As electricity grids become smart, sensors are becoming increasingly relevant for capturing data and providing information about the status and performance of the electricity grid. But sensor performance must also be assessed and measured – and IEC standards and conformity assessment systems play an important role in helping grid and utility operators do this.
A multitude of sensors for different tasks
A wide variety of sensors can be used in the electricity grid. The IEC 61724-1 Standard, which monitors the performance of solar photovoltaic (PV) systems, specifies how to collect accurate and reliable data from various system components, including environmental sensors. This standard only applies to PV systems and the list of sensors involved is enormous. It includes pyranometers, radiation sensors, module and ambient temperature sensors, wind speed and direction sensors and relative humidity measuring equipment, to name a few. In fact, sensors can be used to monitor and measure every aspect of a PV solar system’s environment, and the same can be said for any electrical appliance used in the generation, transmission and distribution of electricity – from power cables and conduits to substations and transformers.
Some experts distinguish between environmental and electrical sensors. According to these experts, the latter are used to monitor energy levels in the electricity grid, including voltage and current levels and power quality. They are becoming increasingly important as intermittent energy sources such as wind and solar energy are integrated into the electricity grid.
Smart sensors for smart networks
One of the most important developments in the field of smart networks are connected sensors and more specifically the so-called smart sensors. According to TechTargetan editorial network specializing in information about the Internet of Things (IoT), “smart sensor technology includes integrated communications capabilities that allow it to connect to a private cloud computing environment or the Internet. This allows sensors to communicate with remote devices.”
TechTarget further describes how smart sensors can be components of a wireless sensor and actuator network. These networks can have thousands of nodes, with each node connected to one or more other sensors and sensor hubs, as well as individual actuators.
Sensor networks ensure that different elements of the electricity grid can communicate with each other and with the energy manager, even with electricity consumers. An example is the use of sensors in digital substations. Dustin Tessier, who is involved in standardization work within the IEC technical committee that prepares standards for the smart grid, IEC TC 57especially the IEC 61850 series, is leading the way in standardizing digital substation requirements. He is also an IEC 61850 system integrator and grid modernization consultant at Tesco Automation. “Digital substation sensors typically refer to merging units (MUs) or process interface units (PIUs) that digitize analog or discrete signals from instrument transformers, circuit breakers or current transformers and transmit these values into digital substations, enabling secure, flexible and efficient digital communications networks that connect field equipment to control and protection equipment in the control room,” he explains.
In other words, these sensors not only capture information, but also digitize it and transmit it in digital format to the utility operator. Disruptions in the electricity grid are becoming increasingly common as smart grids, in addition to periodic energy integration, face an increasing number of cyber attacks (for more information on this, read: Cybersecurity for the smart grid | IEC e-tech) and the proliferation of extreme weather events. (For more information on this, read: Building resilience in the electricity grid | IEC e-tech).
According to the IEC social and trend report Smart detection for future electricity grids“Sensors can be deployed to detect and measure energy flow, voltage level, power quality and equipment conditions throughout the generation, transmission and distribution system, up to end loads. Sensors can detect, protect and control the power grid in a timely and accurate manner. By doing so, it becomes possible to assess the operational status of the power grid in real time, predict its behavior and possible disruptions, and respond quickly to events.”
Grid sensor standards
Assessing the performance of these sensors is critical because the information they capture, digitize and transmit makes it possible to monitor the power grid in real time. Several groups within the IEC have published standards that allow the performance of sensors in the power grid to be specified and monitored. One of the IEC TC 57 standards, IEC 61850-9-2allows MUs to digitize and transmit primary currents and/or voltages for protection, control and monitoring. According to Dustin Tessier: “References to the latest changes IEC 61869-9 for synchronization accuracy and time alignment, ensuring reliable grid integration. This supports interoperability in digital substations.”
ISO/IEC 27019which provides information security controls for the energy sector, covers a very wide range of smart grid-related technologies, including sensors and actuators in the field of monitoring and automation technology. The joint technical committee formed between the IEC and ISO to standardize IoT (ISO/IEC JTC 1/SC 41) has also been published ISO/IEC 30101, specifying the requirements for sensor networks supporting smart grid technologies for energy generation, distribution, networking, energy storage, load efficiency, control and communications, and associated environmental challenges.
Distributed fiber optic acoustic sensing (DAS) is a promising technology for remote monitoring of critical infrastructure such as the power grid. It is increasingly used because fiber optic sensors are immune to electromagnetic interference, making them ideal for use in high-voltage environments, for example in transformers. IEC TC 86 has developed various standards in the field of IEC 61757 series that determine the performance of fiber optic sensors. They include IEC 61757-3-2 specifying the terminology, characteristic performance parameters, related test and calculation methods, as well as specific test equipment for interrogation units used in distributed fiber-optic acoustic detection and vibration measurement systems. (For more information on this, read: Fiber optic sensors and critical infrastructure | IEC e-tech).
Conformity assessment for sensors and the electricity grid
In addition, the IEC quality assessment system, IECQone of the four IEC Conformity Assessment (CA) systems, proposes an approved component certification, which applies to various electronic components, including sensors that meet technical standards or customer specifications accepted within the IECQ system. The IECQ IoT Component Certification is a specific certification program for evaluating and certifying the usability and performance evaluation of features, voice recognition and connectivity stress of components used in IoT devices, including sensors.
Another CA system, IECREthe IEC system for certification of standards relating to equipment for use in renewable energy applications is the internationally accepted conformity assessment system for all power plants that produce, store or convert energy from renewable sources. The CA system ensures that essential quality and safety standards are met, and as a result, reliable performance can be expected.
The International Electrotechnical Commission (IEC) is a global non-profit membership organization that unites 174 countries and coordinates the work of 30,000 experts worldwide. International IEC standards and conformity assessment are the basis of international trade in electrical and electronic goods. They facilitate access to electricity and verify the safety, performance and interoperability of electrical and electronic devices and systems, including, for example, consumer equipment such as mobile phones or refrigerators, office and medical equipment, information technology, electricity generation and much more.
The views and opinions expressed in this article are those of the author and do not necessarily reflect those of the author pv magazine.
This content is copyrighted and may not be reused. If you would like to collaborate with us and reuse some of our content, please contact: editors@pv-magazine.com.
