D-VAR® Systems

Dynamic VAR Support for a More Reliable Power Grid

AMSC's D-VAR product, which comprises an integrated array of AMSC's PowerModule power converters, offers a powerful yet cost-effective way of regulating and stabilizing voltage levels by injecting dynamic reactive power (VARs) into the power grid at precise locations where voltage problems can occur. D-VAR systems can be utilized in a wide range of applications including, voltage regulation and instability, var support for wind farm interconnection to the grid, and optimizing power transfer on stability limited transmission networks.

D-VAR (Dynamic VAR) reactive compensation systems provide a powerful and cost-effective source of dynamic VARs for a wide range of operational needs. They can correct voltage instability problems on transmission networks; provide dynamic steady-state voltage and power factor control and regulation on transmission and distribution networks; protect industrial facilities requiring premium power quality; and support a stable point of interconnection for distributed generation facilities and large-scale wind farms. Classified as Flexible AC Transmission System (FACTS) devices, D-VAR systems utilize an American Superconductor proprietary and advanced control and monitoring system that detects and instantaneously compensates for voltage disturbances by injecting leading or lagging reactive power, measured in VARs (volt amperes — reactive), precisely where it is needed on the grid. D-VAR systems are extremely flexible and scalable, ranging from 2 MVAR to hundreds of MVAR.

At the heart of each D-VAR system are American Superconductor's (AMSC) PowerModule™ advanced power electronic converters. PowerModule inverters are an intelligent, fully integrated four-quadrant power converter with high power density. The D-VAR is composed of rack-able IGBT power module poles capable of producing capacitive and inductive VARs. It is an air cooled, current source system that, unlike capacitor-based systems, is not subject to the square of voltage de-rating factor at lower voltages. This advantage reduces the overall level of MVARs needed for some applications. The inverters also have a short term overload capability of 2.67-3.0x of the continuous rating for up to 2 seconds, providing extra capacity for post-fault voltage recovery.

AMSC' s newest dynamic reactive power product is the D-VAR RT system designed to assist new and existing wind turbines in meeting even the most restrictive grid interconnection requirements. This patent-pending product brings a powerful solution to operators of existing wind turbines that are facing challenges due to the new regulatory requirements such as the Spanish grid interconnection requirement P.O.12.3.

The D-VAR RT in-turbine system is a powerful, cost-effective technology that dynamically stabilizes the wind turbines and also can act to regulate the voltage of the collection system connecting to the power transmission grid. Problems solved by the D-VAR RT system include voltage regulation, power factor correction and low- and high-voltage ride through.

Reactive Power STATCOM Solutions

AMSC's D-VAR system was designed with flexibility in mind to address the many voltage and VAR related problems seen on the transmission grid. More AMSC D-VAR systems have been installed throughout the world than any other inverter-based (STATCOM) reactive compensation device.

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