Research On Starting And Grid Connection Technology Of Static Frequency Converter For 300Mvar Synchronous Condenser

In modern power grid regulation,large-scale synchronous Condenser can not only quickly and flexibly realize load dynamic change tracking,peak load shaving and valley filling,frequency modulation,phase modulation,accident reserve and other functions,but also save energy and no pollution.With the construction of smart grid and the development of new energy,large-scale synchronous Condenser still has great potential in China.At present,as the main starting mode of synchronous Condenser,static frequency conversion starting mode has the advantages of soft starting,frequent starting,wide speed range and so on.It has great research significance.The main work of this paper is as follows:(1)This paper focuses on the start and grid connection of static frequency converter of synchronous Condenser.Firstly,the principle of static frequency converter is studied,and the topology of static frequency converter is analyzed.The working principle of natural and intermittent commutation of back EMF of static frequency converter is described in detail.Secondly,the mathematical model of the Condenser and the starting system of the Condenser are analyzed.The corresponding motor model and control system model are built in MATLAB / SIMULINK,and the starting process is simulated.(2)For the rotor position detection of synchronous Condenser,the rotor position detection method is divided into four stages: initial,0-0.5 Hz,0.5-5 Hz,greater than 5 Hz.The first three small stages are generally referred to as the low speed stage,and the 5Hz stage is called the high speed stage.According to the characteristics of the back EMF in each stage,the corresponding algorithm is adopted to solve the rotor position detection problem.Simulation verification is carried out in MATLAB/SIMULINK and verification test is carried out in the manufacturing plant.The concept of flexible switching is introduced to realize the flexible switching between the low-speed model and the high-speed model.(3)In view of the grid-connected problem of synchronous Condenser after starting,the corresponding control strategy of falling speed grid-connected is put forward.The degradation rate and the impact of the corresponding degradation rate are analyzed,and the possibility of the theoretical synchronization point is calculated.The process of grid-connected is simulated and analyzed on RTDS platform,and the change curve of relevant parameters at the moment of grid-connected is given,which verifies the feasibility of the control strategy of declining speed grid-connected.