Government mandates have triggered aggressive deadlines that are forcing utility electrical distributors to improve energy efficiency by cutting energy losses. Pressures also exist to integrate alternative energy generation and electric vehicles into their grids. To meet the challenge, utilities are adapting strategies that leverage smart grid tools and technologies.
Active energy strategies for loss control
Active energy efficiency means reducing energy consumption through measurement, monitoring and control of energy usage. Examples include dynamic network reconfiguration and voltage optimisation. Distribution system operators face issues that such strategies can resolve.
Issue: Technical losses in medium voltage (MV) networks represent about 3% of the distributed energy.
Strategy: Using algorithms, an Advanced Distribution Management System (ADMS) can:
Optimise network configuration and relieve overloaded network segments
Help minimize losses (up to 4% for yearly reconfiguration) and load unbalance in high and medium voltage (HV/MV) substation transformers and feeders
Achieve an optimal voltage profile and improve voltage quality
Issue: Integrating distributed energy resources (DER) i.e., distributed generators (renewable or backup), controllable loads used for demand response, and energy storage (electrical or thermal), can cause rising and falling voltage at the same time in different parts of the grid. Necessary monitoring of this voltage in older substations is costly and complex.
Strategy: Fine-tune voltage control infrastructure. To acquire accurate, “real-time” voltage data, utilities can:
(Figure 1: Voltage control aided by algorithms can help manage changes introduced by adding distributed energy resources)
Install cost effective voltage sensors like capacitive or resistive voltage divisors at MV/LV ( low voltage) substations level
Use “virtual” sensors to estimate the MV voltage based on more accessible data
Install actuators with smart transformers along MV lines to increase or decrease the low voltage (LV)
Issue: Compared with MV lines, more technical losses occur in the LV network. The LV ends of distribution networks are often heavily unbalanced, which causes losses in wires and transformers.
Strategy: Conduct a detailed analysis of MV/LV level performance data. A monitoring system can gather data on daily load, voltage, power factor, and temperature profiles of a substation and feeders, providing a dashboard overview of events and trends. By addressing load imbalance and helping to reduce energy costs, this strategy accommodates added DER and can improve substation power output by up to 30%.
Issue: Estimates indicate that 90% of nontechnical losses occur in LV networks. Assessing for improvement involves identifying and monitoring these losses, but due to the high number of points, it’s costly.
Strategy: Deploy smart meters. Smart energy meters can act as additional sensors to track network energy performance data. Comparing the energy measured on the LV feeder with the sum of energies invoiced by the smart meters delivers a precise location of losses and, additionally, faster detection and location of LV network outages for improved reliability.
Passive energy strategies for loss control
Passive energy efficiency lessens energy consumption through measures that reduce thermal losses using low-consumption equipment.
Issue: After power lines, distribution transformers have the second highest potential for energy efficiency improvement.
Strategy: Cut costs and losses with transformer technology upgrades. Compared to other distribution equipment, transformers are easy to replace, and modern technology enables significant reductions in transformer losses. Calculations show that the total investment cost of an amorphous transformer is less than a conventional transformer.
4 steps to efficiency for a distribution network
In the smart grid era, utility electrical distributors cannot afford to rely upon old technology. Following these best practices in creating a migration plan will help develop a more efficient network:
Within the next three months, identify areas where waste can occur.
Within the next year, install sensors and applications that can accurately assess efficiency losses.
Within the next two years, implement a pilot project to demonstrate feasibility, quantify the gains and estimate deployment costs.
Within the next 10 years, plan and implement a staged rollout.
Although energy efficiency improvements may increase short-term capital costs, long-term advantages will include lower operating costs, reduced energy waste, and a more integrated and flexible network.