Trends of changes in the power generation system structure and their impact on the system reliability

• Analysis of reliability indices of Polish coal-fired power units.
• Comparison between the indices calculated for Polish and North American units.
• Analysis of the Polish power generation system reliability.
• Presentation of hazards posed by replacing power units with wind farms.
• Analysis of an example of energy storage in a pumped-storage power plant.

The reliability of the electrical power system depends primarily on the reliability of the power generation sector and the subsystem of power transmission. In recent years there has been a dynamic rise in the amount of power obtained from renewable energy sources in the Polish power sector, including power generated in wind power plants in the first place. The efficiency of wind power plants strongly depends on the wind velocity. This paper presents a reliability analysis of the Polish power generation system. The results are compared to the reliability of North American systems given in NERC (North American Electric Reliability Corporation) reports. The analysis takes electricity generation on wind farms into consideration. A forecast of the reliability of the Polish system of power generation is also presented taking account of planned investments and investment projects which are now in progress. The impact of the increased amount of wind energy on the reliability of the bulk system is discussed. It is shown that, from the point of view of the system reliability, there is a limit to the volume of the share of wind energy in the total amount of electricity generated in the system. Increasing the amount of energy generated by wind farms involves the need to store it, e.g. in pumped hydroelectric storage power plants.