Harmonic Filter Design Research Articles

Self-Regulating Active Power Filter Compensation Scheme for Hybrid Photovoltaic-Fuel Cell Renewable Energy System for Smart Grid Applications

This paper presents a low cost DC and AC active power filters to enhance the power quality of hybrid hydrogen Fuel Cells (FC) and Photovoltaic arrays (PV) renewable energy system through reducing the complexity of design and control of active harmonic filters that effectively mitigate power system harmonics. Its main goal was therefore to design, model and test through computer simulation, active power filters that successfully interface FC and PV to form hybrid PV/FC renewable energy system that enhance the system output power quality through the stabilization of load bus voltage and reduction of harmonic currents. Two active power filters schemes were proposed in this paper. The first system consists of a unique two stage DC Power Filter (DCPF) to regulate the DC bus voltage to its set point. The second interface scheme is the active AC Power Filter (ACPF) which served to reduce harmonic three-phase currents on the AC bus. The AC filter used on the AC bus utilizes a hysteresis current controller to generate the switching. Computer models of these two interface schemes were built and simulation studies were carried out using the Matlab/Simulink. The simulation results demonstrate the success of both power filters at meeting their primary objectives through the increased voltage stability and reduction of the Total Harmonic Distortion (THD) of current that was observed as a result of their introduction into the power system.

Inter-harmonics in multi-terminal VSC-based HVDC systems

Multi-terminal voltage sourced converter (VSC)-based high voltage direct current (HVDC) system composes of a number of VSCs connected to an HVDC grid (or dc grid). The dc grid is often configured by cable interconnections between converter stations, thus imposing resonance issues affecting harmonic interaction in the system. Based on the harmonic transfer characteristics of VSC and HVDC systems, the appearance and the interaction of inter-harmonics in the multi-terminal VSC-based HVDC system are analyzed. Simulation models are built and implemented using SimPowerSystems in MATLAB. The simulation results show that, a series of inter-harmonics are produced and tend to be dominant in low-frequency range. Especially in the dc grid, the inter-harmonic transfer can be magnified due to inter-harmonic resonances. The complex resonance issues in the dc grid are investigated in combination with interaction through the VSC, it is beneficial to harmonic filter designs as well as other harmonic mitigation methods.

Discrete–Time Integral Sliding Mode Control with Disturbances Compensation and Reduced Chattering for Pv Grid–Connected Inverter

Abstract In the paper a new discrete-time integral sliding mode control (DISMC) with disturbances compensation and reduced chattering for grid-connected inverter is proposed for active and reactive power regulation. Differently by many SMC proposed in literature that have a time-continuous formulation in spite have been implemented with digital processor, the proposed DISMC is fully formulated in discrete-time, taking into account the effects introduced by a microprocessor-based implementation. As will be demonstrated such approach consents to reduce the chattering about the sliding manifold within a boundary layer of O(T2) thickness instead of O(T) (being T the sampling period of the control algorithm). Moreover it introduces a correction of the control vector which eliminates the influence of modeling error and external disturbances improving stability and robustness of the controlled system. Constant converter switching frequency is achieved by using space vector modulation, which eases the design of the ac harmonic filter. In the paper, after a detailed formalization of the proposed control algorithm, several numerical and experimental results on a three-phase grid-connected inverter prototype are shown, proving the effectiveness of the control strategy.

A Systematic Power-Quality Assessment and Harmonic Filter Design Methodology for Variable-Frequency Drive Application in Marine Vessels

In maritime industry, high fuel costs encourage use of variable-frequency drives (VFDs) for energy-saving applications. However, introduction of such nonlinear loads in the vessel's power distribution network induces harmonics, which can lead to potential risks if are not predicted and controlled. In this paper, a systematic power-quality assessment and monitoring methodology is proposed to calculate VFD contribution to voltage distortion at the point of common coupling (PCC), considering the source short-circuit capacity and the existing vessel's power system harmonics. According to voltage harmonic distortion limits set by marine classification societies, design and sizing of appropriate harmonic attenuation filters is made, including ac and dc chokes and frequency-tuned passive filter options. The effectiveness of the proposed power-quality analyzing procedure is evaluated through a real practical example, which includes harmonic filter design for VFD retrofit application to fan and pump motors that operate constantly during sea-going operation in a typical tanker vessel. Power-quality field measurements obtained through a harmonic monitoring platform implemented on board verify that total voltage harmonic distortion and individual voltage harmonics at PCC are maintained below 5% and 3%, respectively, showing that design complies with relevant marine harmonic standards even in the worst operating case.

Passive Filter Design for China High-Speed Railway With Considering Harmonic Resonance and Characteristic Harmonics

In order to make high-speed trains (HSTs) lighter and more reliable, LC or LCL high-pass filters, which are widely adopted to mitigate high-order harmonics, are not installed in most of China HSTs. Therefore, the harmonic problem is a concern, because of the significant adverse impacts it has on the tractive drive system of the train and power quality of the utility system. The harmful harmonic distortions in high-speed railways (HSRs) are mainly caused by harmonic resonance and massive characteristic harmonics emission. This paper presents the results of harmonic assessment and harmonic filter design for a typical HSR line in China. Harmonic penetration analysis (HPA) is implemented and carried out to determine the harmonic distorted types for a wide range of possible train-operating conditions in a timetable. Both statistical field test and numerical calculation are used in passive filter design for HSRs. A C-type filter is designed here to address these typical harmonic distortions. The studies will be validated by detailed simulations based on the train timetable by counting the 95% index of the 24-h profile of harmonic results.

Optimal harmonic filters design of the Taiwan high speed rail traction system of distributer generation system with specially connected transformers

This paper presents a method for combining a particle swarm optimization with nonlinear time-varying evolution and orthogonal arrays (PSO-NTVEOA) in the planning of harmonic filters for the high speed railway traction system of Distributed Generation (DG) system with specially connected transformers in unbalanced three-phase power systems. The objective is to minimize the cost of the filter, the filters loss, the total harmonic distortion of currents and voltages at each bus simultaneously. An orthogonal array is first conducted to obtain the initial solution set. The set is then treated as the initial training sample. Next, the PSO-NTVEOA method parameters are determined by using matrix experiments with an orthogonal array, in which a minimal number of experiments would have an effect that approximates the full factorial experiments. This PSO-NTVEOA method is then applied to design optimal harmonic filters in Taiwan HSR traction system, where both rectifiers and inverters with IGBT are used. From the results of the illustrative examples, the feasibility of the PSO-NTVEOA to design an optimal passive harmonic filter of Taiwan HSR system is verified and the design approach can greatly reduce the harmonic distortion. Three design schemes are compared that V–V connection suppressing the 3rd order harmonic and Scott connection for the harmonic improvement is better than those of V–V and Le Blanc connection.

Three-Phase Harmonic Analysis Method for Unbalanced Distribution Systems

Due to the unbalanced features of distribution systems, a three-phase harmonic analysis method is essential to accurately analyze the harmonic impact on distribution systems. Moreover, harmonic analysis is the basic tool for harmonic filter design and harmonic resonance mitigation; therefore, the computational performance should also be efficient. An accurate and efficient three-phase harmonic analysis method for unbalanced distribution systems is proposed in this paper. The variations of bus voltages, bus current injections and branch currents affected by harmonic current injections can be analyzed by two relationship matrices developed from the topological characteristics of distribution systems. Some useful formulas are then derived to solve the three-phase harmonic propagation problem. After the harmonic propagation for each harmonic order is calculated, the total harmonic distortion (THD) for bus voltages can be calculated accordingly. The proposed method has better computational performance, since the time-consuming full admittance matrix inverse employed by the commonly-used harmonic analysis methods is not necessary in the solution procedure. In addition, the proposed method can provide novel viewpoints in calculating the branch currents and bus voltages under harmonic pollution which are vital for harmonic filter design. Test results demonstrate the effectiveness and efficiency of the proposed method.

Comprehensive design methodology of tuned passive filters based on a probabilistic approach

This study presents a new method for the optimal design of single-tuned harmonic passive filters considering the probabilistic nature of power system magnitudes. For this purpose, the algorithm uses the measurements acquired by a power quality analyser. The Gaussian mixture model has been applied to actual harmonic measurements to obtain a precise statistical representation which is crucial in the proposed design procedure. The optimisation algorithm considers both probabilistic and deterministic variables involving all the harmonic components including the minor or non-characteristic harmonics. Moreover, the objective function of the optimisation algorithm is formulated taken into account all the harmonic terms overpassing other simplified formulations based only on the fundamental component. This study includes a case study with different optimisation scenarios to clearly highlight the benefits of each of the proposed contributions.

Optimal multiobjective design of hybrid active power filters considering a distorted environment

The development of new passive, active, and hybrid filtering techniques is important; and the issues of higher quality, reduced complexity, higher efficiency, and lower cost are important conditions that need to be addressed with regard to the expected stringent trends in power quality obligations. This paper suggests a new approach for the optimal sizing of hybrid active power filter (HAPF) parameters, which is presented for three-phase industrial power systems. Hybrid filter topology can be used to compensate harmonic currents, as well as for power factor corrections, without concern for importing and exporting harmonics, or simply the series and parallel resonance that may occur. The new trend in harmonic power filter design is not to obtain the best solution from a single objective optimization but to obtain a good compromise solution accomplished under other conflicting objectives. Fortran Feasible Sequential Quadratic Programming is used to determine the proposed filter optimal sizing to minimize the total voltage harmonic distortion as the main objective function, where maintaining the load power factor at an acceptable limit is desired. If the total harmonic voltage distortion achieves the specified goal, then the objective is redirected into minimizing the resultant voltage and current total harmonic distortions. The optimal design of the HAPF is analyzed by means of three case studies.

Harmonic Analysis and Filter Design for the Light Rail Transit Systems

This paper presents the light rail transit system (lrts) impact on the harmonic pollution of distribution feeder. To investigate the dynamic responses of the system voltage and current, the distribution system and lrts models are set up well by using the Alternative Transients Program (ATP). The harmonic analysis of the distribution system with the lrts is executed under various operation scenarios. The 6-pulses and 12-pulses rectifier are adopted for the lrts with a direct current (dc) power supply to the trams. Furthermore, the well-designed filters have also applied to improve the harmonic distortion resulted from the lrts.

A Neural Network Controller For The Direct Power Control Of Doubly Fed Induction Generator


 In this paper a direct power control strategy for a doubly-fed induction generator by using an artificial neural network controller with the multilayer perceptron structure is presented. The control variables direct- and quadrature-axis rotor voltage signals are directly generated by proposed controller from both stator current and voltage that are measured by Hall sensors. The input variables of the control system are the rotor speed, the active and reactive power references and their respective errors. The proposed control strategy allows that the converter connected to the rotor terminals operates with constant switching frequency which simplifies the design of the AC harmonic filter and as well as prevents their power losses. To validate the proposed control strategy, digital simulation and experimental tests are performed for a 2.25\,kW doubly-fed induction generator. A TMS320F2812 DSP is used to implement the neural network controller.

Harmonic Analysis and Filter Bank Design for a New Rectifier for a Cold Roll Mill

The trend in industry to replace motor-generator sets with static rectifiers often results in soft voltage and harmonic distortion issues which must be corrected after the fact that the distribution system not only experiences increased reactive load with the added rectifier transformers but also generally experiences a loss in reactive power when the synchronous motor is removed. In the cold roll mill of this large steel-processing facility, these concerns were addressed proactively early in the planning stages with the design of a stepped harmonic filter to be installed with a new static rectifier. This paper describes the harmonic analysis of the new rectifier and the design of the harmonic filter to correct harmonics and support voltage. The harmonic analysis identified a unique parallel resonance below the filter tuning and quantified the likelihood of the rectifier exciting this resonance. The filter bank design incorporated a small modification to the filter to mitigate this concern. Additionally, this paper presents the analysis of the possible interaction of the harmonic filter with an electrically nearby advanced reactive compensator.

Discrete sliding mode control strategy for direct real and reactive power regulation of wind driven DFIG

This paper investigates a discrete sliding mode control (DSMC) strategy for direct real and reactive power regulation for wind driven doubly fed induction generator (DFIG). The real and reactive power errors are eliminated by directly calculating the rotor control voltages through DSMC. In the stator stationary reference frame, direct real and reactive power control strategy is implemented. Therefore, it does not require the angular information of the stator and rotor currents or voltages. It does not involve any extra current loops which results into simple design. The use of constant converter switching frequency via space vector pulse width modulation eases the AC harmonic filter design and improves the power quality. The use of fast and flexible discrete controller makes the system competent with modern digital world. Detailed simulations have been carried out to validate the method. The simulation results reveal that the real and reactive power references are followed smoothly even in the presence of speed perturbations and performance of the system is robust against parameter variations and system disturbances.

고조파 수동필터의 설계 및 적용

고조파와 관련한 전력품질저하로 발생하는 전기설비사고 및 경제적 손실은 증가하고 있다. 수동필터는 고조파 문제를 해결하는데 경제적이고 효과적이지만 많은 엔지니어들은 그들의 전력시스템과의 직병렬 공진 문제 및 고조파 증폭 문제로 인해 사용하기를 꺼려한다. 본 논문은 수동필터가 잘 설계될 경우 고조파 문제를 해결하는데 매우 유용하다는 것을 보여준다. 고조파 수동필터 설계의 방법과 과정을 서술하였다. 그리고 100HP DC 모터, 압출 기계, 에어 압력기 등과 같은 비선형 부하로 인해 고조파 문제를 갖는 계통에 적용할 수 있는 수동필터를 설계하였다. 제시된 설계 방법과 절차에 대한 검증을 실험을 통해 입증하였다. Accidents involving electric equipment and economical loss by power quality deterioration related to harmonics show a rising tendency A passive filter is economic and efficient in suppressing harmonics but many engineers and designers are reluctant to install a passive filter to defect harmonics at their power system because of problems such as harmonic amplification and the probability of generating series or parallel resonance with the power system. This work introduces that passive filters will be very available to defeat harmonic problems of the power system if passive filters are well designed. We describe method and process of harmonic passive filter design. And the passive filter for the power system having harmonic problems due to use of nonlinear loads like as 100HP DC motor system, an extruding machine, an air blower and other loads are designed. Experimental results verify the performance of the passive filter designed by the described method and procedure.

High-Power Low-Pass Harmonic Waveguide Filter With ${\rm TE}_{{\rm n}0}$-Mode Suppression

In this letter, a new method for the design of high-power low-pass harmonic filters in rectangular waveguide technology is proposed. Based on a 2-D arrangement of bandstop elements of sinusoidal profile, a filter with a wide spurious-free frequency response (up to the third harmonic) for the fundamental TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> mode, as well as higher-order TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n0</sub> -mode suppression, is achieved. Compared to the classical waffle-iron solution, the novel proposal has a highly increased power-handling capability for the same frequency specifications.

Optimal Harmonic Filters Design Based Mean Value Estimation of the Source and Load Characteristics

The fixed-time solutions may not be optimal, and therefore time-variations of the harmonics must be considered in the optimum harmonic filters design. The probabilistic modeling of current and voltage harmonics as an accurate estimation of power system harmonic behavior has become an important indicator for customers and suppliers alike. This patent presents an application of the probabilistic approach based mean value estimation of source and load characteristics, which is enabled by sampling measurements and statistical analysis performed on an electrical plant, which allow appropriate calculation of optimal harmonic filters parameters considering voltage harmonics and source impedance as randomly time-varying quantities. The optimization also considers practical constraints such as load power factor and total voltage harmonic distortion limitations. Also, this patent includes different optimization criteria. Finally, the effectiveness and robustness of the proposed harmonic filters are validated by means of three case studies, including a detailed comparison of the different objectives presented in this patent.

Single-Tuned Passive Harmonic Filters Design with Uncertain Source and Load Characteristics

In this patent, the optimal single-tuned passive harmonic filter corresponding to the maximum expected value of the annual gain due to the power loss reduction is determined. Voltage and load current harmonics, as well as source and load impedances are represented as randomly time-varying quantities. The distribution characteristics of these random variables at a supply bus can be determined by sampling measurements performed on the examined electrical plant, as well as statistical analysis. The major advantage of this method is that it, unlike conventional approaches, guarantees convergence to the optimal solution. The contribution of the developed method is demonstrated in examples taken from existing publications.

Direct Power Control of a Doubly Fed Induction Generator By Using A Neuro-fuzzy Controller

In this article, a direct power control strategy for a doubly fed induction generation is presented. The control variables -- d-axis and q-axis rotor voltages -- are determined through a control system that consists of a neuro-fuzzy inference system and a Takagi- Sugeno fuzzy logic controller of first order. The input variables of the control system are the rotor speed, active and reactive power references, and their respective errors. Constant converter switching frequency is achieved, what eases the design of ac harmonic filter and reduced the power loss in the power converter. Another features are the rotor current-sensorless operation, lower cost implementation and the gain of reliability. To validate the strategy, simulation and experimental results are presented for abrupt and linear variations of active and reactive power.

Passive Harmonic Filter Design Scheme

In this article, a passive harmonic filter design scheme is proposed for offshore power distribution systems with subsea cables. Such an offshore system requires more reliable harmonic filters due to parallel resonance and the resultant large harmonic distortions in the system caused by subsea cables. The new passive harmonic filter design scheme is easy to achieve and more reliable compared to traditional pas sive harmonic filter design. It also offers a flexible power factor control to the offshore platform with generators. The stability, reliability, and flexibility of the offshore distribu tion system with the proposed filters are significantly improved. To avoid subfilter overloading, detuning capacitors and reactor taps should be provided for each subfilter in case detuning is required in the field.

Assessment of Different Objectives for Harmonics Passive Filters Design

Passive filters are extensively used as an effective procedure for harmonic mitigation due to their wide range of frequency response characteristics which can achieve a specific filtering goal, and also due to their straightforwardness and reasonable cost. This article presents an application of FORTRAN Feasible Sequential Quadratic Programming (FFSQP), which it is implemented to tackle a number of conflicting search goals which allow the appropriate calculation of optimal passive filter parameters. The article includes different optimization criteria depending on the designer concerns. In addition, various case studies are presented, including a comparison between the results of different objective functions by means of different numerical examples, considering their source and load nonlinearities. The article presents some promising patents for the assessment of different objectives for harmonic passive filter design.