Substations are often perceived as one of the less exciting components within an electric network. However, Mitch Beedie explains that disregarding the contribution of substations to efficiency would be a mistake.
In today’s world, the manner in which electricity is distributed from power plants to switches is more crucial than ever. Substations, although less glamorous compared to projects like carbon coal sequestration, play an indispensable role in ensuring power stations can meet modern demands.
For years, substations have been overlooked due to outdated technology or insufficient control of metering.
Now, power companies are giving more attention to potential improvements in efficiency in these segments of power distribution, which were once neglected. This includes isolating and repairing faults, upgrading switchgear and substations, and automating these processes while upholding high levels of safety and security.
Some power stations are less likely to utilize collector substations that aggregate energy from renewable sources such as wind turbines. These substations typically increase the voltage to connect with the grid. Power factor correction, control circuits, and meters are employed to optimize the utilization of this energy source.
Power substations are becoming a crucial component of energy efficiency and power supply.
Swift Fault Identification
In a substation, the top priority is swiftly identifying and isolating transmission system failures. In large substations, short circuits or overload currents can lead to electricity loss for thousands.
High-voltage power breakers trip within milliseconds when current transformers detect significant fault currents. Short circuits can generate currents of up to 100,000A, leading to current arcs between contacts. These arcs are typically extinguished using high-pressure gas jets.
Becker conducted research on arc phenomena and found that most switchgear accidents result from human errors during installation, maintenance, or simple inspection. When current passes through insulation and reaches the ground or another phase, an arc is generated. In an instant, up to 40MW of power can be generated. Arc temperatures can reach as high as 20,000°C, potentially causing explosions or fires.
The system detects intense light emitted by a developing electric arc. Fast IGBT solid-state circuits promptly isolate the arc to prevent damage. Retrofitting the system to older, more vulnerable switchgear can extend its lifespan.
Gas-Insulated Compact Switchgear
Gas-insulated switchgear is supplanting air-insulated substations. GIS employs high-pressure sulfur gas in circuit breakers to insulate live switch elements. GIS requires 25% less space, leading to reduced land costs.
Take Areva’s F35 gas-insulated high-voltage substation, for instance. It is designed to operate at 145kV in three-phase indoor operations. The voltage rating is 72/145kV, and the frequency rating is 50/60Hz.
Gas-insulated transformers and gas circuit breakers are also gaining popularity. However, due to sulfur hexafluoride’s identification as a global warming gas, measures must be taken to limit its release into the atmosphere.
Substation Control, Monitoring, and Automation
Microprocessor-based control systems are increasingly integrating remote communications. Centralized access to information about multiple substations is now possible. Operators can monitor statuses and respond swiftly. This could result in cost savings, as some instruments may become redundant in the substation. Centralized analysis of protective actions reduces the need for on-site maintenance.
The automation of substations, in general, enhances the reliability of power networks. While communication protocols have traditionally covered subsystems, IEC 61850 addresses the issue of equipment from different manufacturers communicating through gateways. Substation monitoring has historically focused on individual equipment pieces, but monitoring the entire substation is also beneficial.
Maintaining Substation Power Quality
Maintaining power quality is a pivotal objective for power operators, as it affects the functioning of all transmission and distribution systems. Power quality information is indispensable for the competitive operation of electricity companies.
Power quality measurements, whether portable or fixed, are used to assess power quality at different transmission nodes. Comprehensive, long-term measurements are often necessary to identify equipment causing disturbances and optimize the network.
Utility companies should avoid uncontrolled expansion when measurements or other factors indicate the need for new substations.
Unplanned development and under/over-utilization can lead to issues such as high losses, poor reliability, and voltage and power quality problems.
An often overlooked option during expansion planning is reducing energy demand at consumer premises. This, like in other cases, can yield cost savings throughout the process.
This post was written by Justin Tidd, Director at Beckers electrical! For nearly a half a century, Becker Mining has been at the forefront of industry safety. Becker/SMC is the industry’s leader in increasingly more sophisticated electrical control systems. Most of the major innovations, design features and specialized electrical components have been developed by Becker/SMC.