An Adaptive Virtual Synchronous Generator Based On Multi-Terminal Direct Current

Nowadays,new energies including solar energy and wind energy have been greatly developed,which has effectively alleviated energy pressure and alleviated environmental problems to a certain extent.The proportion of power electronic converter in the power system,however,is increasing.This leads to a decrease of the total inertia of the power system.The stability problem is becoming more and more serious.As a result,virtual synchronous control strategy was proposed,which is trying to simulate synchronous motor rotor inertia and an FM features to make the whole system be more stable in the aspects of the voltage and the frequence.But synchronous motor rotor inertia is constant.This paper proposes an adaptive virtual synchronous control strategy of the virtual rotor inertia by the constant value into adaptive value can change with the system frequency.At the same time,the droop control coefficient changes with the change of frequency in order that the system can control itself more flexibly and be more stable.This paper introduces the background of virtual synchronous machine and its development history and status quo.Then embarks from the contrast synchronous motor,raises the basic principle of virtual synchronous machine.And then we describes several different types of virtual synchronous machine which is commonly used and expound the principle of each virtual synchronous machine control.This paper analyzed the characteristics of different virtual synchronous machine control.Before introducing control methods,we introduced the electric power system about the content of the used in this paper,describes the virtual synchronous machine involved in the basic knowledge of power system,including ac power transmission,active power and reactive power control,the contents of virtual synchronous machine made clear we need to need to solve the problems and challenges.The system level control is introduced,including master control,margin control and droop control.The emphasis is on the introduction of the droop control of the MTDC,including the classification of the droop control and their characteristics.By the preceding foreshadowing,we proposed an adaptive virtual synchronous control strategy which adjust the virtual rotor inertia and droop coefficients based on the system frequency and voltage in order to obtain more stable active power transmission.New England 10 machine 39 node standard test system was built with PowerFactory software.After running the system,the simulation waveform is obtained,and the control method of this paper is analyzed intuitively.Then we use MATLAB software to calculate and process the data.The data is formed into form,which analyzes the virtual synchronous machine control module of the main parameters of the trajectory sensitivity.This paper verify the effectiveness of the adaptive virtual synchronous control strategy.