Installation of 245 kV SVC solution in SS Konjsko
Croatia, Konjsko: The implementation of the SINCRO.GRID - Phase 1 is underway.
Image source: Končar Power Transformers
Croatia, Konjsko: The implementation of the SINCRO.GRID – Phase 1 is underway.
This phase of the project will increase the reliability and security of power supply despite the growing share of electricity being generated from RES. To ensure effective voltage control, an optimal combination of various high-tech advanced devices for the compensation of reactive power and voltage regulation will be incorporated in the Slovenian and Croatian transmission systems.
Installation of 245 kV Variable Shunt Reactors in Croatian substations SS Mraclin (100 MVAr) and SS Melina (200 MVAr) has been finished in 2020 by the main contractor, Siemens Energy d.o.o., while Installation of 245 kV SVC solution in SS Konjsko (25 MVAr) is currently under execution.
At the heart of the SVC plant is a 250 MVA transformer, produced by Končar – Power Transformers Ltd. It is connected to a 245 kV network and a variable reactor or capacitor, depending on the mode of operation (see Fig. 1). As one of the main economic advantages of the SVC solution is reduction of losses in transmission by optimisation of reactive power flow, the losses of the plant are a main concern. Of these losses, the transformer is accountable for about 60 %. In order to achieve the low losses required, low current densities in the windings and flux density in the core were needed. The measured losses were 396 kW for load losses and 92 kW for no load losses, reaching the peak efficiency index of 99,841 %.
The transformer is equipped with a state-of-the-art Končar TMS monitoring system. The monitoring system can record transient overvoltages in real time together with a complete DGA profile (8 gases and moisture) with advanced analysis and bushing monitoring of the unit. Also, a fibre optic system is installed for direct online winding hot spot measurement and, as a result of a joint research measurement, the core temperature is measured in 15 points along the top yoke, controlling the internal temperature of the yoke packages, surface temperature of the core and the temperature of the oil within cooling ducts. The hottest of each of these locations is wired to the TMS and available as real-time data.
Figure 1 – Single line diagram of an SVC plant
Source: Končar Power Transformers
Autor: Slaven Goglia