Coordinated Control Of Energy Storage With Photovoltaic Power Plants And Its Optimal Capacity Configuration

With the energy crisis and environmental problems becoming increasingly serious, photovoltaic generation is drawing universal attention as a sustainable and clean energy source. However, large scale of grid-connected PV power station fails to provide necessary damping and frequency support, and the decrease of system inertia will bring negative effect to the secure and stable operation of power system. As an effective and promising solution to this problem, energy storage system(ESS) is still faced with many challenges which involve in the high cost and the difficulty of profit evaluation. Therefore, the influences and economy of the application of ESS in PV integrated system are studied in this paper. A coordinated control strategy of PV-ES system is proposed to improve the frequency stability of the system from the transient control perspective. Moreover, the economic benefits of PV-ES system participating in frequency regulation and the optimal configuration of energy storage capacity are discussed from steady-state regulation perspective.Firstly, a PV station model is established using state average method to increase the simulation efficiency. The maximum and limited power point tracking methods are introduced and improved in this paper to accelerate the tracking of power reference. And then the low voltage ride through ability of PV station is verified under the current control mode. Besides, the model of lead-acid battery energy storage system is built and simulation results show that fast and accurate tracking of both active power and reactive power is realized.Secondly, based on the influences of inertia on system stability, the inertia of PV-ES system is defined and a coordinated control strategy is proposed in order to provide virtual inertia and dynamic frequency support during disturbance, thus improving the stability of power system. The configuration of energy storage capacity is reduced through reasonable allocation between PV and ESS inverters. Taking into account the requirements of dynamic reactive current support in Grid Code, the reactive current control method is designed to cut down the need for reactive power compensation device. And sensitivity analysis is also performed to study the influences of different control parameters and provide reference for parameter setting.Finally, the profits of different types of ES are evaluated and the potential possibility of PV-ES system taking part in power market ancillary service is discussed in this paper. An optimal configuration method of ES capacity is proposed considering the benefit from system frequency response service in the UK market. Simulation results indicate that the application of ES in the PV power station and the participation of frequency response regulation will increase the total revenue of PV stations. Moreover, it is found that the weather patterns and the prices of ancillary service are the sensitive factors which will affect the configuration results of ES.