Research of hybrid active power filter based on FBD method detection
To fast and effectively detect harmonic current of power system, FBD method is proposed. Compared with method which is based on instantaneous reactive power, FBD method has no complex transformation and transformation, it can be used to detect harmonic current for single-phase, three-phase three-wire and three-phase four-wire system. But FBD method needs a low-pass filter to extract the DC current, it causes delay and phase-shifting problems, to solve these problems, this paper presents a real-time sliding window to extract the DC current instead of low-pass filter. At the same time, shows the principle of hybrid active power filter, and corresponding mathematical model is established. Finally, take a new composite control strategy. Simulation results show correctness of the detection and effectiveness of the new composite control strategy.
A critical overview on zero sequence component compensation in distorted and unbalanced three-phase four-wire systems
The generalized theory of instantaneous powers has been used in power system applications for compensation of instantaneous powers and harmonic cancellation. Nevertheless, this theory results practically desirable solution in three-phase three-wire systems. However, for a three-phase four-wire system, when the power system is unbalanced or distorted, then these definitions introduce unsatisfactory cancellation of the source zero sequence current. This paper analyzes and simulates this problem to show the issues related to the generalized theory of instantaneous powers. Further, complementary analytical discussions are suggested to remedy the raised problem. Finally, the improved definitions are simulated for a three-phase four-wire system that includes significant zero sequence current. Suggested complementary solutions are then compared with those of conventional generalized definitions, which confirm effectiveness of the proposed solutions in cancellation of zero sequence current of the source.
Simulation and control of hybrid renewable energy system connected to the grid
This paper presents a control and simulation of hybrid renewable energy system connected to the grid. The studied system includes a photovoltaic panel, synchronous permanent magnet generator based wind turbine, and a battery for storage energy. The PV array and wind systems are connected to the common DC bus by a boost converter. The battery is connected by a bi-directional DC/DC converter, and then integrated into the AC utility grid via a common DC/AC inverter. In order to extract the maximum energy, a simulation study has been carried out according to the meteorological conditions (wind speed and variable solar irradiance) while maintaining power quality at a satisfactory level. In order to capture the maximum power, a MPPT algorithm is applied for both wind turbine and photovoltaic panel. The modeling and simulation of the whole system has been performed under Matlab/Simulink environment. The obtained results show that the current and the voltage of grid side are sinusoidal and alternative forms, and the power injected to the grid is around the power produced by the hybrid system.