Matthew Rylander

Advanced distribution planning tools for high penetration PV deployment

Solar PV interconnection analyses have historically been addressed by analyzing one or two PV system interconnection requests at a time. As higher penetration levels and numbers of PV systems are realized, the ability to efficiently model and analyze large numbers of PV system deployments and scenarios becomes increasingly important yet difficult. Time and spatial impacts along with uncertainty in the rate of PV adoption must also be considered. Advanced distribution analysis tools are necessary to take into account such factors, and also allow for the quick screening of interconnection requests. This paper discusses some of these issues along with the examples illustrated using an open source distribution analysis program.

Smart inverter settings for improving distribution feeder performance

Photovoltaic (PV) generation is increasingly prevalent throughout power distribution systems. The increased presence of this variable resource can cause adverse impacts to the system due to cloud-induced power output fluctuations. These adverse impacts can be mitigated by allowing PV inverters to absorb and provide reactive power in response to voltage swings. Additionally, properly chosen reactive power response settings can improve distribution feeder metrics such as system losses, number of regulator tap changes, customer consumption, and voltage variability. This paper will assess the impact of smart inverter settings on the performance of a distribution feeder in the United States, identify relationships between suitable settings and feeder variables that may be applicable to other feeders, and show the potential benefit of integrated control.

Methods to determine recommended feeder-wide advanced inverter settings for improving distribution system performance

This paper describes methods that a distribution engineer could use to determine advanced inverter settings to improve distribution system performance. These settings are for fixed power factor, volt-var, and volt-watt functionality. Depending on the level of detail that is desired, different methods are proposed to determine single settings applicable for all advanced inverters on a feeder or unique settings for each individual inverter. Seven distinctly different utility distribution feeders are analyzed to simulate the potential benefit in terms of hosting capacity, system losses, and reactive power attained with each method to determine the advanced inverter settings.

Alternatives to the 15% Rule: Modeling and Hosting Capacity Analysis of 16 Feeders

This project is part of the third solicitation of the California Solar Initiative (CSI3) Research, Development, Demonstration, and Deployment Program created by the California Public Utilities Commission (CPUC) in 2006 to support solar research in California. The program focuses on research to improve the utility application review and approval process for interconnecting distributed energy resources such as solar to the distribution system. The CSI3 program is supporting EPRI, National Renewable Energy Laboratory (NREL), and Sandia National Laboratories (SNL) in their collaboration on the process with Pacific Gas and Electric (PG&E), Southern California Edison (SCE), and San Diego Gas and Electric (SDG&E). At present, the application review and approval process is the most time-consuming of any step on the path to generating power for delivery through the distribution system. Completed CSI3 project tasks include data collection from the three utilities, clustering of feeder characteristic data, detailed modeling of 16 feeders, and analysis of photovoltaic (PV) impacts on those feeders. The distributed PV impacts are being examined to determine gaps and limitations in the current California Rule 21screening process. Updates to Rule 21 supplemental review will also identify when higher levels of PV could be accommodated without initiating the detailed review process. The majority of these updates to the supplemental review originate directly from results of the detailed study. The updates will provide utilities with additional guidance on the information/data and equations needed to better determine the impact from aggregate levels of PV on a feeder. This report highlights the modeling, analysis, and results from the evaluation of PV impacts on the 16 feeders. A subsequent report will discuss suggested modifications to the current screening process and provide validation with additional feeder models developed under the CPUC CSI3 initiative.

Default volt-var inverter settings to improve distribution system performance

Advanced inverters are not smart enough to determine which settings to use in a given set of conditions. Detailed studies are typically needed to determine which settings are most appropriate. Although these detailed analyses can provide the “best” settings for a particular scenario, this single setting cannot be applied to a wide range of feeder and distributed energy resource (DER) scenarios. For the volt-var function to be broadly applied, settings need to be found that are applicable across a wide range of potential conditions. This paper evaluates a proposed default volt-var setting that has been found to provide beneficial response based upon on a wide range of detailed analyses. The benefit from this default setting will be shown to further improve with the combination of additional inverter functions.

Application of new method for distribution-wide assessment of Distributed Energy Resources

Determining the impacts of Distributed Energy Resources (DER), both adverse and beneficial, on distribution systems is straightforward and well documented for single DER systems on single distribution feeders. More complex techniques have been developed and implemented for multiple DER systems on multiple feeders that capture the critical aspects including the DER characteristics, DER size and location of interconnection, as well as the unique distribution feeder and its design and operating characteristics. These complex techniques can require significant time and resources. Systematic methods for analyzing the immense number of scenarios that comprise distribution systems are needed. This paper outlines the components and application of a new method that can be efficiently applied for a distribution-wide assessment of DER. Example results through implementation in an actual distribution system are shown.

Economics of distribution efficiency projects

The economic evaluation of distribution-efficiency projects for six circuits was conducted with a goal to find the most cost-effective planning techniques to improve overall energy efficiency. For each circuit, voltage reduction was modeled along with several efficiency-improvement options such as phase balancing. In many cases, options helped reduce losses while flattening voltage profiles. With flatter voltage profiles, voltage reduction becomes more effective. The costs and economic benefits of each option were calculated so that economically optimal efficiency options could be selected.