Engineering topics

Ueda, Reid

Publications and source records attributed to Ueda, Reid.

6 records

DOE OSTI2018

Residential Advanced Photovoltaic Inverter Pilot Study Results for Select Distribution Secondaries in Hawai'i

Penetration levels of residential rooftop solar photovoltaic (PV) generation on the Hawaiian island of O'ahu have increased significantly in recent years, with many circuits now at the limits of their PV hosting capacity. NREL and Hawaiian Electric have used this opportunity to deploy advanced inverters at new customer installations that would not otherwise have been approved, as a pilot study to gain first-hand operational field data and experience on the impact of inverter-based grid support functions. At each customer location, the deployed advanced inverters were remotely controlled and monitored. Additionally, customer AMI (smart meter) and secondary distribution transformer data was also available for the analysis. The analysis focused on quantifying the customer behind-the-meter voltage rise due to PV production, determining the customer voltage rise with advanced inverters in unity power factor as well as advanced grid support function modes, and estimating the curtailment when inverters have Volt-VAR and Volt-Watt enabled. The results show that: 1) Behind-the-meter voltage rise is often not negligible. 2) An inverter's operating point on a Volt-VAR/Volt-Watt curve depends strongly on the design of the secondary system on which it is installed. 3) The mitigation of voltage rise on the secondary system using Volt-VAR may not be effective if only a small proportion of inverters have grid support enabled, or if the reactance/resistance (X/R) ratio of the grid is low. 4) Volt-Watt curtailment can be estimated using co-located irradiance sensors but there may be opportunities to estimate it using inverter internal electrical measurements. 5) Estimated curtailment is very low for the locations analyzed to date.

14 SOLAR ENERGY↗

DOE OSTI2018

Setting the Smart Solar Standard: Collaborations Between Hawaiian Electric and the National Renewable Energy Laboratory

Driving through many neighborhoods of Hawai'i, it is hard to miss the nearly ubiquitous rooftop solar photovoltaic (PV) systems that have popped up during the past eight years or so. Relatively high electricity costs associated with island grids, coupled with various incentives, have made it cost-effective to install solar over the last eight years, as evidenced by the PV-deployment chart in Figure 1. On the most populous island, O'ahu, the PV nameplate acgenerating capacity of 502 MW totals nearly half of the annual peak load for the entire island, which is 1.1 GW . Of that 502 MW of PVs, 54% is from private rooftop solar-nearly 50,000 residences or roughly one of every three single family homes. But Hawaiian Electric, the local utility, has no way to monitor or control the PV generation, even for most nonresidential systems. This means that on sunny days, up to approximately half of the PV generation is outside of the utility's control. This poses many challenges for utility planners and operators-challenges that Hawaiian Electric has been working diligently to address, along with various partners, notably the U.S. Department of Energy (DOE), the National Renewable Energy Laboratory (NREL), and its Energy System's Integration Facility (ESIF). This article describes how Hawaiian Electric has worked with engineers in NREL's Power Systems Engineering Center to improve the way its grid operates with very high levels of distributed PVs, largely by changing the way the PV inverters are operated.

14 SOLAR ENERGY↗

DOE OSTI2018

Distribution Feeder Modeling for Time-Series Simulation of Voltage Management Strategies

This paper presents techniques to create baseline distribution models using a utility feeder from Hawai'ian Electric Company. It describes the software-to-software conversion, steady-state and time-series validations of a utility feeder model. It also presents a methodology to add secondary low-voltage circuit models to accurately capture the voltage at the customer meter level. This enables preparing models to perform studies that simulate how customer-sited resources integrate into legacy utility distribution system operations.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2018

Integrating More Solar with Smart Inverters: Preprint

In Hawai'i, the relatively high cost of electricity costs coupled with various incentives have made it cost-effective to install solar photovoltaics (PV) on residential homes and larger central-station PV plants. On some of the islands, PV has reached over 50% of the installed generation capacity base. To make sure these inverter-based PV plants can maintain stable and safe operations, new smart inverter functionality is being evaluated and demonstrated at significant scale across the islands This paper describes research conducted to validate high PV penetration scenarios with smart inverters and recent progress on the use of these advanced inverter grid support functions in actual power grids in Hawai'i.

14 SOLAR ENERGY↗

DOE OSTI2018

Distribution Feeder Modeling for Time-Series Simulation of Voltage Management Strategies: Preprint

This paper presents techniques to create baseline distribution models using a utility feeder from Hawai'ian Electric Company. It describes the software-to-software conversion, steady-state, and time-series validations of a utility feeder model. It also presents a methodology to add secondary low-voltage circuit models to accurately capture the voltage at the customer meter level. This enables preparing models to perform studies that simulate how customer-sited resources integrate into legacy utility distribution system operations.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2018

Network Reduction Algorithm for Developing Distribution Feeders for Real-Time Simulators

As advanced grid-support functions (AGF) become more widely used in grid-connected photovoltaic (PV) inverters, utilities are increasingly interested in their impacts when implemented in the field. These effects can be understood by modeling feeders in real-time simulators and test PV inverters using power hardware-in-the-loop (PHIL) techniques. This paper presents a novel feeder model reduction algorithm using a ruin & reconstruct methodology that enables large feeders to be solved and operated on real-time computing platforms. Two Hawaiian Electric feeder models in Synergi Electric's load flow software were converted to reduced order models in OpenDSS, and subsequently implemented in the OPAL-RT real-time digital testing platform. Smart PV inverters were added to the realtime model with AGF responses modeled after characterizing commercially available hardware inverters. Finally, hardware inverters were tested in conjunction with the real-time model using PHIL techniques so that the effects of AGFs on the feeders could be analyzed.

14 SOLAR ENERGY↗