The overall goal of utility substation commissioning is to confirm a facility meets the design intent and the owner’s requirements. For critical facilities, proper commissioning ensures a reliable and resilient operation. Electrical testing solutions such as witness testing and load banks are used during the commissioning process to verify the electrical and thermal systems operate per specifications.
Emerging Utility Commissioning Model
Within the past two years, the industry has worked to develop commissioning standards for utility-scale electric power systems. These standards are applied to both utility-owned and operated systems, as well as interconnected wind and solar power systems.
One reason utilities are interested in a well-developed process is to ensure the substation commissioning facilities perform as expected. Additionally, large utility projects involve many types of companies such as project developers, contractors, EPC firms, equipment manufacturers, and the interconnected utility.The following summarizes some general recommendations:
- Commissioning Process General Requirements
Elements of the substation commissioning process take place in all phases of project execution. The commissioning guidelines shall reference best practices from relevant equipment or industries. Also, clear definition of roles and responsibilities should be set before the project starts and be refined at each phase of the project. A clearly defined and effective comprehensive commissioning test is a key requirement for the overall commissioning process. Finally, contingency plans should be included for special project circumstances that could affect the timing of the commissioning.
- Safety in Commissioning Utility Systems
Safety guidelines are a very critical aspect in dealing with the commissioning utility scale systems. Safety is a major cost that must be factored into the total cost of doing business. It cannot be eliminated but must be considered up front, including the responsibilities in each area as part of the commissioning plan. The commissioning process used for utilities includes the following steps. Guidelines are based mainly on the process observed for distribution-connected projects, and identifies steps throughout a project’s execution that is directly related to commissioning, or, are relevant to assuring successful commissioning.The commissioning process will be described according to the following phases:
- Planning -- The planning phase begins with the identification and definition of grid needs, then translates these needs into requirements. This phase results in an analysis-based decision as to whether or not to proceed with energy storage procurement as a viable and cost-effective solution.
- Procurement -- At this project phase, project managers should confirm the status of any site-specific commissioning requirements that will be in effect during the project construction and start-up processes. Goods or services necessary to comply with these requirements, including the proper electrical testing solutions, should be procured and organized to be on site when needed.
- Deployment -- The deployment phase of a project occurs after the procurement. It is during this phase that equipment is installed and most of the verification tests are performed. The tests should be verified, and the project schedule should coordinate the planned tests during the deployment and integration phase of a project.
- Integration -- Commissioning tests performed during integration phase will support the characterization and validation of an energy storage system’s operational performance. Additional issues to consider relate to the integration with the utility system to provide confidence that the system has been installed and integrated safely and reliably before transferring responsibility over to the operations personnel.
- Operations and Maintenance -- The Operations and Maintenance phase of an energy storage project begins when the system has been commissioned and approved for use in the operations of the electric utility. This phase continues until the end of the project’s operational life. The requirements included in the operations and maintenance phase should flow into the maintenance plans that are put in place for the energy storage system.
- Decommissioning -- System decommissioning is the termination of a system’s operations, and at some point, all utility systems will need to be decommissioned.
Value of Comprehensive CommissioningThe value provided through best practices in comprehensive system testing should involve testing the entire system as installed, providing a load via an electrical testing solution to ensure sensors have enough current to operate, avoiding risk by not having to use a customer load, testing the entire protection system and applying a reactive load if the desire is to test distance relays.Considerations when choosing test method during substation commissioning for transformers:
- Potential damage to transformers from load imbalance.
- Derived load is highly reactive, will not simulate actual conditions for more complex relays.
- Will not properly test distance, directional overcurrent, power directional, or other relays that use current and voltage to operate properly.
- Requires multiple relay settings be manually changed or overridden to “force” the system to test the protection relays.
- Not scalable.
- Metering may need to be bypassed to perform the test.
- Many protection relay faults not likely to be discovered.
Download eBook for More Information…For a more detailed discussion on the importance of load bank testing instead of using the power grid for utility commissioning, download Comrent’s latest eBook titled “Understanding the Commissioning Process for Utility Systems”. This resource will explain how using witness testing, and in some cases load banks, can help make the commissioning process faster and more accurate, leading to greater control and lower costs.Comrent’s team of experts is ready to help ensure your system is successfully interconnected. We are offering a complimentary consultation to review your project and propose the right load bank solution for your application. Contact us today at 888-881-7118 or visit our website for more information on load bank testing.