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Tomorrow's T&D

The most economical energy savings might be found in grid efficiency.

Fortnightly Magazine - February 2010

consumer and the thermal energy is dissipated to the surroundings as losses. To offset the losses, utilities have to generate more power, which usually results in burning additional fuel and increasing the carbon footprint. Since these losses are inherent in the process, they can’t be reduced to zero, but might be reduced significantly with present technology ( see Figure 1 ).

Additionally, efficiency is more than simply minimizing losses. An efficient system should reduce losses, increase utilization of existing T&D assets and enable smart integration of renewable and storage technologies. While we might not be able to achieve optimal efficiency of the T&D system overnight, we must understand the technology and operational options available today to increase overall efficiency. Whenever attempting to change or upgrade the system, efficiency must be assessed together with all other expected benefits of the upgrade such as reliability, capacity and growth.

A clear understanding of the magnitude of T&D losses is the first step in improving system efficiency. This can be achieved by putting in place a system for accurate energy efficiency accounting.

The industry lacks standard methods and a protocol to identify and quantify T&D losses or evaluate the numerous methods for reducing those losses. Having a consistent and uniform protocol would help utilities identify and compare cost-effective loss-reduction options. It also would allow utilities to document energy savings resulting from power delivery efficiency improvements so they can be assessed easily and credited toward possible energy-saving quotas.

As a highly efficient T&D system is built out, sensors, communications, data management, visualization, and control are key enablers to achieving and improving efficiency. These technologies will help provide data that can be used to identify where the losses are, mitigate the losses and increase the overall efficiency of the electrical system. Establishing a baseline of the present system efficiency is a prerequisite for efficiency improvements to be applied to possible renewable and efficiency standards.

The implementation of technology-based solutions for reducing losses and improving overall system efficiency requires utilities to study and assess not only the technologies, but their T&D systems. Utilities need a comprehensive evaluation methodology and strategic planning framework to accomplish this.

Greener Circuits

In 2008, the Electric Power Research Institute (EPRI) took a step towards demonstrating T&D efficiency and launched a distribution efficiency initiative, Green Circuits, to analyze and apply the efficiency measures in numerous distribution circuits with the goal to assess real-life costs and benefits, as well as to identify technical feasibility and obstacles. Preliminary results show that distribution losses can be reduced by 5 to 10 percent over the next 10 to 15 years by using highly efficient components when performing system upgrades. Overall efficiency also can be improved by changing the operating standards and controlling the voltages within a more optimum band for lowering overall losses and end use of energy. Other options include reconductoring, phase balancing or capacitor placement, to name a few.

The Green Circuits distribution project has identified two major areas of focus for potential improvements, including more efficient transformers and voltage optimization.

Studies have shown that one of