The purpose of this study is to find a control method for three-phase four-wire shunt active power filters, which uses a load-equivalent conductance for obtaining a reference…
Abstract
Purpose
The purpose of this study is to find a control method for three-phase four-wire shunt active power filters, which uses a load-equivalent conductance for obtaining a reference signal for compensating non-active current.
Design/methodology/approach
Changes of energy stored in an active filter’s reactance elements are monitored to find the active component of the load current. It is then used as a current reference to be realised as a supply source current. Computer simulation methods were used to verify the presented control method.
Findings
To calculate the reference signal for the active filter action, it is enough to measure the active filter’s DC-side capacitors’ voltages. It has been proved that P regulators are sufficient to realise compensating current and to stabilise active filter capacitors’ voltages. The supply source-neutral conductor current can be zeroed even for nonlinear and unbalanced load-generating DC-component in its neutral conductor. In addition, the active filter can buffer load-active power changes and act simultaneously as a local energy accumulator.
Originality/value
This paper provides an alternative approach to address the problem of the three-phase four-wire shunt active power filter control methods.
Details
Keywords
Shunt active power filters are used to decrease or almost eliminate non‐active currents flowing through the supply source. Numerous control methods of active filters have been…
Abstract
Purpose
Shunt active power filters are used to decrease or almost eliminate non‐active currents flowing through the supply source. Numerous control methods of active filters have been proposed in many papers. The aim of this paper is to demonstrate a simple but very effective method of obtaining the compensated load active current.
Design/methodology/approach
The method allows one to control the shunt active power filter only by monitoring energy stored in the filter. Based on the introduced generic structure of the filter the changes of filter energy are examined in order to obtain the reference current for the filter compensation action.
Findings
This presented method can be implemented to nearly all structures of active filters. It is suitable not only for the single‐phase but also for the three‐phase circuit. Such energy‐controlled filters may be built on the basis of voltage‐ and current‐source inverters as well.
Originality/value
This paper provides an alternative approach to address the problem of the shunt active filter control method. The paper shows that monitoring the filter's energy suffices for proper control of the filter compensation action.
Details
Keywords
Numerous types of shunt active power filters have been proposed in many papers. The classification of these filters depends on various points of view. However, every type of a…
Abstract
Numerous types of shunt active power filters have been proposed in many papers. The classification of these filters depends on various points of view. However, every type of a shunt active filter, which compensates non‐active component of load current, irrespective of the method used to detect this component and control strategies of the filter, should keep supply source current equal to active current of a load‐and‐filter circuit. This goal can be achieved in many ways, using various structures of active filters. But different realizations of filters cause differences in their properties. This paper, which is meant to serve as a review and synthesis of earlier work, shows some possibilities of forming of single‐phase shunt active filter behaviour. The following active filter properties are discussed: operation with an immediate reaction in the supplying source branch to a load current change, and with the reaction only once in each supplying source cycle; regulation by the filter of the non‐active current component of fundamental frequency; active filtering and simultaneous feeding of DC load with stabilizing DC voltage; operation with stabilization of supplying source current amplitude; reducing filter switching frequency; and reducing current distortions in the supplying source branch. All the waveforms presented were produced using a computer simulation method.
Details
Keywords
As arc suppression coils (ASCs), magnetically controlled reactors (MCRs) are usually operated in the single-phase mode. Due to the lack of a third order harmonic compensation…
Abstract
Purpose
As arc suppression coils (ASCs), magnetically controlled reactors (MCRs) are usually operated in the single-phase mode. Due to the lack of a third order harmonic compensation circuit, the current harmonics are high. The purpose of this paper is to propose a novel structure of MCR and a genetic algorithm (GA) to determine the parameters which will result in minimum total harmonics.
Design/methodology/approach
This paper proposes the structure and the working principle of the multi-valve controlled saturable reactor (MCSR). There are several sorts of magnetic valves in the iron cores of the MCSR. The saturation degree of each magnetic valve is different when the same direct component of the magnetic flux is generated in the iron core, therefore current harmonics of different phases emerging, i.e. the total harmonics can be reduced. The magnetization characteristics and the mathematical model of the current harmonics of the MCSR are presented by introducing three parameters. The optimal values of the parameters that result in the smallest total harmonic distortion in the output current are calculated by a GA.
Findings
The simulation and experimental results are coincident with the theoretical analyses, which prove the effectiveness of the proposed method on harmonic suppression.
Practical implications
The method proposed in this paper can successfully reduce the current harmonics of the conventional MCR, including but not limited to the ASC. A prototype MCSR (540 kVA/10 kV) has been designed and constructed.
Originality/value
In this paper, a MCSR is proposed. The mathematical model of the MCSR for harmonic analysis is developed. The optimal parameters that result in the smallest THD in the output current are calculated. The mathematical model can be also used for the harmonic analysis of conventional MCRs.
Details
Keywords
Dariusz Grabowski, Marcin Maciążek and Marian Pasko
The change in the way of active power filters (APF) location can lead to overall cost reduction due to less number or less power of APFs required. The goal of this paper was to…
Abstract
Purpose
The change in the way of active power filters (APF) location can lead to overall cost reduction due to less number or less power of APFs required. The goal of this paper was to minimize the APF currents what is equivalent to solution with less apparent power of installed devices. The next step consists in development of new methods of APF optimal location.
Design/methodology/approach
Some scripts integrating optimization and harmonic analysis methods in Matlab and PCFLO software environments have been developed in order to achieve the goal.
Findings
Solution to the minimization problem determines the current spectrum of an APF connected to a selected system bus in accordance with some optimization strategies which among others enable minimization of THDV coefficients.
Research limitations/implications
The APF control algorithm defined in the frequency domain and based on given current spectrum could lead to some problems with synchronization between APF instantaneous current and compensated current waveforms.
Originality/value
There are many papers on APFs but usually systems in which an APF is connected near a nonlinear load are analyzed. Some attempts to solve the more complex problems of synchronized multipoint compensation have been already made but there is still no generally accepted and commonly used solution.