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System security and how to achieve it

WORLDWIDE: With a growing level of renewable energy likely to be flowing across the European networks, transmission system operators are facing new difficulties in planning and operating the grid in years to come.

Incident analyses will play a major role in learning how to operate and configure the system
Incident analyses will play a major role in learning how to operate and configure the system

There is a general move away from the centralised electricity generation of previous decades because of the geographical spread of renewable sources such as wind, the inclusion of decentralised storage units, and flexible and active loads connecting at low and medium voltage.

On the one hand, the security of the power supply could be threatened by variable energy sources such as wind with the potential for unexpected weather conditions to affect the power supply. But attending to these situations could, conversely, shore up grid development by providing flexibility through solutions such as smart grids - which react to information on supply and demand - and by demand-side management - where power users are encouraged through financial incentives or education to limit use at times of peak demand or low supply.

Balancing the grid system across Europe will be complicated, as confirmed by the European Climate Foundation Roadmap 2050, an independent body offering analysis of how to achieve a low-carbon economy in Europe, which identifies a massive need for back-up generation - especially if grid expansion is slower than renewables uptake. Today, the reserve power capacity is provided primarily by fossil-fuel plants, but these resources are dwindling. This scarcity is likely to substantially increase its cost in the coming years.

Storage technologies

Smart grids and demand-side management are not likely to be sufficient to deal with the balancing challenge for very high levels of renewable energy on the grid. Storage systems will be needed to provide additional flexibility and avoid the need to curtail wind energy. This requires not only the development of new storage technologies, but also a new market approach to integrating them into the system. One possibility to ensure sufficient balancing resources is that transmission operators could participate in the ownership and operation of such storage systems.

Already, tools such as phase-shifting transformers and high-voltage direct-current links, provide flexible solutions, and it is likely that more of these will be developed to provide the flexibility required by this more complex grid system. Supplementing them with monitoring tools such as dynamic line rating, which allows continuous real-time monitoring of an overhead line, will have a huge impact on the way the system is operated and planned.

Slow upgrade

It will not be possible or practical to replace all the ageing equipment and infrastructure at the same time. New designs will need to be incorporated, and transmission system operators will have to use both old and new devices concurrently, pushing each to their limits to complement grid upgrades. Replacement and maintenance programmes will present new challenges.

With a much greater need for real-time monitoring of equipment, data and information needs will increase exponentially. Incident analyses will play a major role in learning how to operate and configure the system. To deliver accurate and up-to-date pictures of system behaviour, data exchange will be necessary on a much larger scale, especially for developing and using new software to support the decision-making processes in real time. Developing complex data platforms and new monitoring functionalities, as well as providing advanced training and simulation of operational processes, will be one way of achieving this.

Strength in partners

A hard task is identifying what knowledge will be key in the future. Developing and capturing this new knowledge in advance will require stronger partnerships with manufacturers, computer software firms, universities and research centres. Grid operators have a systemic mission to incorporate renewable energy on to the grid. This requires integrating technology, finance, markets, ecology, generation and consumption, and to strike a perfect balance between these aspects in doing so. Partnerships will play a key role in bringing together all the requisite knowledge.

Across Europe, transmission service operators are collaborating on a number of research programmes, looking at future infrastructure, the grid and balance management. Studies are already investigating technologies from high-performance conductors to superconductivity, real-time monitoring systems, and asset-management approaches for integrating new with existing equipment. In addition, strategies are being investigated to meet the changing needs of the balancing market.

No transmission service operator will be able to face these challenges alone: interdependency will grow, with coordination and greater observation essential.

STRATEGIES TO MANAGE THE GRID

  • Develop cross-border balancing markets to operate in a larger control area
  • Introduce more flexibility through demand-side management, smart grids and by combining small power producers
  • Facilitate greater storage integration on the market
  • Improve balancing services by dynamic reserve management through more frequent assessment of needs

Hubert Lemmens is chief innovations officer at Elia Group, a transmission system operator in Belgium and Germany.


CONNECTING OFFSHORE HOW THE LEGAL SYSTEM IS AFFECTING GERMAN OFFSHORE CONNECTIONS  

By Heiko Alexander Haller

The absence of a clear regulatory framework for connecting large offshore wind farms to the grid is slowing development as investors fear the associated risk. There are currently no clear design requirements for wind farms and practical experience in this field of technology is very limited.

In Germany, a major player for offshore wind projects, the nearest transmission operator is required by law to connect a new offshore wind farm - including providing cables and electric power transformation substations. The operator receives payment only via the later use of its power grid.

Usually the generated power is transferred onshore via a high-voltage direct-current submarine cable link, but companies are working on more efficient transmission techniques.

In every step of the design and construction, the industry faces manifold technical problems, not dissimilar to the issues of wind turbine manufacturers. The offshore transformer station must be designed to absorb high wind speeds and huge wave loads, be low in weight or floatable for transportation, and the sub-structure sealed from salt, air and water corrosion. Power output must remain high enough to justify the high capital costs.

Connecting offshore wind to the grid is a complex undertaking for which no technical standards yet exist. Work offshore can only be undertaken during short periods of fine weather and delays are not uncommon, which lead the wind farm operator to seek damages from the transmission operator. These financial burdens are increasing as more offshore wind farms request connection to the grid.

While logistics have significantly improved in the industry in the last year, there is no established supply chain. Late delivery of components can affect the construction and fulfilment of the whole project, and again the transmission operator is financially penalised for the delay.

Regulatory improvements

German government round tables have been set up with concerned companies to modify and adapt the current legal framework to the needs of the industry, to overcome existing obstacles and encourage investment.

Proposals include a mandatory offshore grid development plan, co-ordination of the expansion of the grid offshore and onshore, flexibility over short deadlines or unreasonable operational or financial issues. The government will also consider adapting the liability regime to practical needs.

Under the proposed laws, the risks of the transmission network operator will be limited, and the legal framework and liability will be clarified and predictable. Only with such a practical and clear legal framework will the quick and smooth development of power generation with renewable energy sources succeed.

Dr Heiko Alexander Haller is a partner at Baker & McKenzie, legal specialists in infrastructure project disputes.

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