Digital Substations
What is a digital substation?
At its core, a digital substation focuses on converting binary status and analog measured data into digital data - reliably and seamlessly. This makes data easier to transmit and share between devices and substations in real time, so it can be better utilized, processed and acted upon.
Substations with the future built in
Decarbonization, decentralization, digitalization – everything that will shape the energy systems of the future is already highly concentrated in digital substations. With their availability, these substations are able to introduce cost-effectiveness and sustainability into the power supply. The foundation of this development is the fully exploited strength of digitalization.
The heart of the power supply goes digital. Digitalized substations collect valuable data from the entire power grid. This means that the heart of the power supply can also become the heart of energy data communication – and can create added value.
Challenges for grid operators
The energy systems of the future are increasingly decarbonized, distributed, and digitalized. This fundamental transformation is in full swing and poses a wide range of challenges for all stakeholders. Only digitalization will allow us to master these challenges.?Ensuring that the digital transformation succeeds in the energy sector requires decisiveness, flexibility, and intelligent investments in smart digital technology. This is the only way to manage current tasks while creating enough leeway to actively shape the future. Investments in innovative technologies today create future-proof power grids characterized by reliability, efficiency, and sustainability.
A driver of the digital transformation
Substations are an integral component of power grids. They connect grids of differing voltage levels, and their controlling and coordinating function is vitally important to the stability of the overall system. That’s why they’re considered the heart of the power grid. Their digitalization is a decisive step toward successfully shaping the transformation of energy systems.
Digital over the entire life cycle
It turns out that a digitalized substation can be operated much more cost-effectively over its life cycle – from planning and operation to service. A digitalized substation also increases the availability, reliability, and sustainability of the entire power supply. That’s how it provides added value that’s relevant for utility companies and grid operators.
The three most important benefits of a digital substation
?The most important benefits of a digital substation:
1- Investment savings,
2- Reduced lifecycle costs,
3- Predictive maintenance and operational control
It enables operators to significantly increase the availability, efficiency, and sustainability of their grid.
The six aspects are:
1- Digitalization of the substation level
Ensure the optimal deployment of operating resources?
Protection systems and substation automation ensure the optimal deployment of operating resources. They also protect people and investments.
? Offers reliable digital protection in the event of critical grid conditions and faults caused by environmental influences or faulty operating equipment?
? Provides the greatest possible security for personnel and investments
? Seamlessly connects the primary technology and grid control technology
? Communicates via Ethernet per IEC 61850 for optimally coordinated system performance with no lost time (PRP or HSR).
? Optimally deploys operating resources.
2- Digitalization of the process level
Save money and space while ensuring optimal data transmission?
There are tremendous benefits to using innovative technologies in primary equipment and digitally transmitting primary data on current and voltage.
? Requires no copper wiring for signals between primary technology and secondary technology
? Results in a high level of electromagnetic compatibility (EMC) thanks to fiber-optic communication?
? Delivers high cost savings and saves space thanks to low-power instrument transformer (LPIT) technology
? Increases personal safety because all measurement values are transmitted digitally
? Allows for easy engineering and testing thanks to digitally available signals
? Increases overall efficiency of the digital substation?
3- Cybersecurity
Ensure safe, secure, and efficient operation?
Cybersecurity protects industrial infrastructure and processes from malware and targeted attacks from the Internet.
? The security of digital substations can't be ensured without a comprehensive cybersecurity plan
? Provides the required protection of critical infrastructures
? You benefit from proactive compliance with the legal framework
? Prevents downtime, which increases system availability
? Prevents personal injury and damage to assets?
4- Asset management
Keep the value of investments as high as possible?
Asset management based on data collected digitally lowers a substation's life cycle costs and enhances its availability, safety, and security.
? Optimally utilizes the operating resources throughout the entire life cycle
? Reduces substation life cycle costs
? Increases availability of primary and secondary equipment
? Early warning system supports the planning of preventive maintenance measures
? Optimizes strategies for investment, operation, and maintenance (CAPEX/OPEX)
? Substation device management as an example of successful asset management.
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5- Grid operation
Ensure availability of electricity whenever and wherever it's needed?
Unstable conditions in sections of the grid or the entire grid can lead to a complete blackout.?
? Provides efficient condition monitoring for extensive power transmission grids
? Performs dynamic grid simulations to assess grid stability
? Validates protection settings
? Validates and guarantees grid quality
? Prevents downtime, increases availability?
6- Integrated engineering
Optimize the interplay of system planning, engineering, and parameter setting as well as testing and commissioning?
Digitalization simplifies demands in terms of system design and the parameterization of installed equipment and systems.
? Provides higher level of automation in project planning, testing, and commissioning
? Offers fast availability and exchangeability of data
? Improves quality assurance
? Gives asset management access to relevant data at all times
With decades-old protection and control systems replaced by the latest digital automation solutions that adhere to the IEC 61850 standard, Utilities?decentralized assets can now be remotely monitored and managed. This drives major efficiency improvements, reduces employee health and safety risks, and reduces the frequency that employees have to drive to remote stations. With cybersecurity among the technologies integrated into the package,?network reliability is prioritized as a key part of the transition to a digitalized future.
The Primary and the Secondary Technology
A substation consists of the primary technology (including switchgear, GIS, AIS and transformers), the secondary technology (including power system protection, automation and RTUs, voltage regulators, energy meters and communication equipment) and the related infrastructure. The various primary and secondary components interact to fulfil the main task of a substation, which is to ensure the availability of the supply with electrical energy under the given circumstances - available power (generation / distribution), environmental factors (weather), defects and faults in the supply system. Aside from the functional tasks, the safety of persons and the investment have top priority, followed by economic aspects.
How does a traditional substation become a digital substation or when can you call a substation ‘digital’?
This is where digitalization comes into play, which has triggered an innovation boost of products and systems in industrial areas like process automation that offers new opportunities for implementing efficient processes. The use of Ethernet-based communication and as a result the simplified connection of components is only one example.
A similar development can now be observed in the area of power supply, where digitalization creates new concepts and products which in the end help to increase the economic efficiency and profitability of power supply systems.
Implementing Process Bus Technology to Achieve Digital Substation
The process bus solution is implemented by introducing new equipment called Merging Units (MU) near the primary equipment in the switchyard. The merging unit reads the output values of the instrument transformers, converts to digital signals and sends to the secondary equipment (BCU, protection relays) via sampled values (SV) over Ethernet-based connection.
This approach reduces the reliance on external hardware such as hardwired connections between IED and instrument transformer. Process bus technology is developed in compliance with substation communication international standard IEC 61850-9-2, which ensures interoperability between primary and secondary equipment for easy and flexible system upgrade and extension.
IEC 61850
More than 15 years ago, IEC 61850 was introduced by the International Electrotechnical Commission (IEC). It is an international standard of a transmission protocol for the communication within electric substations for medium and high voltage and at the same time acts as a milestone for the digitalization of substations.
Apart from the exchange of information via Ethernet for protection, monitoring, control and measuring, the standard also defines the general description of substations. IEC 61850 is a uniform communication protocol ensuring interoperability of the products of different manufacturers. Worth mentioning: Peer-to-peer services are also possible with this standard.
So-called GOOSE messages (generic object oriented system events) communicate information about status and measured values to other participants via the station bus. This is an easy and most of all quick way of exchanging information without having to use additional signal cables.
In addition, IEC 61850 is today the only protocol for the communication in substations that is constantly evolved by different manufacturers in the standardization committees. In recent years, IEC 61850 has been expanded to include the communication between different substations, for example, the connection of control centers or decentralized generation plants as well as aspects from the area of power quality.
Digital Substation 1.0
One base element of a digital substation is therefore the implementation of IEC 61850. An internationally valid data exchange format and data model that ensures interoperability between the products and systems of different manufacturers. IEC 61850 fulfils all requirements for an up-to-date substation and is flexible enough to be ready for new requirements and functions in the future. The introduction of the standard IEC 61850 was the foundation stone for a Digital Substation 1.0.
Digital Substation 2.0
As mentioned above, the IEC 61850 standard is constantly developed. The introduction of new technologies - for example non-conventional transformers (NCIT) and process bus communication - is the next step in the evolution of substations.
Section IEC 61850-9-2, for example, defines the transmission of sample measured values (SMV) of the primary technology. Analog variables of the current and voltage transformers of the primary technology are converted to measured variables that can be processed digitally, close to the process and are communicated within a substation via process bus. This makes them available to the different applications - for example protection and automation - for further processing. The combination with high-performance and high-availability communication technology based on optical fiber technology and the use of redundancy technologies like PRP (Parallel Redundancy Protocol) and HSR (High Availability Seamless Redundancy) makes this a technology that enables even time-critical applications. It is therefore another important contribution to digitalizing a substation.
The process bus technology is not really new, and there have been developments in this area for many years, but the breakthrough has only happened now. The decisive factor for this is before all the existence of powerful processor and communication technology as well as standardization enabling different manufacturers to develop processes and products to guarantee interoperability. This ensures that customers invest in a technology that is supported by different vendors and that is continuously developed.
Benefits of a Digital Substation
Digitalization allows the power supply sector - like other industries - to use new technologies, methods and processes, particularly in substations, that increase the operational efficiency of the station. Compared to a conventional substation, a digital substation offers the following benefits:
1- Reduced investment and operating costs
■ Decrease in the use of copper signal cables
■ Easier and quicker commissioning including engineering and system testing
■ Saves space and weight, in particular for primary technology, by using state-of-the-art converter technology (NCIT)
■ Optimized grid control because important measurement data are available with state-of-the-art evaluation and analysis procedures
■ Improved asset management and maintenance due to up-to-date measurement data of the equipment.
■ Reduce CAPEX by eliminating duplicated hardware (CT, VT are no longer required)
2- Increased interoperability and future security
■ Implementation of IEC 61850 as internationally recognized data model and exchange format
■ Simpler adaptation and expandable with new technologies
3-Increased personal and property safety
■ Digitalization of process values and use of optical fibers for communication of process values for protection and substation control
■ Implementation of a cyber security policy. This ensures that the system is always state-of-the-art.
■ Improve workforce safety (miles of copper wires are replaced with fiber-optic cables)
4- Other benefits
■?Easier, faster and remote commissioning / testing
■ Improve system reliability through increased situational awareness and asset utilization
■?Compact and space saving to reduce substation footprint by up to 50% through a smaller control room.
■ Open architecture and inter-operability of the IEC 61850 protocols make future expansion or customization easier and less costly in terms of system design work.
■ Reduce engineering work through simplified system drawings
Summary
Digitalization enables unprecedented visibility of a customer’s assets and systems and the efficient harnessing of extensive volumes of data. Digitalization also enables the easy integration of IT (Information Technology) and OT (Operational Technology) systems enabling operators in control centers to interpret key insights in real time and as a result prevent critical failures. With increasing numbers of smart sensors in the field, the amount of process data being collected and analyzed within the substation is increasing correspondingly, allowing for protection and control, or for condition monitoring where the data is run against predictive models and machine learning in the cloud.
Main Aspects:
A digital substation isn't built in a day. The journey typically begins with the upgrade of a single analog relay to a multi-function digital device.