Research Of Energy Storage System And Its Effect On Micro-Grid’s Stability

With the development of new energy power generation and microgrid technology, as well as the urgent requirement of building a harmonious environmental friendly society, more and more new energy power are connected into microgrid. But we need to consider and solve the harmful influence on the microgrid stability caused by new energy power. Energy storage system can provide energy buffer to microgrid quickly, and make the system’s voltage and frequency stable. Energy storage device in the microgrid have a diversity form, flexible installation location. The power storage system can provide certain support for the stable operation of the microgrid under reasonable control. In this thesis, energy storage for island state microgrid to improve the frequency stability of the system has been studied.Firstly, the power controller of energy storage used to apply the PLL method to get the phase angle value for decoupling active and reactive power, but the value is not precise enough and the power calculation is complicated too. This thesis adopt the non PLL method to solve the above problems. And on this basis, a single energy storage power control strategy based on frequency tracking has been established. Through the analysis of simulation results, the proposed energy storage control scheme suppress the frequency fluctuations in the system effectively, and is superior to the traditional control scheme on the improvement of the microgrid’s frequency stability.Then, as more and more new energy generation are connected into microgrid, sometimes the single energy storage scheme is nolonger meet the requirement of microgrid’s power supply quality and stability. Then we need to adopt composite energy storage technology to solve the problem above. In this thesis, we study on the composite energy storage system which is contains battery and super capacitor. And use the fuzzy control strategy to make the battery and capacitor working coordinated. Through the analysis of simulation results, the proposed composite energy storage control scheme can improve the systems’frequency stability, and it is superior to the single energy storage scheme on the improvement of the microgrid’s island frequency stability.Finally, the steps of building a simulation model of microgrid under the MATLAB software and the design of key module has been given in this thesis. At the same time, the thesis also gives the laboratory experimental hardware platform design of the microgrid.