Wobben v Vestas-Celtic Wind Technology Ltd

A patent claim is invalid for added matter where the amended subject matter is not clearly and unambiguously disclosed in the application as filed. The comparison is made through the eyes of the skilled addressee, using common general knowledge but without hindsight.

For insufficiency, the specification must enable the invention across the whole scope of the claims without undue burden. Routine trials are permissible, but inventive development work is not.

An earlier disclosure does not destroy novelty or establish obviousness unless it is enabling. A conceptual advance may nevertheless be obvious where implementation would require innovation and the specification gives no practical guidance.

The claimant brought an action for infringement of three United Kingdom designations of European patents concerning the control of wind turbines connected to electrical networks. The defendant challenged validity on grounds including added matter, lack of novelty, obviousness and insufficiency, and opposed proposed amendments.

The 564 patent concerned continued operation or connection without power emission outside predetermined voltage values. The 691 patent concerned reducing emitted power as voltage fell, including de-rating. The 078 patent concerned reactive-power control by varying phase angle, including control of network switching equipment and separate control for network sub-areas.

The central issues were the construction of the claims, whether the claimed subject matter was disclosed and enabled, whether the claims were obvious, and whether the defendant’s turbines infringed.

1. 564 patent. The expressions “operated” and “connected” conveyed the same essential concept: the wind energy system remained electrically connected and in operation while emitting no real power. “Without any power” meant no power in its ordinary sense, subject only to a practically de minimis amount. The relevant voltage values had to be predetermined and ascertainable.
2. The application as filed did not clearly and unambiguously disclose a system remaining connected and operating without emitting power during severe voltage depression or low-voltage ride-through. The claims therefore added matter and the patent was invalid on that ground.
3. The conceptual idea of low-voltage ride-through was obvious in light of common general knowledge and the publications Improvement of the Grid Compatibility of Wind Energy Converters and Benchmark. But the earlier disclosures were not enabling. Following Synthon v SmithKlineBeecham [2005] UKHL 59, a non-enabling near miss could not itself establish obviousness.
4. The specification was insufficient because implementing low-voltage ride-through was technically difficult, non-routine and required innovation, while the patent gave no practical guidance. The infringement claim failed because the Vestas turbines had no ascertainable predetermined voltage below which no power was emitted.
5. 691 patent. The proposed claims concerned, among other matters, sub-optimal de-rating. The relevant subject matter was not clearly and unambiguously disclosed in the application and was therefore added matter. Claims 1, 6 and 7 were also obvious over common general knowledge and the cited publications. Claim 5 was insufficient because it incorporated the low-voltage ride-through concept. Infringement was not established.
6. 078 patent. Proposed claim 1, combining reactive-power control with control of a tap-change transformer, was not obvious. Proposed claim 2 was obvious as construed, because it required separate control for different network sub-areas but did not require dividing one wind farm into separately controlled parts. The insufficiency objection failed and infringement was not pursued.
7. The allegations of lack of novelty failed in relation to the disputed claims. The court directed that the form of order be addressed if not agreed.