Analysis the power data of a grid-connected photovoltaic (PV) power station in northern China. And analyze its 1 minute or 10 minutes time interval maximum active power variation .Consider grid-connected PV requirements to join the battery energy storage system(BESS) to reduce the photovoltaic power fluctuate caused by light intensity and temperature change of grid photovoltaic power fluctuations. Use battery optimization control strategy to reduce power and capacity of the BESS configuration. Take advantage of the BESS charge and discharge characteristics to reduce the problems of grid-connected PV power output fluctuations. Analysis the smoothing effect evaluation index when BESS rated power and capacity changed. Proposed a control strategy that use BESS to smooth PV grid power fluctuations, and optimize the BESS power and capacity, the simulation results verify the feasibility of control strategy and algorithm.

This document researchs on 55kW GSHP black start based on 250kW/250kWh battery system and 50kW/10s super capacitor. The modeling methods of asynchronous motor, battery system, super capacitor and PCS are given. According to three black start conditions: direct start, star delta start and frequency conversion start, simulates and analyses the results. During black start, the max AC bus voltage drop reaches 60%, and hybrid energy storage system is able to effectively inhibit the inrush current.

Vanadium Redox Flow Battery (VRB) holds unique characteristic as the power and capacity of the physical structure of independent design, which determines VRB different from other battery types in operating characteristics by taking unique operation modes under the circumstance of module degradation or failure in some cases. Paper focuses on how to ride through the case of VRB system with partial degradation or failure during the normal operational conditions, launched a comprehensive experimental study and theoretical analysis. The paper analyzes several situations from the point of view of the battery physical components which should lead VRB system partial failed, and simulated the battery partial degradation or failure by experimental means, and carried out two operation modes to respond to different partial failure situations, which including the use of lower rated power and the use of times rated power. Study proved that those two modes operated in the case of VRB partial failure conditions, has no significant effect to VRB Energy Storage System (ESS) efficiency, as well as be helpful to improve a higher reliability of VRB energy storage system. This paper takes the lead in studying the operational characteristics of VRB- ESS from the angle of partial degradation or failure conditions, which has practical engineering significance for developing VRB -ESS demonstration.

Recently, a lot of PV power systems ranging from 1MW to 10MW have been built in China. However, the power grid can’t accept so much PV power because of their oscillated output power. PV systems are affected by the weather condition a lot, such as the sunlight and the temperature. Embedding energy storage system into PV system could improve the grid-access performance of PV systems as well as expand the functions of original PV systems, including regulating power quality of grid. In this paper, PV-storage topology is presented and the flow direction control (FDC) method is described. Based on the operation data of a 100kW PV system in a certain place of China, simulation studies are performed. The result of simulation verifies the possibility and necessity of building the energy storage system in the PV system. With the decline of the cost of energy storage system and PV system, the development of renewable energy in China will be accelerated and supported by the combination of PV system and energy storage system.