On the occasion of the presentation of the Pueblos Verdes project, in which Ingelectus has participated, it is particularly relevant to focus on a concept that is becoming a key driver of transformation for the electricity system: grid capacity. In this project, which promotes a more sustainable energy model connected to the territory, Ingelectus has demonstrated how the use of advanced tools such as InPhity allows the available connection capacity to be calculated accurately, ensuring that distributed generation is deployed safely and efficiently. Understanding how this capacity is measured and regulated is essential to ensuring a robust, resilient and technically viable energy transition.
Generation capacity and demand: the navigation chart for Icarus’ flight towards the network of the future
According to Greek mythology, Daedalus was an illustrious engineer who, after designing the famous labyrinth that imprisoned the Minotaur, was held captive on the island of Crete with his son Icarus. To escape, he created wings made of feathers held together with wax and instructed him to fly at a medium altitude, away from the humidity of the sea and the heat of the sun. Icarus, intoxicated by freedom, flew too high; the wax melted, the wings fell apart and he fell into the sea that now bears his name. The tragedy shows that even genius needs to respect limits in order to avoid disaster.
It is the prudence that did not accompany Icarus on his journey that we must not lose sight of today, especially in one of the greatest challenges of our time: the energy transition. The fact is that in the flight towards the grid of the future, it is just as crucial to promote distributed generation and make room for new players — from self-consumption facilities and large plants to electric vehicles — as it is to ensure that the journey is made in complete safety. Connecting new distributed generation facilities is key to combating climate change. But the how is just as important as the what. It is therefore vitally important to establish a set of criteria that allow for the expansion of distributed generation without compromising grid security.
To this end, the CNMC approved Circular 1/2021, which sets out the criteria for access and connection of generation and demand: a veritable navigation manual that ensures that the growing penetration of renewables is integrated without overloading the grid or compromising the quality of supply. It details the criteria for calculating how much power can be safely installed at a node in the distribution network.
Such is the importance of ensuring that new connections to the grid are safe that, since last December, the CNMC has required distributors to publish the access capacity at the nodes of their network, known as Capacity Maps. This highlights the need for tools to effectively calculate these Capacity Maps, which must also be scalable to cover the entire distribution network.
This is also of interest when connecting new demand facilities, for which a new detailed specification document is being developed that sets out the criteria for calculating capacity in terms of demand.
Circular 1/2021: the essential manual for preventing grid collapse in the future
Circular 1/2021 establishes a total of five criteria for calculating generation access capacity, which can be divided into two groups:
Electrical simulation criteria:
To verify this, it is necessary to model the distribution network under study. In addition to the system topology, it is essential to have representative demand scenarios on which to apply the calculation. Off-peak demand scenarios and scenarios with a high level of injection from already connected generation involve situations where the connection to the new generation grid would be more limited. This is why these limiting scenarios are considered in the calculation.
There are three electrical simulation criteria:
- Access capacity under conditions of total availability: evaluates the generation connection under normal grid operating conditions, with all elements in operation. The criterion is met when the new generation does not cause overvoltages at nodes or overloads on lines or transformers.
- Access capacity under unavailability conditions in meshed grids with effective N-1 support: on this occasion, multiple scenarios are simulated. In each of them, there is an element (line, transformer, etc.) out of service, which requires a reconfiguration of the system to guarantee supply to all points in the grid. The validity criteria for each scenario are the same as for the previous criterion. The number of scenarios to be simulated depends on the range of possibilities available to the system to resolve N-1 contingencies, which may involve a large volume of simulations and therefore high computational requirements.
- Access capacity under connection/disconnection conditions: in this case, an assessment is made to ensure that the new connection does not involve a sudden change in the voltage values of the node to which it is connected, taking into account not only the new connection but also the generation already connected previously to the same node.
Threshold verification criteria:
In this case, it is not necessary to simulate the behaviour of the system. The aim is to verify that the new connection to be assessed complies with a series of limit values. There are two criteria in this subgroup:
- Access capacity by short-circuit power: to ensure system stability, the ratio between the short-circuit power calculated at the node where the new connection to be evaluated is located and the maximum capacity of the rest of the generation already connected to the system is limited.
- Access capacity by maximum power to be injected at a point: this criterion applies only to networks with a voltage lower than 36 kV, and sets the maximum access capacity at a node to a maximum of 70% of the capacity of the transformer or line to which the new connection to be evaluated is connected.
The following diagram summarises the process for applying Circular 1/2021 to calculate the connection capacity of new production facilities:
In addition to the above criteria, Circular 1/2021 introduces the concept of Capacity Maps. According to the regulations, network operators are required to publish the access capacity at the nodes of their networks. The mandatory nature of these maps came into force last December and poses a challenge for distributors.
Ingrid Platform – InPhity: accelerating the future of the network
At Ingelectus, we are helping distributors in this area of network capacity through the Ingrid Platform with the InPhity application, a tool that incorporates all the algorithms needed to calculate network capacity maps and make them accessible to network managers. InPhity has two key features:
(1) Fast calculation.
(2) Full integration with the distributor’s systems.
The first unique feature, speed, has been achieved through the automation of all the steps described in the detailed specifications, whose calculations have been streamlined through the implementation of optimisation systems developed by Ingelectus, making it 70% faster than conventional methodologies.
The second refers to the ability to be connected to the main systems that the distributor works with on a daily basis (GIS, SCADA, Remote Management, Remote Metering, SABT and Commercial), so that the Ingrid Platform is updated daily with any changes that have occurred in the network and with the new measurements recorded. This means that it functions as another feature of an ADMS (Advanced Distribution Management System), so that both its results and the scenarios studied can be coordinated with other tools or stored in the distributor’s own systems.
As a result, the periodic updating of capacity maps and the carrying out of Access and Connection studies has gone from being a challenge to becoming a reality. This can be seen in the web application, where all the results of the tool can be accessed and also compared with other Ingrid applications.
Almonte as an example: how Green Villages are connecting sustainability and technology
The Green Villages project, specifically the one carried out in the village of Almonte, is a good example of this. This project, promoted by CHC Energía and Grupo CECSA, aims to promote a more sustainable and environmentally friendly local energy model in rural areas. To this end, more than 2,000 solar panels have been installed in over 20 industrial buildings in the town of Almonte, Huelva, supplying 30% of the energy consumed by more than 3,500 homes and businesses in CHC.
Ingelectus has been able to participate in this project alongside CECSA, deploying the Inphity tool. This has enabled the calculation of the nodal capacity in the network area covering the group of industrial buildings studied by the project.
Beyond calculating nodal capacity, Ingelectus has applied advanced analysis techniques to the Pueblos Verdes project, enabling CECSA not only to verify the connection capacity of the new plants, but also to make decisions about connecting them to different points in its network. Furthermore, it has gone beyond the regulations, simulating not only the medium-voltage network, but also the low-voltage network. This has made it possible to verify that the new connections will not have a negative impact on the quality of supply of the network at any level.
Ingelectus’ participation in the Pueblos Verdes project has been a real challenge, demonstrating the benefits of Inphity by taking full advantage of it to obtain optimal results in reasonable computing times that are fully compatible with the distributor’s needs.
Demand capacity: the next regulatory challenge for a more resilient and prepared network
The CNMC is currently working on a Circular on access and connection that will establish the criteria for demand facilities, with a particularly technical approach and a strong focus on evaluating a large number of scenarios that could be critical for the network.
In conclusion, we could say that the day-to-day operation of distribution networks is marked by the growing penetration of new distributed generation sources which, although they are key in the fight against climate change, pose new challenges when it comes to ensuring the security of their systems. Ensuring the stability of these networks is essential to avoid situations such as those experienced last April with the blackout on the peninsula.
The CNMC, through Circular 1/2021, establishes the criteria for calculating generation access capacity, which should guide distributors when accepting new generators into their systems.
Following this roadmap and helping distributors ride the wave of the energy transition, Ingelectus presents InPhity, a new application from the InGrid platform that combines expert knowledge of networks and optimisation in its calculations to respond to the new challenge, having demonstrated its effectiveness in the Pueblos Verdes project.
At Ingelectus, we continue to take steps in our quest to accompany distributors on their journey towards the networks of the future.
