The Bulgarian State Railways, founded in 1888, are among the oldest rail networks in Europe. Providing passenger and freight services, they cover more than 4,200 kilometers and connect diverse geographies – from the snow-capped Balkan mountains to the sunny Black Sea coast, from the bustling state capital Sofia to culture hub Plovdiv, and from Balkan Serbia to Mediterranean Greece.
The National Railway Infrastructure Company (NRIC), responsible for the smooth operation and maintenance of this railway infrastructure and the electrical power that supports it, was facing power quality challenges across the network. In broad terms, the Company’s electrical railway traction system comprises of large and varying loads. This demands large amounts of dynamic reactive power, which leads to low power factor and voltage fluctuations ie. poor power quality. This is harmful to the traction system itself - potentially spreading through the electrical grid and causing disruption to other users as well as incuring financial penalties for NRIC.
ABB designed and supplied a power electronics based compensation solution for dynamically varying reactive power called PQC-STATCON installed at various nodes across the rail network. PQC-STATCON is an instantaneous & stepless compensator for improving power factor and reducing voltage variations. By installing this technology NRIC will experience improved power quality, voltage stability, better compliance to grid codes and avoidance of penalties by the grid. It will also provide added benefits like reliability and availability of the supply network, energy efficiency and lower maintenance costs.