No abstract

Household and industrial electrical energy measurements are advancing into a Smart Grid stage, using solid-state watt-hour meters with communication capability, called smart meters. As electrical products become heavily based on solid-state designs, such as LED lighting and dimmers, electrical loads are not purely resistive, but contain voltage and current spikes, introducing relatively high harmonic power to the grid. This paper describes a testbed laboratory that attempts to model LED household lighting loads, measure the energy by smart meter and power analyzer, and correlate offsets to the waveform variations. Results show that with large current crest factors up to 9, two meters (same manufacturer) out of eight tested show an error near 4 %, with a combined uncertainty of ±0.18 %. Three meters showed no variation outside a 0.07 % standard deviation that was typical for their normal repeatability.

No abstract

In the early spring of 1997, a 900-kVA, utility-tied photovoltaic power station was installed at the U.S. Army Yuma Proving Ground (YPG), in the southwest corner of Arizona (see Fig. 1). The system will be used to offset peak demand and serve as an emergency power system for YPG's water treatment plant. The power station includes 450-kWp of Siemens M-55 modules, 5600-kWh of C&D motive power batteries (see Fig. 2), and a 900-kVA power processing (see Fig. 3) and control system from Trace Technologies. Enhanced by the battery load leveling system, the power station has the capacity to reliably provide from 450-up to 825-kVA to YPG's utility grid during the summer peak demand season. The YPG system has three basic operating modes: (1) daytime utility-tied, (2) nighttime utility-tied, and (3) stand-alone.