HNEI-CVR

About

Conservation voltage reduction (CVR) and Volt-Var Optimization (VVO) are methods used by utilities to improve the efficiency of the electric power grid and manage the quality of electric power service to customers by controlling and optimizing voltage on distribution feeders that run from distribution substations to end-use customers. By controlling and essentially lowering the service voltage across a distribution feeder and at the service point of interconnected customers (while maintaining the service voltage within industry accepted operating standards), customers may experience direct energy reduction savings and utilities may achieve a reduction in energy distribution losses and improved utilization of distribution capital assets. Researchers at Grid System Technologies Advanced Research Team (GridSTART) of the Hawaii Natural Energy Institute (HNEI) within the University of Hawaii have invented a novel methodology and new algorithms that will operate autonomously to first determine the appropriate amount and then dispatch (produce or absorb) reactive power to control the service voltage on a distribution feeder by minimizing the voltage difference across a distribution service transformer (single phase, three phase, and the like) to improve upon the limited effectiveness of traditional CVR and VVO methods while balancing the cost of capital investment needed to achieve the desired goal. The algorithms can either be installed in a stand-alone controller or may be integrated into existing field deployed controllers. The effect of this control is a significantly more even (flattened) and stabilized voltage profile across the length of a distribution feeder. This flattening and stabilization of the feeder voltage profile from end to end will maximize the CVR benefits for the utility and its customers. This method of voltage control is dynamic, automated, and is independent of circuit topology, location, and circuit reconfiguration and operational switching. The current HNEI-CVR algorithm computes the amount of reactive power required to minimize the voltage difference across the distribution service transformer, thereby raising or lowering the service voltage bringing it closer to a uniform voltage throughout the feeder. The reactive power required by the loads on the transformer can be provided using the HNEI-CVR device and other distributed Volt-ampere reactive (VAR) resources thereby eliminating the need for it to come from the electric utility, which reduces system losses. The HNEI-CVR device is a fast acting device that can shift reactive power in the 1-2 second time interval. The idealized solution to maximize CVR potential savings is to maintain a constant voltage along the entire feeder path, thereby allowing the maximum level of voltage reduction and consequent cost savings across the entire distribution feeder. The current HNEI-CVR solution addresses the voltage difference across distribution service transformers which can greatly enhance overall feeder voltage management and CVR value realization. The HNEI-CVR solution currently looks at dispatching reactive power to manage voltage. As the power grid evolves and communication to various distributed resources becomes available, controlling both the real and reactive power can be implemented at a lower cost, thereby creating a better cost-benefit ratio.