Three Commonly Used Methods for Reactive Power Compensation

Reactive power compensation, a key component in power supply systems, enhances the power factor of the grid, reduces losses in supply transformers and transmission lines, improves power supply efficiency, and optimizes the overall supply environment. Thus, reactive power compensation devices play an indispensable and critical role in power supply systems. Selecting appropriate compensation equipment can significantly minimize grid losses and enhance power quality.

The three primary methods for reactive power compensation are:

● Low-voltage on-site compensation

● Low-voltage centralized or group compensation

● Medium-voltage centralized compensation

 

Low-Voltage On-Site Reactive Power Compensation
This method involves connecting single or multiple sets of low-voltage capacitor banks in parallel with specific electrical equipment based on the amount of reactive power generated by the equipment. Through control and protection devices, the capacitors are switched on or off simultaneously with the motor. This approach converts the reactive energy from inductive loads into active energy, which is then fed back to the inductive equipment.

Advantages:

1.Converts reactive energy at the source, significantly reducing line losses, improving distribution transformer utilization, and lowering apparent power.

2.Reactive power compensation is activated when the electrical equipment is in operation and deactivated when the equipment stops, ensuring efficient usage.

3.Compact design, easy installation, effectively reduces apparent power, and delivers notable energy-saving benefits.

Disadvantages:

1.Requires a substantial initial investment, though the returns are greater.

2.Compensation must adjust dynamically with load changes, demanding high responsiveness and precision from the automatic compensation controller. Excessive capacitance may lead to overcompensation, while insufficient capacitance fails to meet needs.

3.Measuring the energy-saving effect for individual equipment is challenging. Accurate results are only achievable when all inductive equipment within the transformer system is equipped with low-voltage on-site reactive power compensation.

 

Low-Voltage Centralized or Group Reactive Power Compensation
This method connects low-voltage capacitors to the low-voltage busbar side of the distribution transformer via low-voltage switches. Jinneng JKW5C Reactive Power Automatic Compensation Controller serve as control and protection mechanisms, managing capacitor switching based on the reactive load on the low-voltage busbar. Capacitors are switched in groups, limiting the ability for smooth and fine-tuned adjustments.

Advantages:
Compensates for the "eddy current effect" caused by reactive energy on transformers, improving transformer utilization to some extent. It also blocks reactive energy from entering the upper-level grid, preventing voltage fluctuations and reducing grid losses. For enterprises, this method offers greater social significance than direct economic benefits. It is a commonly used approach in reactive power compensation due to its moderate economic viability.

Disadvantages:
Low-voltage centralized compensation requires substantial investment but yields limited returns for enterprises. Its primary function is to block reactive energy on the low-voltage side, benefiting the upstream grid and society more than providing significant cost savings for the company.

 

Medium-Voltage Centralized Reactive Power Compensation
This approach involves installing parallel capacitor banks directly on the 6–10 kV medium-voltage busbar of a substation. It is suitable for users located far from the substation or at the end of a power supply line, especially when they have substantial high-voltage loads. This method reduces reactive power consumption from the power system and provides compensation to some extent. The compensation equipment automatically switches based on load variations, optimizing the user's power factor. It blocks reactive energy from entering the upper-level grid, preventing voltage fluctuations, reducing losses, and protecting the upstream grid. Additionally, it simplifies operation and maintenance while delivering significant social benefits.

 

Compensation Method: Static VAR Generator (SVG)
The Static VAR Generator (SVG) is one of the primary devices in flexible AC transmission systems and belongs to the category of shunt dynamic reactive power compensation devices. It can generate or absorb reactive power, with variable output to control specific parameters in the power system. In distribution networks, installing small-capacity SVG devices near special loads (such as arc furnaces, subways, and other impact or rectifier loads) significantly improves power quality at the connection points between the loads and the public grid. Its key functions include enhancing the power factor, addressing three-phase imbalances, and eliminating voltage flicker and fluctuations.

The SVG works by connecting a self-commutating bridge circuit to the grid via a reactor. By adjusting the phase and amplitude of the AC-side output voltage or directly controlling the AC-side current, the circuit can absorb or release reactive current as required, achieving dynamic reactive power compensation.

Product Advantages and Features

1.Flexible compensation methods:

2.Compensates for load reactive power.

   Filters harmonic currents up to the 13th order.

   Supports parallel expansion of up to 10 units.

3.Utilizes advanced IGBT power modules for high power density and reliability.

4.Employs a DSP-based digital control system for high-speed detection and computation.

5.The monitoring and display system includes a remote communication interface for real-time monitoring via a PC.

6.Standard modular design shortens delivery times while enhancing reliability and maintainability.