Alternative Commissioning for Solar PV Power Plants

Comrent is providing solutions for mission-critical power testing infrastructure.

To meet production deadlines and begin producing commercial power as quickly as possible, the complete solar PV power plants, including the operation of the inverters and solar modules, must be load tested.

How do solar PV power plants conduct this load testing?

In many cases, the grid is unavailable. If your solar PV power plant is in a remote area, and transmission lines are not yet available, your only choice is to use load banks. Even if the grid is available, interconnection usually requires prior load testing and commissioning to prove your system. Also, you have no guarantee the grid will be available when you’re ready for power plant commissioning, and the grid provides no control or accuracy.

Don’t Let Project Delays Negatively Impact ROI

Relying on the grid for testing creates avoidable issues that often result in delayed solar commissioning. These delays negatively impact your return on investment.Comrent deploys a microgrid renewable energy solution that is simple, convenient and on-demand, validating the inverter functionality and ensuring each commissioned solution meeting specification.If critical elements delay a project, you can certify completion of construction for rate base additions/capitalizations when a customer site not yet ready for energization. This practice allows complete system testing as installed, resulting in improved reliability and availability.

The Power Plant Commissioning Process

To commission the solar PV power plant systems, you will need to provide a steady power source on the utility side of the PV Inverters. The power source must be sufficient to operate within the threshold of the anti-islanding equipment. For efficient testing, the power source is typically connected at the main breaker of the substation or one of several combiner boxes on site, depending on the testing requirements. Once utility power is simulated in the solar farm, this will activate the internal circuits of the inverters. The solar arrays, which constantly produce power during daylight hours, will then begin to produce power and sync with the power source. The power system is achieved by providing a generator system rated at 120% of the inverter size. For best results, two paralleled generators are used to deter frequency variation caused by load reduction and application.

Depending on the distance of the power source to the solar inverter, which is often well over thousands of feet, an inductive load bank might be required to compensate for the capacitive-reactive energy created by the buried cable runs. The inductive load bank should be rated at a higher amount than the capacitive reactance measured in the field. The customer should measure this prior to providing the equipment, to prevent damage to the power supply.Alternatively, the inverter’s internal circuits may be energized, which typically range from 380VAC to 415VAC. This source should have adjustable frequency, voltage, and be able to provide a load of up to 25KW. The generator will need to be easily transportable by a light weight truck, so that it can move through the arrays with ease. This method requires more time for terminating the generator to the control circuits at each inverter. It also does not provide an over test of the SCADA system. This test is required by some inverter manufacturers.

Advantages of Load Bank TestingLoad bank testing for solar PV power plants provides many advantages, including:

  • Reducing the reliance on grid availability and allowing your solar commissioning and construction schedule to move forward within budget.
  • Simplify the pre-grid testing by making it an on-demand process. You gain greater control over your load testing schedule and can test at any time.
  • Accelerating the testing schedule and fast-track the time-to-revenue. If you must wait for the grid to test your solar PV power plant, you will incur more time and costs.
  • Adhering to contractual obligations and avoiding penalties from utilities and owners of PV systems. Load bank testing lets you supply power within the agreed upon timeframe.
  • Ensuring solar PV power plants are tested completely to operational specifications and validating system performance.
  • Meeting qualifying deadlines for federal and state renewable energy production tax credits.

Solar PV power plant commissioning requires consistency, flexibility, and reliability. Unlike the grid, load banks or grid emulation can provide these capabilities

.The Solution

Comrent’s solutions have incurred zero failures on hundreds of wind turbine tests. The equipment delivers the variable, sustained loads required to meet the strenuous 600+ hours of testing mandated by solar PV power plants.In fact, Comrent provides the only combined load bank and generator solution for solar PV power plant commissioning. With both resistive and reactive solutions, Comrent’s load banks are the only fleet in the U.S. engineered for solar PV power plants.

Download Comrent’s Latest eBookFor a detailed review of utility commissioning, download Comrent’s latest eBook – “Understanding the Commissioning Process for Utility Systems.” This resource discusses the importance of following established standards and proven processes during utility commissioning. It explains in further detail how successful commissioning can lead to greater control, more efficient operations and lower costs.

Comrent’s team of experts is ready to help ensure your system is successfully commissioned. We are offering a complimentary consultation to review your project and propose the right load bank solution for your requirements. Contact us today.

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