The evolution of our existing power-grid system into a Smart Grid system could be described as an ‘energy revolution’. This transformation will undoubtedly provide many opportunities on both the supply and demand side, but also throws up significant challenges, not least how to ensure Smart Grid compatibility and interoperability.
P. Pfisterer & C. Dirmeier, TÜV SÜD AG, Germany
Smart Grids are designed to balance out electricity production and consumption, paving the way for us to attain an intelligent power supply. Experts across the globe are seeking solutions to meet the challenges of advanced networked systems. While Smart Grids offer new and more flexible ways of controlling electricity flows, they also present security and availability risks. Thus, new communication standards are seen as an essential part of this future energy supply concept.
Most industrialised nations are currently launching public funding initiatives to transform their existing power-network architecture into Smart Grids. Industry too is becoming increasingly interested in the subject. The US has initiated over 100 Smart Grid projects. In late 2010, the US Department of Energy counted around 17 million homes ready for Smart Grid connection across the country, with experts estimating this number to rise to 52 million by late 2014.
In addition to expanding and transforming the grids on the European and Northern American market, Smart Grid specialists are also busy establishing such network architecture in the Asia-Pacific region — particularly in China and South Korea.
The reasons for speeding up what many describe as an ‘energy revolution’ are manifold. Key drivers include the soaring demand for energy, the challenge of integrating renewable energy sources into the electricity grids, and the increasingly rigorous legal requirements to cut energy consumption and curb carbon emissions.
When companies with recurring load peaks (consumers) pass on information about their energy consumption to the energy producer, the producer is able to prepare for times of peak loads (better planning). This in turn results in cost savings for the energy producer that can be transferred to the consumer.
Smart Grids can be best described as the ‘brains’ of our future energy supply. They are able to automatically identify and ‘ride through’ faults. The actual intelligence in the grids comes from the use of modern information and communication technologies — particularly in distribution networks.
What is interesting is that the majority of the technologies required for these systems are already available. These systems have been used in the automation of industrial control systems for decades. The challenge now lies in implementing Smart Grid-enabled communication systems and end-to-end networking of the control systems up to the grid control centre via ethernet.
Smart meters, which are an integral part of the Smart Grid concept and are available on the market, enable intelligent communication between consumers, such as buildings and the power grid. In this context, a growing number of connected buildings are turned into ‘prosumers’. Equipped with photovoltaic systems and cogeneration units, for example, these buildings not only consume power, but also feed electricity into the grid.
This dual function offers huge potential for controlling supply and balancing out in the Smart Grid, contributing significantly to grid stability. In addition, smart meters can record all key consumption data, making them effective control instruments for efficient energy management.
Requirement for new communication standard
The integration of energy from renewable sources requires far-reaching changes in our existing grid architecture. To meet the new challenges, modern and more flexible infrastructure will be required at all levels of the grid. In the future, a large number of small, distributed generation systems, complementing large-scale centralised power stations, are envisaged as contributing to the power supply.
However, these small decentralised systems also significantly increase the chances of volatility in the supply. This must be compensated for by ensuring additional storage capacities and fast, intelligent and flexible interaction with conventional power producers to guarantee the security of supply.
In view of the enormous changes, keeping an eye on the core issues — interoperability, safety, security and usability — is essential. The greatest challenge in this context lies in the fact that interfaces, protocols and communication between grids must reliably meet the same requirements, and therefore must be standardised.
The standard IEC 61850 governs the exchange of information and is planned to become the backbone of the Smart Grid. It defines the principles of the transfer of data between electricity producers, distributors and consumers. The standardised data models and nodes provide for easy establishment of a well-functioning overall system. This system permits comprehensive data communication between the connected components, as well as highly automated utility-grid management.
Further advantages of a system based on the IEC 61850 standard include its modular structure and configuration via XML files. These systems also offer interfaces with the standardised IEC 60870-5-101 or 60870-5-104 telecontrol protocols, which are to be gradually replaced by the IEC 61850.
Implementation of the new standards facilitates integration of both existing systems and new components into the grid, and supports the development of clear-cut provisions for industry and manufacturers.
However, implementation in practice of this standard has not yet fully caught on. In a best-case scenario, the high-voltage grids are in compliance with the international standard. As far as medium and low-voltage grids are concerned, however, Germany is just one of the countries that still has some catching up to do, as its grids have not yet been adequately equipped with automation devices.
Thus, grid operators are facing the challenge of having to transform their entire infrastructure into a Smart Grid, while equipment manufacturers must develop and supply devices that reliably fulfil the requirements of the IEC 61850 standard and are capable of communicating securely with each other. Pilot projects are proving that further efforts must be made in the field of interoperability.
Effective information management
Today, certificates of conformity in accordance with the relevant standards are almost a ‘must’ to establish devices on the Smart Grid market. However, certificates of conformity alone do not guarantee that devices made by different manufacturers will actually harmonise in practice. Only additional and impartial tests — i.e. realistic conformity, performance and interoperability tests — can prove the extent to which technical components, such as sensors, actuators, signal generators, security devices or smart meters are suitable for use in practice.
Testing should also be based on Edition 1 and Edition 2 of the IEC 61850 standard (the latter to be available in full shortly) to offer electricity producers and consumers, as well as grid operators, guidance when it comes to selecting and integrating individual devices. This applies specifically to smart meters — the elements linking private consumers and energy suppliers. Most of the meters implemented so far do not yet offer an adequate level of security. Available protection profiles must be expanded and improved in terms of encryption, anonymisation and pseudonymisation of the collected data.
Given this, the provision, quality and security of the required information are essential to the success of the Smart Grid from a broader perspective than that of consumers. Grid owners and operators will also be requesting information from all energy producers connected to their grid. This may prove a complex task for smaller energy producers who lack specialist know-how. They must consider the technical requirements they have to fulfil right from the outset when planning a new power plant. The owners and operators of existing plants should also ensure they are informed in a timely manner about the upgrades that are required for integration into the Smart Grid and how to realise such upgrades in the most cost-effective manner.
Uniform standards minimise hazard potential
Transformation of our electricity supply architecture into a decentralised energy supply not only offers opportunities, but also involves other risk factors. In addition to known threats to the security of supply, which include extreme weather conditions, power station failure and overload, Smart Grids must also be able to cope with highly volatile electricity feed-in and production, lack of grid expansion and an inadequate interoperability of the relevant systems.
Malicious attacks by hackers and spyware, too, must not be underestimated. Targeted interference may put major parts of the network architecture or sensitive information at risk. Given this, grids must be given the best possible protection in terms of operational and data security.
The use of ethernet-based systems, on which the IEC 61850 standard is based, may keep potential hazards to a minimum. Apart from guaranteeing performance and availability, these systems enable the secure transmission of data even in the case of high requirements. They prevent the use of unsafe protocols and interfaces, and can contribute to minimising manipulation by unauthorised third parties or incorrect operation.
Important in this case is to ensure that no information will be lost during transfer, even in the case of the failure of individual system components or a change of transmission paths. Application of the IEC 61850 standard thus meets the highest requirements for availability and data security, also in the case of complex communication structures.
Grid integration of renewable sources
Within the scope of Smart Grid implementation, we must pay special attention to the integration of energy from renewable sources, which are planned to supply ever more of our electricity in the future. For integration to be successful we must ensure the grid compatibility of these renewable sources. However, as some of these sources depend on the sun and the wind, they only deliver electricity intermittently. Given this, new units and plants must be designed in such a manner that they can contribute actively to voltage and frequency stability in the electricity grid.
For energy generators to take over this function, the basic requirements including continuous current-carrying capacity, active and reactive power, and short-circuit rating must be guaranteed. Operation in case of grid failure and fault ride-through performance must also be ensured. Generally, grid compatibility must be proved by means of certification before the unit or system is connected to the grid and placed into service. In this context, we must assume that the applicable rules, regulations and standards differ from country to country, and thus depend on the site of the plant or unit.
Grid compatibility plays an increasingly important role in particular when focusing on the aspect of security of supply. In view of the dynamic expansion of renewables, these sources of energy will have to provide the same system support services as conventional power-generation units in the future. TÜV SÜD’s experts can assist plant operators in identifying possible risks and detail issues of grid compatibility right from the planning stage. This covers a summary of certification procedures and all relevant technical guidelines and standards.
Certification or consulting by a third-party company such as TÜV SÜD provides certainty of compliance with all technical and legal requirements. For this purpose, TÜV SÜD established its Competence Center Smart Grids, which offers strategic consulting services throughout the world. The experienced experts support companies from planning to implementation.
TÜV SÜD’s service portfolio also includes consulting on the new development of equipment, optimisation of Smart Grids, training options for generators and consumers, and comprehensive consulting on the integration of systems and components. In its internal Smart Grid testing laboratory, TÜV SÜD further carries out extensive testing services on the conformity with IEC 61850, and other comprehensive performance and interoperability tests.
Peter Pfisterer is head of the Smart Grid Laboratory at TÜV SÜD and Christian Dirmeier, is product manager Smart Grid at TÜV SÜD. For more information, visit https://tuev-sued.de/smartgrid
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