Chrást 420 kV Substation
Refurbishment and extension

Refurbishment and extension of the 420 kV Chrást substation for ČEPS — complete delivery under full operation of the substation, from dismantling end-of-life infrastructure and construction of a new double-row substation to deployment of the SCADA control system.

The project is being delivered under the demanding conditions of a substation in full operation, which requires maximum coordination of construction and installation work, with uncompromising emphasis on operational safety and occupational health and safety. The initial phase focused on the coordinated dismantling of the existing end-of-life infrastructure and preparation of the site for new construction. As part of these groundworks and civil works, a new main earthing grid with an exceptional short-circuit withstand of 50 kA/0.5 s (125 kA) was built first, forming a safe and reliable foundation for all future technology buildings.

In the main delivery phase, construction concentrates on the civil and technology parts of the new double-row substation, consisting of seven fully equipped bays and one metering bay. Load-bearing structures are being erected, two busbar systems of the W1-W2-W1 type with auxiliary busbar W5 are being installed, and modern primary equipment is being fitted, such as Siemens 3AP2-FI circuit breakers, disconnectors and instrument transformers meeting strict EMC standards. In parallel with the technology part, a new central building and secondary equipment buildings are being constructed to provide protected accommodation for control systems and personnel.

The final stage is devoted to installation of secondary systems, cabling, testing and overall revitalisation of the site. A decentralised SCADA control system communicating over the MOR optical network via the IEC 61850 protocol is being integrated into operation, and duplicated, independently powered protection systems are being installed for each bay. After successful commissioning of the robust auxiliary supply system with 2× 1000 kVA transformers and a standby diesel generator, physical and fire safety systems (TSFO, PMS) and a camera system are installed. The whole construction process ends with environmental finishing works, including final re-grassing of the affected areas and connection of the storm drainage to the existing system.