Grid code compliance in Europe – Ways to a fast and safe grid connection

Solar plants are not merely «plugged» into the grid to feed-in power. To maintain a stable and resilient network, there is a range of standards and requirements to fulfill. Even within Europe, the criteria for project owners can vary, which can complicate commissioning on schedule.

In this pv magazine Webinar, meteocontrol will discuss the effects of grid code compliance harmonization in Europe and what it means for project owners. Markus Holzapfel, product manager at meteocontrol, is an expert in grid code compliance of renewable power plants, hardware, and software solutions for controlling power plants and technical operation management of PV plants.

Looking at examples from Germany, the Netherlands, and Spain, the difference between compliance by testing and certification will be shown. In Germany, compliance by certification has become standard practice, but in the Netherlands, the UK, and Ireland compliance by testing is still an essential part of the commissioning process. Testing procedures, however, are costly and can take up to six months.

Also, joining this session is Bernd Hinzer, the CEO of DNV GL Renewables Certification and head of the grid code compliance section. Drawing on extensive experience, he will discuss how developers, EPCs, component manufacturers, grid operators, and certification bodies have to work hand in hand to enable a successful grid integration of an array. If this close cooperation works smoothly, and a high degree of trust between the various certification bodies of the EU countries is established, a move towards a certification based compliance system is possible.

pv magazine Webinar content:

• How to handle the different requirements in Europe
• What you need to know about compliance by testing or certification
• Real-world examples from Germany, the Netherlands, and Spain
• Cooperation across the value chain, from component supplier to grid operator

Questions can be submitted beforehand or during the webinar through a chat window. The moderator of this pv magazine Webinar is our editor Marian Willuhn.

After the sucessful webinar on 16 July 2020, Markus Holzapfel and Bernd Hinzer went over the questions raised by participants during the event and answered them in more detail in writing.

If a PV Park was commissioned on June 2020 in Spain, does it have to fulfil the U-Q/Pmax requirements?

The draft version of the Spanish Grid Code PO 12.2 requires ‘Reactive power capability’ only for type D power plants (see chapter 5.2.3.2 Capacidad de potencia reactiva) but the technical guideline NTS (version 1.0) clearly states that reactive power capability at maximum (RfG, Article 21(3)(b)) and below maximum capacity (RfG, Article 21(3)(c)) is required for type C and D power park modules. Verification either has to be carried out according to PVVC or NTS. Unfortunately, Real Decreto (RD) 647/2020 does not mention any transitional period as far as we know. The ministerial order (Orden Ministerial – OM) expected in the coming months should provide more clarity here. For more information about technical connection requirements in Spain and PO 12.2, 12.3 as well as Norma Técnica de Supervisión (NTS) we can recommend the recording of the following UNEF webinar: “Los Procedimiento Operativos 12.2 y 12.3 y la Norma Técnica de Supervisión de la Conformidad (NTS): ¿qué diferencia hay?” (Spanish language)

Links:

PVVC (Version 11, 2018/09/26) 

NTS (Version 1.0, 2019/07/18)

PO 12.2 (Draft version, 2018/10) 

RD 647/2020 (2020/07/08)

Why do the NLD and Spain ask for U-Q/Pmax for type B PV Parks? EU 2016/631 does not make it mandatory and sacrifices a lot of Active Power. This sacrifice power is too high for type B. For instance, Germany does not require U-Q/Pmax for type B.

According to Commission Regulation (EU) 2016/631 (RfG), Article 20(2)(a), the relevant system operator shall have the right to specify the capability of a power park module (PPM) such as a PV system, to provide reactive power. According to ENTSO-E’s Implementation Guidance Documents (IGD’s) ‘Parameters related to voltage issues’ and ‘Parameters of Non-exhaustive requirements’ the capability of type B, C and D PPM’s to supply or absorb reactive power is a non-mandatory requirement but can be made mandatory on a national level by the relevant system operator (RSO).

Links:

Commission Regulation (EU) 2016/631 (2016/04/14)

IGD Parameters related to voltage issues (2016/11/16)

IGD Parameters of Non-exhaustive requirements (2016/11/16)

Since EN 50549-1/2 certifications are already in place, what did you mean when you said that EN 50549 is upcoming?

The latest versions of the European technical standards EN 50549-1 (low voltage) and EN 50549-2 (medium voltage) regarding requirements for generating plants to be connected in parallel with distribution networks still have draft status. The European technical standard EN 50549-10 about demonstrating compliance tests of units is currently under development.

Links:

E DIN EN 50549-1 VDE 0124-549-1:2020-03 (2020/02/21)

E DIN EN 50549-2 VDE 0124-549-1:2020-03 (2020/02/21)

Is testing for inverters on site requested for Dutch and Spanish markets?

From our experience, most of the on-site compliance tests / Site Acceptance Tests (SAT) required in the Netherlands need to be performed on plant level instead of inverter level. Capabilities such as active power controllability and reactive power control modes (voltage control, reactive power control and power factor control) need to be carried out at the Point of Common Coupling (PCC). In Spain there are almost no on-site compliance tests required, as verification is done by project certification according to NTS. For a project certification, only supplementary compliance simulations are required which have to be carried out by an accredited certification body (see NTS, chapter 4.1 Aspectos generales, figure 6).

Links:

Power-Generating Modules compliance verification – Power-Generating Modules type B, C and D according to NC RfG and Netcode elektriciteit (2019/12/01)

Norma técnica de supervisión (NTS) de la conformidad de los módulos de generación de electricidad según el Reglamento UE 2016/631 (Version 1.0, 2019/07/18)

Do we need to follow the P-Q curve while designing PV plants and the sizing of inverters?

When designing a PV plant, a suitable sizing of the PV inverters shall be of special interest in order to comply with the national requirements on reactive power capability at maximum (RfG, Article 21(3)(b)) and below maximum capacity (RfG, Article 21(3)(c)). For this purpose, the entire PPM (PV system) shall be operable within the U-Q/P_max-profile as well as within the P-Q/P_max-profile given by the relevant system operator (RSO). The PQ diagram (respectively the PQ curves) of the project-specific PV inverter types need to be considered and there might be the necessity to foresee a continuous active power curtailment in order to comply with the project-specific requirements on reactive power capability. This can be achieved by a Power Plant Controller (PPC).

Links:

Commission Regulation (EU) 2016/631 (2016/04/14)

What is the distinction between compliance by project certification and by simulation and testing? What are the requirements for project certification?

Markus Holzapfel: It was only my rough distinction between markets where you have project certification (compliance by certification) and markets where on-site compliance testing / Site Acceptance Testing (SAT) plays an important role within the compliance verification procedure (compliance by testing and simulation). In practice, it is often not possible to distinguish precisely between these different verification approaches. In Germany, a two-stage project certification and supplementary compliance testing is required. In the Netherlands, there is currently no project certification but a very extensive compliance test campaign required for type C and D PPM’s. In Spain, there is a project certification with almost no on-site compliance testing but supplementary compliance simulations, which need to be carried out by an accredited certification body.

What if a country did not publish the local adjustments to the RfG (e.g. Portugal)? They still have the old grid code online.

In general, we always recommend sharing the connection agreement with the Grid Code Compliance (GCC) related manufacturers (e.g. manufacturer for inverter and plant controller) in order to identify the relevant documents (Grid Code, technical guidelines, etc.). If there is little to no information available in a very early project phase, we offer a pre-screening and the customer gets a document called ‘PPC – Scope of functionality’ as an outcome. This document outlines the most important capabilities regarding frequency and voltage stability on plant level with a reference to the RfG and recommends project-specific parameters such as control accuracy (steady-state error) or control dynamics (rise and settling time). The customer can use this document as a basis for discussion with the relevant system operator in order to find a common agreement regarding GCC.
For Portugal, the non-exhaustive requirements are defined in the ordinance no. 73/2020.

Links:

Portaria n.º 73/2020, Requisitos não exaustivos para ligação dos módulos geradores à Rede Elétrica de Serviço Público (RESP) (2020/03/16)

Is there a recommendation in terms of smaller central inverters or many smaller decentralized units when it comes to frequency behaviour at the point of connection?

We don’t recommend any inverter topology in this context.

Are there laws in place which protect EPCs against the non-standards in different countries? What if a TSO does not answer questions prior to a grid connection?

According to RfG, Article 29(2) the relevant system operator shall clarify and make the details of the operational notification procedure publicly available. Furthermore, according to RfG, Article 41(3) the relevant system operator shall make a list of information and documents publicly available as well as the requirements to be fulfilled by the power-generating facility owner within the framework of the compliance process. Regarding compliance testing, the relevant system operator shall cooperate and not unduly delay the performance of the tests according to RfG, Article 42(3). In some countries, the need for compliance verification is established via legislative rules such as NELEV in Germany or Real Decreto (RD) 647/2020 in Spain.

Link

Commission Regulation (EU) 2016/631 (2016/04/14)

NELEV (2017/06/12)

RD 647/2020 (2020/07/08)

Are you aware of guideline RfG related to validation of simulation models? Do we need tests to validate the models e.g. FRT?

Compliance simulations are an important topic within RfG. See RfG, chapter 6, Articles 54 (type B PPM), Articles 55 (type C PPM) and Articles 56 (type D PPM). According to RfG, Article 54(4)(a) the PPM’s (type B and C) capability to ride through faults in accordance with the conditions set out in point (a) of Article 14(3) shall be demonstrated by simulations. According to RfG, Article 56(3) the model of the PPM (type D) shall demonstrate that it is suitable for simulating the fault-ride-through capability in accordance with point (a) of Article 16(3).

Links:

Commission Regulation (EU) 2016/631 (2016/04/14)

Do you know what the status is for generic models?

From our experience, most of the European system operators accept PowerFactory and PSS/E simulation models. The Spanish TSO Red Eléctrica de España (REE) requires a generic PSS/E model but if the generator doesn’t fit the structure of any of the given predefined models, using a PSS/E user model / custom model (coded in Fortran) is possible. For the plant controller, the generic model REPCAU1 is accepted by REE.

Links:

P.O. 9.0 Información intercambiada por el operador del sistema, Resolución de 11 de diciembre de 2019, BOE 20/12/19 (2019/12/20)

Requisitos de los modelos de instalaciones eólicas, fotovoltaicas y todas aquellas que no utilicen generadores síncronos directamente conectados a la red (2018/08)

Guía descriptiva del Procedimiento de Puesta en Servicio (2018/01)

Listado de modelos dinámicos admitidos por el operador del sistema

For large scale PV projects of 50 MW or more, are there any differences between grid compliance testing for string inverters and central inverters in terms of regulations?

The European regulation 2016/631, also known as Network Code (NC) Requirements for Generators (RfG) does not distinguish between string and central inverters. A distinction is made only between ‘synchronous power-generating modules – SPGM’, ‘power park modules – PPM’ (e.g. PV power plants) and ‘offshore power park modules – OPPM’.

Links:

Commission Regulation (EU) 2016/631 (2016/04/14)

How do you rate the progress of the implementation of RfG at national level – especially for Type A plants for low voltage level connections – residential and small commercial?

The national implementation of the RfG is already approved in most of the countries according to ENTSO-E’s report ‘Monitoring report on connection network codes implementation’. According to RfG, Article 40(1) the power-generating facility owner shall ensure that each power-generating module complies with the requirements applicable throughout the lifetime of the facility. For type A power-generating modules, the power-generating facility owner may rely upon equipment certificates.
In order to give manufacturers and certifiers sufficient time to perform the required type tests of all components according to the new requirements, an extended transitional period is granted such as in Germany. Using a manufacturer’s declaration instead of an equipment certificate in order to show compliance to VDE-AR-N 4105:2018-11 is accepted until the 31^st March 2021. Other countries like Poland have similar transitional periods.

Links:

Monitoring report on connection network codes implementation (2019/12/16)

IGD Special issues associated with type ‘A’ generators (2016/11/16)

VDE-Info zur Veröffentlichung der Vorabversion DIN VDE 0124-100 (VDE V 0124-100) als Grundlage für den Konformitätsnachweis gemäß VDE-AR-N 4105 (2020/03)