Dynamic Modeling And Simulation Of Battery Energy Storage System In Power System

With the increasing application of battery energy storage in the power grid,the industry has put forward higher requirements for battery energy storage models suitable for engineering simulation.The development of a full process dynamic simulation model of battery energy storage and its control system has become an urgent need;The application of appropriate control strategies in the system not only improves the energy quality and system stability of the battery energy storage after being connected to the grid,but also makes the operation of the battery energy storage system more economical.It is also of great significance.This paper has done the following work in the aspects of battery energy storage system modeling,frequency modulation control strategy of battery energy participation in power grid,and grid connection effect analysis:A full-process dynamic simulation model of a battery energy storage system based on large-scale power system simulation analysis software PSD was developed,which can realize the electromechanical transient simulation and mid-to-long-term dynamic simulation functions.This battery energy storage system contains the energy storage battery pack model proposed in this paper,and the typical inner and outer loop control method is applied to the converter control model.At the same time,the low and medium voltage ride-through control model and frequency control of the PSD wind power / photovoltaic model are compiled and debugged.The program interface of the equal model enables the battery energy storage model to have functions such as low voltage ride-through capability and frequency modulation.An adaptive integrated control strategy for battery energy storage to participate in primary frequency regulation of the power grid is proposed.This strategy uses positive virtual inertia control to simulate the inertia response of the generator at the initial stage of load disturbance;negative variable inertia control with variable coefficients is used in the frequency recovery period,and the frequency deterioration degree(maximum frequency difference)and SOC dynamic adjustment output are comprehensively considered to accelerate frequency recovery.;The variable coefficient droop control based on the hyperbolic tangent function is adopted throughout the frequency modulation period.The size of the droop coefficient is related to the SOC,which can ensure the frequency modulation demand while taking into account the battery capacity retention effect.A comprehensive control strategy for battery-assisted thermal power to participate in the secondary frequency modulation of AGC is proposed.In this strategy,the battery energy storage and the AGC system operate in coordination.A control method based on the area control deviation(ACE)signal is used at the initial stage of frequency modulation,and the sensitivity analysis is used to determine the switching timing to avoid this method hindering frequency recovery.After the switching timing is taken into account Thermal power hill climbing rate limit adaptive control strategy.This strategy is based on the thermal hill unit’s climbing rate limit to dynamically allocate the area frequency regulation demand(ARR)and dynamically adjust the battery energy storage output according to the change in SOC,taking into account the frequency modulation effect and the SOC retention effect..Based on the provincial grid data,the simulation model of this paper is applied in PSD software.Based on the reliability of the model in actual engineering simulation,the effect of battery energy storage on controlling the grid overload and improving the voltage support capability is analyzed.