Solar Integration Users Group Scope

Background: Solar generation has been identified as a technology of choice by an increasing number of utilities as a way to meet renewable generation targets and Renewable Portfolio Standards (RPS), or hedge against the passage of climate legislation and rising fossil fuel costs. The Federal Energy Regulatory Commission (FERC) has addressed solar generation in parallel with wind generation through various regulatory activities and mechanisms, while the North American Electric Reliability Corporation (NERC) has done the same through technical reports, such as the reliability assessment reports and the report of the Integration of Variable Generation Task Force (IVGTF), and follow-on standards related activities. The Power and Energy Society (PES) of the Institute of Electrical and Electronics Engineers (IEEE) has focused on solar power in a special issue of the Power & Energy magazine, and in numerous sessions at the annual meetings. The recently-completed Western Wind and Solar Integration Study (WWSIS), sponsored by DOE/NREL, represented a formal analytical treatment of the challenges posed by operating increased amounts of wind and solar generation on the Western Interconnection.

In October 2009, UWIG co-hosted along with the National Renewable Energy Laboratory (NREL), Sandia National Laboratories (SNL), and the Solar Electric Power Association (SEPA) a Utility-Scale PV Variability Workshop to examine issues related to the integration of solar generation and bring together experts from the solar, wind, and electric power industries to discuss what has been accomplished and what needs to be done.

At the request of its members, UWIG has established a Solar Integration Users Group to serve as a knowledge center for issues related to the integration of solar generation on utility transmission and distribution systems. This activity builds on the accumulated wind integration knowledge base that UWIG has helped build, recognizing that both solar and wind integration focus on dealing with the common issues of plant output variability and uncertainty by accessing sources of flexibility, and developing improved forecasting techniques.

Scope: The scope of the user group will cover the following areas:

A. Integration of Solar Generation on Distribution Systems - working in coordination with UWIG's Distributed Wind Applications Users Group, this area will focus on expansion of the capabilities of UWIG's Distributed Wind Evaluation Methodology to incorporate the analysis of distributed solar into the software toolbox. This will include residential as well as industrial/commercial installations. Voltage and reactive power control, flicker and harmonic performance, short circuit current calculation and overcurrent protective device coordination, voltage and frequency ride through, and anti-islanding issues are included in the scope. Case studies will be performed to illustrate the use of the tools and investigate mitigation options.

B. Integration of Solar Generation on Bulk/Transmission Systems - working in coordination with UWIG's Operating Impacts and Integration Study Users Group, and Market Operations and Transmission Policy Users Group, this area will focus on theoretical and observed impacts of utility-scale solar generation installations on the operation of bulk systems and integration into wholesale market operations. This area will touch on such topics as characterizing the variability of the resource, forecasting, treatment of solar generation in markets, and transmission planning and expansion to accommodate solar resources.

C. Modeling and Simulation Tools and Methodologies - working in coordination with UWIG's Modeling and Interconnection Study Users Group, this area will focus on generic models of PV generators suitable for use in transmission and distribution planning software tools for load flow, short circuit, voltage control, and stability studies, modeling and investigation of solar generation performance requirements in normal and abnormal power system operating conditions, and related grid code requirements. This activity will coordinate closely with ongoing related industry development efforts, both nationally and internationally.

Communication and Education: User Group results will be made available by the following methods:

• Tech Briefs for each area
• Fact Sheets for individual topics or studies
• Bibliography with links
• User group meetings at UWIG workshops
• Technical sessions at UWIG workshops
• Seminars
• Participation in industry meetings
• Participation in standards activities

User Group Startup: Numerous methods and studies in the areas above have already been identified, performed or are under way. Significant value can be obtained by analyzing, condensing, and summarizing the existing work to provide guidance for new entrants to the field, as well as help determine the areas needing more attention in the future. We would like to begin by identifying user group members who would like to make a contribution by providing material that can be analyzed and summarized by others, as well as members who would like to actively participate in performing the work themselves. We are coordinating closely with the U.S. Department of Energy's Solar Technologies Program and the Electric Power Research Institute (EPRI) distribution system simulation effort.

DOE/NREL/Sandia/EPRI Participation: The DOE has a very active ongoing program in solar integration on power systems, carried out through NREL and Sandia. The NREL and Sandia program in this area covers a broad range of PV integration issues. UWIG will leverage this body of knowledge and expertise through participation of NREL and Sandia personnel in leadership roles in the user group. UWIG and EPRI are cooperating in the maintenance and upgrading of the UWIG distributed wind analysis tool, which shares a common solution algorithm and engine with the open source EPRI Distribution System Simulator.

For more information, please send e-mail to info@uwig.org