Rongxin power supplies 2 x 500kV series capacitor devices for the Yanshan project.

Boshang SC protection scheme is designed as MOV plus spark gap and bypass circuit breaker. Assuming if an external line fault occurred, the fault current should be bypassed by the MOVs, neither the spark gaps nor circuit breakers are allowed to act; only if internal line faults occurred that the spark gaps and circuit breakers bypass is allowed. This means SC will be always online only except for internal lines faults, giving a high availability.

Yanshan series capacitor station is equipped with MOVs with polymer housings and damping reactors + damping MOVs + damping resistor type damping circuit.

The single line diagram is shown as below:

Capacitor banks, MOVs, spark gaps, damping circuits as well as the HV electronics are located on top of the insulated platform while the control and protection panels are located in the protection chamber on the ground beside the platforms. This project adopts energy supplying CT (on the platform) and laser energized power supply (in the protection chamber), which are the alternative to each other, allowing to significantly improve the reliability of platform equipment, reduce the demand for laser power and extend the service life of laser systems. Due to the redundant design of control and protection systems and fiber-optic systems, the overall reliability is greatly improved.

With commissioning completed in 2016, Yanshan series capacitor station operates stably and reliably so far.

The upgrading of Yanshan series capacitor station improves the transmission capacity, overcomes the transmission bottlenecks and significantly enhances the system stability.