Impact of new unit installations on power system reliability and ancillary services requirements

Installing new power generation unit always effects operation and performance of a power system including balance between load and generation. Consequently, demand for power reserves the power balancing authority has to acquire for keeping the power system in the equilibrium is changing. Restructuring power system in terms of shutting down old generation units, installing new ones or changing operational characteristics of the existing units will result in different needs for the amount and dynamics of power reserves in the respective categories. The paper studies the situation when the portfolio of power generation units is planned to be changed, new units are going to be installed and some old ones shut down. The effect on power system reliability and change in demand for ancillary services (AS) which are needed to meet the reliability standards is analyzed. Power system reliability is expressed in terms of reliability indices as used by the Czech TSO. Two scenarios of future development of power unit portfolio differ in number and capacity of new units. Finally the impact of new units on AS reservation cost is shown and discussed.