Energinet and system requirements: Telemetry, metering and grid code

When an industrial BESS (battery energy storage system) is to be connected to the electricity grid, the local connection with the grid company is only the first step. The connection point itself, that is, the agreement on where and how the facility is coupled to the local grid, is covered in its own article on the application to the grid company. But a battery that both draws and delivers electricity also forms part of a larger whole: the overall electricity system, which Energinet, Denmark's national transmission system operator, is responsible for. That is where the system requirements come in. For a decision-maker they are rarely visible at the outset, but they are a real part of what must be in place before a facility can enter normal operation.

This article explains what sits on top of the local grid connection: the difference between the grid company and Energinet, the technical connection requirements, often referred to as grid code, metering and data communication at system level, and the prequalification that can become relevant if the facility is to deliver services to the electricity system. The aim is to make a technical layer understandable. Concrete technical limit values depend on the individual facility and are fixed in the technical dialogue, not in an article.

Grid company and Energinet: two different levels

The first thing worth separating is who is responsible for what in the electricity grid. The collective electricity grid is divided into two layers. Energinet is Denmark's transmission system operator and responsible for transporting energy at national level, while the grid companies are distribution system operators that run the electricity grid locally at the lower voltage levels. The grid company is therefore the local actor, while Energinet is the one responsible for the whole.

The difference can be illustrated with a road-network analogy. The overarching transmission grid, which the state-owned company Energinet owns and operates, as a rule distributes electricity at voltage levels above 100 kV and handles Denmark's interconnectors with other countries, while the distribution grid is the underlying network that, via roughly 35 grid companies, carries electricity onwards at lower voltage levels all the way out to businesses and households. The transmission grid is the motorways; the distribution grid is the smaller roads. An industrial BESS at a commercial customer is normally connected in the distribution grid, that is, with the grid company, but that does not change the fact that the facility forms part of the electricity system Energinet is responsible for.

Energinet's role is broader than owning lines. Energinet is the entity with system responsibility and the system operator for the Danish electricity system. System responsibility is about keeping the balance between consumption and production so that the frequency in the grid is stable and security of supply is maintained. When a facility can both draw and deliver power, it is relevant to that balance, and requirements can therefore be set that go beyond the local connection. That is the logical reason a system level exists on top of the grid company.

Grid code: the technical connection requirements

The next layer is the technical requirements for how a facility may behave when it is connected to the grid. They are often referred to collectively as grid code. The purpose is that the equipment that is connected does not disturb the grid, but can instead withstand fluctuations and contribute to a stable system.

At European level, a large part of these requirements is gathered in a common rule set. Commission Regulation (EU) 2016/631, often called the RfG Regulation after the English "requirements for generators", sets network codes on requirements for grid connection of generating facilities and structures the requirements according to the voltage level at the connection point and the facility's maximum capacity. In other words, the technical requirements depend on how large the facility is and where on the grid it is connected. The regulation builds on the premise that the networks and the connected facilities must be seen as one coherent unit when it comes to system security, and that secure operation therefore presupposes close cooperation between the facility owner and the system operator.

In Denmark, it is the national technical regulations that implement the framework. The relevant technical requirements are set pursuant to the RfG Regulation by Energinet and the grid companies respectively, depending on which level the facility is connected at. That means the documentation showing that the facility complies with the technical requirements is submitted as part of the connection process, which we describe in the article on the application to the grid company. What matters for a decision-maker is not the individual limit values, but the principle: there is a rule set for how the facility must behave technically, and it must be documented before the facility can enter operation. Which concrete requirements apply to a given facility is a technical assessment that depends on the facility's size and connection.

Metering, telemetry and data communication

A battery that both draws and delivers electricity must be metered correctly, and the metering must be able to be communicated to the right actors. Here there are two matters worth keeping apart: the settlement metering itself, and the ongoing data connection from the facility.

Settlement metering forms part of a central data basis. Energinet is responsible for establishing and operating a data hub for handling metering data and for carrying out the necessary functions and the communication used for settlement. DataHub is the IT system where metering data and market communication are gathered, so that a facility's consumption and any delivery to the grid can be settled correctly. That the meter must be configured to measure both directions, that is, both what the facility draws and what it sends back, is part of the local connection and is covered in the article on the application to the grid company. At system level, the point is that those data must feed into the shared settlement basis.

Beyond settlement metering comes telemetry. Telemetry is the ongoing measurement and status data that the facility sends while it is running, and it is the connection that makes it possible to remote-monitor the facility and to coordinate it with the electricity market to the extent that is relevant. We deliver software that monitors the battery and handles coordination with the market and aggregation partner that is responsible for market participation. We do not state specific technical specifications for the ongoing data connection, because it depends on the facility's configuration and on the requirements partners and the system set. What matters is that, beyond settlement metering, there is an ongoing data connection, which is a precondition for both monitoring and market coordination.

Prequalification if the facility is to deliver to the system

Some battery facilities do more than optimise the company's own consumption. They can also make power available to the system, that is, deliver so-called system services that help Energinet keep the balance and the frequency. If a facility is to do that, an extra step follows.

Before a unit can participate in the system services markets, it must be prequalified and tested with Energinet, and only once the documentation is approved may the unit participate. The process includes tests at which Energinet is normally present, submission of documentation, and a formal approval, and a unit can be prequalified either alone or as part of an aggregated portfolio. Prequalification is therefore not a formality, but a concrete technical process that must be completed before the facility can deliver to the system.

It is at the same time worth being clear about what the market provides. According to the industry, revenue from system services cannot stand alone, and batteries therefore typically also participate in the spot and intraday markets, where larger volumes of electricity are traded. The electricity market itself, system services, and the different revenue sources are a subject in their own right, which we cover in the part of our material that deals with the market and Energinet's market side. The only point here is that prequalification is the technical entry ticket if a facility is to deliver to the system, and that that possibility is a supplement to operation, not a guarantee.

ZynexGroup's approach to facility assessment

The system requirements are part of what we coordinate in a turnkey process. We handle the dialogue with Energinet on the system matters that apply beyond the local grid connection, together with the technical submission to the grid company, so the company does not itself have to navigate two levels and their different requirements. We also deliver the software that monitors the facility and handles the telemetry and the coordination with the market and aggregation partner.

Here there is a boundary that is important to be precise about. We are not the balance-responsible party for the facility towards the system. Market participation itself is facilitated via an aggregation partner, and we work to make market access possible within the technical and contractual framework of the agreement. Whether and when market access can be realised does not depend on us alone, but also on the technical requirements, on prequalification, on the specific site, on the partner, on the grid company, and on the applicable regulation. We can coordinate and prepare the basis, but we cannot guarantee a particular approval or a particular time horizon, because those matters are decided by authorities, partners, and the system. Throughout the process, the company has one fixed contact person with us, so the same person knows the project from the initial dialogue through to the dialogue on the system matters.

Limitations and preconditions

The system level contains matters that lie outside both our and the customer's control. The concrete technical requirements depend on the facility's size and on where on the grid it is connected, and they are fixed in the technical dialogue, not in advance. A prequalification for system services is only relevant if the facility is to deliver to the system, and it is a standalone process with tests and documentation that must be approved by Energinet. Neither can be promised as a particular date or a particular outcome.

There is also a limit to what a general article can say. Some of the most technical matters, such as how a facility's power electronics concretely behave in the grid, depend on the chosen solution and on the applicable regulations and should not be described as fixed properties without a concrete assessment. The same applies to concrete limit values, thresholds, and market volumes. A company that knows those frameworks early can enter the process with realistic expectations rather than being surprised by a layer it did not know existed.

Overall perspective

Beyond the local grid connection with the grid company, there is a system level where Energinet, as system-responsible transmission system operator, has responsibility for the balance in the overall electricity system. That level shows up in three things: technical connection requirements gathered in grid code and, at European level, in the RfG Regulation; metering and data communication where settlement data form part of Energinet's DataHub; and ongoing telemetry from the facility. If the facility is also to deliver system services, that requires a prequalification with Energinet, and market participation itself takes place via an aggregation partner. We coordinate those matters and prepare the basis, but we are not the balance-responsible party, and market access depends on several parties and on regulation, not on us alone. A decision-maker who understands that there is one more step after the grid company has the best starting point for a realistic timeline and expectation.

Assessing the potential for your facility

If you are considering an industrial BESS, the system matters are part of the overall assessment on a par with the local grid connection and the physical installation. We use your grid connection, consumption profile, and historical consumption data for an initial assessment of whether there is a match, and for a data-based dialogue about the further process, including what the system requirements and any market participation realistically involve at your address. You are welcome to contact us here.