Shunt Passive Filter Research Articles

A new power line conditioner for harmonic compensation in power systems

This paper proposes a new power line conditioner consisting of two small rating series active filters and a shunt passive filter. The power line conditioner aims at a general filtering system which will be installed at the point of common coupling in a power system feeding harmonic-sensitive loads and unidentified harmonic-producing loads. One of the two active filters is connected in series with the supply, while another is in series with the shunt passive filter. The purpose of the power line conditioner is to reduce voltage distortion at the connection point, and is to eliminate harmonic currents escaping into the system upstream of the connection point. A control scheme of the two series active filters which play an important role is described in this paper. Its filtering characteristics are discussed with the focus on voltage and current distortion. A prototype model of 20 kVA is constructed to verify the functionality and performance of the power line conditioner. >

Harmonic power detection based on the pq theory and its applications

AbstractHarmonic interference problems generated by bulk semiconductor power converters become more serious in power systems with their wide use in industrial applications. Shunt passive filters consisting of LC tuned filters or shunt active filters using PWM inverters have been used to suppress harmonic currents in distribution systems.To install the passive or active filters, it is necessary to find exactly a dominant harmonic source in distribution feeders. A harmonic power on each phase and order at a receiving terminal has been investigated by using a digital power meter including an FFT analyzer. However, the conventional detection method has a problem in that it is difficult to discuss exactly harmonic power flow because the detected harmonic power is much smaller compared with a fundamental active power at the receiving terminal.In this paper, the harmonic power in three phases, which can be detected on real time, is defined by applying the pq theory. Next, it is verified by a digital simulation that the proposed method can discuss harmonic flows more easily than the conventional method. As a result, it is more simple and precise to find the harmonic source. Moreover, measurement errors of the harmonic power are revealed quantitatively, and the validity of the proposed method is demonstrated by digital simulation.

A Flicker and Harmonic Compensator Using a Series Active Filter.

A specially designed twelve-pulse thyristor rectifier of 5-8MVA is required as a low-voltage high-current dc power supply for super-conductive material tests. It is, however, too susceptible to low frequency variation of the utility voltage, or to the so-called “flicker” to generate a strong magnetic field with high stability.This paper presents a flicker and harmonic compensator based on the combined system of a small-rated series active filter and a conventional shunt passive filter. The main purpose of the compensator is to remove susceptibility to the flicker from the thyristor rectifier. The series active filter, which is connected in series with the utility, can compensate for flicker components present at the utility grid, the frequency range of which is from 1Hz to 20Hz. In addition, it helps almost all harmonic currents produced by the thyristor rectifier to flow into the shunt passive filter installed in parallel with the harmonic-producing load, i.e. the thyristor rectifier.

The Electromagnetic Transients Program (EMTP) as an effective tool to evaluate active power filters for harmonic compensation

The Institute of Electrical and Electronic Engineers (IEEE) ‘Recommended Practices and Requirements for Harmonic Control in Electric Power Systems’ sets limits for the current and voltage harmonic distortions at the point of common coupling in order to maintain an acceptable quality of electric power in the presence of nonlinear loads. Both the utility and its customers share a common responsibility since enforcement of the above practice by the utility would require that the affected customer use a suitable harmonic mitigating method. To this effect, this paper demonstrates how the Electromagnetic Transients Program (EMTP) may be used to investigate two harmonic mitigating methods, namely, the use of shunt passive power filters and the combination of a series active (APF) and shunt passive (PPF) power filters. Both methods reduce the harmonic currents injected into the distribution system; however, the combination of the series APF and shunt PPFs has a better compensation characteristic with a higher capital cost than only shunt PPFs. Before a final decision is reached, the cost of the higher harmonic losses throughout the distribution system when using only shunt PPFs must be taken into account.

Trends in active power line conditioners

Active power line conditioners, which are classified into shunt and series ones, have been studied with the focus on their practical installation in industrial power systems. In 1986, a combined system of a shunt conditioner of rating 900 kVA and a shunt passive filter of rating 6600 kVA was practically installed to suppress the harmonics produced by a large capacity cycloconverter for steel mill drives. More than one hundred shunt have been operating properly in Japan. The largest one is 20 MVA, which was developed for flicker compensation for an arc furnace with the help of a shunt passive filter of 20 MVA. In this paper, the term of active power line conditioners is used instead of that of active power filters because power line would cover a wider sense than power filters. The primary intent of this paper is to present trends in power line using PWM inverters, paying attention to practical applications. >

Analysis and design of a combined system of shunt passive and active filters

AbstractPassive and active filters have traditionally been used to reduce harmonics in power systems. Only recently combined systems of shunt passive and active filters have been proposed in order to overcome the technical problems of passive filters and to reduce the costs of active ones. The paper tries to overcome some drawbacks of a combined filtering system (modified high‐pass filter) which appeared in literature. In particular, improvements in the system structure and in the steady‐state design methodology are proposed to obtain a filtering system with both satisfactory compensation characteristics and low costs. Finally, numerical applications are discussed considering a test case.

Harmonic Power Detection Based on the pq Theory and its Applications.

Harmonic interference problems generated by bulk semiconductor power converters become more serious in power systems as they are widely used in industrial applications. Shunt passive filters consisting of LC tuned filters or shunt active filters using PWM inverters have been used to suppress harmonic currents in distribution systems. In order to install the passive or active filters, it is necessary to exactly find a dominant harmonic source in distribution feeders. A harmonic power on each phase and order at a receiving terminal has been investigated by using a digital power meter including an FFT analyzer. However, the conventional detection method has such a problem that it is difficult to exactly discuss harmonic power flow because the detected harmonic power is much smaller compared with a fundamental active power at the receiving terminal. In this paper, the harmonic power in three phases, which can be detected on real time, is defined by applying the pq theory. Next, it is verified by a digital simulation that the proposed method can discuss harmonic flows more easily than the conventional method. As a result, it is more simple and precise to find the harmonic source. Moreover, measurement errors of the harmonic power is revealed quantitatively, and the validity of the proposed method is demonstrated by digital simulation.

Combined system of a series active filter and a shunt passive filter—an optimum design of the shunt passive filter

AbstractThe combined system of a series active filter and a shunt passive filter that is proposed by the authors has the ability to eliminate a major disadvantage of shunt passive filters, namely, harmonic amplification. The series active filter needs a much smaller kVA rating than a conventional shunt active filter, and as a result, the combined system has good filtering characteristics and high efficiency.This paper presents an optimum design of the shunt passive filter that makes possible a great reduction in the required kVA rating of the series active filter. It can minimize the peak voltage across the series active filter and reduce the required kVA rating of the filter to 60 percent. A computer simulation geared to practical applications of large three‐phase. twelve‐pulse thyristor rectifiers is used to compare the compensation characteristics of the optimized system with those of a combined system that uses a conventional shunt passive filter. Experimental results obtained with a laboratory model of the filter corroborate the design approach.

Compensation characteristics of the combined system of shunt passive and series active filters

A combined system of shunt passive and small rated series active filters, as well as its operating principle and steady compensation characteristics, was previously presented by the authors (1988). The combined system can greatly reduce problems of using only the shunt passive or shunt active filters and is suitable for harmonic compensation for large VA-rated loads in power systems. Transient compensation characteristics and the stability of the system are discussed and analyzed theoretically and experimentally in detail. A control method enables the combined system to be applied to cycloconverter compensation. Some results obtained with the experimental model are presented to demonstrate and confirm the method's validity.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A new combined system of active and passive filters to obtain harmonic compensation for large-capacity thyristor converters

Shunt passive filters, which are connected in parallel to harmonic-producing loads, have been used widely for harmonics suppression in power systems because of low cost and high efficiency. However, they have such inherent problems as series and parallel resonance. On the other hand, shunt active filters, which are also placed in parallel, have such an inherent problem as initial and running costs are high compared with those of shunt passive filters. To solve these inherent problems in shunt passive and shunt active filters, the authors have proposed a combined system of a shunt passive filter and a small rated series-active filter. The purpose of this paper is to reduce the required rating of the series-active filter, considering a practical application of the combined power filter to harmonic compensation for large-capacity thyristor converters. The points are summarized as follows: 1 The required rating of the series-active filter can be reduced less than one-tenth by connecting a series-resonant circuit in parallel to the secondary of current transformer. 2 It is clarified theoretically and verified experimentally that compensation characteristics of the new combined system are equivalent to those of the already-proposed system with no series-resonant circuit.

Teh Combined System of a Series Active Filter and a Shunt Passive Filter. An Optimum Design of the Shumt Passive Filter.

The combined system of a series active filter and a shunt passive filter has been proposed by the authors. It has the ability to eliminate such a disadvantage of a shunt passive filter as a harmonic amplifying phenomina. The series active filter needs much smaller kVA rating than a conventional shunt active filter does. As a result, the combined system shows good filtering characteristics and high efficiency.This paper presents an optimum design of the shunt passive filter for a great reduction of the required kVA rating of the series active filter. It can minimize the peak voltage across the series active filter, and reduce the required kVA rating of the series active filter to 60%. The optimized system is compared in compensation characteristics with the combined system using a conventional shunt passive filter by digital computer simulation, paying attention to practical applications to large rated three-phase twelve-pulse thyristor rectifiers. Experimental results obtained by a laboratory model are shown to verify the design theory.

A New Combined System of Active and Passive Filters Aiming at Harmonic Compensation for Large Capacity Thyristor Converters.

Shunt passive filters, which are connected in parallel to harmonic-producing loads, have been widely used for harmonics suppression in power systems because of low costs and high efficiency, although they have inherent problems such as series and parallel resonance. On the other hand, shunt active filters, which are also placed in parallel, have such an inherent problem as initial and running costs are high, compared with those of shunt passive filters. To solve these inherent problems in shunt passive and shunt active filters, the authors have proposed a combined system of a shunt passive filter and a small rated series active filter.The purpose of this paper is to reduce the required rating of the series active filter, considering a practical application of the combined power filter to harmonic compensation for large capacity thyristor converters. The points are summarized as follows:(1) The required rating of the series active filter can be reduced less than one-tenth by connecting a series resonant circuit in parallel to the secondary of current transformer.(2) It is clarified theoretically and verified experimentally that compensation characteristics of the new combined system are equivalent to those of the already proposed system with no series resonant circuit.

The combined system of series active and shunt passive filters. Analysis of harmonic instability phenomena.

This paper describes a simple and clear approach to analyze harmonic instability of phase controlled thyristor converters with input passive filters. It is shown by analysis and experiment that harmonic instability may occur at the parallel resonant frequency between the passive filter and the ac source even if the ac source impedance is low.A combined system of series active and shunt passive filters has already been proposed as a new approach to harmonic compensation in power systems by the authors. It is confirmed analytically and experimentally that the series active filter used has the capability to suppress the harmonic instability at the parallel resonant frequency. However, it is also shown that the series active filter may cause harmonic instability adversely at lower frequencies. However, harmonic instability at a frequency except for the parallel resonant frequency does not cause any practical problem. The obtained analytical results are confirmed by experiment in detail.

A new approach to harmonic compensation in power systems-a combined system of shunt passive and series active filters

A novel approach to compensating for harmonics in power systems is presented. It is a combined system of a shunt passive filter and a small rated series active filter. The compensation principle is described, and some filtering characteristics are discussed in detail. Excellent practicability and validity to compensate for harmonics in power systems are demonstrated experimentally. Although the source harmonic voltage was only 1%, the source harmonic current reached about 10% before the series active filter was started. After it was started, no harmonic current flowed into the shunt passive filter. In addition, no harmonic voltage appeared at the terminals of the shunt passive filter, because the source harmonic voltage was applied to the series active filter. The total loss of the series active filter was less than 40 W. It is concluded that the combined system is far superior in efficiency to conventional shunt active filters. >

A combined system of shunt passive and series active filters. Stability and compensation characteristics.

A combined system of shunt passive and small rated series active filters has already been proposed by the authors. The operating principle and steady compensation characteristics have been presented also. The combined system can greatly reduce problems of using only shunt passive or shunt active filters and is suitable for harmonic compensation for large VA rated loads in power systems, because the required VA rating of the series active filter used here is considerably smaller than that of a conventional shunt active filter.In steady states, the combined system behaves like an ideal compensator, because the extraction of the harmonics easy. However, some loads such as cycloconverters fluctuate with rapid speed and cannot be regarded as steady loads. It is difficult for a conventional shunt passive filter to compensate for these fluctuating loads because they generate various frequency harmonics. So it is necessary to discuss transient compensation characteristics of the combined system when it is applied to compensation for fluctuating loads.In this paper, focusing on transient states, stability and compensation characteristics of the combined system are analyzed and discussed theoretically and experimentally in detail. The stable and unstable regions of the combined system and the problems faced by improving transient compensation characteristics are revealed. Then, to improve transient characteristics of the system, a new control method is proposed, and the validity is experimentally demonstrated.

A new approach to harmonic compensation in power system‐a combined system of series active and shunt passive filters

A new approach to harmonic compensation in power system‐a combined system of series active and shunt passive filters

A new approach to harmonic compensation in power systems. A combined system of series active and shunt passive filters.

A novel approach to compensate for harmonics in power systems is proposed. The approach differs from conventional passive and active filters in its compensation principle. A practical system configuration to implement the approach is presented. It consists of a small-VA-rating PWM (pulsewidth-modulated) converter and a passive filter. The compensation principle is described, and compensation characteristics are examined theoretically and experimentally. The practicability and validity of the approach are experimentally demonstrated. >