Research On Frequency Regulation Capability Assessment And Regulation Strategy Of Power System With High Wind Power Penetration

As the main power supply of the new power system under the "dual carbon" target,the randomness and volatility of the output power of wind turbine will lead to significant changes in the frequency characteristics of the power grid.The frequency analysis method and control strategy proposed for the main body environment of synchronous generators are difficult to adapt to the new scenario of power systems with high wind power penetration.It is an urgent problem to establish the assessment method and regulation strategy of system frequency regulation capability considering the fluctuation characteristics of wind power in the above new scenarios.In this paper,by analyzing the characteristics of wind power fluctuations,we deeply study how to evaluate the power grid frequency regulation capability in real time and the control strategy to improve the system frequency stability.Firstly,based on the wavelet packet decomposition and reconstruction algorithm,the variance characteristics of wind power fluctuations are analyzed,and the time domain corresponding information between wind power fluctuations and hourly average components of wind power under different time scales of wind farms and wind farm clusters is obtained.Based on a large number of measured data,the monthly and daily variation characteristics of wind power fluctuation variance are obtained;The time-varying characteristics of wind power are characterized based on variation function,and the correlation and time variation characteristics of wind power variation are studied.A large number of measured wind power data are used to verify the effectiveness and universality of the wind power fluctuation variance model and wind power variation model under different time scales and time intervals.Secondly,the frequency response model of power system with large-scale wind power is established,and the frequency domain method is used to qualitatively analyze the frequency regulation capability of the system under different power supply structures,and the highly sensitive frequency band information of system frequency to power fluctuation is obtained;Based on the frequency spectrum characteristics of wind power and load power fluctuation,the evaluation index of primary frequency regulation capability of power system with high wind power permeability is revised and extended to the calculation of primary frequency regulation capability of the system in frequency division band.The secondary frequency regulation capability of the system is evaluated based on the wind power variation characteristics.A regional power system is simulated and analyzed to quantitatively analyze the phased change trend of the frequency regulation capability of the new power system,and the main factors affecting the frequency regulation capability of the system under different power supply structures are given.Thirdly,based on the characteristics of wind power fluctuations,the frequency regulation capability of conventional coal-fired units at different time scales is deeply excavated.Under the condition of satisfying the stability constraint,the control strategy of primary frequency regulation of thermal power unit in frequency division band is improved.The ability of primary frequency regulation of thermal power unit in the highly sensitive frequency band is enhanced by setting a small adjustment coefficient in the highly sensitive frequency band;Based on the wind power variation characteristics and its prediction information,the advanced frequency control strategy of thermal power units is proposed to improve the secondary frequency regulation capability of thermal power units.The analysis of two area system examples shows that both strategies are effective and feasible,and can jointly enhance the frequency regulation capability of power systems with high wind power penetration.Finally,the control method of primary and secondary frequency regulation of wind turbine and wind farm participation system is proposed for the development of new power system.A frequency division primary frequency regulation control method for wind turbine is proposed to realize the response of wind turbine to the rapidly changing frequency fluctuation component of the system under the premise of generating power in the neighborhood of the maximum power tracking point.By defining the participation coefficient of primary frequency regulation of wind farm,the control method of primary frequency regulation of wind turbine in frequency division band is extended to the level of wind farm participating in primary frequency regulation;With the goal of using wind farm reserve capacity to participate in AGC control and share the frequency regulation pressure of thermal power units in the system,a strategy of wind farm participating in AGC control based on wind power variation prediction information is proposed.The simulation results based on the two area system show that the two strategies can improve the system frequency regulation capability and relieve the pressure of thermal power unit frequency regulation.