| In recent years, China has accelerated the utilization and development of renewable energy. However, the power output of intermittent renewable energy, like wind power and photovoltaic power, is unstable, low-density and environmental. With the increase in the proportion of energy capacity, these features will lead to fluctuations in the power output, resulting in problems and negative effects of power grid voltage and frequency fluctuations.In respects of renewable energy grid-connected, power grid stability and power quality improvement and regulating the peak valley difference, the storage system can play an important role, which is also a very active research field in recent years, and its application is more and more widely. In this paper, hybrid energy storage system based on distributed generation is constructed through the application of storage technology, the system topology is designed, the system coordination control strategy is researched, and system software is completed.First of all, the present research situation of the domestic and foreign distributed generation, storage system and typical micro grid structure is analyzed. The hybrid energy storage of lithium battery and super capacitor is selected through study and comparison. The topology of system is designed based on advantages of energy storage laboratory in China Electric Power Research Institute. In paper, each part of the topology is explained in detail.Secondly, in this paper, energy management algorithm and coordinated control algorithm of the multi type energy storage system is studied. Single energy storage and hybrid energy storage coordination control algorithm is declared using typical topology of the system. The smoothing fluctuation algorithm for line power is designed using secondary low pass filter controller and is improved by increasing the limit value management, which improve the service life of the battery. The required power of the energy storage system is calculated by the difference between the actual output and the target power. The charging and discharging power of lithium battery and super capacitor is calculated according to the two stage low pass filter controller and adjusted through the voltage and state of the battery. Different optimization scheduling strategy is developed in grid connected mode, in order to operate the load shift mode, ensuring the stability and security of the system. Due to the state is not suitable to continue to put into use after a long time work, the system should achieve the best state by the implementation of SOC strategy.Thirdly, the system software with functions of remote monitoring, energy management and coordination control is developed through the requirement analysis of multi type energy storage system. This software is developed by C# and SQL Server, and monitors the running status by sending and receiving Modbus message. In this paper, the operating mechanism of software is introduced from data communication, data acquisition, data processing, data display, data storage, event processing, warning and control strategy.Finally, the algorithm of coordinated control presented in this paper is validated by experiment through the system software. In the experiment of smooth fluctuations, the 1 min power fluctuation rate and 10 min power fluctuation rate fall sharply and the SOC of battery and super capacitor does not exceed the limit, which achieve the purpose of prolonging the service life of the battery. In the experiment of track schedule output, tracking control precision and the pass rate has reached the specified index. In the experiment of load shift, the basic control deviation and the SOC of the battery is in a reasonable range. |
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