Dual closed loop structure is often adopted in VSC-HVDC control system, and the PI controller design and parameters tuning can be regarded as the core content in the control system design. This paper first designs the inner current loop follow three methods: typical I-type, typical II-type and second-order system, designs outer voltage loop under the low-frequency model, and then the step response and dynamic performance under different methods is analyzed through simulation. In order to improve the system stability, a novel strategy is also proposed for the outer voltage loop based on cutoff frequency and phase margin. Simulation is carried out to testify the feasibility of this strategy and shows that the PI parameters tuned by this method can drop into the actual value range, and the system's performance can be satisfied, which proves the correctness of this novel strategy.

Research on PI controller tuning for VSC-HVDC system

The PI parameter setting of double closed-loop vector control of voltage source PWM rectifier is very important and largely depending on experience with few references available. In this paper, the influence of the PI parameters on the output dc voltage waveform of the rectifier is studied by simulation in Matlab/Simulink, based on which a simple and step-by-step method for the PI parameter setting is proposed. Some examples are given to illustrate the application and effectiveness of this method.

A parameter setting method for double closed-loop vector control of voltage source PWM rectifier

In order to quicken the dynamic response and strengthen the ability against the disturbance of nonlinear load, three-phase voltage source PWM rectifier widely employs dual loop PI control scheme which consists of inner current controller and external voltage controller. The parameters of dual loop PI regulators have significant influence on the dc-link voltage, AC harmonic components and power factor of three-phase voltage source PWM rectifier. The design of dual loop PI regulator parameters is a very important, complicated and empirical work. With the simulation tool of Matlab/Simulink, this paper analyzes the influence of different dual loop PI regulator parameters on the operating characteristics of three-phase voltage source PWM rectifier. Based on that, a adjustment approach of dual loop PI regulator parameters which is simple and convenient is proposed. The simulation results show the effectiveness and feasibility of the proposed approach.

The design and analysis of the pi regulator of three-phase voltage source PWM rectifier

The design of PI controller plays a significance role in the realization of wind generator system. Recognizing the state-of-art of the control strategy the permanent magnet synchronous generator (PMSG) for wind power generation is designed with different subsystems with different reference, and neglecting the mutual influence between the grid and machine sides PWM control and coordinated with PI parameter coordinated with field test. This paper provides a unified model, which present a systematic viewpoint to the different PI controllers with the same reference. The mathematical description for the grid side converter with PI controller (GCC) and the machine side converter with PI controller (MCC) in the same reference is involved in the proposed model. The model describes the general PMSG system with PI controllers as a differential algebraic equation. Based on the proposed model, the method to determine the coordinated parameter is presented. The RTDS simulation results show the effectiveness of the proposed model and method.

https://ieeexplore.ieee.org/iel5/5980617/6000362/06000802.pdf

Unified model for coordinated control of permanent magnet synchronous wind generator system

Three-phase voltage source PWM rectifier can attenuate high frequency harmonics effectively with LCL-filter which has the advantages such as smaller inductance and less output current’s THD in contrast with traditional L-filter, and suitable for medium and high power applications. In this paper, mathematical model of PWM rectifier with LCL-filter is analyzed and dual closed-loop control structure of inner current loop and outer voltage loop is designed, then the LCL-filter‘s parameters are analyzed and designed. At last, a simulation model of the rectifier is established; the simulation results show that the grid-side currents have lower harmonic distortions and the rectifier runs at high power factor, which verify the validity of the proposed method.

Simulation of Three-Phase Voltage-Source PWM Rectifier with LCL Filter

Based on simplified mathematic model of PWM rectifier with d-q rotation frame, input current is decoupled by introducing PI regulator and power network voltage. The voltage loop and current loop voltage are built. The close-loop transfer functions of voltage and current are gained by simplifying the different loops. PI parameters of current and voltage loops are designed. Amplitude, phase and frequency characteristic of close-loop regulator system are analyzed. The simulation results by MATLAB and the experimental curves are also given.

LI He-ming

Papers

PI regulator and parameter design of PWM rectifier