Impact of harmonics on rail transit electricity consumption

        The rapid construction of urban rail transit has provided people with a more convenient way of travel and promoted urban and social economic development. At the same time, the urban rail transit power supply system uses many cables and the loads (rectifier units, elevators, air conditioners, etc.) are mostly nonlinear, with strong volatility, rich harmonic content, and large capacitive current. It will increase additional losses, cause equipment heating and reduce life, and even threaten the safe operation of the entire urban rail system. The harmonic control solution provided by Xixing Technology can efficiently solve the problem of rail transit power quality and create a green, healthy, safe and stable power consumption environment.

Where do rail transit harmonics come from?

        Many nonlinear loads are used in subway power distribution systems, which are mainly divided into two categories:

         ⚪ Higher harmonics generated by traction rectifier inverters (5th, 7th, 11th, 13th, 23rd, 25th, etc.)

        ⚪ Many nonlinear loads in substations and subway stations (generating 3rd, 5th, 7th, etc. harmonics) such as switching power supplies, variable frequency speed regulators, VVVF-controlled elevators, fans, chillers, modern energy-saving lighting (LEDs, etc.), etc.

        ⚪ The harmonic current distortion rate of rail transit generally reaches about 10~20%.

Pain points caused by harmonics in rail transit construction

        ⚪ Harmonics will lead to increased power loss in the power grid, shortened equipment life, malfunction of grounding protection function, malfunction of remote-control function, overheating of lines and equipment and other power safety issues.

        ⚪ Long-term high harmonic environment will also cause resonance in the power grid, causing large-scale power outages and thus major accidents.

        ⚪ Harmonics will cause additional losses in the equipment and components in the system, causing heating of transformers, cables, motors and other equipment, and accelerating insulation aging of equipment lines.

        ⚪ Cause relay protection or automatic devices of electronic components to malfunction.

        ⚪ Affect the normal operation of electronic instruments and communication systems and reduce communication quality.

        ⚪ Cause the neutral line to become seriously hot, and the outer protective rubber to age rapidly, and in severe cases, there may even be fire hazards!