| transfer function,rapid power control strategy of active power command value voltage control VSG under weak grid,through modeling and analyzing active power control strategy studied.First,aiming at the slow response speed of active power ofIn addition,the key technology of dual-mode PV-VSG application and corresponding stable operation of the inverter when the system SCR changes in a wide range.PV-VSG cannot work stably,smoothly switch to voltage control PV-VSG to realize the dual-mode PV-VSG switching are proposed.In the weak grid,when the current control the current solutions are summarized,and therefore,the principle and technology of the D partition method.Aiming at the stable operation range of the dual-mode PV-VSG,is limited in improving the stable operation range when analyzing SCR changes through dual-mode PV-VSG.Especially based on the parameter adaptation scheme,this method using the impedance ratio criterion to analyze the stable operating range of the impedance model,using the D partition method to design the power loop parameters,and current control PV-VSG are elaborated in detail,and by establishing the sequenceSecondly,the topological structure and control strategy of voltage control PV-VSG control strategy are summarized,and the current main research has been focused.of domestic and foreign references,photovoltaic grid-connected,VSG and PV-VSGFirst,the research background and importance of the task are introduced.On the basis research from several aspects.For the purpose of achieving the above objectives,this article mainly conducts range,that is,when the photovoltaic power generation penetration rate varies greatly.operation even when the short circuit ratio(SCR)of the system has a large variation key technology of dual-mode PV-VSG application is studied.In order to achieve stable paper studys dual-mode PV-VSG and its stable operating range.And on this basis,the control PV-VSG,which is of great significance to photovoltaic power generation.This generation system.Similarly,it can be divided into voltage control PV-VSG and current synchronous generator(PV-VSG)refers to the VSG applied in the photovoltaic power voltage control VSG and current control VSG.Among them,the photovoltaic virtual difference of power loop control in VSG control strategy,VSG can be divided into system due to its inertia and frequency modulation characteristics.According to theVirtual Synchronous Generator(VSG)is widely used in distributed power generation feedforward is proposed.The design principle of feedforward coefficient is given.And the strategy is applied to photovoltaic power generation system to study the condition of constant illumination and sudden drop of illumination.At the same time,in order to suppress the drop of DC-side voltage,the power cut-off negative feedback control strategy is superimposed on this basis.Secondly,aiming at the problem of harmonic amplification caused by the pure differential link estimating the grid-side current when the grid voltage harmonic content is large in photovoltaic power generation system,a non-ideal generalized integrator is proposed to replace the differential link,combining the grid-side current estimation with repetitive control.Simultaneously,the principle of parameter design is analyzed,which improves the suppression of grid-side current harmonics without increasing the system cost.Ultimately,the RTLAB hardware in the loop simulation platform and experimental platform with 20 k W inverters are built,and the composition and function of the experimental platform are presented clearly and credibly.The above theoretical analysis and control strategy are verified through experiments.The most important thing is to test and certificate the theoretical analysis and the proposed control method through experiments,and eventually explain the unfinished work of this paper and the content to be improved. |
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