The power system is controlled centrally. Operation of the national power system is the responsibility of the National Dispatching Centre, referred to as PSE’s dispatching service.
ECONOMIC AND MARKET IMPACTStable operation of the national power system
Key figures(wg stanu na koniec 2023 r.)
Power system in Poland
The secure and economic operation of the power system is the result of having a number of tools in place and engaging in continuous activities. In emergency situations, this involves resorting to extraordinary measures. We take measures that enable our organisation to maintain the continuity of electricity supply to consumers. We monitor and maintain the system reliability and continuity of supply indicators at high levels.
Cross-border interconnections
The national transmission system operates:
- synchronously with the systems of the ENTSO-E Continental Europe countries,
- with dedicated power units of the Dobrotvir power plant of the Ukrainian system,
- non-synchronously with the Swedish system via the DC submarine cable,
- non-synchronously with the Lithuanian system via a back-to-back DC link.
Fig. 1 Cross-border interconnections
Transmission system management in the NPS
Transmission network operation management takes into account the needs of electricity consumers nationwide.
Ongoing operational security of the power grid is ensured by hierarchically organised TSO and DSO dispatching services as well as the O&M services of generators and consumers.
The national power system is organised into the following hierarchy of dispatching services:
- National Dispatching Centre (KDM) – manages the operation of the 400 kV and 220 kV transmission grid as well as selected 110 kV lines of system importance,
- Area Dispatching Centre (ODM) – manages the operation of the transmission grid and switching operations of the 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 distribution network at 110 kV and lower voltages.
The TSO dispatching services cooperate directly with the DSO dispatching services (Central Dispatching Centres, Branch Dispatching Centres), and O&M services of enterprises dealing with electricity generation (Duty Power Plant Operation Engineer – Dyżurny Inżynier Ruchu Elektrowni – DIRE). The cooperation is based on the Transmission Grid Code (IRiESP).
Fig. 2 Organisation of dispatching services in Poland
The TSO’s cooperation with transmission system operators of the neighbouring countries with respect to grid operation management is based on the rules set out in the ENTSO-E/UCTE network codes and conditions laid down 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 timeframes. This process includes annual, monthly and daily coordination plans.
The schedule of planning activities and the scope of forecasted and published data are 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 interconnection exchange restrictions.
In order to ensure the continuity of electricity supply and balance the system even in 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 operational generating units from the pool of units dispatched by the Operator.
- Rescheduling of repair work on grid 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 plants that can pump water to a reservoir at a higher altitude and then to discharge it to a lower reservoir, thus generating electricity. The operation of such plants is analogous to that of energy storage facilities, allowing excess energy to be stored in periods of its oversupply and to use it in periods 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 generated power level above their rated capacity. This 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;
- Contingency purchase of capacity abroad as part of the inter-TSO 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 electricity supply, i.e. by interfering with consumers’ demand:
- Introduction of electricity supply and consumption curtailments, i.e. by announcing so-called “power supply levels”. Entities obliged to reduce electricity energy off-take, and the required scale of reduction are included in the annually updated Plan for introduction of energy supply and consumption 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, while their longer application requires a Regulation of the Council of Ministers. Restrictions in the form of “power supply levels” apply to large consumers whose contracted power is above 300 kW.
- Reduction in the demand by emergency shutdown 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. Consumers shutdowns in the above modes by the Operator (through activation orders) are carried out in cooperation with distribution system operators (who physically perform consumer shutdowns).
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 (CSS):
- participation in primary control,
- participation in secondary control,
- underload or overload operation,
- participation in automatic voltage and reactive power control,
- The start-up service for Generating Units (start-up service)
- Control 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 automatic voltage and reactive power control for generating units not actively participating in the balancing market
- Reliability must-run service provided by non-centrally dispatched generating units (RMR 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 electricity supply from the transmission grid.
To determine the reliability of grid operation in accordance with the applicable legislation, the 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 outages.
AIT – the index of the average interruption time in the power transmission system. Expressed in minutes per year, it is a product of 60 and energy not supplied (ENS) by the power transmission system, divided by the average power supplied by the transmission system, expressed in MW.
As in 2021-2020 and 2018, in 2023 there were no events resulting in emergency power interruptions and outages to consumers at transmission grid delivery points as identified above.
The indicators calculated for 2017, 2019 and 2022 reflect emergency interruptions and outages, the reasons for which are described below.
In 2022, one emergency interruption was registered, which resulted in no power supply to a customer. Its cause was a ground fault on the customer’s power due to lightning strike during a thunderstorm. The total duration of the interruption was 4 hours and 41 minutes.
In 2019, one emergency interruption resulting in a lack of power supply to a customer. The outage lasted approximately 36 hours, and it was due to tripping of the 110 kV line from which the customer taking power off the transmission grid was supplied. The direct cause of the outage was an earth fault due to contact with a tree in the line right of way.
In 2017, one emergency outage occurred, which resulted in a 3-hour interruption of power supply to one of consumers fed from the transmission grid. The outage was caused by an emergency manual disconnection of the power supply lines. The reason for the power cut was an unauthorised person having climbed a 220 kV power line tower. The shutdown of other equipment, lines and transformers connected with the site was dictated by safety concerns.
Low levels of the ENS and AIT indices testify to a high level of operational reliability of the transmission grid managed by PSE and the reliability of power supply to consumers connected to the grid.
GRI INDEXENS and AIT indices for all outages (planned and emergency)
In 2023 and 2022, the values of the ENS and AIT indices returned to their pre-2021 levels, which 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 indices calculated for all shutdowns, when compared to the previous years. It was mainly due to a planned outage, a much longer one than in the previous years, for one of the customers fed from the transmission grid due to an extensive scope of work carried out by the TSO on the consumer’s power supply assets (expansion and modernisation of an autotransformer bay in the 110 kV switchgear). The date of the outage was agreed in advance with the consumer.
The ENS and AIT values remaining at a steady low level have a positive effect on the confidence of customers 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 on transmission network elements supplying the customers. PSE carries out the shutdowns in the case of scheduled outages at times agreed with the customers – usually during periods of no energy consumption as declared by the customers. As a result, during outages, customers adjust their demand or use other methods of supplying electricity (e.g. from the DSO network).
WCD – electricity supply continuity index
To determine the continuity of electricity supply, the so-called WCD index is calculated.
Worth knowing
WCD
The index is calculated as the total amount of electricity supplied to transmission service customers (DSOs and end users) divided by the sum of the amount of electricity supplied and not supplied to those customers during the year.
Maintaining the supply continuity indices at a high level results from the TSO’s operation and maintenance policy for transmission assets.
The amount of electricity not supplied to transmission service customers in a year has been calculated taking into account both scheduled and unscheduled interruptions in electricity supply to consumers. The index used in the calculation of the total amount of electricity supplied from the transmission grid during a year is the volume of electricity taken from the transmission grid at all delivery points by end users and DSOs connected to the transmission grid.
PSE’s actions to maintain the continuity of electricity supply to consumers:
- Development of long- and short-term grid operation coordination plans. The work schedules – for both the maintenance and repair of grid elements and generating units – are determined in such a way as to ensure that the required levels of surplus capacity available in excess of the forecast demand are met over the given period and that the required criteria for secure grid operation, 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 condition of equipment and its operating environment. Owing to those activities, the most depreciated and oldest grid assets – the potential source of emergency and disturbance conditions – are preventively replaced.
- The implementation of the O&M services development programme allows continuous improvement of the competence of PSE’s own O&M services, including those performing field
- Undertaking investment activities optimises the load on transmission lines and eliminates overload conditions on transmission system elements.
- The systematic standardisation of grid equipment and the creation of a storage base allow necessary replacements to be made quickly and in a financially optimal way.
- Close cooperation and making arrangements with transmission service customers at each stage, i.e. from planning to implementation.
Index of electricity losses in the transmission process
The process of electricity transmission is inextricably accompanied by losses, which reduce the amount of electricity supplied to consumers. The amount of electricity transmitted is reduced mainly by technical losses caused by physical phenomena occurring during the transmission of electricity through the transmission infrastructure. Technical losses include current losses (longitudinal) and voltage losses (transverse). Their size depends on a number of factors, primarily on volume and variability of generation, the locations of generation sources and the demand of entities connected to the grid, as well as the volume and directions of cross-border exchange. Weather conditions also affect the volume of losses.
In 2023, price conditions in Europe’s commodity markets stabilised, resulting in a narrowing of electricity price differences between countries, thereby reducing cross-border flows. This had the effect of reducing the volume of losses in the transmission grid to the levels observed before 2022. The decrease in electricity taken off the transmission system operator’s grid was also influenced by the high generation of electricity from prosumers’ renewable sources, which further influenced the decrease in the volume of losses in the transmission grid in 2023.
In grids owned by TSOs in recent years, up to and including 2021, the loss ratio was low and decreasing year-on-year. In 2022, the volume of losses increased, and so did the loss ratio, mainly due to the much higher variability of energy flows than in previous years attributable to variable cross-border flows (both in terms of volume and direction). The above-mentioned phenomenon was a result of the developing mechanisms of the European single electricity market and atypical energy market conditions in 2022. In 2023, the volume of losses and the amount of from the transmission system operator’s grid decreased compared to 2022, while the loss ratio increased, as the value of losses referred to the reduced energy injected into the grid. This was influenced by the high volatility of energy flows on cross-border interconnections as seen in 2022 and increased self-consumption of electricity by prosumers.
According to EU legislation, PSE is a signatory to the ITC agreement between European TSOs, under which the additional costs of energy flows (transit) through a given transmission grid are compensated to operators.
Energy injected and withdrawn in 2014-2023 Loss ratio in 2014-2023
2023 was a record year for PSE in terms of the volume of electricity transmitted through the transmission grid. The year saw the lowest values of energy injected into and withdrawn from the transmission grid in 10 years. The chart above shows that the value of electrical energy transmitted in 2021 and 2022 was significantly higher than the value of energy transmitted in previous years and in 2023. One of the factors that influenced such a phenomenon was the end of the pandemic period, which lasted from early 2020 to mid-2021. The post-pandemic period was characterised by a significant increase in the country’s industrial output and thus an increase in demand for electricity. In 2023, the volume of electricity sent through the transmission grid returned to values close to those before the pandemic period, as a result of the stabilisation of market conditions in Europe and the reduction of transit flows through the transmission grid, as well as the intensive development of photovoltaic sources in Poland, which reduced output of generators connected to the transmission grid and electricity from the transmission grid to the distribution network. In 2023, losses amounted to 1,623,845 MWh, accounting for 1.59 percent of the total energy injected into the system.
Ensuring the security of critical infrastructure
To ensure the protection of the infrastructure facilities at the company’s disposal in 2023, we carried out the following activities:
- We ensured monitoring of risks to critical infrastructure were monitored – depending on the level of risk to a given facility, the appropriate form of physical protection was adjusted;
- We updated agreements with voivodeship governors on the principles of cooperation and the scope of information exchange in the event of energy emergencies;
- We updated and agreed on plans to protect PSE’s critical infrastructure;
- We were taking measures to provide fuel at PSE facilities in case of the introduction of restrictions under the Act on stock of crude oil, petroleum products and natural gas and the rules of conduct in situations of risk to national fuel security and disturbances in the oil market;
- We carried out the activities specified in the Procedure for establishing crisis teams, reporting crisis situations and dealing with terrorist threats at PSE. Activities included the testing of equipment and facility systems, as well as the implementation of procedures resulting from the alarm levels introduced;
- We cooperated with the state administration and other external entities in the field of infrastructure protection (with periodic reporting of the current situation);
- PSE representatives participated in the AMBER-2023 exercise for critical infrastructure operators, which was organised by the Government Security Centre and the Ministry of Climate and Environment. The goal was to conduct stress tests involving designated CI operators and the critical infrastructure they manage, which is vital to public safety and security and the smooth functioning of the state;
- At ODM Warsaw, ODM Radom and KDM, ODM Bydgoszcz, ODM Katowice and ODM Poznań, we expended and launched radio communications with Voivodeship Crisis Management Centres within the Radio Crisis Management Network;
- In cooperation with the Government Security Centre, we maintained the DRA-RL geographic zones for unmanned aircraft designated over PSE facilities;
- We participated in an international exercise on power system operational security.