Authors:
Xunyu Liu; Xiaotian Xu, Yu Qi Pang, Xinyuan Zhang Pages: 73 - 79 Abstract: In terms of large-scale integration of renewable energy into the grid, DC grid technology has obvious advantages over traditional AC grids. The good operation of a DC grid depends on effective control of power flow distribution. However, the adjustment of the bus voltage and its total power by the converter station alone cannot guarantee the control of all branches of the power grid. Therefore, it is necessary to install a DC power flow controller to achieve a reasonable distribution of line flow. This article is aimed at the multi-terminal DC grid, based on the basic power flow calculation method, considers the influence of the power flow controller on the DC grid power flow calculation and adds the influence to the calculation, changing the power equation or resistance parameters of the line, thereby realizing the power flow calculation The grid power flow calculation of the controller is realized by programming in MATLAB. The proposed calculation method can lay the foundation for the power flow optimization and stable operation of the DC grid. PubDate: 2020-07-29 DOI: 10.12691/ajeee-8-3-1 Issue No:Vol. 8, No. 3 (2020)

Authors:
Xinyuan Zhang; Yuqi Pang, Xunyu Liu, Xiaotian Xu Pages: 80 - 83 Abstract: With the development of the automobile industry, the extensive use of automobiles is a key factor in the global energy crisis and environmental pollution, and the clean and environmentally friendly characteristics of electric vehicles have become an ideal means to deal with these two major problems. Connecting household electric vehicles to the home will not only affect the distribution network, but also adversely affect the home electricity network. Therefore, it is necessary to connect electric vehicles to household charging load for quantitative analysis, so as to design energy control methods for electric vehicles to connect to households, and minimize the adverse effects of electric vehicles connected to household power grids. First of all, this article analyzes the uncertainty of electric vehicle access to the grid. After considering the random characteristics of electric vehicle charging load, an electric vehicle charging load model is built based on Monte Carlo simulation. Secondly, according to the electric vehicle charging load power curve obtained by the above method, combined with the daily load probability model of the grid, a household electricity model is established. Finally, based on the Particle Swarm Optimization(PSO), a family energy control method is proposed, and the optimization goal is to minimize the daily load fluctuation of the family, so as to minimize the impact of electric vehicles connected to the grid. PubDate: 2020-07-29 DOI: 10.12691/ajeee-8-3-2 Issue No:Vol. 8, No. 3 (2020)

Authors:
Xiaotian Xu; Xiao Lv, Xinyuan Zhang, Xiaotian Xu Pages: 84 - 90 Abstract: The remaining capacity of the photovoltaic inverter has achieved good results in solving the problem of the voltage limit of the grid-connected point of the distributed photovoltaic power generation system. But at present, in order to increase the reactive power capacity of the inverter, related research mainly focuses on limiting the power output of the inverter, without considering the impact on the penetration rate of the distributed photovoltaic power generation system. This paper clarifies the mechanism of the voltage limit of the grid-connected point of the distributed photovoltaic power generation system, and proposes a coordinated control strategy for the voltage of the distributed photovoltaic grid-connected point that takes into account the local load. Use back-to-back converters to control the local load reactive power of photovoltaic power generation, and change the output power of photovoltaic power generation by controlling the working status of the grid-connected inverter. Set up the brake control link. When the limit is exceeded, the local load reactive power control will be given priority to adjust the grid-connected point voltage, thereby avoiding the impact on the photovoltaic power generation capacity of the distribution network. Finally, experiments based on Matlab/Simulink simulation platform verify the feasibility and effectiveness of the proposed control strategy. PubDate: 2020-07-29 DOI: 10.12691/ajeee-8-3-3 Issue No:Vol. 8, No. 3 (2020)