During the execution of works on the construction of external power supply networks for customer facilities, situations often arise that are not always predictable. And even if they can be foreseen, it's challenging to assess their scale from a technical standpoint at the outset.
Especially when the works on connecting the facility are not carried out in a traditional sequential manner (where all administrative and technical stages of work proceed sequentially), but rather in what is called a "rolling" manner (where technical conditions for connection are obtained in parallel, basic technical decisions are made, and the construction of the facility is carried out).
The occurrence of such situations can be associated with many factors.
Here's a real-life example: the connection of critical infrastructure facilities.
During the process of calculating network operation modes, it was discovered that in the event of a single-phase earth fault, the capacitance current reached a level that the existing equipment at the distribution network operator's (DNO) feeding substation couldn't compensate for. This necessitated the installation of a shunt reactor on one of the sections of the 35 kV busbars of this substation. The delivery time for this equipment is up to 6 months (seriously!), significantly extending the project implementation timeframe.
Considering that this facility is part of critical infrastructure, and we cannot afford a 6-month delay in its commissioning, the specialists of the EDS Substation team proposed a solution to split the Technical Conditions for connecting the facility into 2 stages:
- Connecting the facility with Category 3 reliability from one section of the DNO feeding substation busbars, allowing voltage supply to the facility for commissioning and operation readiness.
- Connecting the facility with Category 1 reliability after installing the shunt reactor on the 35 kV voltage level of the DNO feeding substation.
Taking into account the purpose of the facility, as well as the technical feasibility of its phased connection, the DNO approved the proposal of the EDS Substation company's specialists and made corresponding adjustments to the technical conditions for connecting the facility.
Meanwhile, the electrical installation has already been built and is awaiting voltage supply from the DNO, which will happen shortly.
