Research On The Key Technology Of New Energy Storage

The traditional energy depletion and environmental pollution are two major problems that need to be solved urgently in the current economic development. To realize the sustainable development of economy, the development and exploration of renewable energy have become the world trend. Considering the various factors, solar energy has the most extensive application prospect; therefore, many countries have paid much attention to it. While the application of photovoltaic power generation is developing, the storage system is also being paid more and more attention. The high reliability, high efficiency, high utilization rate of energy can be achieved through the control of energy storage, release and conversion, thus achieving the purpose of saving energy and improving the environment. Therefore, the research of new energy storage system has become the focus of research in the world today.According to the practical requirements of the new energy storage system, a power generation system which includes a PV array, maximum power point tracking (MPPT) controller, storage battery pack, battery management system (BMS), grid-connected inverter, bi-directional DC/DC circuit and the corresponding energy storage power station joint dispatch control system is presented in this paper. And this paper also focuses on the design and study of the key technology of the storage subsystem and photovoltaic power generation subsystem. In the research of bidirectional DC/DC converter in energy storage subsystem, in order to improve its efficiency, the soft-switching technology and the three-phase interleaved parallel circuit structure are adopted in this paper. On the one hand, it helps to reduce the current ripple of the inductor, thereby increasing the power density. On the other hand, it will do well to the selection of the switching devices, thus improving the efficiency of the inverter. Several common storage batteries are studied in this paper. Selection of storage battery is given by comparing the advantages and disadvantages among them. The main functions of the BMS are also studied in this paper, which can not only improve the battery life and the utilization rate of battery, but also the power of the whole system can be put to better use. By studying the bidirectional AC/DC converter in photovoltaic power generation subsystem, the modulation method, the operating principle and modal analysis is given.Aiming at the application of bidirectional flow of energy in the power conversion system (PCS), this paper conducts modeling and simulation respectively on the bidirectional AC/DC converter, the bidirectional DC/DC converter and an energy storage battery, thus designing a controller of bidirectional flow of energy in PCS. In view of the on-grid/off-grid function of energy storage system under the new situation, the on-grid/off-grid operation control principle and mode switching process in PCS are given, and a feed-forward control method of voltage control and current control in the on-grid/off-grid smooth switching is put forward. This method does not need to wait to switch until the grid voltage is zero, which can reduce the burden on regulators, speed up the dynamic response speed of the control system, thus realizing the smooth switching between on-grid and off-grid operation.In this paper, main circuit parameters in PCS are designed, design process and methods of inductance and capacitance are given in detail, and the switching devices are selected. Detailed analysis of the PCS’s power loss and the results of theoretical analysis are presented, thus guaranteeing the validity of the design parameters. The hardware circuit of BMS is designed and the hardware circuit diagram is given. The software process of the main parameter acquisition is introduced. And by using TI’s main digital chip TMS320F28035 as the control core and Maxim’s special battery measurement chip MAX 14921, the full digital control of energy storage system is realized.In this paper, the simulation and analysis of PCS and control strategy are based on PSIM software, and a experimental prototype of energy storage system is developed. The simulation and experimental tests verify the rationality of parameter design and the feasibility of control strategy.