More electricity is being used than ever before, and consumers expect uninterrupted service. The government cares more and more about how well people’s electricity is delivered. This places pressure on electrical utilities to demonstrate the dependability of their electricity distribution. Companies routinely measure the duration and frequency of interruptions in electricity distribution. The Institute of Electrical and Electronics Engineers (IEEE) developed the international standards SAIDI and SAIFI for this purpose.
Electric power utilities often use the System Average Interruption Duration Index (SAIDI) to measure their power’s reliability. SAIDI, which is typically calculated over a year, is the average amount of time each customer experienced power outages. It is calculated using the following formula:
Why is SAIDI so important to distributing system operators (DSOs)?
Most power outages (92% in America) directly result from issues with the distribution network, which is expensive for everyone involved.
A high SAIDI figure is bad news for DSOs as it means their customers are experiencing prolonged outages. Customers are understanding if the time without power is limited, despite the inconvenience. However, if they experience long periods without power, they become less forgiving, less understanding, and more frustrated with their service. This is further amplified if the SAIFI figure is also high, as this indicates these long-lasting outages are frequently happening.
The pressure on DSOs is mounting from all quarters to improve network reliability, especially within the organizations, considering the standard regulatory costs that come with outages. Take Finland, for example, where the regulatory cost per 1 kW for each reclosing is €0.55. If we assume there is a 20 MW power requirement downstream from the reclosing, the costs quickly add up, resulting in a €11,000 regulatory fine for the DSO despite customers only experiencing this as a 0.5-second outage.
DSOs need to rethink their priorities and find a balance between preventative maintenance and system upgrades. Protecting supplies for millions of households and businesses is the top priority.
In addition, keeping up with increasing demand is a challenge for DSOs everywhere. Most of the momentum comes from people wanting to charge their electric vehicles (EVs). This can be anything from a single-car home AC charger (typically less than 3kW) to a massive public DC charger capable of super-fast charging up to 350kW. To sustain these load increases, the grid must be strengthened across the globe.
That said, the underlying problems, such as aging assets and shifting consumer preferences, will remain after this initial crisis has passed. This time around, however, the economy is expected to be tighter, meaning that DSOs will have to provide a more compelling case for every dollar they spend.
How can DSOs best navigate this complex investment climate? DSOs have access to new tools for managing their grids more effectively and integrating a growing number of variable renewables into the system.
SafeGrid offers a unique solution that is the best and most cost-effective solution. Before detailing this solution, it’s important to recognize the differences in SAIDI numbers between countries and why this is the case.
International facts about SAIDI
SAIDI is a bigger problem in countries like North America and Australia due to the increased probability of natural disasters, inclement weather, and larger wildlife populations.
Across Europe, the differences in distribution and authority at the regional and national levels have developed over time, accounting for the wide range of forms we see today. Most DSO’s are local monopolies but for example Ireland as an extreme example, where there is only one DSO.
Typically, most DSOs have network ownership and obtain an operating license from state or federal governments. Concession contracts allow DSOs to manage the network for a set period while the public authorities retain ownership.
This model is used in countries like France and Germany. DSOs are responsible for ongoing maintenance and any necessary upgrades for such setups.
Thanks to past investments, European networks are now among the most dependable in the world, as seen through SAIDI figures steadily improving. It shows that investments in distribution networks are having a good effect.
Due to the reliability of the grid and a manageable increase in new connections, DSOs have accommodated increasing amounts of distributed generation.
However, the challenge is far from over, as the use of distributed generation continues to grow on a grand scale. DSOs will continue to face increasing difficulties in maintaining and modernizing the grid and ensuring a reliable power supply for their customers.
The median duration of a SAIDI for North American utilities is about 1.50 hours per year. In addition:
- In 2019, Columbia, Florida, Arizona, and Nevada experienced the fewest total hours of electricity outages
- Those in Florida only spent an average of 88 minutes per year dealing with disruptions
- And in Washington, DC, it was even lower at 77 minutes per year.
These figures sound promising, but they do not show the whole picture:
- In 2019, Mississippi, California, Maine, Michigan, and West Virginia experienced the most severe outages in terms of total time
- Mississippi saw average SAIDI times of near 7 hours
- While Maine bore the brunt with over 15 hours.
Significant events, such as winter storms in Maine and wildfires in California, were to blame for the lengthy power outages in these states.
Maine and West Virginia have a lot of trees, so it’s not uncommon for their electricity to go out because of branches breaking.
Australia and New Zealand
The Australian Energy Regulator (AER) has found that, on average, a customer will have about 200 minutes of scheduled or unscheduled power outages each year. This is influenced by local conditions and extreme weather events like the tropical cyclones that have plagued Northern Queensland in recent years.
To give some context, a year consists of 525,600 minutes. There will be no more than 0.03% of the time per year when service is interrupted for the typical customer. Networks with the highest average minutes of supply outage per customer during the reporting period can thank the inclement weather filled with cyclones for these issues.
In brighter news, there has been a general decrease in the annual average of unplanned outages measured by SAIFI, with approximately 1.5 outages per year experienced by National Electricity Market (NEM) customers.
How DSOs usually try to reduce SAIDI
By definition, both SAIFI (the number of outages) and SAIDI (how long they last) can be lowered by preventing outages that last for a long time.
- Debris in the line
- Or vehicles hitting poles
If the effects of these factors can be prevented entirely, SAIFI and SAIDI will improve. If DSOs can not find ways to avoid them having an impact, then having ways to deal with them or navigate around them to restore power to customers will increase SAIDI.
There are many solutions that DSOs often implement that are not fully effective:
1. Almost a quarter of all outages in overhead U.S. distribution is due to birds. To stop outages caused by birds, the space between energized conductors can be made bigger by using longer cross-arms, covered jumpers, bird guards and covers, along with devices that stop birds from perching.
2. If lightning is a major cause of outages, then the feeder’s basic insulation level (BIL) should be assessed, and shield wires or additional lighting arresters should be installed. Increasing the distance separating phase conductors from uninsulated guy wires and other grounded equipment is a standard method to increase BIL in overhead circuits.
3. Maintenance patrols and programs can preemptively locate and replace worn or overworked equipment before it fails. Faulty cable elbows, connections, and overloaded transformers can be found through infrared scanning.
4. Due to tight right-of-way constraints and the desire to minimize tree contact, some utilities opt for vertical construction. U.S. utility companies experience five times as many power outages when trees fall onto distribution lines as when they grow into them.
5. Underground cable is resistant to many factors that lead to power outages in the overhead system, but the higher installation cost prevents it from being used more widely.
Unique Safegrid solution
Even with the best designs and maintenance practices, faults can still occur in distribution grids because they are complicated, large systems. Currently, Norway has one of the highest SAIDI figures in Europe, demonstrating that even in Scandinavian countries, which are often considered technologically advanced and forward-thinking compared to the rest of the world, DSOs are struggling to keep up.
While these solutions outlined above would go a long way to improving SAIDI, because distribution grids are vast, complex, and highly integral systems, the sheer cost and logistics of implementing such solutions are unfeasible. Even if DSOs could figure out a way to make this work, the required funds would lead to massive price hikes for consumers in an already volatile energy market. In addition, although SAIDI would improve in the long term, the improvements required to the network would interrupt service more frequently and for longer, causing SAIDI to skyrocket in the short term.
Safegrid recognizes this and understands that faults must be identified and fixed as quickly as possible, ideally before they occur, to restore service and prevent further damage from being caused.
What is Safegrid’s Intelligent Grid System™?
Compared to conventional fault-detection systems, Safegrid’s Intelligent Grid System™is the result of extensive research, the use of cutting-edge architecture, and the implementation of industry-standard components. Safegrid’s Intelligent Grid System™ consists of three components that work together to create a system that provides DSOs with complete, real-time visibility into the grid at all times.
The solution can be used independently of SCADA or any other infrastructure, making for a simple and quick rollout in every kind of network. Flexible REST APIs enable deep integration into back-end systems as needed.
What are GrayHawk™ and GrayFox™ sensors?
Two of the components Safegrid’s Intelligent Grid System™ utilizes are simple-to-set-up wireless sensors that bring unprecedented visibility into the grid. The GrayHawk™ sensors are tailored for overhead lines, and the GrayFox™ sensors are designed for underground cables. They can be installed in as little as 20 to 30 minutes without needing system reconfiguration or downtime. This prevents short-term spikes in SAIDI due to maintenance.
In addition, GrayHawk™ and GrayFox™ sensors also have self-resetting capabilities that contribute to their low maintenance requirements and long service lives, making them highly cost-effective to use.
There is no need for additional communication modules or base stations because each sensor unit is self-contained and self-powered, with built-in wireless communication capabilities that only monitor the network, not control it. For use in areas without cell phone service, the sensor nodes are compatible with both 4G and 5G networks as well as Low-Power Wide-Area Networks (LPWAN).
Upon installation, the sensors instantly and automatically join the network and begin reporting network status data to the third and most integral component of Safegrid’s Intelligent Grid System™: the GridGuardian™ monitoring server, which can be accessed from a mobile app or any web browser.
What is GridGuardian™?
The cloud-based GridGuardian™ analytics and monitoring software acts as the system’s brain and provides high-level insights into grid performance and immediate, actionable alerts when problems are detected. Using complex self-learning algorithms, it scans and analyses the raw data that the sensors continuously transmit to locate different types of fault events that have occurred in the grid, including critical faults in broken wires. Additionally, the system allows DSOs to run preventative maintenance as it can locate cracked or leaking insulators before they cause a critical fault.
Compared to other solutions, which can identify and locate faults with an accuracy of a few kilometers, Safegrid’s Intelligent Grid System™ is far more precise, providing an accuracy of +/- 100 meters. This helps crews repair faults more quickly, as they can find it easier and bring the necessary equipment required for the specific type of fault the Intelligent Grid System™ has identified, decreasing overall costs and downtime.
In addition, when a fault’s location is known with greater precision, the number of switchings can be reduced. This is vital to long-term network maintenance as each switching puts all the components under a great deal of stress and can lead to further faults, such as at disconnector connection points. Furthermore, if switching occurs during a fault, overhead lines vibrate rapidly and can cause further damage to components.
However, if DSOs use Safegrid’s Intelligent Grid System™, SAIDI is reduced, and FLISR (Fault Location, Isolation, and Service Restoration) times are shortened, which benefits both customers and the DSOs’ bottom line.
As a result of the increased accuracy, DSOs can facilitate immediate sectionalizing so that only a small part of the grid is isolated for repairs. This keeps the healthy parts of the network running while minimizing the area and number of customers the fault impacts. SAIDI is significantly reduced as most parts that have suffered an outage can be immediately restored.
Safegrid’s Intelligent Grid System™ achieves this network sectionalization more efficiently, requiring fewer reclosings to isolate a fault. In the long term, the strain on grid components is reduced, resulting in fewer faults caused by damaged equipment.
Safegrid’s Intelligent Grid System™ Enables Both Reactive Maintenance and Preventative Maintenance
The Intelligent Grid System™ goes beyond precise detection and localization of faults to improve reactive maintenance times. The system also aids in fault prediction, allowing operators to perform timely preventative maintenance faster and more cost-effectively than reactive maintenance.
For example, more grid information is gathered by the GrayHawk™ and GrayFox™sensors, allowing the system to detect things like slight overloading conditions, which have previously been difficult to track. This allows the operator to perform necessary maintenance and enhance grid performance before faults occur. SAIFI is reduced, and the equipment lifespan is extended, contributing to happier customers and cost savings.
Furthermore, the Safegrid solution can also identify and locate events that will later generate permanent faults or reclosing in the grid. By proactively addressing these potential issues, the combined outage time is reduced in the long term.
Book a call here with our sales director Klaus Ola to discuss how we can help you.