Power Quality Solution for Railway Industry

Industry Overview

        The rapid development of urban rail transit has made travel more convenient and boosted economic growth. However, the power supply systems rely on numerous cables, and the nonlinear loads (e.g., rectifiers, elevators, air conditioners) cause strong fluctuations, high harmonic content, and significant capacitive currents. These issues lead to equipment overheating, reduced lifespan, and potential safety risks. DINGNUO’s harmonic mitigation solutions effectively address these power quality challenges, ensuring a green, safe, and stable power environment for rail transit.

Power Quality Issues

        The subway distribution system uses a large number of nonlinear loads, mainly divided into two categories:

1. Traction rectification and inversion devices that generate high-order harmonics (such as 5th, 7th, 11th, 13th, 23rd, 25th, etc.).

2.Large nonlinear loads in substations and subway stations (such as switch power supplies, frequency converters, VVVF-controlled elevators, fans, cooling units, modern energy-saving lighting (LEDs), etc.) that generate harmonics (mainly 3rd, 5th, 7th, etc.).

The harmonic current distortion rate in rail transit usually reaches around 10-20%.

Power Quality Challenges

        Harmonics can increase power losses, shorten equipment lifespan, and cause safety issues like overheating and malfunctioning of circuits, grounding protection, and remote controls. Long-term exposure to high harmonics can lead to grid resonance, causing power outages and accidents. They also contribute to equipment overheating, insulation aging, and failures in relay protection systems. Harmonics disrupt electronic instruments and communication systems, reducing quality, and can cause severe heating of neutral lines, rubber aging, and fire risks.

Solution

DINGNUO Series can mitigate 2nd to 50th-order harmonics. The harmonics generated by rail transit are primarily 3rd, 5th, and 7th-order harmonics. For the harmonic issues present in this industry, using DNE Active Harmonic Filters can effectively manage harmonics, balance the three-phase current, and significantly improve the power quality of the system, ensuring the safety of user electricity.