This demonstration program focused on methods to reduce peak electric power and electric energy consumption through Conservation Voltage Reduction (CVR) techniques, specifically, through the application of building voltage regulating equipment.
The demonstration project had two main objectives:
• Reduce peak building power by >4% by reducing voltage from 1.0 to 0.95 per unit.
• Reduce daily energy consumption by >2% by reducing voltage from 1.0 to 0.95 per unit.
The initial project assessed two types of technology:
• Integrated Volt-Amp reactive (VAR) Control which optimally dispatches VAR sources (switched capacitors) and tap changing transformers to shape the feeder voltage profile for base-wide CVR savings.
• Building level electronic voltage regulator which regulates the building voltage level independent of the feeder input voltage, for building-wide CVR savings.
The first two years of efforts focused on advancing the Integrated Volt/VAR Control technology which attempted to incorporate an electrical distribution model with known solar energy sources to shape the voltage profiles of the distribution feeders. This effort was terminated as the voltage profiles were not easily reduced with conventional, low cost switched capacitor banks on the distribution network, and the base did not control the settings of the feeder-head tap changing transformer.
The later years of the project focused on building level voltage control, via existing technology in the form of Electronic Voltage Regulators (EVRs), leveraged from an adjacent market (voltage support to buildings in poor power quality sites).
The net result from the demonstration of CVR at Building 1588 resulted in:
• Peak load reduction of 1.9–5.6% which is within range of the goal of 4–5%.
• Energy consumption reduction of 1.5%, which is less than the goal of 3–4%.
EVR also had an internal loss of 2% which was not accounted for in the above 1.5% energy savings, thus nullifying any benefit.
Note: the voltage reduction is assumed to be set to 95% of rated.
Additional challenges and concerns on applying the technology are listed below.
• The above performances were only applicable to the target building, which had some significant resistive loads, such as electric laundry dryers, and an electrically heated sauna.
• The assessment of CVR impact and savings was very difficult, it required several months of data collection and non-trivial statistical analysis to determine the precise effect.
• The trend for electrical loads is toward constant power loads with closed loop controls. As a base adopts energy conservation measures, the benefits to CVR methods will erode.
The cost effectiveness of the demonstration of EVR technology was zero due to the additional losses in the EVR device, eroding any peak power or energy savings benefit. An alternative method for achieving CVR through manual tap changes on existing transformers proves to be cost effective (as manual tap changes only requires moderate amount of skilled labor applied once, assuming the feeder voltage profile is reasonably constant over time.).
The benefit of CVR methods, at either the distribution feeder level or the building level, is eroding over time as loads become more electronically controlled and behave in a constant power and constant energy manner. Alternatively, energy efficiency efforts should first focus on updating loads which behave in a resistive, un-controlled manner (e.g., the electric laundry dryers with simple run time controller should be replaced with units that have “dryness” or humidity controlled turn off, or be updated with modern gas-fired dryers).