Flexible connection

As a new option, Elering offers clients the opportunity for flexible connection when connecting to the electricity network, where some network element is overloaded due to the transmission of the power requested by the client.

In such a case, the client can choose whether to pay for increasing the transmission capacity of the overloaded network element or to agree to shed the load of their generating and/or consumption capacity in situations where overload occurs.

Flexible connection gives clients the option to not invest in increasing the transmission capacity of Elering’s network and provides the system operator with a more optimal electricity network, which results in reduced investment and maintenance costs.

When drawing up each connection offer, an electricity network analysis is carried out, in the course of which the planned generating and/or consumption capacity is added to the electricity network model and its impact on the power system is determined under different generating and/or consumption limit scenarios. If the network analysis shows that one or more network elements have a probabilistic likelihood of being overloaded depending on the mode, the transmission capacity of that network element must be increased to ensure the generating and/or consumption capacity requested by the client. For clients who are able to use the requested connection capacity during overload, either fully or partially load-shed, Elering can, in addition to the traditional offer of a connection contract with network reinforcement costs, also present an alternative offer, according to which network reinforcements do not need to be carried out. At the same time, such a connection contract specifies the capacity from which one or more network elements are considered overloaded and the network elements in the event of overloading of which Elering has the right to apply load shedding to the client’s consumption and/or generating capacity. No agreements are entered into regarding the duration of load shedding.

Before the client signs the connection contract and makes an investment decision, Elering provides the client with information on which generating and/or consumption scenarios will cause overload according to the model as well as a statistical overview of the occurrence of scenarios causing overload. Elering also provides information about shut-offs of network elements that potentially cause overload in previous years. Knowing the cost of increasing the transmission capacity of an overloaded network element and the probabilistic likelihood of load shedding, the client can make a decision about using flexible connection capacity.

The capacity limitation is only applied in the event of a risk of overloading of the network element, which is agreed with the client in the connection contract. If the network element in question is included in the connection contract of several clients, the flexible capacity limitation starts with the newest client, using up all their flexible connection capacity, and is then followed by limiting the next client and, where necessary, all the way to the earliest client. The client must shed the load of generating and/or consumption capacity in accordance with the system operator’s requirements.

The need to implement flexible connection capacity may become apparent during the modelling of the operation of the power system carried out by the transmission system operator at different times – from planning a year ahead to the start of the operational hour. The client shall be informed of the need to partially or completely shed flexible connection at the earliest opportunity.

Depending on the duration of the outage, the transmission system operator will provide relevant information within the following deadlines:

• If load shedding lasts for more than 120 consecutive hours, the client shall be informed by the 25th date of the month preceding the month of limitation;
• If load shedding lasts up to 120 consecutive hours, the client shall be informed of the maximum permitted consumption and/or generating capacity of their connection point by hours no later than by 12 p.m. on the previous day.

In the event of unscheduled limitation of flexible connection capacity (for example, accidents in the power system or emergency work in the network, etc.), the limitation is carried out automatically by Elering via remote control.

The transmission system operator informs the client of the limitations of flexible connection capacity in accordance with the data exchange format established by the transmission system operator. The client must ensure the functioning of data communications between the transmission system operator’s SCADA and the client’s corresponding system and the adoption of the established data exchange format. The client must also build and test a technical solution that, upon receiving a command from the transmission system operator’s SCADA, changes the permitted flexible consumption and/or generation-oriented connection capacity.