ECONOMIC AND MARKET IMPACTStable operation of the national power system

Key numbers from this chapter(as at the end of 2022)

Power system in Poland

A prerequisite for providing access to electricity is an efficiently operating system that enables its generation, processing, transmission and distribution. All the equipment connected to this system, together with consumers’ installations, form the national power system.

The power system is controlled centrally. The National Dispatching Center, the so-called dispatching service of PSE, is responsible for the operation of the Polish power system.

Cross-border connections

The national transmission system operates:

  • synchronously with the systems of continental European states ENTSO-E,
  • with dedicated power units of the Dobrotwór power plant of the Ukrainian system,
  • non-synchronously with the Swedish system via a DC submarine cable,
  • non-synchronously with the Lithuanian system through a DC back-to-back converter station.

Fig. Cross-border connections

Transmission system management in the NPS

The operation of the transmission grid takes into account the needs of electricity consumers nationwide. 

The current operational security of the power network is ensured by the dispatching services of the TSO and DSO as well as the operational services of generators and customers operating in a hierarchical system.

The national power system has the following hierarchy of dispatching services:

  • National Dispatching Centre (KDM)  – manages the operation of the 750, 400, 220 kV transmission grid, as well as selected 110 kV lines of system importance,
  • Area Dispatching Centre (ODM)  – 220 i 110 kV,manages the operation of the transmission grid and the switching operations of the 750, 400, 220 and 110 kV transmission grid,
  • Central Dispatching Centres, Branch Dispatching Centres (CDM, OCD)  –manage the operation of the 110 kV distribution network and switching operations in the distribution network of 110 kV and below. 

The dispatching services of TSOs cooperate directly with the dispatching services of DSOs (Central Dispatching Centres, Branch Dispatching Centres) and with the operational services of power generation companies (Power Plant On-Duty Engineer - DIRE). This cooperation is carried out in accordance with the Transmission Grid Code.

Fig. Organization of dispatching services in the country

The cooperation of TSOs with TSOs of neighbouring countries with respect to network operation is carried out in accordance with the terms and conditions set out in the ENTSO-E/UCTE grid codes and conditions specified in bilateral agreements.

Balancing of power demand

In order to provide the generation capacity necessary to meet the demand, as a Transmission System Operator, we implement a coordination planning process for different time horizons. This process includes annual, monthly, and daily coordination plans.

The schedule of activities related to the development of plans and the scope of forecast and published data is defined in the Transmission Grid Code.

Coordination plans are designed to allow the levels of excess capacity available over forecast demand to be met as required during the assumed period. This is achievable by coordinating the repair and maintenance schedules of generating units and shutdowns of meshed network elements, taking into account plant and network constraints and planned inter-system exchange restrictions.

To ensure continuity of energy supplies and balance the system even under adverse conditions, the Operator has a number of tools at its disposal during periods of peak electricity demand:

  • Resuming the operation of available generating units by issuing an order to start up available and technically efficient generating units, from the pool of units at the disposal of the Operator.
  • Rescheduling of overhaul works regarding network elements and generating units – where possible, the Operator agrees with operators of generating units on the rescheduling of planned unit overhauls.
  • Use of pumped-storage stations that can pump water to a higher reservoir and then to discharge it to a lower reservoir, thus generating electricity. The operation of such stations is analogous to that of energy storage facilities, allowing to store excess energy at the moments of its oversupply and to use it at the moments of reduced supply.
  • Use of the “overload operation” service, that is using the possibility of additional loading of those generating units that are able to increase the level of generated power above the rated capacity. It applies to selected units and is limited in time.
  • Use of must-run generation services, that is using the opportunity to increase the level of power generation by combined heat and power plants (possible under certain conditions).
  • Use of the demand side management service – consumers ready to reduce their demand submit appropriate bids for capacity reduction to the balancing market.
  • Announcement of the period of demand in the power market – if there is a risk of failing to meet the required excess capacity, the so-called period of demand is announced. In this situation, holders of capacity contracts are required to deliver the contracted capacity to the system and make it available to the Operator by submitting appropriate work plans or balancing bids.
  • Intervention purchase of capacity abroad as part of the inter-operator emergency assistance – where there is such a need, the Operator may apply for support from its counterpart in another country.

Where the above measures fail to balance the system, the Operator is obliged to counteract the threat to the operational security of the system by balancing the system through emergency measures provided for in a situation of risk to security of the electricity supply, i.e., by interfering with the demand of consumers:

  • introduction of energy supply and off-take curtailments, i.e. the announcement of so-called “power supply levels”. Entities obliged to reduce energy off-take and the required scale of reduction are included in the annually updated Plan for introduction of energy supply and off-take curtailments, approved by the President of the ERO. The Operator has an option of announcing such curtailments for a period of no more than 72 hours, and their longer validity requires a Cabinet Regulation. Curtailments in the form of “power supply levels” apply to large consumers whose contractual capacity is above 300 kW;
  • reduction in the demand by trips of consumers, either in the scheduled mode on a rotating basis or in the emergency mode in response to the current situation in the system. Trips of consumers in the indicated modes are implemented by the Operator (it orders their activation) in cooperation with distribution system operators (they physically implement trips of consumers).

Measures to ensure reliable operation of the transmission system, including reliability metrics

PSE purchases system services to ensure secure and economic operation of the Polish power system and, in particular, the achievement of the required reliability and quality parameters.

System Services:

  • Control System Services (RUS):
    - participation in primary control,
    - participation in secondary control,
    - under- or overload operation,
    - participation in automatic voltage and reactive power control.
  • Start-up service for Generating Units (start-up service).
  • Control-related system services representing pumped storage generating units:
    - participation in automatic voltage and reactive power control (ARNE),
    - compensation operation.
  • Control system services as part of the contingency reserve:
    - Contingency reduction of power consumption by consumers based on a bidding process (IRP).
  • Participation in the automatic voltage and reactive power control for generating units not actively participating in the balancing market.
  • Availability service for non-Centrally-Dispatched Generating Units (GWS service).
  • National power system restoration service.

System operation reliability indices (ENS, AIT)

The indices describing the continuity of power supply and the duration of power interruptions (ENS and AIT) were calculated for a group of delivery points, which include end users and electricity DSOs with one delivery point from the transmission grid. Shutting down the delivery point of these customers results in an interruption of energy supplies from the transmission grid.

To determine the reliability of network operation in accordance with applicable regulations, ENS and AIT indices for emergency outages are calculated.

Worth knowing

System operation reliability indices

ENS – the index of energy not supplied by the power transmission system. It is expressed in MWh per year and is the sum of the products of the capacity not supplied due to the interruption and its duration. This index includes short, long and very long interruptions and outages with and without consideration of catastrophic 

AIT – index of the average interruption time in the power transmission system. Expressed in minutes per year, it is the product of 60 and the index of energy not supplied (ENS) by the power transmission system divided by the average energy supplied by the power transmission system expressed in MW.

In 2022, one emergency interruption was registered, which resulted in no voltage to the consumer. Its cause was an earth fault on the consumer’s power line caused by lightning during a thunderstorm. The total duration of the interruption was 4 hours 41 minutes.

In 2018, 2020 and 2021, there were no events resulting in emergency power interruptions and outages to consumers at delivery points from the transmission grid identified as above. The indicators calculated for 2017 and 2019 reflect emergency interruptions and outages, the reasons for which are described below.

There was one emergency interruption resulting in no power to the consumer in 2019. The interruption lasted approximately 36 hours and was caused by a spontaneous shutdown of the 110 kV line from which the consumer drawing power from the transmission grid was supplied. The immediate cause of the interruption was a ground fault due to a tree coming close along the line section.

In 2017, there was one emergency interruption that resulted in an approximately 3-hour interruption in electricity supply to one consumer supplied from the transmission grid. The interruption was caused by an emergency manual shutdown of the power supply lines. The cause of the power cut to the consumer was a third party’s climbing a 220 kV line tower. The shutdown of other devices, lines and transformers associated with the site was dictated by safety concerns.

Low levels of the ENS and AIT indices demonstrate a high level of operational reliability of the transmission grid managed by PSE, as well as to the reliability of power supplies to customers connected to that grid.

ENS and AIT indices for all outages (planned and emergency)

In 2022, the values of ENS and AIT indices returned to the levels observed in the years before 2021. This resulted from the smaller scope of works carried out as part of scheduled shutdowns.

In 2021, there was an increase in the values of the ENS and AIT indicators calculated for all shutdowns, when compared to the previous years. It was mainly due to a scheduled outage, a much longer one than in previous years, for one of the consumers supplied from the transmission grid, due to an extensive scope of work carried out by the TSO on the consumer's power supply assets (extension and modernisation of an autotransformer bay in the 110 kV switchgear). The date of the outage was agreed in advance with the consumer.

The low values of ENS and AIT indices have a positive impact on the confidence of consumers connected to the transmission grid. The reduction of the number and duration of planned outages of the supply of electricity to customers results from, but is not limited to, the implementation of a system to optimise the schedule of repair and maintenance works of transmission network elements supplying the customers. PSE carries out the shutdowns in the case of scheduled outages at times agreed with the consumers – usually during periods of no energy consumption as declared by the consumers. As a result, during outages, customers adjust their demand or use other methods of supplying electricity (e.g., from the DSO network).

Electricity supply continuity index – WCD

To determine the continuity of electricity supplies, the so-called WCD index is calculated.

Worth knowing

The index calculated as the total amount of electricity supplied to transmission service consumers (DSOs and end users) divided by the sum of the amount of electricity not served and supplied to these consumers during the year. 

Maintaining the supply continuity indices at a high level is the result of the TSO's operation and maintenance policy for transmission assets.

The amount of electricity not supplied to transmission service consumers during the year was determined taking into account both scheduled and unscheduled interruptions in energy supplies to consumers. The index used in the calculation of the total amount of electricity supplied from the transmission grid during the year is the volume of electricity taken from the transmission grid at all delivery points by end customers and DSOs connected to the transmission grid.

PSE’s actions to maintain the continuity of electricity supplies to consumers:

Coordination planning of network operation in the long and short term. The work schedules – for both the maintenance and overhaul of network elements and generating units – are determined in such a way as to ensure that the required levels of surplus capacity available over the forecast demand are met over the given period and that the required criteria for safe operation of the network, including the reliability criterion (n-1), are met.

  • The development and implementation of a uniform operating model allows for cyclic, standardised and measurable assessment of the technical condition of equipment and its operating environment, so that the most worn-out and oldest elements of network assets – potential sources of emergency and disturbance conditions – are preventively replaced.
  • The implementation of the operating services development programme allows continuous improvement of the competence of own maintenance services, including those performing work in the field.
  • Investment activities. Taking investment activities optimizes the load on transmission lines and eliminates overload conditions on transmission system elements.
  • The systematic standardization of network equipment and the creation of a storage base allow to make necessary replacements quickly and in a financially optimal way.
  • Working closely and making arrangements with the transmission service consumers at every stage – from planning to implementation.

Index of electricity losses in the transmission process

The transmission of electricity through the electrical power network to consumers is accompanied by energy losses. These are technical losses caused by physical phenomena occurring in the electrical power network. These technical losses include voltage and current losses. Their size depends on a number of factors, primarily on the volume and variability of generation and the demand of entities connected to the network, but also the volume of cross-border exchange. Weather factors also affect the volume of losses.

In networks owned by TSOs in recent years, up to and including 2020, the loss ratio was low and decreasing every year. In 2022, the volume of losses increased, and thus the loss ratio also increased. The main reason for this increase was the huge variability of energy flows caused mainly by the variable (both in terms of volumes and directions) cross-border flows. The above-mentioned phenomenon was the result of (i) the developing mechanisms of the European single electricity market and (ii) atypical energy market conditions in 2022.

According to legal regulations, PSE is a signatory to the ITC agreement between European TSOs. Under this agreement, the additional costs of energy transits (flows) through a given transmission network are compensated to operators.

Fig. Relation of the loss ratio to the electricity input and output in TSO networks.

The years 2021–2022 were characterized by record volumes of transmitted electricity on the TSO network. Carrying out appropriate investments in network infrastructure was a reason for which the record values of transmitted electricity did not result in a great change in the loss ratio. The value of the 2017 loss ratio is comparable to the 2022 loss ratio with an increase by 11.19 percent in electricity input to the TSO network. In 2022, the loss amounted to 1,835,091 MWh, representing 1.56 percent of the total electricity input to the system.

Ensuring the security of critical infrastructure

We are an enterprise of strategic importance to the national security. Our company is:

  • a critical infrastructure operator,
  • the owner of facilities subject to mandatory protection,
  • the owner of facilities of particular importance for the safety and defence of the state,
  • an enterprise of particular economic and defence importance.

Certain tasks and responsibilities have been imposed on PSE in connection with these functions.

As part of measures taken in 2022 by PSE so as to ensure the protection of critical infrastructure facilities at the company's disposal:

  • Risks to critical infrastructure were monitored – depending on the level of risk to a particular facility, the appropriate form of physical security was adjusted;
  • Updates were made in relation to:
    • Agreements with provincial governors on the principles of cooperation and the scope of exchange of information in the event of energy emergencies,
    • PSE critical infrastructure protection plans.
  • In view of the situation in Ukraine, as of February 21, 2022 the President of the Management Board of PSE established a Crisis Team, within which the following were included:
    • logistic support with regard to the availability of fuel for both official vehicles and facilities was provided by:
      • concluding an agreement for the sale along with supply of fuel products as a wholesale customer,
      • taking measures to provide fuel at PSE facilities in the event of the introduction of restrictions under the Act on stocks of crude oil, petroleum products and natural gas and the principles of conduct in situations of risk to state fuel security and disturbances in the oil market.
    • Activities specified in the Procedure for establishing crisis teams, informing about the crisis situation and conducting in a situation of risks of terrorist acts at the PSE were implemented, which included:
      • tests of field devices and systems,
      • implementation of activities resulting from the introduced alarm levels.
    • Additional satellite phones were purchased.
    • In consultation with the Government Security Centre and the Civil Aviation Authority, a long-lasting DRA-RL geographic zone with a low probability of approval to fly BSP systems over PSE facilities was implemented.
    • Cooperation with the state administration was carried out – periodic reporting of the current situation and constant communication were maintained.
    • The cooperation was carried out with other external entities with regard to infrastructure protection.
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