Hardly a news day goes by without coverage of some topic related to the reliability and resilience of our country’s power grid. Whether you speak to an industry expert, casual observer, or an electric utility customer, you’ll find agreement that the distribution grid is faced with a complex set of challenges.
Complementary Solutions Have Better Results
When demands placed on aging infrastructure and the challenges confronting that distribution system are as wide-ranging as they are today, there is no such thing as “one-stop shopping” for solutions. No single approach can solve challenging grid problems as effectively as when multiple technologies are used to gain the best results and cost efficiencies.
With a broad set of innovative grid solutions available, leading utilities have moved to strategically employ multiple technologies to address pressing issues like reliability and resilience improvement.
A Case in Point — Reclosers with Intelligent Line Sensors
One such use of complementary technologies is aimed at reduced outage times and minimizing the number of customers impacted.
Utilities have many technologies to choose from when seeking to improve distribution system reliability. Reclosers and line sensors are two of the most widely employed technologies. While both reclosers and intelligent line sensors are independently effective solutions, the best approach is to use them in combination rather than choosing only one.
When evaluating potentially complementary technologies, it’s important to compare the capabilities and advantages of each. Putting these evaluations side by side identifies synergies, overlaps, and gaps that can help determine an approach which makes the most sense for a utility’s specific needs.
Evaluating Complementary Technologies
For example, the table below lists the capabilities and areas of overlap between reclosers and line sensors. Through this evaluation exercise it becomes evident that each technology offers unique capabilities and attributes which complement the other.
Beyond the capabilities shown in the table, reclosers can also break current to clear momentary faults and act as sectionalizers in coordinated restoration schemes.
Both reclosers and line sensors can provide visibility of the power system for a given location and integrate this data with SCADA or other OT systems. However, line sensors generally offer higher resolution waveform capture and the advantage of being more economical and faster to implement.
Ways to Use Reclosers and Line Sensors Together
Scenario 1: Feeder with one non-communicating recloser
This scenario has one non-communicating recloser midway down the feeder, and only one visibility point at the feeder breaker. The recloser can clear momentary faults downstream of its location but there is no visibility of that activity in SCADA. The addition of line sensors at the recloser provides valuable visibility at this location. With line sensors installed, operations can see how many momentary faults are occurring beyond the recloser and be aware of permanent fault locations on the first half or second half of the feeder.
Scenario 2: Feeder with one communicating recloser
The second complementary use scenario includes one communicating recloser midway down the feeder. The utility has visibility at the feeder breaker and midway along the feeder at the recloser. Here the recommendation is to add two more points of visibility using line sensors. With the additional visibility from the line sensors, the feeder is now visible in four locations, or quarter points. This more granular view of fault location along the feeder enables a dispatcher to send crews to a more precise segment of the feeder to be patrolled in the case of an outage.
Scenario 3: Feeder with one communicating and two non-communicating reclosers
In scenario 3, one recloser midway down the feeder is communicating and two at the quarter points are not communicating. The recommendation is to add line sensors at the two non-communicating reclosers to gain visibility at the quarter points, allowing SCADA operators to see system status at each recloser location.
Scenario 4: Feeder with three communicating reclosers
In scenario 4 there are three communicating reclosers at the quarter points. Good visibility along the feeder exists through the reclosers, so the recommendation is to add line sensors at the beginning of some of the laterals. Adding line sensors along laterals eliminates the need to patrol every lateral in the faulted feeder segment further reducing patrol times.
In all four example scenarios, line sensors add greater system visibility — either at the location of a non-communicating recloser, or at additional system locations.
An Additional Line Sensor Benefit to Consider
Reclosers capture voltage information while most line sensors do not. In contrast, intelligent line sensors like the Sentient Energy MM3® can capture waveform anomalies which are not collected by reclosers because they do not trigger an outage. For utilities looking to be more proactive by identifying and predicting outages before they occur, anomalies can serve as the basis for this type of prediction.
WAVEFORM ANOMALIES CAPTURED BY LINE SENSORS
With analytics, anomalies can be classified and trended to identify feeder segments with high impending outage risk. Utilities can initiate inspections of high-risk segments to mitigate unplanned interruptions. Heading off a larger problem before it happens not only improves reliable power delivery, it can also prevent or defer stress on assets that are expensive and difficult to replace. And, planned maintenance is always less costly than crew outage response.
In Summary
As a singular technology in a fault location isolation sectionalization and restoration (FLISR) scheme, reclosers may be the most powerful tool to improve feeder reliability. But this is an expensive solution which may not be justifiable for all feeders. On many feeders, complementary use of both reclosers and line sensors strikes an effective balance of capabilities and cost. For additional visibility and more targeted location information, line sensors complement reclosers with lower cost per location and faster deployment time, plus offer a path to future predictive analytics.
When it comes to improving distribution system reliability, complementary solutions yield greater progress. Vegetation management, wildfire risk mitigation, energy efficiency improvements, and integration of renewables are all additional examples of grid challenges that are more effectively solved with multiple, complementary solutions.
Visit the Sentient Energy product page to learn more about our overhead line sensors.
