Liu Hui-jin

Power quality disturbances detection and location using mathematical morphology and complex wavelet transformation

Bused on mathematical morphology (MM) and complex wavelet, a novel method on power quality (PQ) disturbance detection and location is presented in this paper. At first, a generalized morphology filter with horizontal linear structure elements is designed to filter impulses and random white noises in PQ disturbance signals. Numerical simulation results show that the characteristics of the original signal can be well retained and the noise interferences are suppressed effectively with the proposed filter method. Then, to the filtered results, the complex wavelet derived by Daubechies real wavelet and its compound information are applied to detect and locate the start and end time that the disturbance occurs. The voltage interruption, voltage sag, voltage swell, high frequency oscillation and harmonic distortion are used to verify the validity of the filter-location approach. Simulation results show the integrated detection approach of morphology-complex wavelet is valid and effective. Besides, it can reduce calculation time and can be implemented easily in the available hardware.

Analysis of the optimal transmission capacity and bundle proportion of wind power combined with thermal power based on multi-objective optimization decision-making

This paper presents a planning method for thermal power that is combined with wind power to get the optimal transmission capacity and bundle proportion of wind power and thermal power. At first, a comprehensive index system is established which takes into account the power demand, level of safety and stability, economy of the receiving system, transmission price and etc. Then these factors are defined as the objectives of the mathematical model with multi-objective function. The non-dominated sorting genetic algorithm-II (NSGA-II) is applied to solve this multi-objective model. After obtaining the non-inferior solutions of the model, the optimal compromise solution is determined by the fuzzy membership function. The proposed scheme can obtain the optimal transmission capacity and also can guarantee the stability of the receiving power system. The simulation is conducted on the IEEE-9 system and the results verify the validation of the method.

Port Controlled Hamiltonian modeling and periodic adaptive L2 disturbance attenuation control algorithm for Active Power Filter

The paper proposes a novel periodic adaptive L2 disturbance attenuation control algorithm for APF based on the averaged Port Controlled Hamiltonian (PCH) model. Based on the energy-dissipative property of APF state equations, the averaged PCH model in the d–q rotating frame with periodic disturbances, aperiodic disturbances and parametric perturbations is first established. The averaged PCH model of error system is further derived in terms of energy balance. Then, the influence of parametric perturbations can be converted into part of periodic disturbances and periodic adaptive L2 disturbance attenuation control algorithm is designed to suppress tracking errors resulted from parametric perturbations and disturbances: The periodic adaptive control compensates periodic disturbances, while the L2 disturbance attenuation can be used to stabilize the error system, ensure the convergence of periodic adaptive control and suppress other aperiodic disturbances. In addition, according to the demand in practical implementation, the proposed control algorithm is modified by ignoring the ripple component on dc-side capacitor reference voltage. Experimental results verify the validity of the proposed algorithm.