The intent is to operate and expose the plant to all the operating modes and transitions without restrictions and as often as possible. As more and more automation and supervision is added to the plants the commissioning and RR tests get more and more involved.
Each plant owner may dictate different constraints for RR. The rules may also depend on the unit performance during the commissioning. If the plant has been failing often, owners may impose more stringent conditions. In general, the unit must operate 30 days, 24 hours a day without a major failure that would cause the unit to reduce its capability to carry load. If that happens, the RR is restarted from the beginning. For instance, a failure of a pump with a successful automatic transition to the healthy pump will not be a cause to stop the RR, but considered a successful operating action.
It is much easier to commission a plant if you had followed it through the design and construction into commissioning. Sometimes a commissioning engineer may be invited to do a commissioning on a plant that he/she may not be familiar with. There were a number of cases like this. One of difficult ones was in Lahore, Pakistan, where we were invited to conduct a commissioning and RR test after it has failed in 12 earlier attempts over a period of two years. It was a 5 × 30 MW thermal plant.
During the RR, the plant was supposed to operate flawlessly for seven days without a single alarm while being tested under all the operating conditions. In addition, there was a specific test during the RR while all the plant units were running, called “Islanded Test.” An unexpected three‐phase fault is arranged on the HV line, connected to the plant. To pass the test, the plant had to separate itself from the grid, shutting down four units, while one unit was supposed to be left running and maintaining the plant station service load.
Well, this time, it worked well, and the plant passed the test. We knew that this time, we had to take a different approach. We modified the protective relay settings and readjusted the governor transfer functions. Every short circuit is different, and the units are required to conform accordingly. Perhaps we were just plain lucky. It is hard to tell. This time the protective relays operated selectively and the new governor settings acted correctly.
1.3.4 Power Plant Grid Tests
The power plant or a unit connected to a HV grid is often subjected to a number of grid tests that must be completed to confirm its compatibility with the grid and to operate from the dispatch center. Here is a list of some of the grid tests:
Load dispatch following capability
Reactive power dispatch follow
Isochronous capability (droop)
Dispatch MW ramp rate
Fast ramp MW response
Synchronous condenser mode switchovers
Primary/secondary high‐frequency response
Under‐frequency trip setting check (simulation)
Loss of station service AC supply – switchover to standby power
Black start, synchronizing on islanded grid dead bus
House load operation on generator power for two hours
1.3.5 Commissioning Reports
Most commissioning engineers observe the testing in a passive way, and at the end of the test, they ask for the commissioning reports by the contractors. In their preprepared reports, you will never find a hick up or any failure noted. So, why bother having the reports, when everything is 100% perfect. In fact their reports are already done before they even start testing. Everything is Yes, Yes, OK, OK! There are tests that indeed go smoothly. Faults do happen and often due to multiple reasons that can be either fixed quickly or postponed and fixed later. That has to be recorded, as well as all the temporary deviations due to missing components, etc.
We do our own commissioning or precommissioning report for reasons noted below. We do it directly on our PCs as the events evolve. We sit with the test engineers at the end of a large desk in front of the main control panel and observe and write:
We do not make a story. We write the action.
The testers pay more attention to their work in our presence. They cannot hide the actual facts.
As active people, we can ask for repeat tests or test it from a different perspective or condition.
Our report is chronological and timed as it happens. One never knows what and when something unusual will happen. It does happen and often. One wants to capture the moment and to include all the background details on what was in action before the occurrences of a failure.
It includes the failures as a record, why and how they were resolved and made to be OK.
Later on during the operation when something fails, one can look into the commissioning reports and figure out if this is a recurrence of the same fault and likely to be expected to happen again.
1.4 Project Economics
1.4.1 Budget Estimate
A typical project passes through a number of development phases, starting from an initial estimate, conceptual design for feasibility study, detailed design, construction, and start up.
Let us name some typical projects:
a power plant: hydro, diesel generation, gas combined cycle, etc., and
an industrial project that may be an ore exploitation process, a factory of detergents, potato chips, and any other similar facility.
Utilities typically take care of the large power projects of this nature. They make a budget estimate of the project cost and evaluate it against the revenue based on the kWh to be sold to the consumers. The projected cost will include the initial capital for the equipment, materials, and labor over the years of construction, cost of money and plant maintenances, and operation (see Section 1.4.2)
The overall cost must include the transmission line from the power plant to the major switchyard. In case of a hydro project, the transmission lines are inevitably long and at higher transmission voltages. Diesel generation plants, on the other hand, are generally built for specific consumers in remote isolated areas. This may be a case of a mine up North needing 10–20 MW of power, for which the cost of building a transmission line would be rather prohibitive, in particular, if one evaluates it on the basis of the cost of km of line per MW delivered.
It is not only the utilities that are involved with power generation. There are small power producers called Independent Power Producers (IPPs) for generating anywhere from 2 to 100 MW. They generally do not get involved with power distribution and readily sell all the power to the local utilities.
The cost of fuel over the years of plant exploitation is always the most prevalent factor in the evaluation of a project development. This is where the hydro facility jumps ahead in spite of its huge cost of civil infrastructure. A gas fired plant will certainly be less costly on the basis of the initial cost of the plant and transmission line, but it is the cost of fuel per kWh produced that matters over the life of the plant. A diesel generation
