PTAB

IPR2017-01135

Gridco Inc v. VaRenTec Inc

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Systems And Methods For Edge Of Network Voltage Control Of A Power Grid
  • Brief Description: The ’867 patent describes systems for regulating voltage on a power distribution network using multiple, shunt-connected, switch-controlled Volt-Ampere Reactive (VAR) sources located "at the edge of the network." The core inventive concept asserted during prosecution was the use of different, predetermined time delays for each VAR source to prevent system instability, a condition known as "infighting" or "hunting."

3. Grounds for Unpatentability

Ground 1A: Claims 1-2, 8-10, 15-18, and 22 are obvious over D'Aquila in view of the Green Book

  • Prior Art Relied Upon: D'Aquila (Patent 5,402,057) and the Green Book (Electric Utility Engineering Reference Book, Vol. 3).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that D'Aquila, which describes a system for regulating voltage to a load by switching shunt reactances, teaches every element of independent claim 1 except for the specific delay mechanism. D'Aquila discloses a programmable logic controller that monitors voltage and connects or disconnects capacitors to maintain a constant load voltage. Petitioner contended that the Green Book, a foundational reference for power distribution engineers, explicitly teaches the missing elements: using definite, unequal time delays for multiple voltage regulators (including switched capacitors) to prevent "pumping" (an equivalent of the patent's "infighting").
    • Motivation to Combine: D'Aquila explicitly recognized the problem of "hunting" and taught the use of time delays as a solution, but did not detail the mechanism. A person of ordinary skill in the art (POSA), faced with implementing the time delays mentioned in D'Aquila to prevent hunting, would have been motivated to consult a standard industry reference like the Green Book. The Green Book directly addresses this coordination problem and provides the explicit solution of using predetermined, unequal delays.
    • Expectation of Success: Petitioner asserted a POSA would have a reasonable expectation of success because combining the well-understood delay strategies from the Green Book with D'Aquila's voltage regulation system involved applying known techniques to solve a known problem, yielding predictable results.

Ground 1B: Claim 3 is obvious over D'Aquila and the Green Book, further in view of IEEE SVC

  • Prior Art Relied Upon: D'Aquila (Patent 5,402,057), the Green Book, and IEEE SVC (a 1994 IEEE Transactions paper on Static Var Compensation models).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground specifically targets claim 3, which adds the limitation that the delays of at least two VAR sources are equal, while the delay of a third is not. Petitioner argued that while D'Aquila and the Green Book establish the baseline system with different delays, IEEE SVC teaches the rationale for using equal delays in certain situations. IEEE SVC describes the sequential insertion of multiple shunt banks with different delays to prevent hunting, but also contemplates the "simultaneous switching of two or more shunt banks" if a voltage disturbance exceeds a certain threshold.
    • Motivation to Combine: A POSA designing a robust voltage regulation system based on D'Aquila and the Green Book would seek to optimize its response to large voltage fluctuations. IEEE SVC provides the motivation to modify the unequal delay scheme by allowing for simultaneous (i.e., equal delay) switching of some capacitor banks to permit a response proportional to the magnitude of the disturbance, thereby achieving a larger, faster voltage correction when needed.

Ground 2A: Claims 1-2, 8-10, 15-18, and 22 are obvious over the Green Book in view of NoMAX

  • Prior Art Relied Upon: The Green Book and NoMAX (an instruction manual for 900 Series Switched Capacitor Controls, 2007).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted this combination shows the claimed invention is merely the implementation of old principles (from the Green Book) using modern technology (taught by NoMAX). The Green Book, published in 1965, taught all the functional elements of the claims, including placing switched capacitors near loads and using unequal time delays to prevent pumping, but implemented them with analog timing and control circuits. NoMAX is an instruction manual for a modern, processor-based controller for switched capacitors that performs the exact functions described in the Green Book, including programmable, predetermined time delays.
    • Motivation to Combine: A POSA would be motivated to update the older, circuit-based control systems described in the Green Book with a modern, processor-based controller to improve reliability, flexibility, and performance. NoMAX provides an off-the-shelf example of such a controller, making the combination a simple and obvious technological update. The problem of voltage drop and the solution of using coordinated, time-delayed switched capacitors were both well-known, and NoMAX provided a known, modern component to implement the known solution.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including combinations of D'Aquila and NoMAX (Ground 3A), and grounds adding IEEE SVC to the Green Book/NoMAX and D'Aquila/NoMAX combinations to address claim 3 (Grounds 2B and 3B). These grounds relied on similar design choice and technological update rationales.

4. Key Claim Construction Positions

  • "at an edge of the distribution power network": Petitioner argued this key phrase, which is central to all independent claims, should be construed broadly as "on that portion of the distribution power network that is close to the load that is to receive power, which portion may be on a medium voltage portion or a low voltage portion of a distribution feeder." This construction was argued to be supported by the specification's definition and the doctrine of claim differentiation (as dependent claim 8 specifically recites a "low voltage side"). This broader construction is critical to Petitioner's arguments, as it allows prior art that discloses VAR sources on medium-voltage primary feeders (not just low-voltage secondary feeders) to be applied against the claims.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-3, 8-10, 15-18, and 22 of Patent 9,014,867 as unpatentable.