The ANAPF series of active power filter devices are connected to the grid in parallel. By detecting the harmonic and reactive components of the load in real time, PWM converter technology is used to generate a corresponding harmonic component and reactive component from the converter. The inverse component is injected into the power system in real time to achieve harmonic control and reactive power compensation.
It has many functions such as improving power supply quality, improving power factor and equipment utilization, saving energy and reducing loss, and thus obtaining obvious economic benefits. The investment recovery period is generally 1 to 2 years. This paper takes a chemical plant as an example to briefly introduce the technical and economic performance of the low-voltage harmonic filter device.
2 User Power Situation Profile A chemical plant's load distribution transformer capacity of 5.2MVA in 2010, there are two 1.6MVA distribution transformers, one 2.0MVA distribution transformer, the high voltage side voltage of the distribution transformer is 10kV, and the low voltage side is 0.4kV. The equipment for generating harmonics is mainly a rectifier cabinet. The capacity of the rectifier equipment is 1.344 MVA. It is concentrated on the 0.4 kV side of the No. 1 distribution transformer (1.6 MVA), as shown in the simplified diagram. The main harmonic currents generated by the rectifying device 5 times, 7 times, 11 times, 13 times the current actually measured values shown in Table 1.
The load No. 1 of the low-voltage side of the distribution transformer was originally equipped with a 0.4kV side reactive compensation capacitor of nearly 600kvar. After two years of operation, it has been damaged and replaced by about 60%. Due to lack of reactive power, the electricity rate is adjusted according to the force rate. Pay more than 100,000 yuan (statistics in 2010).
In order to eliminate the adverse effects of harmonics, reduce production loss, extend equipment life, improve production efficiency and product quality, and also meet the requirements of reactive power compensation, a chemical plant replaces the original compensation capacitor bank with a low-voltage harmonic filter device. .
No. 1 distribution transformer bus test value
It can be seen that before the harmonic filtering device is installed, the parallel resonant circuit is formed between the original capacitor compensation branch and the load and the distribution transformer, so that the harmonic current of the capacitor and the distribution transformer is significantly amplified, and the resonance point is 13 times. nearby.
It reflects that after inputting the harmonic filtering device, the user's various energy indicators are significantly improved; no supply and demand is reduced by 50%, the power factor is increased from 0.734 to 0.917, and the voltage and current distortion are reduced by half.
After the ANAPF active filter device is put into use, it absorbs most of the high-order harmonic current generated by the rectifying device, greatly reducing the pollution to the power grid. After the 0.4kV side of the transformer was put into the harmonic filtering device, the harmonic current value of the injection system was reduced from 301A to 108A five times, from 13A to 36A in 7 times, from 24A to 24A in 11 times, and from 36A in 13 times. 12A; the absorption efficiencies for the 5th, 7th, 11th, and 13th harmonics are 64%, 72%, 50%, and 66%, respectively.
3.4 Capacity Design for Harmonic Suppression and Governance 3.4.1 Harmonic Current Estimation Harmonics are generated by nonlinear devices, and the actual operating conditions of each device are different. Therefore, the actual harmonic current needs to be measured by special equipment. Considering the technical and economical equipment, the rated harmonic compensation current of the harmonic control device should be slightly larger than the system harmonic current. Since the measurement and calculation of the harmonic current itself is complicated, it is often difficult to collect enough harmonic data in the use of electrical equipment during design. The harmonic current can be estimated according to the following formula.
If passive harmonic suppression is used, it can be converted into harmonic suppression current according to the coefficient of 0.2-0.3 according to the reactive power per kilowatt (kVar). For example, the 100kVar harmonic elimination reactive compensation current is 144A, according to the coefficient. 0.2 conversion is to suppress the harmonic current of 28.8A.
If an active filtering device is used, the design can be selected according to the estimation value in the filtering scheme selection block diagram.
Example: The distribution transformer capacity of a company is 150kVA, the transformer transformation ratio is 10/0.4kV, the K1 value is 0.8, and the K2 value is 25%. Try to select the active filter with the current level to satisfy the suppression harmonic. The need for waves.
According to the current harmonic formula:
3.5ANAPF active power filter device price and main components list
Capacity increase and loss: Due to the installation of filter compensation, effective local reactive power compensation can be performed. The No. 1 distribution is equivalent to an increase of 310kVA. At the same time, the loss is greatly reduced. From March to November 2012, a chemical plant saves electricity. The expenditure was 205,000 yuan, and the electricity consumption of the product was reduced from 514Kw.h/t to 475.5Kw.h/t, a decrease of 7.5%.
Improve product qualification rate: After the filter compensation device is put in, the harmonics are reduced, the voltage is stable, and the power quality is obviously improved, thus improving the product quality. The first-class product rate is increased from 97.1% to 98.29. In 2012, the first-grade product profile is increased by nearly 100t.
Extend equipment life: After the filter compensation device is put into operation, the reduction of load current, harmonic voltage and harmonic current will reduce the heat loss of the equipment, reduce the vibration, reduce the damage rate of the rectifier components, slow down the insulation of the equipment, and reduce the failure rate. Safe operation level. The extension of equipment life, single capacitor, in the past, the plant damaged about 200kvar capacitors, the filter compensation device put into operation for nearly 2 years, the components of the device itself normal operation without failure.
According to the conclusion, the harmonic filtering device takes into account the compensation and filtering functions. After the harmonic filtering device is put into operation, not only the 5th, 7th, 11th and 13th harmonics are filtered out, but the harmonic content is in line with the "Power Quality". . Utility Grid Harmonics allows for harmonic current values. Moreover, it compensated for the reactive power, and the power factor reached 0.9 or more, which eliminated the penalty for electricity charges. Since the harmonics are filtered out, the pollution of the power supply system is reduced, and the device is operated normally. The harmonic filtering device has a strong filtering capability and is a fundamental measure to eliminate harmonic pollution and hazards, so it should be promoted and used.
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