Back to Blog

MV Sensor System Accuracy on the Smart Grid: Q&A with IEEE Standards Committee Member Nick Nakamura

MV Sensor System Accuracy on the Smart Grid

Smart-grid sensors are reviving aging electric grid infrastructure across the globe, injecting powerful real-time insights that help utilities shore up transmission and distribution resiliency. In fact, sensors are becoming such a vital part of grid infrastructure that analysts project the global market to reach $2 billion by 2031.1

Recently, Powerside published a blog about the case for new standards being developed by the Institute of Electrical and Electronics Engineers (IEEE) intended to help validate performance accuracy of medium voltage sensor systems.

Separately from his role at Powerside, Nick Nakamura is part of the IEEE PES PSIM Sensors Task Force and a contributor to these standards. As a follow up to our last article, he shares some additional context about the work the IEEE team is doing — and what it means for the industry.

Q: Utilities have been using voltage and current sensors for years. Aren’t there already operating standards for these devices?

Nick: Yes and no. It’s important to understand the big picture of what IEEE is working to address with this standards framework.

While standards for sensor accuracy do exist — the International Electrotechnical Commission’s IEC 61869 family of standards provides requirements for instrument transformers and low power instrument transformers (sensors) — neither the IEC nor IEEE has published standards that address smart-grid sensor systems as a whole.

Meanwhile, utilities have been busy modernizing their grids to optimize reliability and efficiency. The typical scenario is to implement equipment and components from various sources. It’s not uncommon to purchase a sensor and cable from one manufacturer and a control/intelligent electronic device (IED) from another manufacturer.

What the industry has discovered through this process is that bringing these high-performing components together doesn’t necessarily correlate to a high-performing composed system. In this case, the whole is not always greater than the sum of the parts. So IEEE formed a task force to develop standards through this collective lens.

Q: What are some of the performance challenges that have come to light in sensor systems?

Nick: Well, there are many external influences that can alter how sensor system components operate. For example, weather extremes and pollution buildup have been linked to diminished sensor system performance. You may also experience a measurement error when sensor system components are exposed to electrical disturbances, such as crosstalk from adjacent phases. Or you might experience signal interference from the cable connections between the sensor and IED. There’s a laundry list of potential issues that can occur due to system architecture, external influences, and operating characteristics of each component.

But in the larger picture, developing what the task force has coined “conditional accuracy” is really about having reliable measurements across a range of operational conditions, intended to sustain high levels of sensor system measurement performance and enable optimized grid resiliency and efficiency. More and more, utilities depend on real-time data to better respond to grid disturbances and potential disruptions from storms on demand. They need actionable data, trusted data, to make the right decisions in the moment. If that data isn’t accurate, they run the risk of flawed analyses, false alarms and wasted energy, possibly violating regulations. Or perhaps they run less efficiently than expected, negatively impacting not only their operating costs but also their environmental goals.

Q: You talked about how sensor system design can play a role in operating performance. Can you provide some examples?

Nick: Sure. Let’s start with a look at some of the components of an end-to-end smart grid and where they fit.

One design is using analog sensors connected to an external IED. The IED interprets the information from the sensors and either takes action or forwards the information to an application or control center for further processing.

Another sensor system may have a sensor integrated with an IED device that performs processing and measurement. That sensor data may be sent remotely to SCADA or an application for further processing.

Let’s say you are working with a grid that includes solar energy distribution. A consideration is the intermittent nature of solar generation, such as large (greater than 1 MW) utility scale solar. The inverters in these intermittent generation sources switch at high frequencies to convert DC to AC and can cause power quality issues including harmonics, conducted emissions, voltage flicker, sustained over- and undervoltage, etc. To maximize reliability and resiliency, it’s important to have grid visibility and the power quality data that’s essential to problem analysis and resolution. One solution is to enhance this solar site by adding a sensor system with high performing voltage and current sensors combined with power analyzers on the output of the inverter, the transformer it’s feeding, or both.

Q: What can utilities and their manufacturer/supplier partners do to prepare for compliance with the pending conditional accuracy standards?

Nick: First, it’s important to remember that these kinds of industry standards are not laws. They’re best-practice guidelines, and businesses can choose to comply or not. However, adhering to the guidelines tells the industry that your product or project meets a validated level of performance.

It’s in the best interest of the utility industry and its partners to be aware of these emerging challenges as the grid continues to modernize. Ideally, utilities, manufacturers and suppliers should be having collective conversations focused on the whole system.

In my case, I’m aligning with other sensor manufacturers to ensure we’re all working toward mutual signal compatibility, with testing that documents this performance for customers. There are labs available for manufacturers to perform type testing against the standards. Some utilities have labs, test beds and resources to perform compatibility testing and validation.

It will take some time for the industry to become more aligned in sensor system compatibility. At this stage, I hope to simply increase awareness that there are sensor system performance challenges, and that staying educated about potential ways to address them is an important first step for utilities to take.

Interested in learning more about measurement accuracy in smart-grid sensor systems? Read our blog: What Is Conditional Accuracy, and Why Is It Critical to Smart-Grid Sensor Systems? And, visit IEEE to order your copy of Technical Report PES-TR102: MV Smart Grid Sensor and Sensor Systems: Measurement Accuracy and Uncertainty Considerations.

1 Allied Market Research, 2023 Smart Grid Sensors Market report