Renewable energy power plants generally connect to power grid via several step-up transformers,and the electrical connection between renewable energy power plants and power grid is weak,which deteriorates the system stability.There is an urgent need to improve the grid adaptability of renewable energy power plants.In this paper,the impact of voltage feeding mode on inverter stability is analyzed.Based on this,a virtual node voltage feedback(VNVF)control scheme is proposed.In this VNVF control scheme,virtual nodes voltage is calculated by controller,no additional voltage sensor is required.An inner virtual node voltage loop is cascaded inside the current loop to improve voltage control performances.The design method of relevant control parameters from inner loop to outer loop is explained comprehensively step by step.The output impedance model considering frequency coupling effect is also established,and then the stability of the proposed scheme is researched.It can be shown from the experimental results that,the VNVF scheme can not only improve the stability in weak grid,but also has high stability performances in strong grid.It can be concluded that the grid adaptability of inverter is enhanced.
维普
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