Two 185kW air compressors are installed in a gas station in Zhejiang Province. The actual load current of each air compressor fluctuates from 100A to 350A with the gas filling, the power factor range is 0.5-0.84, and the distance between the power distribution room and the field control cabinet is about 300m. Before the transformation, when the load is large, the air compressor sends out over-current alarm from time to time, the terminal voltage drops from 227.5vac to 215vac, and the line loss increases. The field measurement data are as follows (measuring instrument: FLUKE43B):
Reactive power compensation scheme
According to the load and actual site conditions, reactive power compensation is carried out at the control cabinet. The configuration is as follows:
SFR-L series low voltage power capacitor module is mainly composed of two (△ type) or one (Y type) compensation capacitor, which is highly integrated with composite switch modules, microprocessors and various functional modules. The product adopts modular structure, small volume and convenient maintenance. It is mainly used for reactive power compensation where the harmonics are not very serious. It is not only suitable for local compensation, decentralized compensation, but also suitable for centralized compensation. This series of products adopt double zero-crossing switching technology to ensure that over-voltage and high inrush will not be generated when switching capacitors, so as to prolong the service life of capacitors and the switching life of switches for millions of times.
The product has complete protection functions, with special protections such as capacitor internal temperature, power grid harmonic content, overcurrent, overvoltage, undervoltage, three-phase unbalance and so on, making the product more safer and more reliable. The product can be used with multiple building blocks. When multiple units are used, the host is automatically generated, and the rest are slaves, forming a reactive power automatic control system. Individual faults automatically exit from the host without affecting the work of other machines. Host faults automatically exit, generating a new host and forming a new system work, with a high degree of intelligence. At the same time, this series of products also integrate the function of power meter, which can measure the conventional electrical parameters of the system.
After the implementation of the scheme provided by Sfere Electric, the expected goal was achieved. The power factor of the air compressor circuit is increased to 0.98, the air compressor operates stably without overcurrent alarm, and the terminal voltage is increased to 219.5V, ensuring the long-term stable operation of the terminal load and power supply line.
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