Power Generating Module (PGM)
Power Generating Module (PGM) is either a Synchronous Power Generating Module or a Power Park Module (PPM) (Article 2(5) of the Network Code on Requirements for Grid Connection of Generators (NC RfG)).
NC RfG introduces four categories of PGMs:
The significance of PGMs is based on their size and effect on the overall system. According to Article 5 of NC RfG, PGMs are categorised as type A, B, C or D depending on both the installed capacity and the voltage level at the connection point. Paragraph 2 of the same Article specifies a voltage-related criterion and sets out limits for capacity thresholds that are defined at national level.
As observed by the ACER Policy Paper of 26 September 2022 (on the revision of the network code on requirements for grid connection of generators and the network code on demand connection):
‘The proportionality of technical requirements for PGMs is dependent on the appropriate determination of significance. It may be achieved by applying criteria that accurately reflect PGMs size and their effect on the system. Therefore, the following policy options could be considered:
a) Removal of the voltage criteria – as a result, significance determination for types A, B, C and D of PGMs or for some of them would be based on the maximum capacity only; it may be followed by the amendment of capacity thresholds or introduction of other criteria;
b) Amendment of the voltage criteria – possible range of amendments span from the application of voltage criteria only above specific capacity threshold (also referred to as ‘removal of the voltage criteria up to a capacity threshold’) to subjecting the final value to national decisions;
c) Hybrid solution encompassing selected elements of discussed alternatives.
Furthermore, the feasibility of harmonisation and possible adaptation of the new criteria at national level shall be assessed”.
Technical requirements for types B, C and D PGMs are set out in the NC RfG and are divided by two criteria: exhaustiveness (exhaustive and non-exhaustive) and compulsoriness (mandatory or non-mandatory). Depending on their kind, requirements could be further specified at the national level in the course of implementation to accommodate system needs in particular countries. However, as observed by the ACER Policy Paper of 26 September 2022 (on the revision of the network code on requirements for grid connection of generators and the network code on demand connection), at the national level sometimes requirements for larger units permeate down to smaller units, additional requirements are introduced or requirements are outside of the prescribed ranges. Current level of discretion resulted in the introduction of diverse national rules and, consequently, broadening the range of technical requirements across the Member States. An insufficiently harmonised regulatory framework for types B, C and D PGMs may limit the level-playing field, hamper the economies of scale, and impede other benefits of the common connection rules.
As ENTSO-E guidance document for national implementation for network codes on grid connection (Selecting national MW boundaries, Draft for consultation, 30 June 2016) underlines, categories of PGMs are introduced by following the principle of subsidiarity and proportionality. The capacity thresholds are defined as limits of capacity threshold which define the maximum lower limit of each category leaving its final determination to the national level.
Type B, C, D thresholds need to be determined at national level regarding the following points:
- maintaining requirements which already exist from previous national regulations and have proven their need and benefit through operational experience in normal and emergency network situations,
- taking into consideration the national generation portfolio characteristics and its evolution (e.g. level of penetration of renewable energy sources),
- taking into consideration national system characteristics and its evolution (e.g. rural/urban conditions, density of load and generation),
- ensuring that requirements needed for guaranteeing security of supply will be fulfilled considering the peculiarities of each national system (e.g. dependency on power imports from abroad).
The aforementioned ENTSO-E guidance document of 30 June 2016 evidences the following key rationales for choosing the pertinent thresholds:
- A/B threshold: the need of fault-ride-through (FRT) capability of small generation units if otherwise the loss of a large volume of generation in case of a fault on the transmission network would jeopardize system security, and the need to increase observability of small generation units.
- B/C threshold: as regards frequency control capability of renewable energy sources (RES) generation: in case of high volumes of RES generation a large amount of conventional generation resources will be displaced and hence not be available to manage system security during certain periods (in these cases, the need of additional capacity to control frequency must be evaluated, regarding the amount needed and the expected size of new generation units).
- C/D threshold: need of FRT capability of large PGMs and units connected to typically the highest voltages of the grid, to guarantee the stability of the grid.
Winter Energy Package (Annex to the Proposal for a Regulation of the European Parliament and of the Council on the internal market for electricity (recast), 30.11.2016, COM(2016) 861 final 2016/0379 (COD)) provides for the regional outage coordination of Power Generating Modules. This task is entrusted to Regional Operational Centres (ROCs - later renamed as Regional Coordination Centres (RCCs). Pursuant to the said draft each ROC would perform outage coordination "in order to monitor the availability status of the relevant assets and coordinate their availability plans to ensure the operational security of the transmission system, while maximizing the capacity of the interconnectors and/or the transmission systems affecting cross-zonal flows". Each Regional Operational Centre would also maintain a single list of relevant grid elements, Power Generating Modules and demand facilities of the system operation region and make it available on the ENTSO for Electricity operational planning data environment.
Further, each ROC would carry out the following activities related to outage coordination in the system operation region:
(a) assess outage planning compatibility using all Transmission System Operator's (TSOs') year-ahead availability plans;
(b) provide the transmission system operators of the system operation region with a list of detected planning incompatibilities and the solutions it proposes to solve the incompatibilities.
Relevant Power Generating Modules
Network Code on System Operation In Articles 84 - 86 envisions the establishment of the lists of "relevant Power Generating Modules" (along with the list of "relevant Demand Facilities"). According to Article 103(1) and (2) of the Network Code on System Operation each Power Generating Facility owner must ensure that all relevant Power Generating Modules it owns:
- are ready to produce electricity pursuant to their declared technical capabilities when necessary to maintain operational security, except in case of forced outages - in case of modules which are declared ‘available’,
- do not produce electricity - in case of modules which are declared ‘unavailable’.