Grid code compliance in megawatt projects – Practical commissioning in the Netherlands

In this pv magazine webinar, together with our initiative partner meteocontrol, we are taking a deep dive into the process of fulfilling grid code compliance in the Netherlands. In addition, recourse is also made to Germany. Both countries are examples for most common procedures widely used in Europe.

Last year, meteocontrol discussed the difference between fulfilling the requirements for generators by testing or by documentation in theory. In this webinar, after a year of first hand experience with the verification process of a megawatt scale project in the Netherlands, Ehsan Nadeem Khan, Grid Code Compliance Engineer at meteocontrol, can share with us his practical experiences and personal takeaways from co-operating with the investor, the certification body and the transmission system operator. Khan will also focus on the certification process of the plant and the extensive testing procedures in the Netherlands.

Join the free webinar to learn more about grid code compliance standards and how different approaches in Europe require different actions from plant owners. The webinar will include detailed technical presentations along with interactive Q&A sessions – providing attendees with the opportunity to put their questions to the speakers and become a part of the discussion.

pv magazine Webinar content: 

• The what and the why of „Grid Integration“
• Brief introduction to GCC norms and rules
• Power plant controller responsibilities
• Discussing two markets Netherlands and Germany
• Tests, procedures and troubleshooting based on examples from practice

Questions can be submitted beforehand or during the webinar through a chat window. Marian Willuhn, editor at pv magazine, will be the host of this webinar.

Registration for this pv magazine Webinar is free of charge.

(This webinar was originally scheduled for April 27th and has now been postponed to April 28th.)

Why are there two different reactive power thresholds for the voltage control? Why are these referred to as dynamic and disturbance thresholds? And what is the difference between the dynamic and the disturbance threshold for reactive power?

For voltage control, Netherland has two submode. These are known as Voltage submode 1 and voltage submode 2.

The dynamic and disturbance thresholds are considered for voltage submode 1. There are, in principle, just two reactive power thresholds(values), and as soon as these thresholds are violated, specific actions are to be conducted. These actions depend on which threshold is being violated and can be found in the compliance verification document.

These actions are to ensure grid stability in case of voltage drops or increases. Details of this method are in the compliance document.

Wind turbines can provide FFR, but how about PV + Storage?

This has been a topic of research, but I haven’t yet seen FFR or synthetic inertia being required from a PV plant.

Is there any limitation or regulations about the feed into the grid to avoid the bottleneck?

The grid operator, through telecontrol, always has the ability to control the power output of the plant. This is already considered when you apply for a feed-in grid connection, and the agreed connected active power is issued after considerations like a bottleneck, grid strength, etc.

Inverters inject or supply reactive current as a function of voltage. Is the reactive power supplied initially from inverters or PPC?

The initial reactive power can come from other equipment in the plant, e.g., the cables’ inductances or the transformers.

What are the costs of these tests?

The costs related to SAT are project-specific. Please get in touch with our team, and we will be happy to assist you. 

Are the documents Netcode elektriciteit (July 2020) and Netbeheer Netherland’s guidelines publicly available in English?

Both the documents are publicly available, but only one is available in English.

Power-Generating Modules compliance verification can be found in English: https://www.netbeheernederland.nl/dossiers/regulering-20/documenten

Netcode elektriciteit is only available in Dutch: https://wetten.overheid.nl/BWBR0037940/2021-04-30

Based on your experience, what is approximately the rise time and settling time during voltage droop control?

The requirements were 2.5s rise time and 7 seconds settling time. We experienced rise times as fast as 2s, and settling times were usually below 4s.

When issuing Q/U/cosphi setpoints, there is a certain delay time. Can you point out the values of delay time for PV plants based on your experience?

These delay times are highly dependent on the hardware used. In an ideal case, the total delay should be below 500ms, as we are already experiencing 1s settling time requirements in Europe.

Who issues the project certificate and the declaration of conformity? Is it an independent 3rd party or the project company?

For Germany, the project certificate (Anlagenzertifikat) and the declaration of conformity (Konformitätserklärung für die EZA) are issued by the certification body, which would mean an independent 3rd party.

It is important to note here that the certification body for the declaration of conformity must be different from the body that issues the commissioning declaration (Inbetriebsetzungserklärung).

For Type D plants: How do we do active power tests during the winter months? Is the alternative to do desktop modeling?

We did initial tests with very limited power to show basic functionality, which allowed us to feed in power until the summer. Then we conducted the tests on full power.

Are the grid requirements imposing lower DC/AC ratios for PV plants so that the PV plants can comply?

Not that I’m aware of. There is, however, a strict requirement on the power that is fed into the grid.

Can you elaborate on the allowed difference between agreed grid-connected power and actually installed power? To what extent are you allowed to exceed the agreed grid power?

The plant owner is responsible for ensuring that the agreed connected active power at the PCC is not exceeded and that the required reactive power is always available. In my experience, there isn’t a cap on how much you can oversize the plant, but when oversizing, please take care that the feed-in power is well regulated by a power plant controller.

Would it have been permitted to control right away? Or are the 15 Minute intervals compulsory?

The grid operator provides in the ATO the frequency of checks per minute. 4 checks per hour translate to the 15 mins checks. It is not permitted to control right away. The control action is only conducted at the check, I.e., 15 mins.

Can you briefly explain a PQ capability curve in PV?

PQ capability curve tells us the reactive power requirement based on a given active power. Please refer to the PQ capability graphs in the RfG or the grid codes of either Germany or the Netherlands.

Is the dynamic threshold always the same in NL, or is it different from one plant to another?

The dynamic threshold is based on the total reactive power of the plant and thus different for every plant.

What is the requirement of FON for plant operators?

For FON, the plant operator needs EON and ION. Or better yet, refer to the extract from the compliance document.

“The Power Generating Facility Owner (PGFO) shall submit a statement of compliance to the RSO for issuing a FON. This statement of compliance refers to the following documents and reports:

• An ION;
• Final report on power quality measurements approved by the RSO;
• Final report full on-site tests approved by the RSO;
• Simulation models, validated against test results (as built);
• Motivation and/or re-simulations approved by the RSO, as result of as-built values.“

For the certification process, how are no conformities handled? Do the plant owner can go online with minor non-conformities and plan to solve them?

In case of failure to comply, a detailed reason needs to be given to the grid operator. The final verdict lies in the hand of the grid operator if you are allowed to feed in or not.

Based on your experience in Europe, once a plant gets certified, when do they have to recertify their operation to keep going, assuming they keep the size fixed?

Unless major changes have been made, recertification, in my experience, is not required. There are country-specific compliance monitoring requirements through which the plant operator must continue to show that the plant is compliant with the requirements it was commissioned on. The grid operator, in this case, can ask for proof of certain functionalities. 

For the on-site testing, is it on the plant level or inverter level? If on plant level, how is it done?

On-site testing is conducted on a plant level. Every test has its requirement; some are done by changing the setpoint others are done by changing the frequency or voltage.

Do you know the timeline for the regulation of the type B connection level in the Netherlands? At the moment, grid providers don’t even have an on-site commissioning certificate for the type B category.

Unfortunately, no timeline was provided.

When do you expect this will extend to other countries like America or Southern Africa?

Most of these requirements are already, in some form, being implemented all over the world. Stricter requirements are based on how much renewable energies have penetrated in these countries and how stable the grid is.

How would you conduct, e.g., an LFSM-O response test on a plant in operation?

By changing the frequency that the controller “sees”. Instead of the measured frequency, the simulated test frequency is used.

If certified for Germany, is it also acceptable in Netherland if the requirements are common?

The Netherlands does accept German-type tested equipment, which is based on TG3. If it applies to each and every requirement has to be seen on a project level.

Are they not permitting alternative DC sources to provide the power if PV can’t produce power in December?

Providing power with an alternate source would defeat the purpose as testing the PV plant at full capacity is the goal here.

How is the voltage changed in the field? Are signal generators provided by grid operators?

A simulated test voltage is being used instead of the actual measured voltage. Voltage values are simply transmitted to the required register in the PPC through MODBUS

Are derogations permitted when the code changes between SAT if you don’t meet a new requirement?

The latest version of the grid code, which is present at the time of registering your plant with the grid operator, is applicable, and new regulations can be ignored. This, of course, also depends on when the plant is taken into commissioning.

Do the German grid code requirements from NELEV prevail over the ones established in the European RfG then?

German technical guidelines from VDE (FNN) supersedes RfG. This is also the case for all other European countries, which is why each country has its own grid code.