Bio: M.T. Haque is an academic researcher from University of Tabriz. The author has contributed to research in topics: AC power & Compensation (engineering). The author has an hindex of 1, co-authored 1 publications receiving 88 citations.
••07 Nov 2002
TL;DR: The theory of instantaneous reactive power compensation of single-phase circuits is presented in this paper, which is a general case of well-known pq theory and it is usable in single phase as well as three phase circuits.
Abstract: The theory of instantaneous reactive power compensation of single-phase circuits is presented. This theory is a general case of well-known pq theory and it is usable in single-phase as well as three-phase circuits. A new definition of instantaneous active and reactive powers in single-phase circuits that is based on space vector concept is also presented. The principle of operation is explained using analytical analysis. The validity of the presented method and its comparison with original pq theory is studied through simulation results.
TL;DR: In this article, the LVRT capability of three mainstream single-phase transformerless PV inverters under grid faults is explored in order to map future challenges, and control strategies with reactive power injection are also discussed.
Abstract: Transformerless photovoltaic (PV) inverters are going to be more widely adopted in order to achieve high efficiency, as the penetration level of PV systems is continuously booming. However, problems may arise in highly PV-integrated distribution systems. For example, a sudden stoppage of all PV systems due to anti-islanding protection may contribute to grid disturbances. Thus, standards featuring with ancillary services for the next-generation PV systems are under a revision in some countries. The future PV systems have to provide a full range of services as what the conventional power plants do, e.g., low-voltage ride-through (LVRT) under grid faults and grid support service. In order to map future challenges, the LVRT capability of three mainstream single-phase transformerless PV inverters under grid faults is explored in this paper. Control strategies with reactive power injection are also discussed. The selected inverters are the full-bridge (FB) inverter with bipolar modulation, the FB inverter with dc bypass, and the Highly Efficient and Reliable Inverter Concept (HERIC). A 1-kW single-phase grid-connected PV system is analyzed to verify the discussions. The tests confirmed that, although the HERIC inverter is the best candidate in terms of efficiency, it is not very particularly feasible in case of a voltage sag. The other two topologies are capable of providing reactive current during LVRT. A benchmarking of those inverters is also provided in this paper, which offers the possibility to select appropriate devices and to further optimize the transformerless system.
04 Jul 2010
TL;DR: In this article, a single-phase inverter for distributed generation systems requiring power quality features, such as harmonic and reactive power compensation for grid-connected operation, is proposed, where the inverter controls the active power flow from the renewable energy source to the grid and also performs the nonlinear load current harmonic compensation keeping the grid current almost sinusoidal.
Abstract: Power electronic converters are commonly used for interfacing distributed generation systems to the electrical power network. This paper deals with a single-phase inverter for distributed generation systems requiring power quality features, such as harmonic and reactive power compensation for grid-connected operation. The idea is to integrate the DG unit functions with shunt active power filter capabilities. With the proposed approach, the inverter controls the active power flow from the renewable energy source to the grid and also performs the non-linear load current harmonic compensation keeping the grid current almost sinusoidal. The control scheme employs a current reference generator based on Sinusoidal Signal Integrator (SSI) and Instantaneous Reactive Power (IRP) theory together with a repetitive current controller. Experimental results obtained on a 4 kVA inverter prototype demonstrate the feasibility of the proposed solution.
TL;DR: In this paper, the authors proposed a new functionality of UPQC in which both the shunt and series APFs supply the load-reactive power demand, which not only helps to share the load reactive power demand but also helps to reduce the SHunt APF rating.
Abstract: This paper presents a novel philosophy to compensate the load-reactive power demand through a three-phase unified power quality conditioner (UPQC). Most of the UPQC-based applications show the dependency on shunt inverter for load-reactive power compensation, whereas the series inverter is always looked as controlled voltage source to handle all voltage-related problems. This paper proposes a new functionality of UPQC in which both the shunt and series APFs supply the load-reactive power demand. This feature not only helps to share the load-reactive power demand, but also helps to reduce the shunt APF rating, and hence, the overall cost of UPQC. This results in better utilization of the existing series inverter. The theory and complete mathematical analysis termed as ldquopower angle control (PAC)rdquo is presented. The simulation results based on MATLAB/Simulink are discussed in detail to support the concept developed in the paper. The proposed approach is also validated through experimental study.
TL;DR: In this paper, a novel structure for a three-phase four-wire (3P4W) distribution system utilizing unified power quality conditioner (UPQC) is presented.
Abstract: This paper presents a novel structure for a three-phase four-wire (3P4W) distribution system utilizing unified power quality conditioner (UPQC). The 3P4W system is realized from a three-phase three-wire system where the neutral of series transformer used in series part UPQC is considered as the fourth wire for the 3P4W system. A new control strategy to balance the unbalanced load currents is also presented in this paper. The neutral current that may flow toward transformer neutral point is compensated by using a four-leg voltage source inverter topology for shunt part. Thus, the series transformer neutral will be at virtual zero potential during all operating conditions. The simulation results based on MATLAB/Simulink are presented to show the effectiveness of the proposed UPQC-based 3P4W distribution system.
TL;DR: In this article, a comprehensive review of neutral current compensation methods, their topologies, and their technical and economical limitations is presented, and simulations are also carried out in MATLAB/SIMULINK environment for comparing the existing methods.