- Joint project aims to stabilize medium-voltage power distribution (20 kV [kilovolts])
- New method for regulating wide voltage variations resulting from renewable energy sources connected to the grid
- Intended primarily for rural regions
Brilon/Essen/Mannheim, November 19, 2014 - RWE and ABB today unveiled a prototype of a new line voltage regulator for decentralized regulation of voltage fluctuations at the medium-voltage level. The event was held in Brilon, Sauerland, Germany. This type of regulator may be needed when the voltage in the distribution grid fluctuates strongly due to intermittent generation. The quality of the supply voltage and its maximum allowable tolerances are defined in an European standard. When the supply voltage varies beyond these limits, there is a risk that electrical equipment will no longer operate properly and that it may be damaged.
Some power networks have started approaching the limits of their design values due to decentralized and strongly fluctuating power being fed in from renewable sources, especially solar and wind. Often the limiting factor is not the amount of power to be transmitted: The challenge is rather to maintain the voltage within the specified tolerance band. This is especially true in rural areas, where 80% of renewable power is generated. Many wind turbines are situated on hillsides, while large numbers of solar panels located in open fields or on barn roofs are already today generating large amounts of power that is fed into the grid. The typical design rating for supplying electricity, which takes into consideration that not all users will demand peak power of 30 kW simultaneously, is 2 to 4 kW (kilowatts) per connection. However, the power fed in simultaneously from solar and wind turbines is usually several multiples of this.
The conventional approach to dealing with any voltage problems that arise is to upgrade the network; for example, by installing larger cables. However, such solutions are no longer always the most cost effective. Another alternative is to use adjustable power transformers in local grids. But this normally entails replacing several existing power transformers in the local grid. Line voltage regulators (LVRs) can be used to avoid this expense. These regulators can be installed at the medium-voltage transmission level to maintain the voltage within a specified tolerance band. An existing grid retrofitted with a line voltage regulator can have more renewable power generating systems connected to it following the upgrade.
This type of line voltage regulator for medium-voltage transmission lines has to date not been used in Germany or Europe. RWE and ABB are both participating in the federal smart grid project "Networks of the future/Smart country". The first line voltage regulator was developed and tested in conjunction with this initiative. The two companies worked together steadily and have now taken advantage of the operating experience and knowledge acquired to develop a completely new regulator at ABB's Brilon factory. The prototype medium-voltage regulator is very efficient, as demonstrated by low losses and a compact footprint, among other things. It can already be applied cost-effectively in today's power grids. ABB is manufacturing cast resin dry-type transformers for voltages up to 72.5 kV in Brilon for over four decades.
The development project focused on achieving high energy efficiency and safe and easy integration into existing distribution grids. The solution presented by the companies is completely integrated into a standard concrete substation. If the regulator is no longer required at a particular location, the concrete substation can simply be moved to and installed at a new site. It has an efficiency of over 99.75 percent at every regulation setting. The pilot installation can regulate up to 8 MVA of transmitted power within a voltage tolerance of +/-10 percent.
Representatives from RWE and its sister utility Westnetz were impressed by the features and reliability of the new line voltage regulator when they witnessed the acceptance tests at ABB's factory in Brilon. "This innovative piece of equipment from ABB is an important module that enables us to meet the needs of the "Energiewende". We are especially pleased that this technology is being developed and manufactured in Sauerland, Germany, where up our core network is situated," says Dr. Joachim Schneider, chief technical officer of RWE Deutschland. Dr. Martin Schumacher, responsible for power systems at ABB in Germany, added: "The development of this line voltage regulator once again demonstrates our engineering expertise in Germany and at the Brilon facility in particular. This new product is another ABB contribution toward successfully implementing the "Energiewende" in Germany."
The voltage regulator will be installed in RWE/Westnetz's distribution grid in the coming weeks, and after the startup and a brief test phase, will be operated fully automatically. Alternatively, it can also be controlled by RWE's network management system.
The first prototype of a low-voltage regulator from Brilon, designed for low-voltage network applications, has been operating successfully every day since early summer in Switzerland. This regulator has been smoothing out the typical voltage fluctuations generated by a very large solar power station that was installed in the countryside. Here too, the low-voltage line voltage regulator is tied into the utility's process control system and can thus be accessed remotely if it becomes necessary to override its normal automatic operation.
In 2013, ABB in Germany generated sales of 3.37 billion euro and employed about 10,000 persons. ABB is a leader in power and automation technologies that enable utility, industry, transportation and infrastructure customers to improve performance while lowering environmental impact. ABB Group operates in around 100 countries and employs about 145,000 people worldwide.
