Harmonic Characteristics Generated by Rail Transit Power Distribution System

In response to the application and development trend of new technology applications in rail transit, Chinese community owners have already considered how to create a new way of intelligent operation and maintenance of rail transit to ensure safe, green, reliable, high-efficiency, and low-cost operation of urban public transportation .
Electric high-speed rail train: consumes the electric energy of the power supply system, converts the electric energy into mechanical kinetic energy, and keeps the offset. The power lighting power supply system provides power for various lighting, escalators, blowers, pumps and other power machinery equipment in stations and sections, as well as power for communication, signal, automation and other equipment. The switching power supply of the power engineering lighting system includes the blood pressure lowering distribution station and the power engineering lighting lamps and lanterns distribution equipment.


The described power supply system is described in detail from the perspective of indoor space, in which many power supply devices are located under each distribution station. AC and DC can divide power supply equipment into AC system and DC system.
Harmonics in urban rail mainly come from the traction belt power supply rectifier inverter unit, followed by a complete set of DC power supply units, lighting, elevators, monitors, air conditioners, drainage pipes and other devices. The key harmonics are the 5th, 7th, 11th and 13th harmonics, with some 3rd harmonics also included. Ineffective reserves in the high-order harmonic consumption system increase line loss, affect the reliable operation of relay protection and automatic controllers, and reduce the operational safety of electrical equipment used, thereby generating electromagnetic interference in communications and signals. Harmonics can also have a destructive effect on other reactive power compensation devices in the line. At the same time, the reactive power compensation device will amplify the harmonics, forming a vicious circle.

User Value of Harmonic Governance
Urban rail, especially the power supply and distribution system of subway stations, requires very strict power supply reliability. Pulse current is the main cause of the threat to the reliability of its power supply. The application of active filters can reasonably control harmonics, minimize the harm of harmonics to power supply and distribution systems, and ensure the safe and stable operation of urban rail. At the same time, after the harmonic filter, the harmonic loss of the system is reduced, and the original capacitor compensation device can be used normally, further reducing the system loss.

Problems you may encounter?
1. The power factor is low, and the traditional reactive power compensation device cannot be put into operation or is often damaged;
2. Load change
3. The high fluctuation rate of harmonic current affects the reliable operation of relay protection and automatic control system equipment;
4. The three-phase imbalance of the Internet in the power supply system is serious.

Our solution:
1. In order to reduce the content of high-order harmonics, a source filter device is installed on the 400V secondary bus of the step-down substation for filtering
2. Adopt the dynamic form of Hongyan series dynamic reactive power generators to supply reactive power to each phase of the system and manage the harmonics of the system at the same time
3. Choose Hongyan dynamic safety compensation equipment, effectively design capacitor and series reactor parameters according to the pulse current status of the system, improve the power factor through reactive power compensation, and improve the power quality of the urban rail power supply and distribution system.
4. Hongyan’s dynamic safety compensation equipment adopts the hybrid compensation method of three-phase separation compensation and three-phase co-compensation, and considers the compensation requirements of the three-phase unbalance of the system software.

Post time: Apr-12-2023