Research Of The Control Strategy For Grid-Connecting And Islanding Of Energy Storage Based Distributed Generation

The energy issue is becoming more and more serious in the modern society,while the fossil energy is becoming more and more exhausting.The development and research of renewable energy has already been put on agenda since decades ago.The application of renewable energy has beem widely accepted by a great number of countries.So both the lack of fossil energy and the problem of environmental pollution have been improved in some case.This article takes wind power generation and photovoltaic power generation as key point.Introduce the wok principle of wind power generation and photovoltaic power generation.Summarize the characteristics and models of the two renewable energies.Meanwhile,introduce several other kinds of distributed generations.Focus on the work principle,characteristics and mathematical model of the nickel metal hydride batteries,lithium battery and super capacitor.On the basics of those argued above,Study balance management and storage distribution of energy management system in the energy storage power station.Simulate the control strategy of grid-connecting and islanding in PV station with storage system Main contents are as follows:(1)Research on balance management of MH-Ni battery pack in storage station.BP neural network based on variable step size and equalization control method for trickle charge 200 Ah MH-Ni battery was proposed,since theoretical analysis of typical voltage equalization control and SOC equalization control was particularly described.Bulk charge and small current equalization were both applied to this equalization system.Gassing and recombination were both taken into consideration.Simulations of battery pack were conducted.Conclusions showed that voltage detection accuracy was improved.Both equalization efficiency and speed were fine.(2)Research capacity distribution method of composite energy storage in storage station.Propose capacity distribution method of composite energy storage based on discrete wavelet transform.Adopt the way of wavelet entropy optimization method to optimize capacity configuration of the two kinds of storage forms used in storage station.(3)Based on(2),optimize capacity configuration of maximum power and maximum capacity of lithium battery and super capacitor in an actual wind farm.(4)Research the control strategy of grid-connecting and islanding of PV station with storage system.PQ control strategy is applied in PV station with storage system when it is grid-connecting to restrain the voltage in a reasonable range of the point of common coupling.V/f control strategy is applied to PV station with storage system when it is islanding to restrain the voltage and frequency in a reasonable range of the point of common coupling.