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As a new feature, Elering is now offering customers the opportunity for a flexible connection to the power grid. This applies to connections where a grid element could become overloaded as a result of transmission of the capacity desired by the customer.

In such a case, the customer has a choice of whether to cover the cost of increasing the capacity of the overloaded grid element, or agree to reduce their generation and/or demand capacity in overload situations.

A flexible connection gives a customer the option of not investing into increasing the capacity of the Elering grid, while for the TSO, it means an optimal power grid, with resulting decrease in investment and maintenance costs.

In preparing each connection offer, a power grid analysis is conducted, in the course of which the planned generation and/or demand capacity is added to the power grid model and its impact on the electricity system is determined in various generation and/or demand limit scenarios. If the analysis shows that one or more of the grid elements are likely to become overloaded depending on the operating mode, the grid element’s capacity must be increased in order to guarantee the generation and/or demand capacity desired by the customer. Besides traditional connection agreement offers, which include expenses on upgrading the grid, Elering can make alternative offers to customers allowing them to use the desired connection subject to restrictions. No investments into increasing grid capacity need to be made in such cases. Such alternative connection agreements also specify the minimum capacity starting for which one or more grid elements are considered overloaded, and which grid elements, when overloaded, entitle Elering to limit or turn off the customer’s demand and/or generation capacity. No agreements are reached in regard to the duration of the restriction.

Before the customer signs the connection agreement and before the making of an investment decision, Elering will give the customer information on the types of generation and/or demand scenarios where the model shows potentially overloaded elements, and a statistical overview of the occurrence of scenarios that cause overload. Elering also provides information on the cases in previous years where grid elements that potentially cause overload have been switched off. With this knowledge about the cost of upgrading the capacity of the potentially overloaded grid element and the likelihood of the temporary restrictions, the customer can make a better-informed decision on whether to opt for a flexible connection.

The restriction on capacity will be applied only if there is a risk of overloaded grid elements, and connection agreement with the customer specifies which elements these are. If a given grid element is included in connection agreements with more than one customer, the restriction of capacity will start with the customer who established the connection to the grid most recently, and so on, until the oldest connection is reached. The restrictions on generation and/or demand capacity must be executed by the customer pursuant to the grid operator’s requirements.

The need for utilizing flexible connection capacity becomes evident in the course of modelling of the operation of the electricity system carried out by the TSO at different points in time – starting from planning for the year ahead to the start of the operational hour. Customers will be notified as soon as possible of the need for a partial or full restriction placed on a flexible connection. Depending on the duration of the outage, the TSO will provide corresponding information at the following times: ·

  • If the capacity restriction lasts over 120 consecutive hours, the customer will be notified by the 25th day of the month prior to the restriction; ·
  • If the capacity restriction lasts 120 consecutive hours or less, the customer will be notified by 12 noon on the previous day of the maximum allowed demand and/or generation capacity for each hour.

In the case of unscheduled restriction of a flexible connection capacity (such as a malfunction in the electricity system or extraordinary works on the grid etc.), the restriction will be implemented automatically by Elering by way of remote control.

The TSO will notify the customer of restrictions related to flexible connection capacity pursuant to the data exchange format established by the TSO. Customers must ensure the functioning of data connection between the TSO’s SCADA and the customer’s corresponding system and the adoption of the data exchange format to be established. The customer will also have to build and test a technical solution that upon receiving a command from SCADA alters the flexible demand and/or generation capacity.