Conducting a Power Plant Performance Test

During the part I of this post we discussed all the preparations for an official performance test. Now it is the turn to oversee the activities to evaluate the plant performance of a power plant.

Among the activities required to conduct a performance test, is the installation of the high-precision instrumentation at site. This instrumentation will be installed in a temporary basis.

To conduct the instrumentation installation, the company executing the test will arrive to site with the tools and personnel to complete this installation.

Usually, the performance testing team arrive to site 5 to 10 days prior to the testing date. This depends on the scope the service. Also, it could be that the precision instrumentation that needs to be installed for testing well before the expected performance testing date.

This has proven to be a good idea to minimize the installation time of the equipment during the early activities of commissioning.

If the instrumentation is installed several months before the expected testing date; it is important to verify the calibration certificates will be valid by the time of the test.

As with most of things in life, preparation is everything.

Even if we plan for all possible unexpected events. For example, some of the locations where the equipment will be installed might be difficult to access or the place where the instrument was supposed to installed got damaged during commissioning (i.e. a thermowell or a pressure tap)

An experienced performance engineer will need to asses the impact on the test accuracy and discuss with the other parties involved in the test the lack of this measurement or alternatives.

PREPARATIONS

Prior to conducting a plant performance test, there should be a coordination between all the parties involved. The main points to agree will be.

• Status of the testing preparations
• Activities to be conducted by each of the parties
• Expected schedule for the test execution
• Discuss any possible deviations from the testing procedure
• Agree on site support for the days/nights of the performance test

Among the list of activities to conduct prior to the test is the data collection of the following sources:

• Permanent instrumentation
• Precision instrumentation
• Data collected manually

Power Plant Stability

The team should agree on the thermal stability of the plant during the test. This might affect the schedule of testing.

In some cities the grid is fairly stable and in the ones that frequency can fluctuate beyond the actual allowable stability limits set per ASME PTC 46, the team should look for a period when the grid is more stable, usually during the night.

The same happens for weather conditions, mainly ambient temperature, humidity as well is impacted if we observed sudden changes in ambient temperature.

Based on the weather forecast, the ideal is to look for a time period when the ambient temperature is as stable as possible.

For coal plants, specially, another source of instability could be the coal used during the test. As much as possible the team should look to burn coal from one of the more homogenous silos at site.

Prior to the test, there should be a written agreement among the involved parties for accepting that an official test is conducted.

CONDUCTING A PLANT PERFORMANCE TEST

During a performance test, the conducting party will act as the test director. Establish the time to start the test is the first task. At least 3 hours to the start of testing, there should be confirmation of being ready to conduct the official test. From instrumentation, process preparations, conditions to comply with the stability requirements and the coordination of the personnel supporting the test.

During the test, it is important to monitor constantly the following:

• Power plant thermal stability in accordance with the site specific performance test procedure and ASME PTC 46 or equivalent testing code.
• Data acquisition from the DCS, PI, Temporary Instrumentation and Manual Data Collection
• Walk-down to check if any steam or water leaks can be prevented.
• Power plant cycle isolation.
• Fuel sample collection

At the time specified for the conclusion of the test, all parties should get together and agree that the testing can be officially accepted. Once this is done, the site coordinator should distribute data among all the parties involved.

AFTER TESTING

Once the actual test is completed, a preliminary results report will be created and discussed before removing the temporary testing instrumentation. All the fuel samples will be pack and prepared for shipping to the laboratory. The preliminary results will be calculated using the contractual fuel analysis.

At this point the testing team will demobilize from site to continue with preparing official power plant performance test report from the office.