Research Of The Gas-Steam Combined Cycle Unit Reliability Model

In recent years, people pay close attention to the environmental problem, something which are good for the environment have contain more concerns. The gas-steam combined cycle unit with its high energy utilization, environmental pollution, the installed capacity, and start-up/shutdown quickly becomes more and more popular in the power system. Moreover, there are some unusual running modes which is "no steam no power, one gas only a half power", making some work to evaluate the reliability of the combined cycle unit. The main contents are as follows:1、The model of the generation and transmission composed systems reliability varying with gas-steam combined cycle unit and revised parameters is presented.Considering combined cycle units to run four different states, an assessment model for generation and transmission composed systems with "2+1" combined cycle units was proposed based on the Mote Carlo simulation method with state transition sampling. Corresponding procedure was developed on MATLAB and used to evaluate the reliability of the IEEE-RTS79test system with combined cycle units and revised parameters. The result is that the reliability indexes of the test program which combined cycle units total output capacity of1/4,1/3,1/2in generation and transmission composed systems were significantly reduced. Two reliability indexes which present the combined cycle unit reliability impact to the generator and transmission composite system expected duration of load curtailments and expected energy not supplied.2、Gas-steam combined cycle unit maintenance period optimization based on system reliability.The gas-steam combined cycle unit maintenance period optimization model is presented, which is considered the minimum of the system maintenance costs, loss of power failure, loss of system maintenance based on the system reliability. The gas-steam combined cycle unit MTTF which are adjust to the working time are fixed by the particle swarm optimization, the4"2+1" gas-steam combined cycle units system reliability is calculated by the Monte Carlo simulation with state transition sampling. Using month as the calculating unit, not only compare and test fixed MTTF and not-fixed MTTF system reliability and economy based on the different maintenance period, but also compare the system reliability and economy in different load ratio. The optimum maintenance period of the gas-steam combined cycle unit considered before is given.