Jessica Morrison and Diane Broad
Project developers and grid operators have a history of battling over the benefits and process of integrating alternative energy into the transmission grid. This conflict is driven primarily by the perception that renewable generation, particularly wind, is at odds with the grid operator’s objective to provide service to customers at the lowest possible rates and maintain a robust, stable grid. Developers focus on completing projects quickly to secure financing and tax credits, and this conflicts with the grid operator’s system planning process. Tension between the two parties frequently leads to stalled, cancelled or unexpectedly expensive projects, which negatively impacts the grid operator’s ability to diversify generation and meet customer demand, and the developer’s objective to deliver the product to market at an acceptable rate of return. When both parties keep the lines of communication open and make an effort to understand the needs of the other, they are more likely to find common ground.
The fundamental question of why the grid operator should embrace alternative energy underlies the tension between the two parties. Of interest to the utility, wind energy can be brought into the generation mix on a much shorter development timeline than traditional generation and can be increased incrementally. Wind farms utilizing modern turbine design and active compensation techniques also contribute to, rather than degrade, the stability and quality of the power supply. Additionally, renewable generation is expected to become increasingly prominent in the nation’s electricity mix. Market conditions spurring this growth include growing consumer demand for green power, renewable portfolio standards in more than 20 states, and a growing movement toward CO2 emission legislation. In some parts of the country, the cost of alternative energy has actually dropped below that of electricity from the standard portfolio of coal, natural gas and nuclear. Most renewable generation growth in the United States is expected to come from wind energy, with the American Wind Energy Association (AWEA) forecasting 3,000 MW to be added in 2006.
In addition, the federal Public Utilities Regulatory Policy Act of 1978 (PURPA), combined with favorable state policies and Federal Energy Regulatory Commission (FERC) rulings, is aiding the growth of small-scale renewable energy projects by obligating the grid operator to purchase the output of qualifying facilities on a long-term contract at a fixed rate.
the importance of open communication
Open communication and a willingness to understand the other’s position is essential to build trust and respect. One way to build collaboration is to encourage staff to become more educated about the needs of the other party. According to Robert Gramlich, AWEA’s policy director, more experience and education is needed among the utility planning staff with regard to wind energy.
“Integrating wind is a new engineering task for utility planners, requiring training in the experiences of other utilities in the U.S. and abroad, and best practices for integration methods. Likewise, developers need to have experts on staff that have either worked for utilities in the past, or are knowledgeable about utility planning and operations to know how to help them maintain grid reliability,” Gramlich said.
Gramlich suggests that transmission planners become involved in the Utility Wind Integration Group, and that developers attend North American Electric Reliability Council (NERC) and Western Electricity Coordinating Council (WECC) meetings.
The Energy Trust of Oregon, a non-profit funded through PacifiCorp and Portland General Electric, has taken another approach by hosting an interconnection workshop for large and small-scale developers and utilities. In the workshop, participants learn about required agreements and studies and typical timelines for completion.
Renewable generation is expected to become increasingly prominent in the nation’s electricity mix. Click here to enlarge image
According to Adam Serchuk, senior renewable energy program manager for Energy Trust of Oregon, it’s important for the developer and grid operator to discuss interconnection requirements early in the process. “Some developers tell us that they can’t find a list of the steps in the interconnection process, how long each step is expected to take, and what criteria the utility will use in making its determination,” Serchuk said. “The developer ends up hiring consultants and lawyers to tell them what to expect and what is reasonable, which further adds to the expense and stress associated with the process.”
One of the biggest challenges for developers is the absence of standardized interconnection procedures. The procedures and agreements outlined in the May 2005 FERC rulings, Order Nos. 2003 and 2006, are intended to bring some uniformity to the process. However, no penalty exists if the grid operator misses a deadline, which makes it difficult for developers to estimate the time and money needed to complete the process. Additionally, the grid operator typically takes a “one solution fits all” approach to wind projects, even though the time and resources needed to interconnect a small project vary significantly from those needed for a large-scale facility. California, Texas and New York have implemented statewide interconnection standards that have reduced uncertainty for both the developer and the grid operator, and greatly increased grid access for renewable energy projects and other distributed generation.
grid operator viewpoint
The grid operator’s biggest challenge is to maintain a complex system with extremely high reliability, and effectively plan for future system changes over five- to 10-year periods. The interconnecting utility operates in a highly regulated world, from the requirements of the FERC, NERC and regional entities like the WECC, to the rulings of each state’s public utility commission and the overall standards and codes of good utility practice, including the National Electrical Safety Code (NESC), the National Electrical Code (NEC) and the standards promoted by the Institute of Electrical and Electronics Engineers (IEEE).
With respect to system operational needs such as reactive power and grid stability during and after faults, the grid operator has been faced with the choice of evaluating individual interconnection requests or some combination of multiple proposed projects. The utility typically has limited resources and has to process many requests for interconnection, without knowledge of which projects may eventually be completed.
Stakeholders, including AWEA, NERC, developers, manufacturers and grid operators, have worked together over the last few years to resolve common wind interconnection challenges. Their combined efforts resulted in FERC ruling 661A, which outlines operational requirements for wind energy installations of 20 MW or more, as well as interconnection study guidelines. This ruling establishes requirements for low-voltage ride through (LVRT) in case of system faults, power factor limits, and a transition period so wind turbine manufacturers can produce new turbines that meet the standards. It specifies that the LVRT will apply to all new installations, rather than placing the burden of proof on the grid operator through the system studies.
Larry Soderquist, transmission engineer for PacifiCorp, said that for wind generating facilities, the FERC and WECC rulings regarding LVRT and reactive power usually require the addition of supplemental reactive compensation. “PacifiCorp requires that generating facilities connecting to its transmission system be capable of delivering a +/-95 percent power factor at the point of interconnection, and the reactive source must be controllable on voltage. These generating facility requirements, for facilities less than 10 MW, interconnecting to PacifiCorp’s transmission system, will depend on system performance estimated by studies using models of the electrical network.”
case in point
Western Wind Power, a Washington-based developer of small-scale wind projects, confronted the challenge of interconnecting a small project to the grid. In 2005, the company initiated an interconnection request for the China Hollow wind project, which involves a single GE 1.5 MW SLE wind turbine on a 20.8-kV distribution line in Oregon. The interconnecting utility, PacifiCorp, had concerns about possible voltage flicker and harmonics. Since no real-world flicker data was available from the turbine manufacturer, the developer accessed GE 1.5 SLE turbines at another nearby wind energy facility, and paid for power quality monitoring. The developer and the utility jointly analyzed the results and discovered that short and long-term flicker did not meet PacifiCorp standards. Mitigation options included reconductoring the distribution line or adding a reactive power source. It was agreed that a static VAR compensator of 275 kVAR would be adequate to mitigate the effects of voltage flicker, and could be implemented at a cost acceptable to the developer. Communication and joint collaboration on the problem led to a successful resolution satisfactory to both parties.
To address grid operators’ concerns about grid reliability and stability, and developers’ focus on meeting project deadlines and rate of return requirements, both parties must work together to jointly devise realistic timelines, expectations and policies regarding the uniform application of interconnection standards. This collaboration will help ensure mutually advantageous solutions supporting the smart, controlled growth of renewable generation.
Jessica Morrison is the energy marketing manager for David Evans and Associates, a Portland, Ore.-based engineering design firm active in energy, land, water and transportation. Diane Broad is an electrical engineer for TriAxis Engineering, an electric utility design firm based in Corvallis, Ore. Jessica and Diane will be co-presenting at the American Wind Energy Association conference in June on wind interconnection. For more information, please visit www.deainc.com and www.triaxiseng.com.