The Application of Auto-Disturbance Rejection Control Optimized by Least Squares Support Vector Machines Method and Time-Frequency Representation in Voltage Source Converter-High Voltage Direct Current System.

Liu YP, Liang HP, Gao ZK - PLoS ONE (2015)

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pone.0130135.g002: The ADRC controller diagram for the constant DC voltage control.
Mentions: In order to improve the system response speed, the TD part in ADRC controller is ignored in this paper. In the rectifier side for VSC-HVDC system, according to the mathematic model shown in Eqs (13) and (14), the ADRC controller for DC voltage loop is designed with the input signal of and the output signal of the given d-axis component . The ADRC controller diagram is shown in Fig 2. Its working principle is as follows: In accordance with the above ADRC theory, the output signals of ESO are z1 and z2, where z1 is the tracking signal of the actual DC voltage value UDC, and z2 is the estimated value of the system disturbance. Then we can get the error between the given DC voltage value and its actual value UDC. With this error as the input signal of NLSEF, and substitute it into the mathematical model of NLSEF shown in Eq (14), we can get the initial control signal from NLSEF which is u0. After that, with the feedforward compensation of the estimated disturbance z2, the control signal of ADRC can be obtained.

Bottom Line: Firstly, we deduce the high frequency transient mathematical model of VSC-HVDC system.We ignore the tracking differentiator in the ADRC controller aiming to improve the system dynamic response speed.On this basis, we derive the mathematical model of ADRC controller optimized by LSSVM for direct current voltage loop.

View Article: PubMed Central - PubMed

Affiliation: School of Electrical and Electronic Engineering, North China Electric Power University, Baoding, Hebei Province, 071003, China.

ABSTRACT
In order to improve the performance of voltage source converter-high voltage direct current (VSC-HVDC) system, we propose an improved auto-disturbance rejection control (ADRC) method based on least squares support vector machines (LSSVM) in the rectifier side. Firstly, we deduce the high frequency transient mathematical model of VSC-HVDC system. Then we investigate the ADRC and LSSVM principles. We ignore the tracking differentiator in the ADRC controller aiming to improve the system dynamic response speed. On this basis, we derive the mathematical model of ADRC controller optimized by LSSVM for direct current voltage loop. Finally we carry out simulations to verify the feasibility and effectiveness of our proposed control method. In addition, we employ the time-frequency representation methods, i.e., Wigner-Ville distribution (WVD) and adaptive optimal kernel (AOK) time-frequency representation, to demonstrate our proposed method performs better than the traditional method from the perspective of energy distribution in time and frequency plane.

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