Listen to our Grid Code experts PHDs Keith Chambers and Marcelo Algrain discuss the evolving terrain of codes and standards around the world.
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Listen to our Grid Code experts PHDs Keith Chambers and Marcelo Algrain discuss the evolving terrain of codes and standards around the world.
Email us: powerbytes@cat.com
LinkedIn: https://www.linkedin.com/showcase/cat-electric-power/
Facebook: https://www.facebook.com/Caterpillar.Electric.Power/
Intro: Good Day and welcome everyone to Power Bytes! I am your host Lou Signorelli and Power Bytes is your destination Podcast for power generation conversations. As always please know how much we appreciate you, our listeners. We hope you find our topics helpful and interesting. There are several ways for you to get in touch with the show. You can send us an email at powerbytes@cat.com, visit us at Cat Electric Power on Facebook or LinkedIn. Please remember to subscribe wherever you listen to our show… it really helps.
We have all heard about the evolving landscape of grid codes. These are codes that come into play when you want to connect your site assets to the grid.
Today it's my distinct pleasure to have for you two experts in their field. Both are PHDs, have numerous papers and patents to their credit and are involved daily in grid code activities.
Today's Guests are Keith Chambers and Marcelo Algrain.
Lou: Keith can you tell us about your role?
Keith
Hello Lou, it's a pleasure to speak to you today and welcome to all of our listeners. I am the Grid Code Integration Manager for Caterpillar Electric Power Division. It is my role to understand grid code requirements across the world, and help our dealers and customers to understand what grid code means and how does it apply to their projects. I lead a team that is responsible for evaluating grid codes and guiding our Engineering teams to develop compliant products. We also work closely with accredited certification bodies to certify the product where that is needed. I participate in several Industry Associations and Working Groups related to grid codes, including the EUGINE Task Force on Network Codes, and the EUROPGEN Grid Codes Working Group. I am also an active member of the ENTSO-E Grid Code European Stakeholder Committee, and I participate in some Expert Groups on developing European grid codes and International Standards.
Lou: Marcelo, can you do the same?
Marcelo
Hello Lou and thank you for the opportunity to talk about gride codes. Just to give a bit of background on myself, as Tech Steward for CAT Electric Power my areas of responsibilities include emergency power system analysis and design for critical operations (data centers, healthcare, industrial and commercial), integration of distributed generation to the bulk electric power systems integration initiatives, generator set control system developments, new technology applications, and represent Caterpillar on Code and Standards development organizations. I was heavily involved in the development of IEEE 1547 which is the standard for connecting generation assets to the electrical distribution system, and its associated compliance test standard IEEE 1547.1, and UL 1741 edition 3 which is the certification standard for IEEE 1547.
Lou: What is Grid Code? Seems like a broad title. Is it the same everywhere?
Keith
A grid code is basically a set of requirements that a distributed energy resource, being a power generating unit or facility, must meet in order to be granted approval to connect to the grid. It can range from a very basic set of requirements, to a very extensive list depending on the size and complexity of the installation. In simple terms, the grid code is the "rule book", and if you don't meet all of the requirements then you cannot connect.
There are many different grid codes across the world, in fact every country has one. There may even be multiple grid codes depending on if the equipment is being connected to the medium-voltage distribution network, or the high-voltage transmission network.
Lou: Marcelo, what drives the need for a grid code.
Due to the increasing penetration of renewables and the transition from centralized to distributed generation there has been a focus in recent years, particularly in Europe and North America, on developing a more structured set of rules that power generating units and facilities must meet in order to connect to the grid. In Europe this is widely known as the Network Code on Requirements for Generators, or NC RfG, and in the US is known as IEEE standard 1547 for the interconnection of distributed generation to the electrical distribution system.
Lou: When/why does someone really need to pay attention to their local/regional grid code?
Keith
Very simply, if it is intended to connect a power generating unit to the grid, then the grid code must be considered. However, there are a few points to be aware of......in some countries there are specific exemptions such as temporary paralleling of standby generation to soft transfer load back to the utility following a power outage if not longer than a few minutes per month, or perhaps in a scenario where a new generating technology is being connected to the grid for prototype testing. In these "edge" cases it is a good idea to contact the local grid operator for advice, and of course Caterpillar can assist with any questions.
Marcelo
It is also worth noting that there could be differences in operational practices from jurisdiction to jurisdiction which could lead to the use different settings, such as tripping points and other control parameters. The local grid conditions would drive those additional requirements.
Lou: Do grid codes apply to all types of power generation?
Marcelo:
By and large they do. Some codes specify requirements by technologies, for example rotating machinery vs power electronic based generation. Others specify requirements based on the type of connection, that is whether generation is connected to the electrical distribution system, or to the sub-transmission or transmission system. In particular, IEEE 1547 is technology agnostic and specifies requirements for connection to the electrical distribution system. The standard does recognize different capabilities by technologies and specifies various level of performance to accommodate various technologies. However, it leaves it to the interconnection authority to specify the performance category required for the given area. For gensets the applicable performance levels are Category I for fault ride through and Category A for voltage regulation.
Keith:
Like the US, European grid codes are also technology agnostic, but there are some requirements specific to synchronous generating units, and others specific to power park modules (or inverter-based technologies).
The model in Europe, defined by the Network Code for Requirements for Generators (NC RfG), is to split the requirements into types A, B, C and D. Type A requirements are typically some basic rules applicable to small generating units in the tens of kilowatt range, and the requirements then increase in complexity for Types B, C and D. Each European country defines the boundary or power threshold for each of the different types, so it is worthwhile to check how this is defined for any given project and ensure that the generating units meet the required type classification.
Lou: Are there differences between different regions of the world?
Keith
Yes, there are a few differences to highlight between the European and US grid codes:
• Firstly, fault ride-through, which is the capability of the power generating unit to remain connected and support the grid during a fault. The fault ride-through requirements are stricter in some European countries than in the US for synchronous generating units, and in particular for larger units which are often expected to remain connected when the grid voltage dips to zero for a time duration up to 250ms in some countries. Typically the worst-case requirements in the US are to ride through faults where the voltage dips to 50% for up to 160ms, so quite a contrasting difference.
• Secondly, partial grid requirements, which define the operation of the genset in an islanded portion of the grid, for example caused by a distribution feeder breaker opening. In the US, the strategy is to disconnect the power generating unit and wait until the main grid connection is restored before reconnecting. Whereas in some European countries the strategy is to remain connected and supply the local load (or partial grid) until the main grid connection is restored.
• And thirdly, Simulation model requirements – in many European grid codes there are very clearly prescribed requirements and validation procedures to develop a representative simulation model of the power generating unit. In the US while a simulation model may still be required by some grid operators, the grid code itself does not go as far as to define the model requirements and validation procedures to be used.
Marcelo
One area where the US is leading the charge is in Interoperability which is somewhat new to the power industry.
IEEE 1547 is the early adopter of this technology, but we are beginning to detect activity in other grid codes as well.
Interoperability is the basic ability of different computerized products or systems to readily connect and exchange information with one another.
As distributes generation becomes more prevalent, there is a higher need for managing those generation assets remotely.
This capability is at the core of the smart grid initiative to maximize efficiency, reliability, and resiliency.
Lou: Why would there be a difference?
Marcelo
It is not surprising that there would be differences from one continent to the other.
After all we have different voltages and frequencies.
Distribution systems around the world have evolved into different forms and have specifics needs.
Most importantly, they differ in layouts, configurations, and applications.
In Europe, the roads, buildings, and tightly packed houses were already in place when the electrical system was developed, so the design had to fit in.
In North America, many of the roads and electrical circuits were developed at the same time.
So that led to different operational practices and ways to add load and generation.
Each grid code reflects what would be consider best practice for local conditions.
Even within Europe codes differ from country to country although there are ongoing efforts to harmonize as much as possible.
Keith
If I go back to the three differences I mentioned earlier:
• Regarding fault ride-through, each country has it's own perception of "risk", and definition of "typical" and "worst-case" fault conditions. Also, the evaluation of the consequences of units disconnecting during a fault will differ in each country and region. Therefore the FRT requirements tend to be defined based on what individual grid operators perceive as typical conditions in their network area and this can vary widely across continents depending on the grid architecture.
• Regarding partial grid operation, there are differing opinions on how to handle this – some countries share the view that the priority is to keep as much as possible of the network connected to generation, and quickly balance the load with available generation capacity. Whereas others have a view that all equipment should first disconnect, and then the network should be restored in a structured manner. Both approaches have pros and cons - what we learn from this is that there is not a "one size fits all", and individual countries and grid operators will have different preferences on the right strategy.
• Regarding simulation modeling, many of the European grid operators have well established simulation models of their network areas which are used for load flow analysis, short-circuit studies, and fault analysis. The models are becoming ever more granular and therefore expectations are increasing for accurate models of equipment to be provided before connecting to the grid. The grid operator will use the model to perform simulation studies and evaluate the behavior of the generating unit during fault conditions as part of the overall process of approving the grid connection. This is an area I would expect to see more and more countries following the European approach in future.
Lou: Do products have to be compliant or is it done at a site level?
Marcelo
In most cases it is not an either or answer.
A site combining multiple generation assets would certainly be required to be compliant in order to be approved for connection to the grid.
The best approach is to start with equipment that has been certified to the applicable code.
It may not make the entire installation compliant depending on complexity, but it certainly will go a long way toward achieving compliance at the power plant level.
Certifying equipment is a considerable undertaking involving type testing only achievable in specialized test facilities.
Attempting to conduct those compliance tests in field at site level would be costly and impractical.
Demonstrating compliance at the site level is typically done as a combination of equipment certification, design evaluations, analytical methods, computer simulations, and commissioning tests.
Keith
As Marcelo mentioned, starting with compliant and certified equipment is the best and recommended approach.
The grid operator expectation is that the entire facility or installation meets the grid code requirements, and in some countries a plant certificate is required to be obtained by the site owner from an accredited certification body.
However, the process is greatly simplified if the equipment installed has already been certified to meet the grid code requirements by the manufacturer. In this case, the certification body will generally accept the equipment certificate as evidence of compliance, and therefore issue a plant certificate without requiring extensive testing or simulation.
Lou: OK, so just how hard is this to get done? As in meeting the standards or being "compliant" as a site owner?
Marcelo
Well that would depend on the generation capacity and complexity of the installation.
The higher the impact the site has on the grid area the more rigorous the compliance verification becomes.
Additionally, certain jurisdictions may impose additional requirements beyond what a grid code specifies.
For example, Hawaii requires additional capabilities beyond IEEE Standard 1547 due to the large penetration of renewable generation and the variability of grid conditions.
Keith
Grid codes can be complex, but of course we can help. Start by understanding which grid code applies, and what are the expectations of the local grid operator in terms of testing, certification and simulation modeling of the equipment to be installed. Also find out what is needed in terms of plant or facility level certification.
Once that is understood, the next step is to consult the equipment manufacturer to ensure that the power generating unit and any auxiliary components meet the applicable requirements, and have been certified where that is needed.
Lou: Clearly our listeners are going to need to have an expert to lead them through this process. Let me provide a few resources:
1st Cat dealers are a great place to start. If you're inclined to do a bit of research on your own… here are a few links to help you in your journey.
cat.com/ieee1547
cat.com/futuregridcode
If you'd like to review all of Cat Electric Power's white papers, hers is a convenient url: cat.com/epwhitepapers
With that I'd like to thank our guests Keith Chambers and Marcelo Algrain. And a special thanks to you, our listeners for joining us today on Power Bytes.
Remember, there are several ways for you to get in touch with the show. You can send us an email at powerbytes@cat.com, visit us at Cat Electric Power on Facebook or LinkedIn. Please remember to subscribe, review, and leave us your comments wherever you listen to our show… it really helps.
Until next time, thank you and have a great rest of your day.