Vestas American Wind Technology Inc v. General Electric Co

1. Case Identification

• Case #: IPR2018-01029
• Patent #: 6,921,985
• Filed: May 4, 2018
• Petitioner(s): Vestas-American Wind Technology, Inc. and Vestas Wind Systems A/S
• Patent Owner(s): General Electric Co.
• Challenged Claims: 1, 3, 6-8, 12, 14, 29-30, 32-45, and 64

2. Patent Overview

• Title: Low Voltage Ride Through for Wind Turbine Generators
• Brief Description: The ’985 patent relates to a wind turbine generator with low voltage ride-through (LVRT) capability. The disclosed technology uses an uninterruptible power supply (UPS) to power critical components, such as the blade pitch control system, enabling the turbine to remain connected and operational on an electrical grid during a temporary drop in grid voltage.

3. Grounds for Unpatentability

Ground 1: Claims 1, 3, 6-8, 12, 14, 29-30, 32-45, and 64 are obvious over Cousineau in view of EON.

• Prior Art Relied Upon: Cousineau (Patent 6,265,785) and EON (a 2001 German grid code publication, "Supplemental Network Connection Rules for Wind Energy Systems").
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Cousineau taught a wind turbine with all the key elements of the challenged claims, including a blade pitch control system, a turbine controller, and a "secondary power source" (e.g., a battery or capacitor) to power the control system during a grid power outage. Cousineau's system was designed to control rotor overspeed by using aerodynamic braking (pitch control) when external power was lost, which is the core mechanism of the ’985 patent.
  • Motivation to Combine: Petitioner asserted that the EON grid code, which was published before the ’985 patent’s priority date, provided the explicit motivation for the combination. EON mandated that wind turbines remain connected to the grid during severe voltage drops (down to 15% of nominal voltage). A POSITA, faced with the market and regulatory requirements of EON, would have been motivated to adapt Cousineau's existing UPS-backed overspeed protection system not merely for safe shutdown, but to achieve LVRT and maintain grid connection as required.
  • Expectation of Success: A POSITA would have had a high expectation of success because the combination involved applying a known solution (Cousineau's UPS-backed pitch control) to address a known problem (rotor overspeed during a grid fault) to meet a well-defined market demand (EON's LVRT requirements). No new or unpredictable technology was required.

Ground 2: Claims 1, 3, 6-8, 12, 14, 29-30, 32-45, and 64 are obvious over Enercon, EON, and Rosch.

• Prior Art Relied Upon: Enercon (a 2000 project report describing the E-66 wind turbine), EON, and Rosch (a 1986 PC Magazine article).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner contended that Enercon disclosed a wind turbine with an active pitch control system powered by battery-backed "emergency units" upon detection of a grid failure. Rosch was cited to establish that using a UPS to power critical computer and electrical systems during power failures was well-known and conventional.
  • Motivation to Combine: Enercon's system was configured to use its battery backup to feather the blades and bring the rotor to a complete standstill, disconnecting from the grid. Petitioner argued that a POSITA, motivated by the EON grid code's mandate to remain connected, would modify Enercon's control logic. Instead of using the existing battery power to halt the turbine, a POSITA would use it to continue operating the active pitch control system to manage overspeed and ride through the fault. This modification represents a simple change in purpose for an existing, battery-backed system to meet a clear market need.
  • Expectation of Success: Modifying the control strategy of the Enercon turbine was a predictable design choice. A POSITA would expect that using the existing battery power to maintain operational control, rather than initiate a shutdown sequence, would successfully allow the turbine to meet the LVRT requirements specified by EON.

4. Key Claim Construction Positions

• Petitioner argued that several claim terms should be construed as means-plus-function limitations under pre-AIA 35 U.S.C. §112(6), which would limit their scope to the specific structures disclosed in the ’985 patent specification.
• "means for detecting a low voltage event": Petitioner proposed this term should be construed as a function of detecting the event, with the corresponding structure being a turbine controller that processes data from one or more system sensors (e.g., voltage sensors).
• "means for providing power from an uninterruptible power supply...": Petitioner proposed this term should be construed as a function of providing power from a UPS to components like the blade pitch controller, with the corresponding structure being electrical wiring, optionally including transformers.
• The proposed constructions were central to Petitioner's arguments, as they contended that these corresponding structures were explicitly taught or would have been obvious from the prior art references.

5. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1, 3, 6-8, 12, 14, 29-30, 32-45, and 64 of Patent 6,921,985 as unpatentable under 35 U.S.C. §103.