Western utilities calling for smart inverters
August 9, 2013 | By
Barbara Vergetis Lundin
Output of renewable energy systems can change significantly within short periods due to environmental conditions -- like clouds that cover the sun or wind that stops blowing -- causing voltage swings on distribution lines. To realize the potential of renewable energy, the intermittency challenges renewables pose must be addressed. The Western Electric Industry Leaders (WEIL) Group is attempting to do just that.
Traditionally, electric utilities have controlled the voltage on electric distribution lines with legacy electromechanical equipment like line regulators and capacitors. However, as the penetration level of PV generation increases, the magnitude and frequency of the voltage swings will become increasingly difficult to control, causing the legacy equipment to operate excessively, requiring additional maintenance and operational costs, and early replacement. One way to mitigate the voltage swings caused by PV systems and manage the voltage within the allowed operating range is to use inverters with enhanced functionality like dynamic reactive power control similar to those deployed in Europe. The WEIL Group is pushing for the installation of "smart inverters" on all new solar generators in the Western region as a cost-effective solution to this intermittency challenge. With more than 100,000 solar arrays already installed in the region, WEIL Group member companies (including Southern California Edison, Salt River Project, Puget Sound Energy, Arizona Public Service, Sacramento Municipal Utility District, Portland General Electric, NV Energy, Pacific Gas & Electric, Xcel Energy and others) have studied this issue extensively and found significant improvement in power quality when smart inverters are placed on the system. Smart inverters would allow the effective integration of these solar installations by providing the necessary voltage support for these intermittent renewables resources and help ensure the integrity and reliability of the overall electrical system to enable the increased use of clean renewable energy. If smart inverters are not installed, voltage swings could potentially damage utility equipment and home appliances; increase overall cost of maintaining the grid; require installation of larger, more expensive alternatives; and contribute to distributed outages, the group contends. "As more and more solar generators are placed on the regional electric grid, we need to work together to smoothly bring these clean resources onto our system by fitting them with smart inverters to counter the voltage fluctuations that occur with these intermittent renewable resources," said Mike Niggli, president and chief operating officer of San Diego Gas & Electric (SDG&E), a WEIL member. "This will ensure the integrity, safety and reliability of our system and enable the continued adoption of more clean, environmentally-beneficial solar power for our communities." In fact, Germany has ordered a mass retrofit of smart inverters on solar installations at a cost of hundreds of millions of dollars. WEIL says it has the opportunity to avoid this costly scenario by planning ahead and installing the smart inverters before grid reliability is affected. In the U.S., for a solar installation costing $12,000, the new smart inverter technology will only cost about $150 more than current inverters -- approximately 1 percent of the overall cost. For more:
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