Benjamin L. Schenkman

Initial operating experience of the 1.2-MW La Ola photovoltaic system

The 1.2-MW La Ola photovoltaic (PV) power plant in Lanai, Hawaii, has been in operation since December 2009. The host system is a small island microgrid with peak load of 5 MW. Simulations conducted as part of the interconnection study concluded that unmitigated PV output ramps had the potential to negatively affect system frequency. Based on that study, the PV system was initially allowed to operate with output limited to 50% of nameplate power capacity to reduce the potential for frequency instability due to PV variability. Based on the analysis of historical voltage, frequency, and power output data at 50% output level, the PV system has not significantly affected grid performance. However, it should be noted that the impact of PV variability on active and reactive power output of the nearby diesel generators was not evaluated.

Evaluation and sizing of energy storage systems for microgrids

This paper evaluates the energy storage systems (ESS) in the microgrids. The ESS unit is regarded as an added energy resource in microgrid system to support the power balance when regular distributed energy resources (DERs) are incapable of matching the load demand. Sizing and specifications of ESS are investigated in this paper using several test case scenarios. An overall evaluation of the energy storage functionality is carried out for the microgrid by looking at different storage options for diverse operating scenarios.

PhotoVoltaic distributed generation for lanai power grid real-time simulation and control integration scenario

This paper1 discusses the modeling, analysis, and testing in a real-time simulation environment of the Lanai power grid system for the integration and control of PhotoVoltaic (PV) distributed generation. The Lanai Island in Hawaii is part of the Hawaii Clean Energy Initiative (HCEI) to transition to 30% renewable green energy penetration by 2030. In Lanai the primary loads come from two Castle and Cook Resorts, in addition to residential needs. The total peak load profile is 12470 V, 5.5 MW. Currently there are several diesel generators that meet these loading requirements. As part of the HCEI, Lanai has initially installed 1.2 MW of PV generation. The goal of this study has been to evaluate the impact of the PV with respect to the conventional carbon-based diesel generation in real time simulation. For intermittent PV distributed generation, the overall stability and transient responses are investigated. A simple Lanai ”like” model has been developed in the Matlab/Simulink environment (see Fig. 1) and to accommodate real-time simulation of the hybrid power grid system the Opal-RT Technologies RT-Lab environment is used. The diesel generators have been modelled using the SimPowerSystems toolbox swing equations and a custom Simulink module has been developed for the High level PV generation. All of the loads have been characterized primarily as distribution lines with series resistive load banks with one VAR load bank. Three-phase faults are implemented for each bus. Both conventional and advanced control architectures will be used to evaluate the integration of the PV onto the current power grid system. The baseline numerical results include the stable performance of the power grid during varying cloud cover (PV generation ramping up/down) scenarios. The importance of assessing the real-time scenario is included.

Electrical analysis of Proton Exchange Membrane fuel cells for electrical power generation on-board commercial airplanes

Fuel cells have been considered for all types of trasnport including automobiles, buses, submarines, motorcycles and airplanes due to their high efficiency and their environmentally friendly nature. In most transportation applications, fuel cells are used to augment the existing electrical system and not as a stand-alone power source. The addition of a fuel cell to any type of transport, however, will have an influence on the dynamic behavior of the electrical system within the transport and may even cause instability in a previously stable system. This paper analyzes the consequences of integrating a Proton Exchange Membrane fuel cell to the existing electrical generation and distribution system of a Boeing 787-8 aircraft through modeling and simulation tools. Physical testing, although beneficial and critical, is expensive and time consuming. The modeling approach in the initial scoping stage provides an early indicator of the feasibility of fuel cell use on an airplane in addition to possible challenges that should be addressed with hardware testing. Simulation results are presented using MATLAB, Simulink, and SimPowerSystems environments.

City of Hoboken Energy Surety Analysis: Preliminary Design Summary

In 2012, Hurricane Sandy devastated much of the U.S. northeast coastal areas. Among those hardest hit was the small community of Hoboken, New Jersey, located on the banks of the Hudson River across from Manhattan. This report describes a city-wide electrical infrastructure design that uses microgrids and other infrastructure to ensure the city retains functionality should such an event occur in the future. The designs ensure that up to 55 critical buildings will retain power during blackout or flooded conditions and include analysis for microgrid architectures, performance parameters, system control, renewable energy integration, and financial opportunities (while grid connected). The results presented here are not binding and are subject to change based on input from the Hoboken stakeholders, the integrator selected to manage and implement the microgrid, or other subject matter experts during the detailed (final) phase of the design effort.

Test report : Raytheon / KTech RK30 Energy Storage System

The Department of Energy Office of Electricity (DOE/OE), Sandia National Laboratories (SNL) and the Base Camp Integration Lab (BCIL) partnered together to incorporate an energy storage system into a microgrid configured Forward Operating Base to reduce the fossil fuel consumption and to ultimately save lives. Energy storage vendors will be sending their systems to SNL Energy Storage Test Pad (ESTP) for functional testing and then to the BCIL for performance evaluation. The technologies that will be tested are electro-chemical energy storage systems comprising of lead acid, lithium-ion or zinc-bromide. Raytheon/KTech has developed an energy storage system that utilizes zinc-bromide flow batteries to save fuel on a military microgrid. This report contains the testing results and some limited analysis of performance of the Raytheon/KTech Zinc-Bromide Energy Storage System.

Venetie, Alaska energy assessment.

This report summarizes the Energy Assessment performed for Venetie, Alaska using the principals of an Energy Surety Microgrid (ESM) The report covers a brief overview of the principals of ESM, a site characterization of Venetie, a review of the consequence modeling, some preliminary recommendations, and a basic cost analysis.

Economic evaluation of energy storage options in a microgrid with Flexible Distribution of Energy and Storage resources

In this paper, an economic evaluation is carried out for energy storage options in an industrial microgrid comprising four distributed energy resources (DERs). It is assumed that each DER unit is accompanied by Li-ion battery and/or supercapacitor for load following under islanded mode of operation. Cost estimates are made for different energy storage options based on present value of life cycle cost. The cost calculations use published information from the U.S. Department of Energy (DOE), Sandia National Laboratories, and Electric Power Research Institute (EPRI). Two different scenarios of project life, viz., 20 and 30 years, are covered. The economic advantage of using the Flexible Distribution of EneRgy and Storage resources (FDERS) framework in microgrid operation is analyzed.

Proton Exchange Membrane Fuel Cell Systems for Airplane Auxiliary Power.

Deployed on a commercial airplane, proton exchange membrane (PEM) fuel cells may offer emissions reductions, thermal efficiency gains, and enable locating the power near the point of use. This work seeks to understand whether on-board fuel cell systems are technically feasible, and, if so, if they could offer a performance advantage for the airplane when using today’s off-the-shelf technology. Through hardware analysis and thermodynamic simulation, we found that an additional fuel cell system on a commercial airplane is technically feasible using current technology. Recovery and on-board use of the heat and water that is generated by the fuel cell is an important method to increase the benefit of such a system. Although the PEM fuel cell generates power more efficiently than the gas turbine generators currently used, when considering the effect of the fuel cell system on the airplane’s overall performance we found that an overall performance penalty (i.e., the airplane will burn more jet fuel) would result if using current technology for the fuel cell and hydrogen storage. Although applied to a Boeing 787-type airplane, the method presented is applicable to other airframes as well.