| In order to respond to the call of the national "double carbon action" and realize the transformation of the national energy strategy.vigorously developing wind power.photovoltaic and other new energy is an important direction for the development of the power system.At present,the proportion of new energy is increasing,the inertia and damping of the new energy sending system are weakened,and the frequency stability of the system is greatly reduced.The control of using wind farm-level energy storage to provide virtual inertia for the wind turbine has become the key technology to improve the frequency stability of the wind turbine grid-connected system.However,the oscillation stability of the new energy sending system may be affected by the improper selection of the parameters of the virtual inertia based on the energy storage system.Therefore.it is necessary to study the stability of the new energy sending system caused by the virtual inertia control based on wind farm-level energy storage,and then analyze the energy storage capacity required by the wind-storage sending system under different restrictions,and optimize the virtual inertia control parameters,so as to improve the safety and stability of the new energy delivery system.Firstly,aiming at the problem that the inertia support capability of energy storage systems is greatly limited under short circuit faults,the impact of virtual inertia control based on energy storage on system frequency stability under short circuit fault is quantitatively analyzed,and the capacity configuration evaluation method that takes into account the fault ride through characteristics of energy storage is proposed.Aiming at the virtual inertia control based on energy storage,considering the low voltage ride through(LVRT)of wind turbine and energy storage respectively.the frequency dynamic characteristics are quantitatively analyzed based on the change of system active power,and the inertia and damping contributions of energy storage to the system are obtained;The virtual inertia and virtual damping parameters are configured according to the frequency response index,and the energy storage capacity under short circuit fault is quantitatively evaluated by taking into account the LVRT control of the wind turbine and energy storage system and the limitation of the system frequency.The correctness of the of the quantitative relationship between the system frequency,energy storage capacity and virtual inertia control parameters,the voltage of the wind turbine is verified by the simulation results.Secondly,aiming at the problem that the virtual inertia control based on energy storage is prone to cause system oscillation,a quantitative analysis method for the impact of energy storage virtual inertia control on the oscillation stability of the wind-thermal-storage sending system is proposed,and the frequency stability index and the oscillation damping ratio index are taken into account to modify the capacity configuration evaluation method of energy storage system.The rotor motion equation of the synchronous machine under the influence of the wind-storage system is analyzed,and then the quantitative relationship between the virtual inertia damping coefficient of the virtual inertia control based on energy storage and the dominant oscillation frequency and the oscillation damping ratio is deduced;Based on the energy storage configuration evaluation method mentioned above,the energy storage capacity is modified taking into account the frequency stability index and the oscillation damping ratio index;The correctness of the above analysis method and the adaptability in different simulation systems are verified by simulation analysis in the single machine system with wind-storage system and the actual power grid simulation system.Finally,aiming at the problem that improper selection of energy storage virtual inertia control parameters can worsen the stability of the sending end system,a method for optimizing energy storage virtual inertia control parameters based on NSGA-Ⅱ algorithm is proposed,and the energy storage capacity requirements when considering the system frequency stability and oscillation stability are analyzed quantitatively.Aiming at the virtual inertia control based on energy storage,taking into account the system frequency stability and oscillation stability,the minimum of the maximum frequency deviation and the maximum of the damping ratio of the system oscillation mode is taken as the objective function,the virtual inertia parameter optimization strategy based on energy storage is proposed to improve the system stability of the wind-thermal-storage sending system.According to the optimal virtual inertia and damping parameters,the energy storage capacity satisfying the optimal stability of the sending system is calculated.The correctness of the proposed parameter optimization method and energy storage capacity calculation method is verified by the simulation results. |
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