| Driven by the goal of "carbon peaking and carbon neutrality",wind power is expected to play an important role in the future energy mix.However,the large-scale utilization of new energy represented by wind power makes the power grid face the challenges of random volatility and intermittency,which brings adverse effects on the safe and stable operation of the power grid.Energy storage can effectively improve the power grid’s capacity to accept new energy,and is one of the key technologies to suppress the wind power fluctuation.Therefore,it is of great significance and practical value to study the control strategy of energy storage applied to wind power fluctuation suppression.This paper mainly completed the following research work:(1)The working principle of supercapacitor and lithium battery is expounded;The characteristics of topology structure of wind-storage combined system are analyzed.The mathematical models of bidirectional DC/DC converter and bidirectional DC/AC converter are established.The charge and discharge control strategy of power outer loop and current inner loop and the grid voltage oriented grid-connection control strategy are studied,and the simulation model of battery charge and discharge control and grid-connection control is built.The simulation results verify the effectiveness of the control strategy.(2)There is a problem that when energy storage is applied to wind power fluctuation suppression,it is difficult to coordinate the effective fluctuation suppression with the reduction of energy storage battery burden.A wind power fluctuation suppression method considering the operating life of energy storage battery is proposed.The wind power is decomposed adaptatively,and the grid-connected power reference value that meets the standards of wind power gridconnection is obtained,and the fluctuation power needed to be suppressed by energy storage battery is reduced.Then,the dual-battery are used to suppress the fluctuating power,and the battery life is evaluated by rain flow counting method.The calculation example shows that the proposed method can effectively suppress the fluctuation of wind power,reduce the burden on energy storage battery,and extend the service life of battery.(3)Aiming at the problem of unbalanced charging and discharging energy in the process of dual-battery suppressing wind power fluctuations,which affects the long-term stable operation and service life of battery.An optimal control strategy based on two-stage power correction is proposed,and an adaptive low-pass filter is designed to perform the primary power distribution between the supercapacitor and the dual-battery.A power correction model based on state of charge feedback is established to complete the secondary correction of the target power of dualbattery.Based on fuzzy logic,the optimal control strategy of dual-battery state of charge is proposed,and a fuzzy rule is established which takes the power first-order instruction,the balance of the state of charge of dual-battery as input variables and the power correction factor as output variables.The power correction factor is obtained by fuzzy rules to complete the power secondary correction.The simulation results show that the two control strategies can effectively improve the balance state and prolong battery life. |
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