Lappeenrannan Energiaverkot Oy in Finland set out to test how to use software robotics in network planning. The target was to improve electricity distribution network reliability. The utility ordered a service package from Trimble where a planning robot Network Optimizer was used to find new switch locations in the medium voltage network. The experiment paid off, as now the replacement and prioritization needs of the utility's switching devices can be justified by numbers.
Support for electric network development plan
As with any innovative pilot project, curiosity played a part in the decision to try out switch optimization. The proposal to test switch optimization came from Ensto, a supplier of electrification solutions looking for a utility to participate in the project. The idea was to look at the location of switching devices in the network from an economic point of view, i.e. to calculate payback periods for the switching devices in terms of avoided outage costs.
– We became interested in network optimization early on when Network Optimizer was presented at Trimble User Days. We wanted to see what Optimizer could do in practice, and now that we had the opportunity to test it on our own network, we decided to get involved in the project, says Antti Lintunen, Operations Manager of Lappeenrannan Energiaverkot.
The timing for testing switch optimization was perfect, as Lappeenranta was in the process of updating its electricity network development plan.
– Switch optimization is a good support for the development plan, says Lintunen.
Prioritization needs for switching devices
Initially, optimization was meant to be done for only one substation area.
– In the first meetings, it quickly became clear that we should optimize the switching devices for the entire medium voltage network in the rural residential area," Lintunen continues.
Reclosers as well as remote and manual disconnectors were included. The optimization process was used to determine where new switching devices should be placed in the utility's medium voltage network and what type of devices should be purchased. Remote disconnectors were of particular importance. The work was based on the existing network and switching devices of Lappeenrannan Energiaverkot.
So how was the project implemented?
Trimble's Software Specialist Jaakko Anttila explains that the first step was to define the initial changeable parameters related to switches, prices and operating time. Then Network Optimizer was adapted to work with the data. Some modelling was done on the electric lines in terms of fault frequencies.
– A final report was prepared for Lappeenrannan Energiaverkot, presenting the results in as clear a form as possible. And since the network was so large, we went through the results region by region to see what they looked like, Anttila says.
In the final report, the overall picture was presented on a map in a browser, showing all the locations of the new switching devices. You could navigate to them, and for each switch, you could see how much the switch would save you in avoided outage costs. Based on the savings, a payback period was calculated for the switching devices.
– That clarified the order in which to start purchasing the switching devices, Anttila explains.
Network Optimizer needs some parameters to calculate switching device locations, types, and payback periods. These parameters are always utility-specific, which means that it is up to the utility to define them.
– From our point of view, the workload was not huge, says Antti Lintunen.
– At the beginning, we defined the parameters. They were very much in line with the data from the Energy Authority. The interest rate was set, then the load growth for our network and the review period. Next, the price level for the installation of a manual disconnector, remote disconnector station, and recloser was determined, as well as the operating time. Then the fault frequencies and the average network restoration time. Providing this information was everything we had to do, Lintunen explains.
Decisions driven by numbers
Lappeenrannan Energiaverkot has set smart grids as their strategic goal. Increasing automation in the electricity network is a separate construction program, and the optimization of switching devices is an excellent response to the automation need.
– Switch optimization helps us choose which reclosers, remote disconnectors or manual disconnectors to place and where to place them in the network. It supports decision-making when the numbers are visible. It is also easier to justify internally why it’s worth investing in switching devices when you have the euros in the arguments, Lintunen says.
The utility received a final report consisting of a prioritized list, starting with the switching device that had the greatest savings in avoided outage costs. It turned out that the list included many of the same switching devices that had already been considered by Lappeenrannan Energiaverkot. Also for these switching devices, prioritization was made easier by switch optimization.
– The payback period for the switching devices was calculated, and it facilitated decision-making when the euros became visible, Lintunen continues.
– The prioritized list is clear, starting with the items where the savings are the greatest. Once we have them in the building program and the euros earmarked for them, we can start to implement them, he adds.
New valuable switch locations
The fact that the results of the optimization largely correspond to what Lappeenrannan Energiaverkot had considered by themselves, confirmed the confidence in the utility's own work, but also in the reliability of switch optimization. Network Optimizer, however, also found completely new switch locations.
– There was a line where no recloser had ever been thought of. It was not even a very long line and already had three remote disconnectors, but Optimizer still added one more recloser to it. The payback period was only 1.5 years and the savings in interruption costs over 20 years were in the hundreds of thousands. So yes, these switch locations were valuable to us, says Lintunen.
How to move forward with the results?
So the utility also got new switch locations for its construction program to increase automation. How will they utilize the results?
– The order of priority is clear, starting with those switching devices that offer the greatest savings. Once we have them in the construction program and the euros earmarked for them, we can get on with implementing them. My idea was to take the 30 or so best reclosers and remote disconnectors and subtract from that number the switches that we have coming up anyway with large regional renovations. The rest will then be added to the network at a rate of two to five switches per year, according to the program, says Lintunen, explaining the plans for the future.
Optimizing switching devices is a quick and cost-effective way to improve network reliability and save on outage costs, which directly affect the calculation of the allowed revenue.
Antti Lintunen says that if all the changes brought about by switch optimization were implemented in one go, over a 20-year review period, the savings in avoided outage costs would be around seven million.
– That’s a big number. And now, in the first year, the savings amounted to 900 000 euros. The best individual savings for a recloser were about 300 000 over that 20-year period, says Lintunen.
– In the light of these results, we can recommend it to other utilities. Especially if your utility has never calculated the return on investment for switching devices before. And then, if it is a challenge to include automation projects in construction programs, it makes it easier when you can show in euros that a disconnector or recloser will save this much in a certain period of time and has this payback period. That's where switch optimization helps, says Lintunen.
