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Power quality integratedWith the development of national economy in China, the non-linear, asymmetric and impulsive loads in the power grid are increasing, which will cause the following adverse effects: 1) The reactive power and harmonic current generated by the nonlinear load infiltrates into the power system in large quantity without control for a long time, increasing the loss of the system. 2) The rapid impact load (such as rolling mill, welding machine, large punch, etc.) absorbs reactive power from the power grid while generating voltage fluctuation and flicker to reduce the effective output of the motor, which reduces the product's finished product rate and shortens the service life of the equipment. 3) Unsymmetrical load intensifies the imbalance of the power grid. In view of the above situation, IN-Power Electric takes the lead in introducing LSVG dynamic filtering compensation device, which combines advanced power electronic technology with traditional filtering compensation method, with the following functions:
1) Harmonic control functiona) 2nd -51st wide range filtering, filtering rate ≥95% a) Harmonic elimination for neutral line
2) Reactive compensationa) Bidirectional reactive power output a) Accurate reactive compensation c) Target power factor setting d) Capacitor status monitoring
3) Balance three-phase currenta) Accurately adjust the system three-phase current b) Reduce the operating current of the neutral line
4) Other functionsa) Energy-saving working mode b) Time setting c) Fault self-recovery d) Function of over-temperature capacity reducing
Technical advantages1) Unified control The active filtering unit directly controls the switching of the traditional filtering compensation unit to avoid capacity impact between the two. 2) Diverse combinations For different working conditions, the active filter can be combined with the common compensation capacitor, the separate compensation capacitor (L-N，L-L) and the intelligent capacitor. 3) High cost performance The product makes full use of the economical efficiency of traditional filter compensation products and the advanced nature of power electronic products. The traditional filter compensation unit performs coarse adjustment for basic reactive power and absorbs some harmonics; the active filter unit makes fine compensation for the rapidly changing reactive power demand and harmonic current. At the same time, the reactive power bidirectional regulation of the active filter unit can be used to effectively control the reactive power releasing and make up the inherent deficiency of the traditional filter compensation device. 4) Low self-loss Compared with the pure power electronic solution, LSVG products have replaced most of the capacity with traditional filtering compensation products. As the loss of traditional product itself is much lower than IGBT switch loss, the active filtering capacity accounts for a small proportion and the loss of the complete device is low. 5) High reliability LSVG products have advanced fault-tolerant operation function, that is, when an active filtering unit or a traditional filtering compensation unit exits due to failure, the LSVG control system will automatically screen the fault unit to ensure the normal operation of other normal units. Meanwhile, when the active filter unit is stopped due to transient state fault, the traditional filter compensation unit can still operate independently.
Product combination mode:1) Active filter + common compensation capacitor The solution is applicable to industrial loads with low power factor, serious harmonic pollution and basic balanced three-phase current. The traditional filter compensation unit compensates the basic reactive power of the system and absorbs a small amount of harmonic current; The active filter unit is used to control the harmonic current of the system. The surplus capacity of the active filter can compensate the rapidly changing reactive power linearly and provide the power factor of the system.
|Before control||After control|
|Current waveform diagram|
|Power grid parameters|
|Effect: Before control, the system current waveform distortion was very serious, showing an "M" shape, the total harmonic distortion rate (THD) of the current was as high as 29.8%, and the power factor of the system was only 0.70.After control, the total harmonic distortion rate (THD) of the current is only 1.4%, the current waveform is basically sine wave, and the power factor of the system is as high as 0.96.|
|Before control||After control|
|Current parameter of the system|
|Power parameter of the system|
|Effect: Before control, the three-phase current of the system was seriously unbalanced, the maximum current distortion rate (THDi) was 52.38%, the current waveform was seriously distorted, the minimum power factor of the system was 0.8681, and there was reactive power releasing (reactive power was negative).After control, the three-phase current of the system is basically the same, the maximum current distortion rate (THDi) is 4.23%, the current waveform is basically sine wave, and the power factor of the system is over 0.99.|