Four-wire Power Distribution System Research Articles

Experimental Validation of Photovoltaic System with Isolated Dual Inductor dc-dc Converter for Grid-Connected Application

Abstract This article presents a double inductor–based converter for a grid-connected photovoltaic (PV) system with the utilization of the battery bank. This converter used to give continuous power to the three-phase four-wire power distribution system from the PV array. In order to increase the low magnitude of the PV array output voltage into a high dc voltage required for the three-phase dc link, the proposed system offers two boost stages. The double inductor–based converter gives power to the load in both the switched ON and OFF conditions of the chopping switch over buck, boost, and Cuk converters utilized in the PV-coordinated grid-connected applications. The operations of the proposed double inductor–based converter sustained three-phase four-wire power distribution system are analyzed and presented. The digital simulation and hardware experimental prototype results are presented to examine the performance of the presented double boost converter fed to the three-phase four-wire power distribution system.

Real-Time Load Balancing and Power Factor Correction of Three-Phase, Four-Wire Unbalanced Systems with Dstatcom

This paper presents the design and implementation of a distribution- level static synchronous compensator (DSTATCOM) used for the real-time load compensation of three-phase, fourwire power distribution systems with unbalanced loads. First, use of the symmetrical components method derives a feedforward compensation scheme for the DSTATCOM. The system block diagram of the DSTATCOM is then built. A computer simulation is performed for preliminary verification. Finally, a hardware prototype is built using a TMS320C6711-based controller. Experimental results verify the functionality of the DSTATCOM.

Integral‐resonant control for stand‐alone voltage source inverters

This study deals with a newly-conceived voltage control method for three-phase four-leg voltage source inverters (VSIs) which are being required in autonomous power generating units devoted to supply both three-phase and single-phase electrical loads in four-wire electric power distribution systems. To deal with VSI operating conditions providing three-phase voltage supply of both unbalanced loads and non-linear loads, an integral + resonant (I + R) voltage control structure is discussed and experimentally verified by means of a 25 kVA rated power converter prototype. It is shown that the proposed voltage control allows simplifying the overall control configuration, achieving zero-overhead power factor regulation and fast compensation of load unbalances. Further to that, a complete current limiting strategy is described and tested under different load conditions.

Comparison of Three leg and Four Leg VSC DSTATCOM for Power Quality Assessment

A new three-phase four-wire DSTATCOM (distribution static compensator) based on three-leg VSC (voltage source converter) and a star/delta transformer is proposed for power quality improvement. The star/delta transformer connection mitigates the neutral current and the 3-leg VSC compensates harmonic current, reactive power and balances the load. Three single phase transformers are connected as star/delta transformer for interfacing to a three phase four-wire power distribution system and the required rating of the VSC is reduced. However, a 4-leg VSC (voltage source converter) based DSTATCOM (Distribution Static Compensator) is used for the load compensation and neutral current compensation in 3-phase 4-wire distribution system. For extracting the reference source currents, Instantaneous Symmetrical Component Theory (ISCT) based control algorithm is modified for voltage regulation and used with indirect current control technique for controlling the DSTATCOM currents. The DSTATCOM is controlled for power factor correction and voltage regulation at PCC (point of common coupling). Simulations are performed for various load conditions such as a reactive linear load, an unbalanced load and a non-linear load in Power Factor Correction (PFC) mode and in Zero Voltage Regulation (ZVR) mode in MATLAB environment using SIMULINK and Sim Power System (SPS) toolbox.

Three-phase four-wire hybrid power filter using a smaller power converter

In this paper, a hybrid power filter is proposed to solve problems of line harmonic currents and neutral line currents of three-phase four-wire power distribution system. This hybrid power filter is configured by a there-phase tuned power filter and a three-phase power converter. The tuned power filter is configured by a capacitor and an inductor, and its tuned frequency is setting at the frequency of third-order harmonics. The three-phase power converter has a four legs bridge structure and is connected to the inductor of the tuned power filter in parallel. The three-phase power converter is applied to solve the problems of series/parallel resonance and improve poor filter performance. Furthermore, it also forces the fundamental current of the tuned power filter and the dominant harmonic current of the nonlinear load to flow through the inductor of the tuned power filter. In this way, the voltage rating of the three-phase power converter is reduced because it is serially connected to the power capacitor of the tuned power filter, and the current rating can be diminished because it is connected to the inductor of the tuned power filter in parallel. Hence, the power rating of the power converter applied in the proposed hybrid power filter is minimized. A DSP based prototype is developed and tested to verify the performance of the proposed three-phase four-wire hybrid power filter. Experimental results show that the proposed three-phase four-wire hybrid power filter achieves the expected performance.

Characteristics Analysis of Voltage Sag and Voltage Swell in Multi-Grounded Four-Wire Power Distribution Systems

Characteristics Analysis of Voltage Sag and Voltage Swell in Multi-Grounded Four-Wire Power Distribution Systems

Star-hexagon transformer and non-isolated three-leg VSC based three-phase four-wire DSTATCOM

A new three-phase four-wire DSTATCOM (distribution static compensator) is proposed for power quality improvement in the distribution system. The DSTATCOM is based on a star/hexagon transformer and three-leg VSC (voltage source converter). It compensates harmonic current, reactive power and balances the load along with neutral current compensation. Each of the three single phase transformers has three windings and the secondary windings are connected in star/hexagon configuration for interfacing to a three-phase four-wire power distribution system. The IGBT (insulated gate bipolar transistor) based VSC is a capacitor supported and it is controlled for the required compensation of load currents. The DC bus voltage of the VSC is regulated even during dynamic load variations. The DSTATCOM is tested for power factor correction and voltage regulation along with neutral current compensation, harmonic elimination and load balancing under linear loads as well as non-linear loads. The performance of the three-phase four-wire DSTATCOM is validated using MATLAB software with its Simulink and SimPower System (SPS) tool boxes.

A T-Connected Transformer and Three-leg VSC Based DSTATCOM for Power Quality Improvement

In this paper, a new three-phase four-wire distribution static compensator (DSTATCOM) based on a T-connected transformer and a three-leg voltage source converter (VSC) is proposed for power quality improvement. The T-connected transformer connection mitigates the neutral current and the three-leg VSC compensates harmonic current, reactive power, and balances the load. Two single-phase transformers are connected in T-configuration for interfacing to a three-phase four-wire power distribution system and the required rating of the VSC is reduced. The insulated gate bipolar transistor (IGBT) based VSC is supported by a capacitor and is controlled for the required compensation of the load current. The DC bus voltage of the VSC is regulated during varying load conditions. The DSTATCOM is tested for power factor correction and voltage regulation along with neutral current compensation, harmonic elimination, and balancing of linear loads as well as nonlinear loads. The performance of the three-phase four-wire DSTATCOM is validated using MATLAB software with its Simulink and power system blockset toolboxes.

Mitigation of third‐harmonic voltage for three‐phase four‐wire distribution system based on a series active filter for neutral conductor

AbstractThis paper proposes a series active filter for mitigation of the third‐harmonic voltage in a three‐phase four‐wire power distribution system in a building. The active filter which consists of a single‐phase inverter can suppress the harmonic voltage of the system. The active filter is characterized by acting not only as a capacitor but also as a resistor for the third‐harmonic components. A Hilbert transformer is applied to the controller of the active filter in order to realize accurate third‐harmonic detection on a single‐phase active filter. Measurement results of harmonic distortion of source voltage in a building is also shown in this paper. It is clarified in a simulation and experiment that the active filter can suppress the third‐harmonic voltage without increasing neutral conductor current. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(1): 62–70, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10379

Harmonic elimination, reactive power compensation and load balancing in three-phase, four-wire electric distribution systems supplying non-linear loads

In this paper, a new control scheme of a three-phase active power filter (APF) is proposed to eliminate harmonics, to compensate reactive power and neutral currents and to remedy system unbalance, in a three-phase four-wire electric power distribution system, with unbalanced non-linear loads. The APF is realized using three single phase IGBT based PWM-VSI bridges with a common dc bus capacitor. A hysteresis rule based carrierless PWM current controller is used to derive gating signals for the IGBTs. Three-phase balanced reference supply currents are estimated using load currents, dc bus voltage and supply voltages. The reference currents of the APF are derived by taking the difference of corresponding reference supply current and load current. The APF forces the compensating currents to conform to the desired reference currents. The APF is found effective to compensate reactive power and neutral current while eliminating harmonics with load balancing.

THREE-PHASE COMPENSATOR FOR LOAD BALANCING AND REACTIVE POWER COMPENSATION IN THREE-PHASE, FOUR-WIRE ELECTRIC POWER DISTRIBUTION SYSTEMS

This paper deals with a three-phase active power compensator (APC) to compensate reactive power and to balance unbalanced loads in the three-phase four-wire electric power distribution system. An APC is realized employing three single phase IGBT based VSI bridges with a common dc bus capacitor. Reference supply currents are estimated using P-I control over the average dc bus voltage and three-phase supply voltages. APC reference currents are derived from reference supply currents and load currents. A hysteresis rule based carrierless PWM current control is used over compensating currents of the APC and its derived reference currents. Simulated performance of the APC for the single phase, two-phase and three-phase lagging power-factor loads is illustrated to demonstrate the reactive power compensation and load balancing features of the APC.

The Inductive Coordination of Common-Neutral Power Distribution Systems and Telephone Circuits*

Early installations of three-phase, four-wire power distribution systems of the multi-grounded or common-neutral type in some cases created noise problems involving neighboring telephone circuits. Operating experience, studies of specific situations and comprehensive cooperative research over a period of years have developed means of largely avoiding difficulties of this character. The relative importance of various features of the power and telephone systems which have been found to affect the noise induction problems involved is discussed and the general cooperative procedures, most helpful in conversions to or extensions of these types of power distribution systems, are outlined.