Smart Grid Sensors: Well-positioned to Improve Reliability at Brazil’s Mega Utilities

by Kim Getgen, Tollgrade Communications

During the past decade, Brazil’s economic boom has spurred a major transition in its energy needs.

With easier access to credit and millions of households’ growing Brazil’s middle class, the country finds itself among the world’s top 10 consumers of cars and personal computers.

All of this consumerism is good for the economy, but it is increasing electricity demand.

Brazil is predicted to add 6,000 MW of capacity every year just to keep pace with the new demand.

Brazil’s mega utilities already are some of the largest and cleanest compared with their U.S. and European counterparts.

For example, Electrobras is the 10th-largest and fourth-cleanest power utility in the world.

Meeting demand, however, is only half the battle. Keeping the lights on and restoring power as fast as possible are equally important.

This is never easy in a country that has one of the world’s largest highway systems and worst traffic where fewer than 15 percent of roads are paved.

Fighting difficult terrain and traffic and trying not to let extreme weather get the best of line crews are many of the key reasons Brazil is turning to new technology that can lessen drive times while still improving reliability. It should come as no surprise that these mega utilities are the trendsetters when it comes to grid modernization. Brazil plans to make smart grid investments of $36.6 billion by 2022, according to the Northeast Group.

Many utilities are turning to the new breed of smart grid sensors that allows them to receive real-time information about grid conditions where they remain most blind: the millions of miles of largely unmonitored feeder networks that connect cities and stretch into rural Brazil. With this real-time sensor data, many Brazilian utilities find they can be armed with the data they need to improve reliability dramatically and, in some cases, prevent outages at a fraction of the cost of other technologies.

Top 5 Advantages of Smart Grid Sensors

Smart grid sensors offer many advantages. The following are the top five reasons smart grid sensors have been a good fit in Brazil, which can help other utilities weigh the decision or evaluation criteria in making such an investment:

1. Sensors are lightweight, affordable and easy to install.

Smart grid sensors offer the perfect retrofit solution for improving reliability because they are extremely lightweight (often weighing about 5 pounds) and can be installed easily on power lines. Some of the most advanced sensors have clamp-on designs that require crews to use a hot-stick only once. The sensors are so safe that there is no need to take an outage during an installation, and they can be on the line in less than five minutes.

In addition, smart grid sensors are affordable-a fraction of the cost of other smart grid technologies such as smart reclosers and smart switches. Although most smart grid sensors cannot offer full automation-they can only monitor-they can give the fault location. Some sensors can send all vital information before an outage, allowing some utilities to take measures first (see more about this in No. 5). This is what many Brazilian utilities need to improve reliability dramatically, shorten drive times and stretch their capital investments further across their large network footprints.

2. The latest generation of smart grid sensors are battery-free, so there is no maintenance.

The new breed of smart grid sensors are inductively powered, meaning they require no batteries to be operational. Prior to these new sensors, batteries or even solar panels were used as the power supplies, and that required utilities to send field crews to the sensors after they were installed to replace batteries or fix solar panels. Battery-free means 100 percent maintenance-free and is a big breakthrough in the reduction of O&M expenses. Better yet, the new breed of smart grid sensors are software-defined and can be remotely programmable over the air, meaning key parameter settings can be changed and firmware can be upgraded; utilities can take advantage of new features long after sensors have been hung on the line. This maximizes their worth and delivers a low-risk, future-proof investment.

3. Reliable, flexible communications are a reality.

Many communications options exist when considering a smart sensor solution. Many sensors provide integrated communication options with various Wi-Fi and cellular coverage options. Many smart grid sensors can work on advanced metering infrastructure (AMI) backbones such as those provided by Silver Spring Networks or Tropos so utilities with smart meter investments can leverage them further.

4. Smart grid sensors deliver the fault location so crews can restore power faster.

Most smart grid sensors can detect and locate faults in two ways: circuit segmentation and distance to fault estimation. Some utilities have a preferred method, but both approaches allow power to be restored faster.

A. Circuit segmentation. Some utilities segment or sectionalize their circuits with sensors. When a fault occurs, it is captured by all smart grid sensors on that circuit. The centralized sensor software receives all fault and outage notifications on the circuit, analyzes them and notifies the crew of the fault location via email or text or via DNP3 messages to other back-office systems (supervisory control and data acquisition, energy management system, historian, etc.) in near real time. When multiple sensors are deployed on a circuit, only the sensors closest to the fault are reported. Some advanced sensor packages include Google Maps so they can plot the outage on the map and crews can plan the safest route, use the best roads and avoid the most traffic.
B. Distance to fault estimation. Some utilities prefer to use the RMS fault current measurements from smart grid sensors with their circuit impedance models. When a fault occurs on a circuit, sensors report the phase or phases affected and the RMS fault current. If control center operators have access to impedance models for the circuit (individual spreadsheets integrated with DMS or other tools) and circuit maps, dispatchers can identify one or more candidate locations for crews to investigate. If multiple fault locations are possible, dispatchers might be able to identify specific candidate locations based on customer outage calls, smart meter notifications and downstream sensors’ notifications.

Regardless of their desired approaches, utilities should look for smart grid sensors that can email or text notifications with the following information:

  • Event type: permanent fault, momentary fault, power off, power on;
  • Timestamp;
  • Substation/circuit/phase (multiple phase events may be reported together or independently);
  • Fault current magnitude (configurable to report RMS or peak current); and
  • Sensor’s logical and GPS location.

5. Smart grid sensors can help utilities prevent the next outage.

There is a new breed of smart grid sensor that can provide sophisticated waveform analysis of disturbances and grid events to review disturbances on the grid continuously and keep a watchful eye to spot specific patterns or abnormalities. Several seconds of waveform samples from each disturbance can be analyzed. These predictive grid analytics packages can evaluate parameters such as the disturbance surge magnitude, number of surge cycles, rate of decay of surge, and pre- and post-disturbance load levels. Analytics rules can be defined to filter out disturbances’ resulting from standard network operations (e.g., load switching events), as well as to alert network operators to inefficient operating conditions, system failures or indications of anomalous behavior that might be early indications of future failures. Having this level of analysis makes it possible to filter nonevents that have been notorious in tripping earlier sensor technologies such as fault circuit indicators (FCIs), tricking them into reporting faults although no power outage exists.

Events that can be detected by smart grid sensors to help prevent outages include:

  • Failing underground cables;
  • Blown capacitor bank fuses;
  • Blown fuses from vegetation, animal disturbances or both;
  • Improper coordination of circuit protection timing;
  • Slack span faults; and
  • Disturbances from trees or vegetation growth.
Waveforms Captured by a Smart Grid Sensor Indicating a Failing Underground Cable
Waveforms Captured by a Smart Grid Sensor Indicating a Failing Underground Cable

Field Deployment: Top 3 Lessons Learned

One of Brazil’s leading utilities deployed Tollgrade LightHouse Smart Grid Sensors to improve its network reliability. The solution helped the utility monitor load, identify emergency load levels and help pinpoint outages to reduce drive times in hazardous conditions. The Tollgrade LightHouse Smart Grid Sensors were the first to receive homologation certification and be approved for use by the Brazilian government.

The field deployment yielded lessons that highlight the value of real-time monitoring to restore power faster and, in some cases, prevent outages.

1. Outage avoidance. During the deployment, sensors determined circuits that were significantly overloaded and coincided with outages. By configuring high-current alarms for these circuits, engineers can respond to overloaded conditions as they happen before they lead to outages. Sensors detected a series of momentary outages on one phase of a circuit over a week. Shortly after, a permanent outage took nearly 24 hours to repair. Now, the utility can monitor this circuit for frequent momentary faults so crews can investigate and resolve problems before an outage.

2. Restore power faster. Sensors detected an outage on some circuits and detected the faults on Google Maps to help crews get to fault locations and restore power faster.

3. Load monitoring. Sensors monitored the load of the circuits to see emergency overloading and if phases were in balance. The utility quickly pinpointed what circuits were out of balance so it could redistribute loads to free up additional capacity and reduce technical line losses.

Conclusion

Brazil will be a trendsetter for developing useful cases for the advancement of smart grid sensors. The first deployments in Brazil already show this affordable technology can improve reliability. When it comes to making the smart grid sensor investment, look for solutions that are: battery-free, software-defined and flexible in their communications options so you are not hit with hidden O&M expenses over the lifetime of the deployment.

Reliability is being improved because sensors pinpoint outages and can help utilities avoid outages. By monitoring networks for faults that are the precursors of outages, utilities can prevent outages. Most smart grid sensors have built a value proposition around delivering better fault location, but utilities should consider the impact predictive grid analytics could have on their networks. The more utilities that can prevent, the more reliability can improve and the less crews drive to restore power in treacherous terrains and bad conditions.

Kim Getgen is vice president of marketing at Tollgrade Communications. Before joining Tollgrade, she worked as a marketing executive for smart metering company Echelon Corp. and cybersecurity companies including a venture-backed start-up she co-founded, which was later acquired by McAfee. Getgen received a Bachelor of Arts from Wake Forest University and an M.Phil in International Development Studies from Oxford. Reach her at kgetgen@tollgrade.com.

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