Research On Frequency Response Of Gas Turbine Based On Retired Battery Compensation

The fluctuation of the equivalent load of the system is exacerbated with high proportion of renewable energy connecting to the grid and the probability of high-power disturbances is increased by the development of cross-region UHV transmission and the connection of largecapacity units,which dramatically intensify the pressure of system frequency adjustment.Meanwhile,taking up a portion of the conventional units,renewable energy power generation weakens the system frequency regulation capability and intensifies the contradiction of the system frequency response.Gas turbine is a promising power resource for fast frequency regulation due to its rapid start-up and high power ramping characteristics.It's necessary to conduct further research to improve the effectiveness and accuracy of its frequency response.Based on the in-depth analysis of the frequency response mechanism of gas turbine,the problem that how to avoid the ‘Air Hammer Effect'(AHE)which leads to a frequency reverse adjustment in the initial stage and severely restricts the effectiveness of the frequency response is needed to be solved.As a result,a method of using retired batteries to compensate the reverse adjustment is proposed with the purpose of avoiding the negative impacts caused by AHE and give full play to the advantages of gas turbine.In view of the existing models,more attention is paid to the influence of the quasi-steady-state of output power,but the dynamic frequency response is not accurately reflected.The response time constant of the combustion chamber is introduced and consequently the dynamic frequency response model for gas turbine considering AHE is built.In addition,the simplified dynamic model is built after linearizing the Inlet Guide Vanes(IGV)opening process and neglecting the temperature loop,in which the dynamic frequency response characteristics of gas turbine can be analytically deduced.Moreover,the frequency modulation model for the gas turbine-retired battery combined system is established.And on this basis the gas turbine-retired battery cooperative control strategy and the retired battery State-of-Charge(SOC)management strategy under two frequency response modes of "following" and "command" are designed for the frequency response requirements of various systems that concern frequency quality under small disturbances and frequency safety under large disturbances.What's more,considering the frequency adjustment economics of the combined system,it is proposed to extend the SOC recovery target of the retired battery from a strict intermediate SOC value to a range with a certain bandwidth that is close to this value.Furthermore,a gas turbine-retired battery collaborative optimization model is built to complete reasonable configuration of capacity and the optimal selection of the upper and lower limits of the standby recovery bandwidth harmonizing safety and economy.The simulations performed demonstrate the accuracy of the dynamic model for gas turbine,the effectiveness of the gas turbine-retired battery cooperative control strategy,and the improvement of the system frequency adjustment capacity.Besides the simulations also give the suggested values of the SOC standby recovery bandwidth and configuration capacity of the retired battery considering the frequency adjustment economics of the combined system.The research work in this paper can provide useful alternatives for the rational use of gas turbines in the system frequency response.