Research And Application Of Electric Spring In Microgrid

Global crises such as resource shortages,environmental pollution,and ecological damage have forced human beings to pursue cleaner and more efficient power sources,and new energy power generation has emerged.As the penetration rate of new energy power generation increases year by year,the intermittentness and uncertainty caused by its own greater natural environment will inevitably lead to the unpredictability of new energy power generation,and the resulting voltage fluctuations will have an increasingly significant impact on the stability of microgrid systems.The proposed electric spring provides a new demand-side response solution to solve the above problems,and this paper studies the electric spring,and the main work content is as follows:(1)The working principle of electric springs and their working conditions,mathematical models and control principles in theory and practice are analyzed in detail,and the topological development of AC electric springs and DC electric springs and common control strategies are briefly introduced.(2)Focusing on the topology and working principle of AC-AC based active electric spring,the problem of slow response speed and large overshoot of ACAC based active electric spring PI control is proposed,and the parameter selfoptimization fuzzy PID control based on the improved particle swarm optimization algorithm is proposed.The improved particle swarm optimization algorithm overcomes the shortcomings of fuzzy control over-dependence on expert experience to achieve self-optimization of fuzzy control input quantization factor and output scale factor.The introduction of Cauchy variation and Gaussian variation to mutate particles with a large degree of similarity makes it difficult for the improved particle swarm algorithm to fall into the local optimal solution;and the particle swarm algorithm is improved into an online calculation to achieve the purpose of real-time tuning;the speed and position of the particles are updated by using the optimal solution of each generation and the optimal solution of each generation,and in order to make the final output result more representative,the three particles with the best adaptability in each generation of particles are synthesized into the optimal solution of each generation in the proportions of 70%,20%,and 10%,respectively.The three generations with the best adaptability in each generation of optimal solution are combined into a ten-generation optimal solution at a ratio of 70%,20%,and10% every ten generations.Simulation experiments show that the control strategy has a better control effect than the original PI control.(3)The new interleaved parallel two-way DC/DC converter is applied to the electric spring device to form a new DC electric spring,the working principle of the new DC electric spring is analyzed in detail,and the multi-PI control strategy of inner ring plus outer ring is designed.Simulation experiments verify that the new DC electric spring can achieve the function of stabilizing voltage.(4)The relevant applications of electric springs in microgrids involved in voltage compensation and frequency adjustment,treatment of three-phase imbalance,and cooperation with energy storage devices are summarized.