| In recent years, as a higher requirement of social development for electric energy and depletion of traditional fossil energy, a growing number of nations, enterprises and researchers fall in favor of renewable energy sources with a series of virtues, such as widely distributed, pollution-free, recycling. But compared with fossil energy, there are some disadvantages for power generalized from renewable sources, intermittence, instability, low density, changing with time and season, and so on. With the increasing of the proportional of electric power produced from renewable sources in power system, the above shortcomings of renewable sources will bring negative effects to the normal operation of power system. To overcome the above shortcomings of renewable sources, after researchers’numerous researches, a great number of solutions have been proposed. A main developing and research trend of the above solutions is that, before electric power produced from renewable sources being connected to power grid, an energy storage system is matched with distributed renewable energy generation. This energy storage system can provide energy relieving, power balance and back-up power for generation system of renewable energy to solve the problem of intermittent power generation. Lots of researches have shown that, matching an energy storage system with distributed generation of renewable energy is the best way to solve the problem of intermittent power generation. Based on the research results of projects, this paper researches the modeling and control of the energy storage systems of wind power generation systems and solar power generation systems. Main work of this paper includes:(1) A hybrid energy storage system based on triple-ports bidirectional DC/DC converter is proposed. This system, mainly used to the management of dual energy sources, not only can reduce the number of converters and decrease the cost of energy management but also can achieve efficient centralized control of energy. Based on the research of topologies and their characteristics of power conversion systems (PCS) of numerous storage systems, a modular topology of PCS of storage systems is put forward. This modular topology can well achieve organic combination of triple-ports bidirectional DC/DC converter with whole bridge structure and PWM inverter. Additionally, by analyzing the equivalent circuit of topology structure of triple-ports DC/DC converter, the mathematical model of the converter based on state space average method is constructed, and the coupling relationships between different ports of the converter input variables are decoupled. Meanwhile, the double closed-loop control system of converter is designed, and phase-shifted PWM controlled strategy was adopted to realize the energy complementary control of dual power supply composed of battery and super capacitor.(2) The application of hybrid energy storage model in renewable energy generation system is put forward. The above-mentioned hybrid energy storage model is constructed by lithium battery and super capacitor. Due to the complementary advantages of lithium battery and super capacitor in energy density and power density, the above hybrid energy storage can improve energy stability and fast response capacity of grid systems. Unscented kalman filter (UKF) is selected as evaluation tool to assess the state of charge (SOC) of lithium battery and super capacitor. Meanwhile, the equivalent circuit of lithium battery and super capacitor, and the influence factors and parameter recognition methods of mathematical modeling, is analyzed in this part. Based on the results of the above analysis, implementation process, influence factors of estimation accuracy and configuration of system volume parameters of SOC is analyzed.(3) The mathematical modelings of wind power generation system and sober power generation system is constructed, and power compensation of storage system is simulated. The influence of moment of inertia of generator, stiffness factor of shafting, damping coefficient and fans on the instantaneous response ability to wind power system is improved and verified. To make sure that photovoltaic power generation system obtains the highest possible power, the mathematical model of photovoltaic ("PV") battery of photovoltaic power generation system and maximum power point tracking algorithm of photovoltaic array is researched. Finally, with the dynamic model of power system, the improve effects of storage system on the bus voltage and frequency of power grid is analyzed in confirmatory simulation study.(4) An experimental platform applied to simulate power grid is constructed. This platform, composed of wind power generation simulation system, photovoltaic distributed power generation simulation system and storage system, is used to test the application of triple-ports bidirectional DC/DC converter in energy management of dual energy sources. The climate data is applied to predict the data of wind power generation and photovoltaic power generation, which will be used as simulating output power in the process of control of grid-connected inverter to entering orders of wind power generation and photovoltaic power generation. The impacts of the above simulating output power on the realization of storage system in wind power generation system and photovoltaic power generation system, such as energy relieving, power complementary, back-up electric power, is verified. |
PDF Full Text Request