The dynamic frequency modulation model of the whole regional power grid is composed of thermal power units, energy storage systems, nonlinear frequency difference signal decomposition, fire-storage cooperative fuzzy control power distribution, energy storage system output control and other components. Fig. 1.
Based on the above analysis, a control strategy based on cooperative frequency modulation of thermal power units and an energy storage output control system is proposed to improve the frequency stability of the power grid.
Under the four control strategies of A, B, C and D, the hybrid energy storage participating in the primary frequency modulation of the unit |Δ fm | is 0.00194 p.u.Hz, excluding the energy storage system when the frequency modulation |Δ fm | is 0.00316 p.u.Hz, compared to a decrease of 37.61 %.
According to the above information, when the coupled hybrid energy storage of the thermal power unit participates in primary frequency modulation, the output power is significantly reduced, and the safety and stability of the unit are improved to a certain extent.
In this strategy, part of the power commands are assigned to the energy storage system through fuzzy control, so as to establish the primary frequency modulation scheduling module of the thermal power unit coupling energy storage system, which can ensure the power generation revenue of thermal power units.
In practice, the frequency fluctuation of a unit is generally caused by continuous and irregular load fluctuations, therefore, simulate the impact of coupling a hybrid energy storage system and a single energy storage system on the primary frequency regulation of thermal power units under continuous disturbances.