Customer Needs
Yanshan series compensation station is equipped by another supplier in 2009, aiming to improve the transmission capacity, stability and reliability of Wenshan-Daxin 500kV line, reduce the loss and optimize the power grid.
Due to changes in line parameters, Yanshan series compensation station is upgraded from 2x435Mvar (rated current 2700A) to 2x 355Mvar (rated current 3150A) in 2015.
The main replacement equipment includes: MOVs, damping reactors, control and protection systems.
Other work includes: adjusting the capacitor bank, increasing the number of parallels and reducing the number of series; adjusting the spark gap distance and test; rewiring and completing commissioning tests.

RXPE Solution
Rongxin power supplies 2 x 500kV series compensation 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 compensation 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.

Customer Benefits
With commissioning completed in 2016, Yanshan series compensation station operates stably and reliably so far.
The upgrading of Yanshan series compensation station improves the transmission capacity, overcomes the transmission bottlenecks and significantly enhances the system stability.