Unified Power Quality Compensator Research Articles

A new-fangled connection of UPQC tailored power device from wind farm to weak-grid

A significant portion of wind power conversion systems worldwide comprise wind farms (WFs) that use Squirrel Cage Induction Generator (SCIG) and are directly linked to the power grid. In facilities that generate electrical energy at a moderate level, WFs are connected by means of distribution systems that use medium voltage (MV). It is not uncommon for such a system to produce a scenario in which the amount of electricity generated corresponds to the grid’s transit volume. When a wind farm’s wind power generation system is connected to a weak grid, the lack of potential control of the Point of Common Coupling (PCC) is a primary issue. This strategy is called a “Wind Farm with Weak Grid Connection.” Therefore, the amalgamation of weak grids, fluctuating electricity from wind, and variations in load on the system cause disruptions in the PCC voltage, further degrading the Power Quality (PQ) and the WF stability. Either the control method at the production level or the compensating strategies at the PCC level can improve this situation. If wind farms are built on SCIG and are directly linked to the grid, it is essential to utilise the last substitute. The technology known as Custom Power Devices (CUPS), proved extremely helpful for this type of application. This study presents a compensation technique based on a specific CUPS device, known as the Unified Power Quality Compensator (UPQC), as a possible solution. The potential terminals of WF needed to be regulated, and the voltage fluctuations on the grid side required to be reduced, so a custom-made control strategy for the UPQC device was designed internally. The control of power, such as active and reactive in the UPQC’s series and shunt converters, as well as the transmission of power via the UPQC DC-Link between converters, are the foundation of the internal control strategy that has been developed. Compared to other bespoke tactics that use reactive power, this strategy increases the UPQC’s capability to provide compensation. The suggested study calculates THD using a FUZZY controller. The results are compared to PI controller results. Simulation findings show how the suggested compensating strategy can minimise THD values and improve wind farm power and stability. The simulations suggest that the proposed compensating strategy enhances WF power and stability.

Power Quality Improvement Using Unified Power Quality compensator

Power quality has become an important factor in power systems, for consumer and household appliances with proliferation of various electric/ electronic equipment and computer systems. The main causes of a poor power quality are harmonic currents, poor power factor, supply voltage variations, etc. In recent years the demand for the quality of electric power has been increased rapidly. Power quality problems have received a great attention nowadays because of their impacts on both utilities and customers. Voltage sag, swell, momentary interruption, under voltages, over voltages, noise and harmonics are the most common power quality disturbances.It proposes a new connection for a unified power quality compensator (UPQC) to improve the power quality of two feeders in a distribution system. It illustrates how UPQC can improve the power quality by mitigating all these PQ disturbances. The proposed configuration of the UPQC is developed and verified for various power quality disturbances by simulating the mode using MATLAB.

AC–DC–AC Single-Phase Multilevel Converters Based on Three-Leg Modules Cascaded-Connected Through Transformers

This article investigates a family of single-phase ac–dc–ac multilevel converters that are capable of mitigating sags/swells and voltage harmonics in the grid supply, ensuring regulated load voltage (with fixed amplitude and frequency), and grid current with high power factor and low harmonic content. Thus, the converters are suitable to operate as a unified power quality compensator or uninterrupted power supply. The proposed topologies are composed of three-leg (3L) modules cascade-connected through transformers at the grid side. From the generalized model presented, topologies with two and three 3L modules are discussed. System equations, PWM strategies, and a control system are developed. Compared with the conventional one, the proposed topologies present better results in terms of harmonic distortions, semiconductor losses, and switching frequencies. Simulation and experimental results in different load conditions are provided to validate the feasibility of the system under grid disturbances and load transients.

Performance of Interline Unified Power Quality Conditioner IUPQC With PI, Fuzzy and ANFIS Controllers

Several artificial intelligent control schemes are highly used in several applications, in that ANFIS controller has been greatly recognized due to enhanced performance over the classical PI and Fuzzy controllers. At present the multi-feeder power distribution system is deteriorated with continuity of supply and poor power quality standards. In this multi-feeder distribution system, it is a regular consumer related issue which is acquired due to malfunctioning of massive non-linear loads. These loads create the voltage or current imperfections on distribution networks which disrupts the power quality of distribution system. An efficient and reliable active compensation scheme is used for attaining enhanced power quality features at PCC of multi-feeder distribution system with effective control functions. The Multi-Feeder Unified Power Quality Compensator (MF-UPQC) is optimal choice for attaining enhanced power quality features and it is a combined shunt or series compensator driven by common DC-link. This paper recommends the Adaptive Neuro-Fuzzy Intelligent Controller (ANFIS) based prediction technique for generation of optimal switching states to enhance performance of proposed MF-UPQC to compensate all voltage-current PQ imperfections. The performance of proposed MF-UPQC is verified by classical PI, Fuzzy and proposed ANFIS control functions by using MATLAB/SIMULINK tool and results are conferred with proper comparisons.

RETRACTED: A reformed adaptive frequency passiveness control for unified power quality compensator with model parameter ability to improve power quality

In semiconductor technology, wide range of nonlinear loads are used in the power system is increased, so this usage of nonlinear loads is produced many power quality problems. Power quality (PQ) is one of the major concerns in Distribution System to increase the sensitivity of current and loads in this system. The quality power is given to the consumers and power supplier with help of power electronics controllers. The solution of the power quality problem of the consumer is used to filtering the hybrid filters, active power filters and passive filters, and this filter is not sufficient to reduce the power quality problem. So new techniques are used to reduce the power quality problem on distribution system and given to the consumers control instruments. In this work, an attempt has been established for selection of custom control device like Unified Power Quality Compensator (UPQC) for the improvement of power quality in manufacturing industries by using Adaptive Frequency Passiveness Control (AFPC) technique. The performance of AFPC technique was validated through Matlab simulation implement with a non-linear load, to compensate line current harmonics under balanced and unbalanced loads. As a result of the simulation, it is found that an AFPC technique is the better way to reduce the total harmonic distortion (THD) of 1.76%.

Power Quality Enhancement in Multi-Feeder Distribution System using Mf-Upqc Device

The significant usage of power semi-conductor devices in modern single or multi-feeder distribution system is increasing a lot in present situation. The non-linear characterization of power distribution is highly responsible for degradation of power-quality standards. The usage of large-sized non-linear loads provokes the harmonic pollution, voltage interruptions, voltage sag/swell issues are the key problems faced by distribution systems. Over the various compensation methodologies, the highly validated universal device is Unified-Power Quality Compensator. The multi-feeder universal devices play a prominent role and provide the attractive performance with improved characteristics in multi-feeder distribution system. In this work, Multi-Feeder UPQC device is used to compensate all voltage and current related PQ issues in multi-feeder distribution systems and also furnishes load-sharing between adjacent feeders, reduce the power-shortages, maximizes the stable performance. The performance evaluation of proposed MF-UPQC is verified under various case studies with the help of Computer-Simulation tool, results are validated with improved PQ features.

A Fuzzy adaptive hysteresis band controller for three phase four wire UPQC

Unified Power Quality Compensator (UPQC) is used to protect the sensitive loads in the distribution system from voltage and current disturbances. The compensation capability of UPQC depends on the control strategies used for shunt and series converters. Conventional adaptive hysteresis controller pulse width modulation technique had failed to track exactly during transient conditions and disturbances at load and source side. In paper fuzzy adaptive hysteresis controller is proposed for three phase four wire UPQC for compensating voltage sag/swell, current harmonics, voltage harmonics and neutral current compensation. Fuzzy adaptive hysteresis controller can effectively compensate the power quality problems during the transient conditions. A comparative simulation analysis of proposed and conventional methods are presented in this paper using MATLAB/SIMULINK tool.

Single‐phase ac–dc–ac topology for grid overvoltage and voltage harmonic mitigation

A single-phase ac–dc–ac topology to improve power quality is proposed in this study. This configuration is obtained from the addition of a floating capacitor H-bridge converter on the grid side of the conventional ac–dc–ac three-leg topology. The role of the structure is not only to ensure regulated load voltage with fixed amplitude and frequency, grid current with low harmonic content and unitary power factor, but also to mitigate fundamental overvoltage and voltage harmonics at the grid. As a consequence, the proposed topology is suitable to operate as unified power quality compensator or uninterrupted power supply. It does not use isolation transformer and is capable of generating multilevel input voltages due to the cascaded H-bridge. The operation with asymmetrical dc-link voltages is considered to increase the number of voltage levels and reduce the harmonic content of the generated input voltages. Two pulse-width modulation techniques and a control system are developed to regulate the dc-link voltages and to decrease the harmonic distortion (HD), lowering the switching stress and also the power losses. The proposed configuration is compared with the conventional one with respect to HD and semiconductor losses. Simulated and experimental results are presented for validation purposes.

Method for Enhancement of Power Quality at Point of Common Coupling of Wind Energy System

In this paper a compensation strategy based on a particular Custom Power System (CUPS) device, the Unified Power Quality Compensator (UPQC) has been proposed. A customized internal control scheme of the UPQC device was developed to regulate the voltage in the WF terminals, and to mitigate voltage fluctuations at grid side. The voltage regulation at WF terminal is conducted using the UPQC series converter, by voltage injection “in phase” with point of common coupling (PCC) voltage. On the other hand, the shunt converter is used to filter the WF generated power to prevent voltage fluctuations, requiring active and reactive power handling capability. The sharing of active power between converters is managed through the common DC link. Therefore the internal control strategy is based on the management of active and reactive power in the series and shunt converters of the UPQC, and the exchange of power between converters through UPQC DC–Link. This approach increases the compensation capability of the UPQC with respect to other custom strategies that use reactive power only. The proposed compensation scheme enhances the system power quality, exploiting fully DC–bus energy storage and active power sharing between UPQC converters, features not present in DVR and D–STATCOM compensators. Simulations results show the effectiveness of the proposed compensation strategy for the enhancement of Power Quality and Wind Farm stability.