Innovative T&D Switching Equipment and Development of its Testing Technology

A short overview of the developments in the overall transmission and distribution industry in South East Europe is presented in this contribution. Furthermore, as the present journal focuses on breaking and switching in HV and MV switchgears, several technology innovations in T&D switchgear have been identified, at global level. In almost all cases, the ongoing energy transition is the main driver of these innovations. In this contribution, based on test-experience and overview of the industry, innovations are grouped by drivers, with each of them having its impact on testing technology.

These drivers are the following:

1. Increase of ratings: the ongoing trend of co-existence of micro-, local- and super-grids. The consequences for testing of switchgear for UHV and very large current are highlighted:

2. Offshore transmission: compactness and reliability are requirements stretched to the limit for this application. Very long cables for AC and HVDC power transmission, even in a multi-terminal topology will have impact on switchgear.

3. Health safety and environment: here, the major switchgear related discussion is on SF₆ replacement and reduction of electrical losses. Various issues related to SF₆ replacement will be highlighted. In addition, a recent project intended to quantify the hazard of aluminium bus bars in power stations affected by long duration fault arcs is described.

4. HVDC and power electronics: circuit breakers are going to be installed in multi-terminal HVDC grids. Testing of HVDC breakers, regarding the complete interruption current process is described.

5. Digitalization: switchgear is going to be communicating with the IEC 61850 communication protocol. This will impact testing for which laboratories need to prepare. The introduction of smaller micro-electronics (sensors, IED) closer to primary HV components and its high-frequency transients need careful consideration regarding operation, endurance, and lifetime.

6. Resilience and fault mitigation: Resilience against severe weather conditions, vandalism and cyber-attacks calls for resistant equipment and robust mobile equ ipment/substations that can 6be deployed very rapidly still having an extreme degree of readiness and availability.

7. Quality assurance of products in the face of a pandemic and a lockdown requires adequate methods of a remote digital access to test, and factory sites for type testing and inspection.