Grid Stability for Wind Energy

PCS Green Line 1000 provides improved grid integration for e.n.o energy


Berlin, August 2011 – Equipment made by PCS Power Converter Solutions in Berlin enables wind turbine type e.n.o. 82 by e.n.o. energy to meet the German SDL bonus requirements. So far, 26 MW worth of wind turbines have been fitted with the Green Line 1000 reactive power converter.

The accelerated expansion of renewable energy calls for more adaptive networks and system-supporting functions on the part of power plants. Indeed, new wind parks will have to meet these requirements. It is a job quickly and affordably realised using PCS Green Line 1000 type reactive power converters. These enable wind turbines to maintain their system support during voltage dips (FRT – fault ride through). In the field, the Green Line 1000 device has already proven itself in systems of various makes and with a total output of 130 MW.

The e.n.o. 82 plant system, fitted with the Green Line 1000, received its Type Certificate on the wind turbine level from Germanischer Lloyd. The simple integration into existing systems as well as an outstanding value-for-money ratio persuaded e.n.o. energy to opt for the deployments of Green Line 1000. Stefan Bockholt, Development Manager of e.n.o. energy, was thrilled after joint trial runs: “The technical performance data are demonstrably superior – it was a convincing presentation.” Reactive power characteristics can be individually configured, making it possible to preset the respectively applicable grid code. For the e.n.o. 82 wind turbine, the Green Line 1000 was placed parallel to the original converter. The variably adjustable pulse frequency in the PCS device helped to prevent unwanted resonances and beat frequencies. This means the wind turbine will produce and supply its energy reliably and in a grid-compliant way in the future.

The Upgrade Solution for Many Wind Turbines

Many countries are currently developing stricter grid fault tolerance standards. These so called grid codes ensure that legacy wind turbines are upgraded to continue to qualify for ongoing remuneration, or to be permitted to feed in their power at all. PCS therefore offers the Green Line 1000 as retrofit product up to a maximum amperage of 2500 A. It is also suitable for wind turbines with outputs of up to 2.5 MW. The reactive current can be provided for up to 6 seconds in continuous operation. A major share of the existing wind turbines is fitted with doubly-fed induction generators with or without partial load converter, and may be optimised with this power converter type. Wind turbines using synchronous generators, too, can be retrofitted if necessary.

Fully Satisfying all Standard Requirements

The generator of a wind turbine will normally feed the major share of the energy produced directly into the grid. Whenever the line-side voltage drops, the whole plant system needs to feed reactive current into the grid (low voltage ride through, LVRT). The Green Line 1000 splendidly copes with these requirements, and does so in compliance with the applicable feed-in directives. On the low-voltage side, it is parallel-connected to the power mains of the wind turbine. If the line voltage drops below 90 percent of the nominal voltage, the converter will start feeding reactive current into the grid. The reactive current will increase in linear proportion to the extent of the line voltage dip, and up to a predefined value. All standard LVRT requirements are fully met by the device: Balanced grid faults are mastered up to 15 percent of the line voltage, and unbalanced grid faults actually up to 0 percent of the line voltage. The device is also able to ride through several consecutive line voltage dips. The DCU control unit developed by PCS will autonomously detect and handle such incidents.

e.n.o. – Built on Quality for a Safe Future

The e.n.o. energy GmbH emerged from a project planning office set up in 1999, and is active as project developer, wind turbine manufacturer, and provider of turn-key wind parks. The company generates its turnover essentially in two areas: The first business area combines the development, project planning and realisation of wind parks in Europe, with Germany the main target market. The second area includes the production and sale of proprietary wind turbines. In addition, e.n.o. energy provides the maintenance, servicing and reinstatement of wind turbines as a service.