Research On Frequency Regulation Of Renewable Energy Generation Participating In Receiving Power Grid

The characteristics of the renewable energy,such as randomness and far away from the load center,provide a serious challenge to the integration and consumption of large-scale renewable energy and the safe and stable operation of the he power system.The voltage source converter based high voltage direct current(VSC-HVDC)has the advantages of rapid inversion of power flow and decoupling control of active power,reactive power,which has provided the feasible solution to the integration and interconnection of cross-regional power networks.With the isolation of VSC-HVDC,power grid from the sending end and that from the receiving end have their own frequencies.For example,in the Zhangbei VSC-HVDC Project in China,the power grid from the sending end can not sense its frequency change and not participate in frequency adjustment in case that the power gird from the receiving end has the frequency shift.With the constant increase of proportion of VSC-HVDC transmission power,the reduction of proportion of synchronous generators in the power gird from the receiving end can decrease the system frequency control ability.Therefore,it is necessary to study the frequency coordination and control strategies for the VSC-HVDC interconnection area.Taking the renewable energy generator as the basic research unit,this paper studies the aspects such as the basic operating principles of the renewable energy generator,the unbalanced power drive-phase response model and coordinated control strategies of renewable energy power generation and VSC-HVDC.In the study of basic operating principles and control strategy of the renewable energy generator,it studies those of the renewable energy generators(double-fed wind generator,photovoltaic power generation)under different structures,including maximum power tracking control strategy;builds the simulation model of wind generator and photovoltaic power generation to study the sub-second power output performance of them.In the kinematical modeling study of renewable energy generator under slow time-scale,the phase motion model of it under slow time-scale can be studied based on multi-time scale feature and typical vector control strategy of renewable energy generator.The dynamic response of renewable energy generator under unbalanced active power drive is built to understand the phase dynamic performance of it in depth,and the influences of different type of renewable energy generators on their incentive response relationship are summarized.The influence of different control parameters and operating conditions on its inertia characteristics are analyzed to provide mechanism explanation and systematic guidance for the design of renewable energy generator actively participating in the grid frequency adjustment control strategy;The active control technology principles of double-fed wind generator,and photovoltaic power generation participating in grid frequency adjustment are studied;The inertia control strategy for double-fed wind generator,and photovoltaic power generation,that is,frequency response strategy based on optimized phase-locked loop dynamic state,is designed.In the study of the inertia control of renewable energy power generation and the coordinated operation control of VSC-HVDC,the technical requirements for coordinated frequency modulation of renewable energy power generation clusters accessing to the VSC-HVDC interconnected areas are studied;In order to make full use of the fast controllability of power electronic converters in renewable energy generators,the coordinated operation control strategies of renewable energy generator,VSC-HVDC and synchronous generator are studied;The validity and feasibility of the control strategy are verified based on time-domain simulation.