DNV Voltage Total Distortion Elimination Stabilizer
 

• The concept of total voltage distortion rate
  1. According to the national standard requirements for total voltage distortion rate, according to the national standardGB/T 14549-93Harmonics in Power Quality Public Grid

Limit values for harmonic voltage (phase voltage) of bus voltage in public power grid

The nominal voltage of the power grid is KV	Voltage total harmonic distortion rate%	Content of each harmonic voltage,%
		Qi Ci	My times
0.38KV	5.0	4.0	2.0
6KV	4.0	3.2	1.6
10KV
35KV	3.0	2.4	1.2
66KV
110KV	2.0	1.6	0.8

 

1. 2. What is the total distortion rate of voltage waveform

Voltage waveform distortion rate, also known as total harmonic distortion rate, is an important indicator used to measure the harmonic content of voltage in power systems. It reflects the severity of harmonic pollution caused by loads on the power grid and the emission of harmonics in the power grid by power equipment.

1. 3. Calculation method for total distortion rate of voltage waveform

The voltage waveform distortion rate is usually represented by THDu, and the calculation formula is:
THDu=((∑Un)/Un)1/2x100%
Among them, Un is the fundamental value of the voltage, Un is the effective value of the fundamental voltage, and ∑ Un is the sum of squares of all harmonic voltages.

1. 4. The origin of high total voltage distortion rate
2. The harmonic current of the load equipment is too high, and the superposition of each harmonic voltage is too high, resulting in excessive distortion of the total voltage harmonics.
3. Background harmonic voltage, harmonic voltage of different orders of power grid connection, and high distortion rate of power supply background voltage caused by voltage equipotential feedback to the low voltage side.
4. Different new energy sources such as photovoltaics, wind power, and energy storage are connected to the grid. The unstable grid voltage causes voltage pulling, resulting in abnormal voltage waveforms and high voltage distortion rates.

• The harm of high total voltage distortion rate

2.1. High total voltage distortion rate poses a threat to transformers, causing increased transformer noise, loud iron core screams, and increased iron and line losses. Severe cases can cause an increase in magnetic flux, leading to severe overheating and burnout of transformers.
2.2. Excessive total voltage distortion rate poses a risk to the distribution switch coil and protection, causing voltage breakdown in the secondary operation coil and triggering voltage breakdown in the protective instrument circuit board, which can burn out electronic circuit components.
2.3. Excessive total voltage distortion rate poses a threat to instruments and can directly cause voltage breakdown and burn out the power module of the instrument.
2.4. The harm of high total voltage distortion rate to electric motors can cause changes in motor excitation, voltage breakdown of motor coil insulation, and burning of the motor.

• Selection scheme for handling high total voltage distortion rate

3.1 Many industries believe that high voltage distortion rates are caused by harmonic currents. As long as harmonic currents are controlled, voltage distortion can be reduced. For voltage distortions caused by the load side, it is indeed possible to control harmonics and reduce the total voltage distortion rate to meet national standards.
3.2. The development of power electronics has undergone a qualitative change, and most load devices are now equipped with electronic filtering functions. Due to the characteristics of electronic filtering, it can only eliminate harmonic currents of various orders and cause an increase in the harmonic values of various voltages fed back to the grid side. The superposition of different harmonic voltages in the grid has led to an increase in the total voltage distortion rate.
3.3. Many on-site applications of power electronics have reported a problem where the proportion of harmonic voltage is relatively high under conditions of low harmonic current, and the total voltage distortion rate ranges from 6% to 30%. Often causing electronic burnout or malfunction alarms in load devices.
3.4 In response to the problem of high total voltage distortion rates, Lite Electric has developed a new type of voltage total distortion rate elimination stabilizer. DNV voltage total distortion rate elimination stabilizer is a compensation tool designed to eliminate different voltage harmonics. It can eliminate the total distortion rate of load voltage or the total distortion rate of grid side voltage.

• DNV - Product Application

1. Semiconductor industry (chip manufacturing, testing, and packaging)
2. New energy industry (solar polycrystalline silicon, monocrystalline silicon pulling silicon, battery testing, aging and packaging, etc.)
3. Medical device industry (medical testing equipment, radiotherapy and chemotherapy equipment, liquid phase analyzer, etc.)
4. Automotive manufacturing industry (automatic welding, painting, paint baking, etc.)
5. Food and beverage industry (food baking, packaging, canning, bottle making machines, etc.)
6. Petrochemical industry (refueling machines, refineries, kowtow machines, chemical plants, etc.)
7. Textile industry (screen printing machines, winding machines, winches, etc.)

• DNV - Product Principle
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• DNV - Product Wiring Diagram