| With The gradual increase in the utilization rate of renewable energy,the proportion of its installed capacity is also gradually rising.In order to further improve the configuration of new energy power generation,the state encourages and issues a series of energy save policies,thus the energy storage skill beguins to develop quickly.Due to the constraints of region,season and heat storage,at present,the conventional generating units(hydropower and thermal power units)in our country have long climbing time and slow response speed,which exposes many shortcomings when dealing with the gradually diversified and complexed power grid system.Therefore,in order to solve the bottleneck of intermittent power grid connection and the influence on power grid volatility,and improve the frequency index of power grid,it's very important to provide some reasonable energy storage devices for the future power grid to ensure the flexible application of renewable energy and the flexible operation of the power grid.Firstly,this paper studies the influence of pumped-storage power station(PPS)with fast response,flexible control and not constrained by operation state of wind turbines on load frequency control(LFC).Based on the LFC model of two-region reheat steam turbine unit and considering some nonlinear factors existing in the power grid,the LFC method of PPS is proposed.According to the two working states of generating and pumping operations,a two-stage PPS secondary frequency control model with nonlinear factors is constructed.The simulation experiment results prove the rationality of LFC model of PPS is proved,and the influence of nonlinear factors on the frequency modulation of power grid is analyzed,and the positive role of pumped storage in quickly suppressing load disturbance of the system and accelerating the speed of power grid recovery is illustrated.Secondly,this paper studies the control strategy optimization of secondary frequency modulation of the power grid,and designs a Fractional Order Active Disturbance Rejection Control(FOADRC),which achieves a full integratation of Fractional-Order Calculus(FOC)Control and Active Disturbance Rejection Control(ADRC).The controller has the advantages of fast response speed,high precision and wide parameter range.Based on this,A LFC strategy based on FOADRC is proposed,and the LFC model of PPS based on FOADRC technology is built.The simulation experiment results of different controllers prove that the FOADRC designed in this paper has better control result,and its robustness and stability are higher.Finally,aiming at the problems of long construction period,insufficient reserve capacity and slow response speed of dynamic regulation of PPS,this paper introduces a new auxiliary frequency modulation method of electrochemical energy storage,which improves the frequency modulation result by virtue of its fast response and accurate tracking characteristics.Based on the frequency modulation characteristic parameters of electrochemical energy storage,the equivalent model of battery power supply is established.The LFC method of interconnected power grid based on FOADRC is proposed,which combines electrochemical energy storage and PPS.At the same time,the impact of demand response on frequency modulation of power grid is considersd,a combined LFC model of pumping/storage considering demand response under generating and pumping operations is established.Simulation experiment proves that adding electrochemical energy storage can significantly improve the dynamic response capability of secondary frequency modulation,and provide effective guarantee for the safe and stable working of power grid system.Moreover,considering the supplementary control of demand response properly,it has a certain positive significance to realize the rapid stability of power grid. |
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