The Tennessee Valley Authority said Oct. 7 that the Paradise Combined Cycle Plant in western Kentucky, which will replace two of three coal-fired units at the site, is 84% complete, with Oct. 10 scheduled for first fire in Unit 1.
“We’ll admit natural gas fuel into the combustion turbine, establish ignition and bring the turbine up to operating speed,” explained Roger Waldrep, general manager, TVA Major Projects, about the first fire milestone. “That will tell us whether the combustion system works, vibration is good, etc.—it’s kind of like cranking your car to check the health of the engine. No electricity will be generated on day one of what will be a 19-day testing process. We’ll just be generating heat and doing our pre-operation checks.”
This will also satisfy the General Electric requirement to have a several hour heat run to condition the new rotors. Day two of the testing is when the real action happens, TVA added. “We’ll refire the engine, bring it up to normal operating speed, and match frequency and voltage to the TVA grid,” Waldrep said. “Then we’ll close the breaker and connect to the grid, which is initial synchronization. That’s the first time we’ll be generating power, and that power will be available on the grid. That’s a big day.”
On day three, TVA will again synchronize the unit to the grid and incrementally increase power until it gets to full load. At that point, the unit operators and tuning engineers will be ready to fluctuate the loads over the next few days. Waldrep likens the process to the recent ascension testing that happened in the start-up phase of Watts Bar Nuclear Plant’s Unit 2. “We will go to low loads and make sure our control systems and voltage regulators are working,” Waldrep says. “Then we’ll move the load around, going up to 200-225 megawatts and coming back down, focusing on testing, control and tuning in the subsequent days.”
Unit 2 and Unit 3 will be tested first sequentially and then concurrently with Unit 1. Once the testing of the combustion turbine units is complete, Paradise will face another round of testing—this time including all of the steam systems. “We’ll spend another three weeks refiring the gas turbines to make steam that we’ll blow through the boilers and steam piping systems,” Waldrep said. “That way we’ll ensure that the steam system is sound and that all the piping systems are free of any debris.” This period is referred to as “steam blows.”
Waldrep expects that this initial testing and steam system restoration should be complete by January or February 2017. Then the plant will undergo full load testing with all three combustion turbines and the steam turbine-generator in operation, as well as completion of all contractual performance and reliability acceptance tests. The goal is for the Paradise Combined Cycle Plant, which will be able to produce 1,025 MW at full capacity, to be in commercial production in time to help meet the peak demands of summer 2017.
TVA plans to retire the coal-fired Units 1 and 2 at the site when this new project is completed, while leaving the Unit 3 (1,150 MW) coal facility in operation.