Legacy electrical substations are older substations that have been in service for an extended period, typically using technology and equipment that were state-of-the-art at the time of their construction but may now be considered outdated compared to modern standards. There are a significant number of legacy substations in the United States and Canada. This is due to the extensive development of the electrical grid throughout the 20th century, especially during periods of rapid industrialization and urban expansion.
Despite their age, the equipment in legacy substations is often still functional and has significant remaining operational life. The infrastructure is generally robust, but it may lack modern features such as automated monitoring, digital controls, and real-time data collection. One of the key characteristics of legacy substations is the absence of sophisticated sensing and monitoring systems. Unlike modern substations, which are equipped with advanced sensors and communication technologies that enable real-time data collection, legacy substations typically do not provide detailed insights into their operational status. This can make it more challenging to perform maintenance, manage loads, and plan for upgrades. While legacy substations may not have all the features of modern substations, they are often still relied upon for the daily operation of the electrical grid. Their continued operation is critical for maintaining the stability and reliability of the power supply.
Upgrading legacy substations to modern standards can be challenging and costly as it involves integrating new technologies, such as advanced sensors, digital controls, and communication systems. This process can be technically challenging, especially when dealing with older infrastructure that was not designed with modern technology in mind.
CO7’s LineWatch-M sensing and monitoring devices can be quickly and easily installed on each feeder outside the substation fence, offering a low-cost, highly accurate SCADA-capable sensing and monitoring solution.
The LineWatch-M sensor (shown in Figure 1) provides enhanced visibility into substation performance by monitoring current, voltage, and power flow, all without requiring a neutral connection. The absence of a “hard” neutral connection significantly increases both the ease and safety of deployment.
Figure 1: LineWatch M Current, Voltage and Phase Angle Sensor
The LineWatch-M sensor measures voltage through the capacitive coupling between plates on the exterior of the sensor case and ground. The LineWatch-M sensor incorporates patented design features and advanced algorithms that enable accurate voltage measurement within +/- 0.5%, even under extreme weather conditions.
Because these sensors can be installed rapidly, typically in about 30 minutes for a three-phase system, and provide precise power flow data, they are an excellent solution for utilities seeking to monitor substations without incurring the significant costs associated with upgrades within the substation fence. This makes LineWatch-M sensors a practical and cost-effective option for improving the operational efficiency and reliability of legacy substations.
The Need for Sensing in LineWatch-M Sensors Legacy Substations
A large number of legacy substations exist in North America. The substations are classified as “legacy” because, although the equipment is functional and has significant remaining life, there are no measurements of ongoing substation operation. In contrast, equipment like reclosers in more modern substations collect detailed data about substation operation, reporting that data to a centralized location or Energy Management System. Additional sensing is needed in legacy substations for several reasons:
Feeder Maintenance
For legacy substations, there may be no visibility into the immediate loading of the substation. For maintenance purposes, it is often desirable to reconfigure feeders so that work can be done on a particular feeder without causing outages.
Without load monitoring, it is difficult to know whether or not loads are low enough to reconfigure the system without creating overloads. Maintenance is then pushed to times of the year when the expected load is low, or personnel must be sent out to the substation to take manual measurements, adding unnecessary delay. If load information is available remotely (e.g. via LineWatch-M sensors), maintenance planning and execution can be streamlined.
Infrastructure Planning
LineWatch-M sensors can continuously meter power flow, identifying areas where loads are high and identifying changes in load over time. Load flow information is vital to planning future expansions and upgrades of the distribution system.
Health Monitoring and Fault Logging
LineWatch-M sensors also take detailed power quality measurements like harmonic content of voltage and current through the 13th harmonic. If faults occur, the sensors also record o scillographs of the fault as it occurs. This information can be used to diagnose both impending problems and faults.
LineWatch-M Use Cases for Legacy Substations
In many cases, the high cost of upgrading a substation stems from the need to upgrade the communications infrastructure at the substation. Additional infrastructure may be needed at the substation itself to collect information from Intelligent Electronic Devices (IEDs) and transmit it to a centralized location. More importantly, installation of an expensive SCADA system or EMS system is required to receive data back at the utility operations center. Smaller utilities may not have this existing Head End infrastructure, and costs of installing such a system can be high. CO7 solutions meet every utility’s requirements regardless of whether they are fully SCADA enabled or have no existing SCADA infrastructure. These various cases are described below:
SCADA Sensor Use Case
For utilities that already have an existing SCADA infrastructure, LineWatch-M sensors are ready to integrate with the existing paradigm. The sensors have a complete DNP3 interface that enables interaction with third-party SCADA systems. The sensors can be polled via a cellular interface or any other communications platform that may already be in place such as WiMAX routers, network interface cards or mesh radio networks. If faults occur, the system pushes notifications about the faults via DNP3. Fault oscillographs can be downloaded from the sensors, aiding in diagnosis and localization of faults.
Daily Meter Reading Use Case
Some users prefer a meter-like paradigm, where sensors are polled once daily, returning all readings for the day in some standard format. The LineWatch-M sensors have a Web API that allows the sensors to be programmatically queried for data, returning the desired data in a .CSV format.
For example, the web query at https://address/myQuery.phpdate=24Jan2024 would return all readings from January 24, 2024. By specifying other keys in the call to the API, the time range, reporting interval, and specific data items returned can be specified in detail.
Through the use of this web interface, it is straightforward to integrate the sensors with
existing historian applications or to write simple scripts that automatically download data from sensors and add it to a database of sensor readings.
Stand-Alone Monitor Use Case
For the utility that is interested in trialing devices and/or has no existing SCADA systems, LineWatch-M is available with 4G LTE and 3G GSM or CDMA modems for data backhaul. In the Stand-Alone Monitor use case, users connect directly to a LineWatch-M sensor installation via a secure Internet connection. The front page of the website is shown below as Figure 2. All quantities of immediate interest (e.g. voltage, current, power flow) are immediately viewable. If desired, users have accessibility to the data at many levels of granularity. Every measured quantity can be plotted over the web interface, as shown in Figures 2 - 4. Plots can span up to one months’ worth of data on up to six sensors. For more detailed off-line analyses, data can also be downloaded from the sensor in .XLSX format for easy integration with other analysis tools.
Figure 2: LineWatch-M stand-alone web interface
Figure 3: Plot of measured voltage
Figure 4: Power Quality Information
LineWatch sensors can also communicate their collected data in a number of ways:
Stand-alone secure web server accessible via the Internet. Allows users to directly view sensor data and/or download the data in .XLSX format;
Secure Web API that allows data to be sensor accessed programmatically, returning the results in .CSV format;
Complete DNP3 polling interface, for integration with an existing SCADA system.
Conclusions
LineWatch-M sensors have the capability to provide utilities with critical data on legacy substation operations. LineWatch can be installed on the feeder outside the substation fence quickly, easily and safely using a hot stick, at a significantly reduced cost compared to an inside the fence retrofit. The sensing and monitoring devices are designed to support any communications platform and the existing utility infrastructure. For utilities that have existing SCADA infrastructure, LineWatch is fully capable of interfacing via DNP3 with a SCADA head end. As an alternative to traditional SCADA, a flexible Web API is also available for collecting data from the sensor, e.g. in the form of daily sensor reads. For a utility who is interested in trialing the LineWatch devices, or who has no existing SCADA infrastructure, the sensors can also be installed in a stand-alone feeder monitoring application. In any use case, LineWatch-M can help extend the life of legacy substations at a significantly lower cost than “inside the fence” retrofits by monitoring the health and load levels of their feeders without the need to replace otherwise functional substation equipment.
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