What is the harmonic filter for capacitor banks, and what is its application?

I will introduce to you the concept and applications of the harmonic filter for capacitor banks so that you can better utilize this tool. The harmonic filter for capacitor banks acts as a protective device against various harmonics. Its primary function is to control and regulate harmonics to minimize their entry into the capacitor. On the other hand, the filter compensates for reactive power, which is one of the tools for optimizing energy costs, and it facilitates a quick return on investment.

Harmonic filter for capacitor banks utilizes advanced materials and technologies in its production, leading to the creation of capacitors with low losses and reduced size. This enables the construction of highly reliable capacitor banks.

What is a harmonic filter for capacitor banks, and what is its application?

Allow me to introduce the concept and applications of the harmonic filter for capacitor banks to enhance your understanding and utilization of this tool. The harmonic filter for capacitor banks serves as a protective device against various harmonics. Its primary function is to control and regulate harmonics to minimize their entry into the capacitor. Additionally, it plays a crucial role in compensating for reactive power, serving as one of the tools for optimizing energy costs and facilitating a prompt return on investment.

Harmonic filter for capacitor banks incorporates innovative materials and advanced production technologies. This results in the creation of capacitors with minimal losses and reduced size, enabling the construction of entirely reliable capacitor banks.

The Importance of Awareness Among Consultants and Consumers Regarding Complex Challenges in the Field of Capacitor Banks

In the electrical domain, the phenomenon of harmonics is rapidly expanding due to the increasing use of non-sinusoidal loads in low-voltage networks. Non-sinusoidal currents flowing through the network lead to voltage drops across the network impedance, resulting in disturbances in the sinusoidal voltage of the system.

These disturbances can be explained through the concept of Fourier series, where all waves (or Fourier series components) with frequencies that are multiples of the fundamental frequency (or network frequency) are recognized as harmonics. This phenomenon causes voltage drops and disturbances in the power system, which are highly significant in optimizing electrical networks.

One crucial question in this field pertains to the harmonic distortion levels. Studies indicate that 5% of the harmonic domain consists of the fifth harmonic, 4% from the seventh harmonic, and 2.5% from the eleventh harmonic. This information holds importance for both industrial and residential loads.

Non-linear loads are identified as the primary generators of harmonics in the power network, often occurring at the third, fifth, seventh, eleventh, and thirteenth orders. This reality underscores the importance of examining and optimally managing these harmonics in electrical systems.

Harmonics Origin: Exploring the Technological Realm

In the world of technology, harmonics play a crucial role in electrical systems, especially in industrial environments with varying-speed induction devices operating under low voltage conditions.

Beyond industrial settings, harmonics are present in residential and commercial buildings as well, where devices such as televisions, computers, and energy-efficient light bulbs can serve as sources of harmonics. This reality underscores the importance of thorough examination and precise management of harmonics in all aspects of life within the technology and electrical domain.

The Impact of Capacitors on Harmonics: A Comprehensive Guide

The origin of harmonics typically depends on the number of non-linear loads in the network. For instance, the installation of a 6-pulse thyristor converter with a power representing 50% of the transformer’s capacity can generate fifth and seventh harmonics with domains of 4% and 3% in the network.

The installation of numerous thyristor converters and the phase difference of their currents can minimize the impact of harmonics. For example, installing a thyristor converter with a total power of 25% of the rated transformer power can produce harmonics with various amplitude percentages in the main wave domains.

The Effect of Capacitor Banks Without Filters Increases Resonant Voltage and Currents near Resonant Frequencies. This information aids engineers and decision-makers in optimizing electrical systems.

In the design of capacitor banks for managing harmonic networks, precise collection and utilization of data obtained from harmonic voltage and current measurements without the presence of capacitors play a fundamental role in creating an optimal design strategy. This data, including theoretical calculations related to resonance frequencies and maximum harmonic values extracted from network analysis, is highly effective.

For example, in a low-voltage network with a 1000 kW transformer, installing a complete capacitor bank (with a capacity of 400 kW) triples the fifth harmonic and quadruples the seventh harmonic.

Furthermore, the presence of various harmonics in medium-voltage networks requires thorough examination. If the harmonic voltage domain exceeds the standard limit, the use of a capacitor bank with a reactor is recommended, especially if the harmonic domain of the fifth order is more than 2% or the harmonic orders of 7 and above exceed 1%.

The Importance of Information in Capacitor Bank Design: A Comprehensive Guide. In selecting a capacitor bank, important considerations include using capacitor banks with filters and avoiding simultaneous use of capacitor banks with and without filters in a low-voltage network. Additionally, installing capacitor banks equipped with filters with different resonance frequencies in parallel can reduce the likelihood of overloading the bank with a higher resonance frequency. These guidelines assist engineers and decision-makers in selecting and optimizing capacitor banks.

Types of Harmonic Filters in Capacitor Banks

When the resonant frequencies of the network align with harmonic frequencies, the occurrence of resonance becomes undesirable. In such conditions, the network voltage experiences minimal changes during resonance, but the current in the capacitor bank significantly increases, posing a risk to capacitors and equipment. To prevent this situation, the use of harmonic filters is essential, which can be divided into two main categories: active and passive.

Passive filters are further divided into Tuned and Detuned categories. They are typically used in situations where cost-effectiveness is crucial, and there is no need for an active filter. These filters can minimize the effects of resonance frequencies in the network due to their operational characteristics.

Detuned filters are employed in conditions where the power factor of the network is low, and capacitor installation is necessary. They help prevent resonance and reduce the resonance frequency, preventing the capacitor from matching the dominant harmonic frequency in the network.

The choice of dominant harmonic in the network determines the use of P=14% and P=7% filters. These filters have the capability to eliminate harmonics from the fifth order and above, or the third order and above, respectively. However, the cost of 7% filters is approximately twice that of 14% filters.

In situations where the goal is to reduce harmonics at nonlinear load connection points and the need to reduce the current total harmonic distortion (THD) in the network or keep it below a certain limit, the use of Tuned filters is recommended. These filters are usually accompanied by a Thyristor Switched Reactor (TCR) and are recommended for conditions where the load is relatively constant.

Improving Capacitor Bank Performance with Harmonic Filters

Active filters, by generating a counter-current equal in magnitude to the harmonics, can contribute to improving the power factor of the network and reducing the Total Harmonic Distortion (THD) of the current. Simultaneous use of both active and detuned filters in the capacitor bank can lead to correcting the power factor, reducing the likelihood of resonance, and decreasing THD.


This article has delved into various types of harmonic filters in capacitor banks. The roles and functionalities of passive and active filters in preventing resonance and reducing harmonics have been examined. Additionally, the importance of measuring harmonics, the impact of capacitor banks on harmonic domains, and considerations in selecting a capacitor bank have been highlighted.

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