The low power factor of the distribution network system is caused by various household appliance loads, and the popularity of energy-saving household appliances has led to a higher harmonic content in the distribution network system. The harmonic hazards and severe losses in the distribution network system are significant

The user side of the 400V low-voltage distribution system is almost always a single-phase load, and the electricity consumption is uncertain, which makes the distribution system prone to three-phase imbalance and serious imbalance exceeding the standard.

The 400V low-voltage distribution system has a long power supply radius, which can easily lead to voltage exceeding the limit due to three-phase imbalance and the influence of high and low power consumption periods. The voltage drop caused by long-distance transmission lines results in low voltage on the user side

Distributed transformers widely use grouped switching capacitors with compensation steps, but the compensation effect is poor (prone to overcompensation or undercompensation). Capacitor banks are prone to amplifying harmonics in the system, leading to increased harmonic losses and posing a threat to system safety. They are unable to efficiently save energy and improve the voltage quality of the terminal power grid.

Due to the obvious peak valley phenomenon of electricity load in the distribution network system, the compensation device is frequently switched on and off, causing the capacitors to charge and discharge frequently, which affects the life of the capacitors. At present, the normal service life of traditional compensation devices in distribution networks is only about 1-2 years. In addition, the transformer is severely overloaded, resulting in insufficient output, severe heating, high noise, reduced transformer life, and even burnout of the transformer.

Our YBPW-SXTZ101 three-phase load imbalance device can quickly compensate for reactive power, filter out harmonics, and achieve a filtering rate of over 80%. This device has strong ability to suppress voltage fluctuations and flicker, effectively compensating for voltage drops with a depth of 50% and a width of less than 2s, and effectively suppressing three-phase imbalance. At the same time, the device has superior reliability and stability, with a response time of less than 20ms, which can solve the shortcomings of traditional parallel capacitor compensation and meet the requirements of power quality and energy-saving applications in distribution networks. The design principle of this device is as follows:

(1) Principle of Three phase Unbalance Compensation

The device can improve power grid imbalance in different situations. If the three-phase imbalance is caused by the load current, it can be improved by adjusting the distribution of three-phase currents; If the three-phase imbalance is caused by the voltage on the grid side, it can be improved by generating inductive or capacitive reactive power. It can effectively suppress the imbalance of three-phase current in the power grid and dampen the resonance of the power grid.

(2) Principle of reactive power compensation

The device detects the state of the grid current leading or lagging voltage to determine whether the grid is inductive or capacitive, and emits reactive current of the same frequency as the grid but opposite to it to offset it. That is, when the grid is inductive, it emits capacitive reactive power, and when the grid is capacitive, it emits inductive reactive power to achieve the purpose of compensating reactive power. It dynamically compensates for the reactive power of the system and completes the mutual conversion from the rated capacitive reactive power to the rated inductive reactive power in a short time. It can compensate for impulsive loads without problems such as overcompensation or undercompensation, which is beyond the reach of traditional reactive power compensation equipment.

(3) Principle of harmonic filtering

The device adopts high-frequency PWM conversion technology, high-performance DSP control chip, and fully controlled power electronic devices. It uses advanced control theory and fully digital control methods to detect the load current in the power grid in real time, quickly separate the harmonic current components, and generate control instructions based on the magnitude of the harmonic current. It injects compensation currents of equal magnitude and opposite direction into the power grid in real time to achieve instantaneous filtering of harmonics.

(4) Principle of voltage fluctuation and flicker suppression

The device suppresses voltage fluctuations and flicker in the system by real-time tracking of the compensation point voltage. When there is a single-phase or three-phase sudden rise or drop in voltage, and the sudden rise is within 110% of the rated voltage, the sudden drop is within 50% of the rated voltage, and the width is within 2 seconds, the device can increase the grid capacity by emitting inductive or capacitive reactive power, thereby achieving the goal of stable voltage.

　　·Simultaneously compensating for reactive power, harmonics, three-phase imbalance, voltage fluctuations, and flicker in the power grid

　　·Improve abnormal situations such as voltage flicker caused by lightning strikes, short circuits, overloads, etc

　　·Modular structure design, small size, light weight, easy to install and debug

　　·Unique heat dissipation design, low noise, long service life, maintenance free equipment, saving labor costs

　　·Automatic current limiting function, avoiding long-term output overload, safe and reliable operation

　　·High reliability compensation effect, real-time compensation, response time less than 20 milliseconds

　　·No capacity attenuation, increase grid capacity, reduce losses, purify the grid

　　·Continuously adjustable reactive power compensation capability to overcome the insufficient graded compensation capability of capacitors

　　·Multiple protection functions: over-voltage protection, over-current protection, short-circuit protection, etc., suitable for various harsh environments

　　·Significantly reduce transformer and line losses in low-voltage distribution networks, thereby increasing the actual transmission capacity of the distribution network

　　·Filter out harmonic currents generated by user devices in the distribution network, eliminate losses caused by harmonic currents on the lines, and eliminate interference with other electrical equipment

　　·Efficiently reduce zero line current, minimize power line losses, improve power supply quality, and extend equipment lifespan

　　·Adopting IGBT to form a current source type fully controlled compensation device avoids the resonance phenomenon caused by traditional capacitors from a mechanistic perspective, making it more stable and safe

　　Note:Provide internal module parallel cabinet products, with a maximum capacity of 400kvar per cabinet and the ability to increase capacity by parallel connection of multiple cabinets.

　　·A power system that requires comprehensive compensation for reactive power, harmonics, and three-phase imbalance

　　·The field of electrolysis industry using special AC voltage

　　·Low power factor area electrical systems, such as factories, enterprises, etc

　　·Production enterprises that use high-power non-uniform loads, impact loads (such as air pumps, etc.)

　　·Remote areas with poor electricity conditions, such as rural areas, mountainous areas, wind farms, etc

　　·Power systems with high requirements for grid quality, such as hospitals.