Distribution line monitoring is an absolute requirement for utilities that want to reach a truly optimized and self-healing smart grid. Electric utilities today are faced with an antiquated distribution system that lacks transparency; and without a full understanding of the distribution system in real time, they are unable to react in a timely manner, making decisions from the substation to the edge of distribution system. A major focus in today’s smart grid projects is Distribution Automation (DA), which is creating a fully controllable, flexible distribution system with embedded intelligence. This grid intelligence stems from Information (Distribution Line Monitoring) and Communication and the link between this hardware and software is communication. Distribution Automation stems into two main areas called self healing and also known as FDIR (Fault Detection Isolation & Restoration) or FLISR (Fault Location Isolation and Service Restoration) and Grid Optimization better known as Volt VAR Control (VVC) or Volt VAR Optimization (VVO). Implementing these latest smart grid applications requires nodes or monitoring points to provide utility distribution systems with real time intelligence.
Volt VAR Control or Volt VAR Optimization requires a mix of hardware, software, and communication. Integrating LTC, Capacitor banks and Voltage regulators are controlled in real time based on data from the field. These various types of hardware help provide some intelligence, however, integrating monitoring points throughout the distribution line to end of line (EOL) is the true back bone and support of these smart grid applications. To truly optimize the distribution system coordinated control of the voltage and VAR is paramount. This hardware in the field must be operated in coordination in order to create an efficient distribution system. This enables more efficient distribution of power while better utilizing utility assets, preventing over burdening of equipment or hardware. Voltage and current sensors must be integrated into the field to support these Volt VAR applications; these monitoring points can be integrated on either the primary or secondary side. The primary side is typically referred to as medium voltage (MV) and the secondary side is referred to as low voltage (LV). Monitoring provides utilities with the tools to better anticipate problems and make fast, localized control decision throughout the distribution system.
Volt VAR Control or Optimization (VVO)/ (VVC) provides utilities with the ability to be more efficient and reliable. Across the country many states have set ambitious goals to reduce energy consumption and CO2 emissions (greenhouse gases). In order to reach these goals the electric utilities will need to significantly invest in their distribution system with technologies such as VVO and VVC which enable these utilities to reduce electrical demand, losses and energy consumption. The benefits of VVO or VVC are significant for both consumers and the utility. VVO/VVC reduces peak demand and increases the grids capacity which presents the need for additional infrastructure and new generation. Consumers also benefit from reduced power consumption, which equates to lower electric bills and finally the environment benefits from reduced waste of early product failures and reduced greenhouse gas emissions. By actively monitoring the distribution system utilities are able to better respond to the increasing customer demand for higher reliability and power quality. Distribution line monitoring and VVO/VVC provide utilities with actual data rather than inaccurate modeled responses, providing a multitude of system benefits.
Implementing VVO or VVC provides significant benefits. Operating the distribution system at lower voltage levels can provide a one percent to three percent reduction in total energy. This results in a two to four percent reduction in kW demand and a four to ten percent reduction in kVAR. VVC and VVO enables utilities to be more efficient, and if the United States was just five percent more efficient, the impact would be monumental equating to the elimination of the fuel and greenhouse gas emissions from 53 million cars.
One main technology that can be utilized in order to provided real time monitoring are line post sensors. These line post sensors must however be integrated with intelligence as to pull the data back to the utility control center or SCADA system. Integrating end of line sensors with line posts sensors provide utilities with the means for grid intelligence, which will enable the line post sensors to provide real time information, equipping utilities to make decisions to optimize the distribution system.
Another form of monitoring to consider is on the secondary side of the distribution transformer. This form of monitoring also provides support and intelligence to VVO/VVC applications. Smart Transformers or secondary distribution transformer monitoring is an application expected to grow significantly over the next seven years. This form of monitoring requires the integration of monitoring devices such as end of line sensors or products with the secondary distribution transformers, which can be single, or three phase pole top or pad mount transformers. Integrating this throughout the distribution system provides utilities with the capabilities to manage critical customers; the utilities assets and it can also provide visibility into the electric distribution system. This form of real time monitoring can greatly vary depending on the device. Some simply supply only voltage while others provide more sophisticated monitoring and measurements. The devices typically provide utilities with voltage, loading and external temperature of the transformers, which allows the utilities to optimize the use of their assets. New transformer monitoring devices being announced at DistribuTECH 2014 will provide a more comprehensive view of these assets. They will a provide gas analysis called TCG (Total Combustible Gas), internal oil temperature along with voltage and current reading. These new monitoring technologies provide utilities a way to more effectively and efficiently utilize their assets within the distribution system. Some may say the cost of these transformers does not warrant monitoring, however, secondary transformer monitoring can be integrated and leveraged with a variety of utility smart grid projects in order to offset the cost while improving the distribution system. Secondary transformer monitoring can also be leveraged with Volt VAR Optimization, Outage Notification, Revenue Protection (Electricity Theft), Asset Management and Power Quality smart grid applications.
Secondary transformer monitoring will also become increasingly important as distributed generation (DG) or Renewable Energy becomes more abundant. As distributed generation is integrated into the distribution grid, additional complications will arise such as power quality issues, load and phase imbalance, reverse power flow and there could even be safety implications. The key to handling DG is to implement bi directional sensors and VVC or VVO, which will provide awareness and real time monitoring.
Another form of distribution in need of line monitoring is theft detection, a major problem for utilities across the world. Electricity theft in the United States equates to $6 billion in losses annually, which can cost utilities one to three percent of their revenue. These losses are then passed on to the consumer. The integration of AMI or AMR (Smart Meters) has helped alleviate some energy theft at the meter but where the largest problems lie are when thieves wire into the distribution system or hook up to distribution transformers. This is where distribution line monitoring can be most beneficial in detecting and preventing further losses for the utilities and their customers, these devises help give the utility the upper hand by providing real time data to compare with AMI/ AMR Meters. If discrepancies and usage are different, electric utilities are able to detect and pinpoint where the electricity theft is occurring.
A self-healing grid is another area of focus for utilities; a self-healing grid utilizes FDIR (Fault Detection Isolation and Restoration) or FLISR (Fault Location Isolation and Service Restoration) to improve reliability and performance of the distribution system. This allows utilities to quickly respond to faults and restore power to as many customers as possible by quickly isolating or sectionalizing the affected area. Distribution line monitoring is a key support tool for this application.
These intelligent sensors through the distribution system provide real time outage notifications enabling utilities to quickly react and restore power to the majority of the customers in minutes, not hours. A self-healing grid provides many benefits to both the utility and the customer; FDIR and FLISR greatly reduce the number and duration of outages, which improves the reliability and delivery of power and also reduces maintenance and improves the safety for utility workers. Distribution line monitoring provides FDIR and FLISR software with real time data reducing the time to get customers back on line and helping to pinpoint and direct utility workers to the affected areas, saving time and money.
Distribution line monitoring provides utilities with the information needed to make decisions at the edge of the grid and it is imperative to grid optimization and the future self-healing grid. The addition of smart sensors will provide utilities with the ability to make intelligent decisions to control voltage, VAR, outages, power quality and a slew of other issues. This real-time, accurate voltage and current sensing provides utilities with a comprehensive view of the distribution systems load and voltage conditions leading true smart grid.
About the author
Scott Zajkowski is part of the North American Business Development group with IUS Technologies who develops end of line devices for the smart grid including their Born Smart TM series of sensors. With an MBA from Indiana University Kelley School of Business, Scott is an ambitious and driven marketing professional with proven success in developing and executing strategic marketing and advertising campaigns with companies such as Lakeshore Energy and HP Products. Previous to IUS, Scott worked at International Truck & Burger King in Packaging Engineering and Management utilizing his undergraduate degree in Packaging Engineering from Michigan State University.
