By using a high-power thyristor switching switch, the controller can control the thyristor switch to quickly switch the multi-stage capacitor group based on system voltage, reactive power, and two-phase criteria. The thyristor switch adopts a zero crossing triggering method, which can achieve capacitor input without inrush current or impact, stabilize system voltage, compensate for reactive power in the power grid, improve power factor, and enhance transformer carrying capacity. It can be widely used in power, metallurgy, petroleum, ports, chemical, building materials and other industrial and mining enterprises as well as residential distribution systems.
Device structure and technical performance of main components
1. Device structure
The low-voltage reactive power dynamic compensation device consists of a controller, a contactless switch group, a parallel capacitor group, a reactor, a discharge device, and a protection circuit. The whole machine is designed as an electromechanical integration.
2. Main component technical performance
(1) Controller
The controller of the low-voltage reactive power dynamic compensation device is a brand new digital design, with modular software and hardware, high integration, electromagnetic compatibility, and strong anti-interference ability. It has 12 output terminals and can achieve compensation in three ways: phase separation, balance, and phase separation plus balance. Widely applicable, it can meet the compensation needs of different types of loads. The non-contact switch group can be switched on and off according to the system voltage and reactive power control, with manual and automatic operation modes, and has protection functions such as overvoltage cut-off, overvoltage lockout, undervoltage cut-off, and overtemperature alarm.
(2) Contactless switch group
The contactless switch group is the main executing component of the device, consisting of thyristor switches, heat sinks, fans, temperature control switches, zero crossing trigger modules, and resistance capacitance absorption circuits. The integrated design allows for a maximum controllable capacity of 90kvar per group. The thyristor switches are imported components with high power and safety factor.
(3) Parallel capacitor bank
High quality self-healing parallel capacitors are selected, which can be flexibly encoded and combined according to different capacities. There are multiple switching stages, and large capacity compensation can be achieved in one go.
Basic working principle
The controller monitors the changes in system voltage and reactive power in real time during the operation of the device. When the system voltage is lower than the power supply standard or the reactive power reaches the set capacitor bank switching threshold, the controller gives switching instructions. The zero crossing circuit quickly detects the voltage difference between the two ends of the thyristor (i.e. the voltage difference between the capacitor and the system). When the voltage at both ends is zero, the thyristor is triggered, and the capacitor bank achieves no inrush current input or cut-off.
Main technical parameters
1. Rated voltage AC220V/380V ± 10% 50Hz
2. Wiring method: three-phase four wire
3. Switching is based on system voltage and reactive power
4. Response time ≤ 20ms
5. Switching delay 0.1-30s (continuously adjustable)
6. The average cutting accuracy is ≤+2%
7. Compensation capacity ranging from 60kvar to 1080kvar
8. Switching levels 1-18
Environmental conditions for use
1. Working environment temperature -25 ℃~+45 ℃
2. Relative humidity of air ≤ 85%
3. Altitude ≤ 2000m (High prototype is used for elevations above 2000m)
4. The installation environment is free from flammable, explosive, chemically corrosive, flooded, and severely vibrating areas
5. Installation method: indoor screen type, outdoor box type
6. Installation conditions: The harmonic content in the power grid shall comply with the provisions of the 0.38kV clause in GB/T14549
Protection function
It has multiple protections for overcurrent, overvoltage, undervoltage, and temperature exceeding limits. The device can automatically shut down in case of external faults and power outages, and automatically resume operation after power transmission.