THE UNIFIED POWER QUALITY CONDITIONER: A REVIEW

This thesis addresses the Unified Power Quality Conditioner (UPQC) which is a major custom power solutions capable for load balancing, power factor-correction, voltage regulation, voltage and current harmonics mitigation in a three-phase three-wire distribution system for different combinations of linear, non-linear and dynamic loads. The unit template technique (UTT) is used to get the reference signals for series active power filter and shunt active power filter which utilizes two closed loop PI controllers. The design of three- phase three-wire UPQC includes the design of shunt controller (SHUC) and series controller (SERC).

ANALYZE THE EFFECT OF TIME DELAY ON THE STABILITY OF HYBRID ACTIVE POWER FILTER

Hybrid Active Power Filter (HAPF) has highly effective in improving the power quality of power system. In this paper, a stable analysis of HAPF considering the time delay was made. The mathematical model of HAPF with time delay has been established. Based on that, the stable domain of the HAPF parameters was determined based on the Routh’s stability standard. Simulation results based on Matlab software have shown that: time delay has a marked impact on the stability of the HAPF system. This research has practical significance in the design and control of HAPF in real system.

Harmonic suppression compensation of photovoltaic generation using cascaded active power filter

The wide spectrum of electromagnetism that explains current and voltage at specific time and location in a power system is referred to as power quality. Alternative energies are becoming more popular due to concerns about power quality, safety, and the environment, as well as commercial incentives. Moreover, photovoltaic (PV) energy is one of the most well-known renewable resources since it is free to gather, unlimited, and considerably cleaner. Active power filter (APF) is an effective means to dynamically suppress harmonics and solve power quality problems caused by the DC side voltage fluctuation. Therefore, this paper describes a substantial advancement in the harmonic suppression compensation algorithm, as well as the cascaded active power filter. Also, this paper focuses on compensating the error of photovoltaic grid-connected generation based on optimized H-bridge cascaded APF. The details of the working principle and topological structure of the APF used as the compensation device are analyzed. The H-bridge cascaded APF is optimized using the segmented variable step-length conductance increment (SVSLCI) algorithm. The overall cascaded APF control strategy is designed and simulated using MatLab/Simulink environment. By the simulation results comparing the existing traction network power quality control measures, before and after compensation, the effectiveness of the proposed control strategy is verified. The proposed controller strengthens the compensation of specific odd harmonics to improve the system work models and criteria to improve power quality. Moreover, the proposed algorithm showed positive significance for optimizing the quality of photovoltaic grid-connected power, reducing the current harmonic, and improving the equipment utilization of photovoltaic inverters.

Intelligent Fault-Tolerant Control for AC/DC Hybrid Power System of More Electric Aircraft

This paper presents a novel intelligent fault-tolerant control method for a kind of more electric aircraft AC/DC hybrid electrical power system, in order to ensure the safe operation of the engine and improve the power supply quality. The more electric aircraft electrical power system was combined with an aircraft engine, two generators, two AC/DC rectifiers, two DC/AC inverters, DC loads, and AC loads. A multi-objective optimization intelligent sliding mode fault-tolerant controller was obtained for aircraft engine with actuator faults. Each of AC/DC rectifiers is 12-pulse autotransformer rectifier unit with active power filter. Active power filter was used to realize the desired performance of DC bus. Intelligent fractional order PI controller is presented for AC/DC rectifier by considering multiple performance indexes. In order to guarantee the AC-side has satisfying voltage, current, and frequency, no matter the sudden change of AC load that happens or DC/AC fault that occurs, the virtual synchronous generator control method was used for DC/AC inverters. Simulation results verify the effective of the proposed more electric aircraft AC/DC hybrid electrical power system.