Modernization of the excitation system

The situation

DTEK Zaporizka TPP contacted the DAKAR team when they faced a need to modernize the first power unit TG-1.
The plan was to replace the old generator excitation system with a capacity of 300 MW with a modern thyristor excitation system from the ABB company. Additionally, an increase in the power unit by 25 MW was required.
Before replacing the equipment, it is necessary to conduct a study, investigating the impact of modernization of the power unit on the sustainability of the Integrated Power System of Ukraine. The study is performed on a digital model.

To solve this problem, the DAKAR team performed the following actions:

1. Сollected and analyzed data on the existing and new excitation systems. Since there was no corresponding model of the new excitation system, the team independently developed a mathematical model in accordance with IEEE Std 425 ™ -2005.

2. Designed and agreed on current digital models of the Integrated Power System of Ukraine: for the typical load modes of winter maximum and summer minimum.

3. Carried out the analysis of all repair and emergency modes of the 330-750 kV network of the Zaporizhzhya NPP power supply area.

4. Conducted a study of static and dynamic stability of the Integrated Power System of Ukraine at the stage of commissioning the modernized generator in accordance with the requirements.

5. Verified the digital model of the power plant with real measurements in the power system.

6. Determined the optimal settings of automatic excitation regulators, taking into account their effect on both low-frequency oscillations of generators (based on a modal stability analysis) and the damping of transients during accidents.

The result

In 3 months, the DAKAR team conducted a detailed analysis of power unit modernization impact on various aspects of the operation of the Integrated Power System of Ukraine. Also, we provided recommendations for setting up a new excitation system, which were taken into account during commissioning at TG-1 of Zaporizhzhya TPP.