response is illustrated. Based on that,the paper also introduces a novel algorithm to enhance the participation of doubly-fed induction generator(DFIG) in existing frequency regulation mechanisms. The proposed approach takes advantage of the fast response capability associated with DFIG, allowing the kinetic energy stored by rotational masses to be partly and transiently released in order to provide earlier frequency support.Simulation results are described which illustrates the proposed strategy can greatly improve system frequency regulation.The capability of providing power support of a wind turbines generator and conventional power Plants in the system frequency control are analyzed.A new hierarchical structure based frequency control strategy of the whole wind farms is proposed, Thought reserve control strategy of wind farms power, wind farms can provide the short-term extra active power support,this could be beneficial for a hydro dominated system in arresting the initial frequency fall; at a certain wind speed, wind farms can also provide a long-term excess active power. Simulation results show that wind Farms can participate in frequency control like conventional power plants to a certain extent.Thirdly, due to the uncertain characteristics of the wind production, the general way of the reserve management for wind integration is to provide additional reserve margin by conventional plants. Such a strategy could not only increase the operating cost but also impose additional unit stress during the frequency event. This paper presents a strategy that takes advantage of the fast response capability of VSWT, to actively provide primary reserve for frequency control. This control strategy de-loading a wind turbine to ensure a primary power reserve even for a large range of wind speeds. Atlast, the simulation experiments indicate the regularity of the power reserve and the ability to contribute to frequency control.Finally, the main disadvantage of wind power generator with conv entional power control strategy are analyzed, and a new control strate gy, which does not need auxiliary equipment is proposed. Based on a nalyzing of wind power fluctuation spectrum,an active power smoothin g control strategy which combined with the pitch control and speed c ontrol had been proposed. The simulation results show that the propos ed control scheme can effectively reduce the wind farm output power fluctuation. A wind generator system with supercapacitor in the DC-li nk is also studied. The new control strategy do not change control str ategy of grid-side and the machine-side converter,smoothing control ou tput active power can obtain on the basis of energy control strategy o f super capacitor energy storage system.