Enhancing the reliability of the 220 kV switchyard at a thermal power plant through modernization

Abstract

The article is devoted to the development of a project for the restoration of the electrical equipment of the 220 kV open switchyard (OSY) of the Thermal Power Plant, taking into account the requirements of integration into the ENTSO-E synchronous zone and the N-1 criterion. Based on the analysis of the technical condition, significant wear of switching devices and instrument transformers was identified, which leads to increased failure rates and operating costs. Methodologically, the study relies on the regulatory framework (IEC, DSTU, PUE, ENTSO-E recommendations), calculation of short-circuit currents according to IEC 60909, verification of thermal and electrodynamic stability, engineering calculations of grounding and lightning protection, as well as a techno-economic assessment. The proposed solutions include the replacement of air circuit breakers with SF₆ circuit breakers HPL-245B1, the use of SGF-245 disconnectors, IMB-245 current transformers and CPA-245 voltage transformers, as well as PEXLIM surge arresters; digitalization of protection and control (IEC 61850) and integration into SCADA/EMS are also foreseen. The calculation results confirm the compliance of the selected equipment with I²t and short-circuit withstand requirements; grounding resistance ≤ 0.5 Ω and complete lightning protection coverage are ensured. Economic calculations demonstrate an annual effect of UAH 2.03 million and a payback period of ≈3.25 years, which indicates the investment attractiveness of modernization. The scientific novelty lies in the comprehensive integration of technical, protection and control, environmental, and economic components of the 220 kV switchyard reconstruction; the practical value lies in the reproducibility of the approach for the modernization of similar substations and TPPs in Ukraine