Economic Feasibility in Secondary Frequency Regulation Considering Hybrid Energy Storage Cycle Life Model

In allusion to the life loss of the energy storage battery participating in the secondary frequency regulation of power grid, a control strategy for hybrid energy storage participating in frequency regulation, in which the lifetime of the battery was taken into account, was proposed. Firstly, in a hybrid energy storage system containing lithium iron phosphate battery and lead-carbon battery, considering such factors as the depth of discharge, the cycle times and so on, a battery life model was built. Secondly, in the link of power distribution, the first order low pass filter was utilized to divide the high frequency signal in area regulation requirement from the low frequency signal. And then, overall considering such constraints as loss of hybrid energy storage, demand of frequency regulation and evaluation indices and taking the filtering time constant as the optimization variable, a frequency regulation model of hybrid energy storage system, which took the maximized economic benefit as the object, was established. This secondary frequency regulation model of regional power grid containing hybrid energy storage was simulated and verified by Matlab/Simulink, and simulation results show that the proposed model not only can improve the frequency regulation performance effectively, but also possesses importance in reducing both battery loss and later-stage replacement cost.