`
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`UNITED STATES PATENT AND TRADEMARK OFFICE
`
`____________________________________________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`
`____________________________________________
`
`VESTAS-AMERICAN WIND TECHNOLOGY, INC. AND
`VESTAS WIND SYSTEMS A/S,
`Petitioner,
`
`v.
`
`GENERAL ELECTRIC CO.,
`Patent Owner.
`____________________________________________
`
`Case IPR2018-01015
`U.S. Patent 7,629,705
`____________________________________________
`
`DECLARATION OF DR. WILLIAM MACK GRADY
`
`
`GE 2012
`Vestas v. GE
`IPR2018-01015
`
`
`
`IPR2018-01015
`Declaration of Dr. William Mack Grady
`I, William Mack Grady, declare as follows:
`Introduction
`1. My name is William Mack Grady. I have been retained by counsel
`
`I.
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`for General Electric Co. (“GE” or “Patent Owner”) to serve as a technical expert in
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`this inter partes review proceeding of U.S. Patent No. 7,629,705 (“the ’705
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`patent”). I have been asked to provide this declaration to explain the teachings of
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`the ’705 patent and the references that make up the instituted grounds in this
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`proceeding, as well as to respond to characterizations made in both the petition and
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`the Declaration of Professor Blaabjerg (Ex. 1003). I have previously prepared
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`declarations for submission in the previous inter partes reexamination of the ’705
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`patent, Control No. 95/000,633, as well as in the concluded ex parte reexamination
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`of the ’705 patent, Control No. 90/012,587. I have also provided expert consulting
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`services, including submitting expert reports and offering expert testimony in
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`depositions and at trial, on behalf of GE in a litigation involving the ’705 patent:
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`General Elec. Co. v. Mitsubishi Heavy Indus., Ltd., No. 3:10-cv-00276-F (N.D.
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`Tex).
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`2.
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`I have reviewed and am familiar with the ’705 patent, filed on
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`October 20, 2006, and its prosecution history. I understand that claims 1-9 of the
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`’705 patent are subject to this proceeding before the PTAB and have reviewed the
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`original petition and the Board’s Decision on Institution (“DI”). I have also
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`reviewed the various exhibits, including the Declaration of Professor Blaabjerg,
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`that were filed in support of the petition. In this declaration, I will describe: the
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`teachings of each reference asserted in the petition; how those references would be
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`understood by a person having ordinary skill in the relevant art; and what each
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`reference does and does not disclose with respect to the challenged claims of the
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`’705 patent. I understand that my technical analysis and opinions will be used to
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`support legal conclusions presented in GE’s Patent Owner’s Response.
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`II. Qualifications
`I graduated with a B.S. in Electrical Engineering from the University
`3.
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`of Texas, Arlington in 1971, and then went on to receive an M.S. in Electrical
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`Engineering from Purdue University in 1973. From 1974 to 1980, I worked as a
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`System Planning Engineer for Texas Power & Light Company (now Oncor) in
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`Dallas. My responsibilities included transmission system planning in one of the
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`four geographical divisions of Texas Power & Light. During that time I also served
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`as chairman of the Dallas Chapter of the IEEE Power Engineering Society and as a
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`member of the Edison Electric Institute Computer Committee.
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`4.
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`I returned to Purdue and graduated with a Ph.D. in Electrical
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`Engineering in 1983. I joined the faculty at the Department of Electrical and
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`Computer Engineering, University of Texas, Austin in 1983, where I attained the
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`title (now Emeritus) of Professor and Jack S. Josey Centennial Professor in Energy
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`Resources. On September 1, 2012, I joined the faculty at the Electrical and
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`Computer Engineering Department at Baylor University. My current title is
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`Professor of Electrical and Computer Engineering.
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`5. My areas of specialization are electric power systems, power quality
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`and harmonics, renewable energy integration, power electronics, and
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`synchrophasor applications in power grids. My present research funding comes
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`from the Electric Reliability Council of Texas (“ERCOT”), Schweitzer
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`Engineering Labs, and the U.S. Department of Defense’s Defense Threat
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`Reduction Agency (“DTRA”). I have held a security clearance through DTRA
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`since 2008 to study the impact of nuclear weapons, specifically MHD-E3 (slow)
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`and MHD-E1 (fast) events, on power systems.
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`6.
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`I am also a Department of Energy contractor for Idaho National
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`Laboratory. In 2012 and 2013, I participated in a series of grid tests on the topic of
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`HEMP at the Idaho National Laboratory. Now, through my project work at
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`Baylor, I use the data collected in Idaho to determine how best to protect the grid
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`from MHD-E3 and MHD-E1 attacks. I am also a regular technical advisor to the
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`FBI on critical power system infrastructure issues.
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`7.
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`Presently, I am working on an ERCOT project using ERCOT’s
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`synchrophasor data to determine stability limits associated with the large wind
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`turbine generation percentage in Texas. On some days, ERCOT’s power
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`generation reaches 40% or more for hours. Occasionally, it exceeds 50%, but is
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`curtailed beyond that due to stability concerns. Details of my DTRA and ERCOT
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`work are attached in Appendix B to this declaration.
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`8.
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`I currently teach courses in power systems, power electronics, and
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`renewable energy at Baylor University. In 2000, I was elected an IEEE fellow for
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`“contributions in the analyses and control of power system harmonics and power
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`quality.” I have twice won the annual Texas Execs Award for Outstanding
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`Teacher in the College of Engineering. Other honors and awards that I have
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`received are listed in Appendix A to this declaration. I have been a Registered
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`Professional Engineer in Texas (#48629) since 1981.
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`9. While my entire career has dealt with electric power systems, wind
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`and solar integration in power grids, as well as defending against nuclear MHD-E3
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`and MHD-E1 attack, has been the main focus of my research for the past ten years.
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`In particular, the emphasis has been on the use of synchrophasors as “health
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`monitors” of grid stability so that more of the existing wind generator fleet in the
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`Electric Reliability Council of Texas (ERCOT) can be utilized. My paper with
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`David Costello of Schweitzer Engineering, “Implementation and Application of an
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`Independent Texas Synchrophasor Network”, describes the Texas Synchrophasor
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`Network at U.T. Austin that I developed with EPRI and Schweitzer for the purpose
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`of wind integration in ERCOT. A 200+ page summary report of our findings—
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`consisting of weekly, monthly, and event reports—is on my Baylor web page, and
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`I made presentations on this subject in the last ten years at conferences sponsored
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`or regularly attended by NERC, FERC, NASPI, UWIG, numerous IEEE
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`conferences, invited presentations and training sessions at Sandia National
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`Laboratories and other institutions, and smaller audiences. One of the key
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`contributions thus far is to illustrate with actual data that wind generation does not
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`reduce ERCOT’s grid inertia as commonly believed. For the past ten years, I have
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`continued to produce synchrophasor reports which now also include the Eastern
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`and Western grids. I routinely collaborate with engineers at ERCOT and American
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`Electric Power, where I visit wind farms to understand wind turbine operation,
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`real-world issues, modeling, and simulation. My contributions include
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`determining and identifying when wind curtailment is necessary based on my
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`experience in power grids and wind generation, as well as my synchrophasor
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`measurements and data interpretations procedures.
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`10.
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`In 2010, I testified in court on behalf of the Texas Attorney General’s
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`Office in a case involving El Paso Electric. My testimony provided the judge with
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`a description of how grids operate and to explain the role of power distribution
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`equipment (e.g., distribution feeders, service drops, protection) and how it differs
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`from transmission-level equipment.
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`11. A copy of my curriculum vitae is also attached as part of Appendix A,
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`providing a more complete list of my experience.
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`III. The Practical Effects of Zero-Voltage Events on Both The Grid and
`Real Wind Turbine Equipment
`12. Zero-voltage faults on the grid are caused by a three-phase short-
`
`circuit. Ex. 2013, 145 (“… switches, circuit breakers, and fuses [] protect key
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`components and [] allow different segments of the system to be isolated for …
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`during emergency faults (short circuits) that may occur in the system.”) As has
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`been the understanding of a POSITA for decades, a short-circuit across all three
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`phases (or lines) of the grid, while the least common type of fault, “is the most
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`severe fault.” Ex. 2014, 246; Ex. 2015, 14 (Acknowledging that “[t]he smallest
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`number of faults, roughly 5%, involve all three phases and are called three-phase
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`faults.”); Ex. 2016, 496-497 (further characterizing three-phase faults). The
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`Declaration of Dr. William Mack Grady
`severity of three-phase short-circuit faults is precisely why EON and FERC set out
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`requirements based on them: they are the worst-case scenario.
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`
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`Ex. 2014 showing three-line (i.e., phase) short-circuits in Figures 7.l(d) and (e).
`
`13. Operators of electric power grids have long recognized the importance
`
`of generating units riding through short-circuit faults to minimize blackouts. As
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`explained by Professor Luther (see e.g., Ex. 1031), operators routinely evaluate
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`grid security for a variety of such faults, with a three-phase short circuit fault
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`reducing the grid voltage to a magnitude of zero volts being the worst case. This is
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`the condition contemplated by EON.
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`
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`EON, Figure 5a illustrating line-to-line voltage magnitude during and subsequent
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`to a “Near-to-generator three-phase short-circuit” (Ex. 1007, 18)
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`14. Power system engineers have also long recognized that during the
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`period immediately following when the fault clears, the grid will be in a disturbed
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`state. One aspect of this post-fault condition is an abnormal grid voltage, either
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`lower than normal (as shown in EON’s Figure 5a) or higher than normal due to
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`electrical transients that linger on long AC transmission lines. But another aspect
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`of the post-fault scenario is that both generator speeds and voltage phase angles
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`will swing from their pre-fault values—often dramatically. Ex. 2017, 331
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`(“During a fault … the synchronous machines of the system undergo changes in
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`the relative positions of their rotors. With constant internal generated voltages, the
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`phase angles between these voltages will vary until a new condition of equilibrium
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`is established; or, if the disturbance is sufficiently severe, loss of synchronism will
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`result.”) If a generator is close to the faulted point, its voltage drops during the
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`fault, power flow out of the generator drops, and the rotor speeds up due to power
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`imbalance. The worst case is when the voltage output is zero, because all
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`mechanical output power goes towards increasing inertia via speed. This condition
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`is referred to as asynchronous voltage and EON expressly warns that this condition
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`can exist once the fault is cleared.
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`Ex. 1007, 17.
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`
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`15. The conventional response of older turbines to such voltage
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`fluctuations on the grid was to trip offline (i.e., disconnecting the machine from the
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`grid) until the asynchronous fault cleared, allowing the turbine to reconnect to a
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`measurable and stable grid voltage. Ex. 2018, 245 (“Somewhere in the circuit
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`between the generator and the electrical grid are circuit breakers or fuses. These
`
`are intended to open the circuit if the current gets too high, presumably as a result
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`of a fault or short circuit. Circuit breakers can be reset after the fault is
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`corrected.”); Ex. 2015, 13-14 (“The opening of circuit breakers to isolate the
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`faulted portion of the line from the rest of the system interrupts the flow of current
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`in the ionized path and allows deionization to take place.”); Ex. 2013, 145.
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`16. This was an acceptable response when wind turbines were not a large
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`contributor to power generation. However, as the percentage of wind turbines
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`increased, becoming a substantial contributor to total power generation in grid
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`networks, the prospect of entire wind farms tripping offline due to voltage drops
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`became a grid issue, as opposed to simply a wind farm operator issue. For
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`example, if an entire wind farm trips offline, the surrounding region is likely to
`
`experience a large voltage drop, which may cause a blackout in extreme
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`conditions. Because it became increasingly important for the wind turbine
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`generators to remain connected immediately following a zero-voltage fault in a
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`controlled manner to help maintain overall grid voltage close to the normal
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`operating range, challenging standards like EON and FERC requiring such
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`capability for grid-connected wind turbines were developed. See e.g., Ex. 1031.
`
`17. Wind turbine generators are designed with a predefined tolerance of
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`currents or voltages that fluctuate above the normal operating range. Should a
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`combination of a grid voltage transient and wind turbine control action cause either
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`current or voltage to exceed this tolerance—during, for example, the unpredictable
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`recovery period after a zero-voltage fault—then protective action will trip (i.e.,
`
`disconnect) the machine from the grid, thereby failing ride-through. See e.g., Ex.
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`1001, 5:26-5:29, 6:47-6:55. Therefore, it is important for the wind turbine control
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`to manage both current and voltage within equipment rating. Proper phase
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`synchronization of the wind turbine control is also essential to ensure that the
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`actual currents follow the commands generated by the control functions that
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`regulate current and voltage. E.g., Ex. 1001, 8:37-8:46.
`
`18. When experiencing a zero-voltage event, however, the wind turbine’s
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`control system is no longer able to sense the frequency and phase of the grid
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`voltage signal that are ordinarily relied on to maintain synchronization because the
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`voltage of the grid itself has decreased to approximately zero volts. In other
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`words, not only is the wind turbine blind during a zero-voltage event, but there is
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`also no grid voltage present to see. As such, ZVRT presents, at the wind turbine, a
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`much more complex problem to solve than either low voltage ride through,
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`including single and two-phase faults, (where there is at least a low voltage present
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`on the grid to sense) or an open circuit condition in the network (where the wind
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`turbine cannot measure the grid voltage temporarily, but can still remain
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`synchronized because the grid voltage is not changing in frequency or phase).
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`IV. Person of Ordinary Skill in the Art
`19.
`
`I have read that Petitioner and Professor Blaabjerg submit that a
`
`POSITA would have “completed at least a Master’s-level academic program in
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`electrical engineering and obtained two or more years of industry experience in
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`that field, or completed a Bachelor’s-level program in electrical engineering
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`supplemented by at least four years of industry experience.” Petition, 16 citing Ex.
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`1003, ¶¶16-18. Although I generally agree with this level of ordinary skill, based
`
`on my own experience and opinion, “industry experience” is simply too broad for
`
`the technology at issue. The challenges created by zero-voltage events in the field
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`in 2006, as well as the specific solution described and claimed by the ’705 patent,
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`are specific to power electronics used in large-scale, grid-connected, wind turbine
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`generators. Accordingly, the level of ordinary skill in the art should include
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`specific “industry experience” in power electronics tailored to wind turbine
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`generators.
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`20.
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`I believe that a person having this level of skill—including the
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`appropriate industry experience in the relevant fields of power electronics tailored
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`to wind turbine generators— would appreciate that in the context of the specific
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`technical problem of zero-voltage ride for wind turbine generators, the asserted
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`prior art is not applicable. However, even under Petitioner’s definition of a
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`POSITA, I would come to the same conclusions that I discuss below.
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`12
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`V. The Challenged Claims of the ’705 Patent Recite An Implementation for
`Facilitating Zero-Voltage Ride Through
`21. Connecting a wind turbine to the electric grid when the turbine
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`voltage phases are not synchronized with the grid voltage phases can result in
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`significant damage to the wind turbine equipment. This risk of damage is
`
`heightened when a wind turbine is already coupled to the electric grid and the grid
`
`experiences a severe fault. When a severe grid fault occurs, the amplitude of the
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`grid voltage can decrease to zero volts on all three phases (“zero voltage event”).
`
`As a result, the wind turbine can no longer synchronize its voltage phases with the
`
`grid because the grid fault caused the grid voltage amplitudes to decrease such that
`
`the grid voltage is no longer present for the wind turbine to sense.
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`
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`22. As wind turbines proliferated and became a greater percentage of the
`
`electric grid, grid operators promulgated requirements that wind farms remain
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`connected to the grid during voltage decreases of a certain duration and magnitude.
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`Necessarily, the capability of a wind turbine generator to remain electrically
`
`connected to the electrical grid when the voltage of the electrical grid drops to zero
`
`volts was required. Ex. 1001, 8:29–46. This capability is called “zero voltage ride
`
`through” or “ZVRT,” and it is my opinion that the claims of the ’705 patent
`
`capture the specific features necessary to facilitate ZVRT.
`
`23. For example, stepping through the “configuring the electrical machine
`
`and the control system...” limitation of independent claim 1 highlights each of the
`
`
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`claimed requirements for facilitating ZVRT. I note that corresponding language is
`
`also recited in independent claim 7.
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`24. First, the electrical machine (e.g., the wind turbine) and its control
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`system must be configured such that “the electrical machine remains electrically
`
`connected to the electric power system,” as highlighted in the annotated portion of
`
`challenged claim 1 below.
`
`Ex. 1001, claim 1
`
`
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`25. Consistent with the requirement of ZVRT originally contemplated by
`
`the grid operators and set out in the grid codes, the plain language of the claims
`
`confirms that the wind turbine does not disconnect from the grid during (or
`
`subsequent to) a zero-voltage event on the grid. Electrical disconnection can be
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`achieved, generally, using mechanical devices like switches and circuit breakers, or
`
`electrical circuit components such as rectifiers that prevent current flow. In either
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`14
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`case, where electrical disconnection occurs, the electrical machine has not
`
`remained electrically connected to the grid.
`
`26. Moreover, to remain electrically connected means that the electrical
`
`machine has already connected to the grid in the moments before the fault. In
`
`other words, ZVRT is facilitated in an electrical machine that is already connected
`
`to the grid (and must, therefore, ride through the fault) and not upon its initial
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`connection to the grid.
`
`27.
`
`Second, the claim language confirms that the condition during which
`
`ZVRT is facilitated is a grid fault—that is, when “the voltage amplitude of the
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`electric power system” decreases to “approximately zero volts,” as highlighted in
`
`the annotated portion of challenged claim 1 below.
`
`Ex. 1001, claim 1
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`
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`28.
`
`It is clear from both the plain language of the claim highlighted above
`
`and the meaning of “approximately zero volts” that I understand the Board has
`
`adopted, that the condition necessitating ZVRT is a grid voltage fault in which the
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`grid voltage has decreased. Put differently, instances in which the grid voltage has
`
`not decreased—such as when grid voltage is still present, but an electrical machine
`
`simply cannot sense or read the grid voltage due to a lost connection or defective
`
`sensor—are not a condition requiring ZVRT, as confirmed by the challenged
`
`claims.
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`29. Third, the challenged claims require that, when the electrical machine
`
`remains electrically connected to the grid when the grid voltage amplitude
`
`deceases to approximately zero volts, it remains connected both during and
`
`subsequent to the zero-voltage event. This is also highlighted in the annotated
`
`portion of claim 1 below.
`
`Ex. 1001, claim 1
`
`
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`30. When grid voltage recovers from a zero-voltage event (i.e., the grid
`
`voltage amplitude increases to an operating magnitude that enables the connected
`
`electrical machine to sense and synchronize with the grid voltage phase), the phase
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`of the grid voltage can be at any angle relative to that of the connected machine.
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`This is especially true of unusually long fault periods, such as 0.15 seconds.
`
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`Further, the frequency of the grid may differ from that of the connected machine
`
`and the relative phase will continue to move away in value from that of the
`
`connected machine. In other words, the phase of the grid will be asynchronous to
`
`the phase of the connected machine. Practically speaking, this means that to
`
`facilitate ZVRT as recited by the challenged claims, the electrical machine must
`
`remain connected to the grid both during the time period of the zero-voltage event
`
`(when it senses no voltage from the grid) and during the time period subsequent to
`
`the zero-voltage event (when it can sense an unsettled voltage having any number
`
`of completely unpredictable asynchronous voltage phases). Accordingly, an
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`electrical machine that disconnects from the grid, even subsequent to the zero-
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`voltage event has not facilitated ZVRT as claimed.
`
`VI. How the Grid Codes are Meant to be Applied
`I note that Petitioner and Professor Blaabjerg rely on the ZVRT
`31.
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`requirements set out in grid codes, such as EON and FERC, to establish the
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`purported motivation to make the combinations proposed in its grounds. E.g.,
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`Petition, 17-18, 38. And, as both Petitioner and the Board have observed, “the
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`E.ON requirements [(EON, Ex. 1007)] provided powerful incentives to produce a
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`wind turbine that would ride through a zero voltage grid fault.” DI, 50 citing Ex.
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`Declaration of Dr. William Mack Grady
`1028, 44. I agree with this statement: EON (and FERC) promulgated standards
`
`that required wind turbine ride through of “a zero voltage grid fault” (i.e., ZVRT).
`
`32. That said, a POSITA would first recognize that EON and FERC apply
`
`to high power wind turbine generators rated on the order of 1.0-1.5MW, which is
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`consistent with the high power and voltage of the grid rated at more than 100 kV.
`
`Ex. 2013, 145-146 (“The utility grid system starts with transmission lines that
`
`carry large blocks of power, at voltages ranging from 161 kV to 765 kV.”); Ex.
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`2015, 13 (describing “faults on transmission lines of 115 kv and higher.”) In
`
`contrast, small-scale generators, like the 11kW turbine in Teodorescu (Ex. 1010, 1-
`
`2) or the static power converter of Deng (Ex. 1009; Ex. 1012, 1:38-39 (“An
`
`alternative to large power plants is the use of small low cost power generators …
`
`AC power sources, such as static power converters (SPCs) drawing power from
`
`batteries, fuel cells, and the like, have been used as low cost power generators”)
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`would neither fall under the scope of EON and FERC, nor give rise to a POSITA
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`even considering those grid codes. Instead, a POSITA would expect that small-
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`scale systems are applied to the grid with the design intent that they must
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`disconnect in the presence of a severe, zero-voltage fault. Ex. 2013, 523-524
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`(“The power conditioning unit absolutely must be designed to quickly and
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`automatically drop the [small-sized, static] PV system from the grid in the event of
`
`a utility power outage.”)
`
`33. EON warns that: “Once a fault in the ENE network is cleared or after
`
`a three-phase automatic reclosure, the operator of a generating unit must expect
`
`that the voltages in the networks of ENE and at the network connection of the
`
`connectee could be asynchronous.” Ex. 1007, 17. An asynchronous grid voltage
`
`appearing on the grid subsequent to a zero-voltage event on the grid (during which
`
`the voltage amplitude of the grid decreased to zero volts) is a specific problem that
`
`necessitates ZVRT capability. In contrast, when a system (like that of either Deng
`
`reference) loses sight of the grid voltage due to an open circuit condition (e.g.,
`
`caused by switch “bounce”), the grid itself has not changed its phase.
`
`34. The scope of FERC is comparable: “Order No. 661 requires public
`
`utilities that own, control, or operate facilities for transmitting electric energy in
`
`interstate commerce to append to their standard large generator interconnection
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`procedures and large generator interconnection agreements … and technical
`
`requirements for the interconnection of large wind generation.” Ex. 1005, 1.
`
`Footnote 6 of FERC defines that the “large wind generating plants” to which it
`
`applies “are those with an output rated at more than 20 MW at the point of
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`interconnection. The interconnection requirements for small generators rated at 20
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`MW or less are set forth in Standardization of Small Generator Interconnection
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`IPR2018-01015
`Declaration of Dr. William Mack Grady
`Agreements and Procedures, Order No. 2006, 70 FR 34190 (June 13, 2005).” A
`
`POSITA would recognize that, because FERC applies to large plants or wind farms
`
`rated at more than 20 MW, each wind turbine generator in that plant would be
`
`rated for approximately 1.0-1.5 MW. It follows naturally that no POSITA,
`
`motivated by EON or FERC, would look to small-scale references like either Deng
`
`(or even Teodorescu’s 11-KW system) to find a solution for achieving ZVRT.
`
`VII. Each and Every Instituted Ground Fails to Describe or Teach an
`Implementation That Achieves ZVRT as Recited by the Challenged
`Claims
`It is my opinion that the references identified by Petitioner and
`35.
`
`Professor Blaabjerg do not describe an implementation to facilitate ZVRT, nor do
`
`they even consider the unique problem presented by ZVRT as I have discussed
`
`above. I will discuss my analysis of these references and the proposed
`
`combinations of references below, with reference to each ground instituted in this
`
`case, and will explain how they do not describe what Petitioner or Professor
`
`Blaabjerg suggest they describe.
`
`A. Ground 1: Deng ’988 in combination with Janssen fails to teach
`an implementation that achieves ZVRT
`36. The Janssen patent makes clear throughout its disclosure that it is
`
`directed to low voltage ride through (LVRT) scenarios only, not ZVRT. Ex. 1008,
`
`1:6-9 (“More particularly, the invention relates to supporting low voltage ride
`
`through for wind turbine generators coupled with a power distribution grid.”),
`
`
`
`20
`
`
`
`IPR2018-01015
`Declaration of Dr. William Mack Grady
`4:32-33 (“As described in greater detail below, in order to protect the wind turbine
`
`generator against low voltage events,..”), 4:65-5:3 (“During a low voltage event
`
`converter controller 430 selectively activates crowbar circuit 440 to maintain
`
`current levels in a safe range. Thus, crowbar circuit 440 and converter
`
`controller 430 are part of a system that allows a wind turbine generator to ride
`
`through low voltage events and remain synchronized to the power grid.”), 5:26-28
`
`(“To support low voltage ride through capability, turbine controller 500 detects a
`
`low voltage event and responds to the event.”).
`
`37. The ’705 patent, in contrast, distinguishes its ZVRT capability from
`
`LVRT capability: “ZVRT is contrasted to low voltage ride through (LVRT)
`
`features known in the art that facilitate mitigating wind turbine generator 100 trips
`
`during transients wherein the voltage amplitude rapidly decreases, yet does not
`
`decrease to zero volts.” Ex. 1001, 6:63-67. The ZVRT capability of the ’705
`
`patent, as recited in the ZVRT claims and described in the specification, is
`
`fundamentally different from Janssen’s LVRT. This fundamental difference
`
`between Janssen’s LVRT and the ’705 patent’s ZVRT only confirms that Janssen
`
`on its own cannot describe or teach the implementation of ZVRT recited by the
`
`challenged claims of the ’705 patent.
`
`38.
`
`I understand that Petitioner proposes a combination of Janssen with
`
`Deng ’988 that collectively shows how to achieve ZVRT, as recited by the
`
`
`
`21
`
`
`
`IPR2018-01015
`Declaration of Dr. William Mack Grady
`“configuring the electrical machine and the control system…” limitation of claim 1
`
`(and its corresponding features recited in claim 7). Petition, 24-27. However,
`
`Deng ’988 describes a solution to an entirely different problem than zero-voltage
`
`events, which cannot be implemented to facilitate ZVRT, and is directed to a
`
`technology that no POSITA would look to with any expectancy of successfully
`
`applying its teachings to the wind turbine of Janssen.
`
`1.
`
`A POSITA would not look to Deng ’988’s static power
`converter when seeking to modify the wind turbine system of
`Janssen
`39. Deng ’988 describes a system and method for synchronizing
`
`alternating current power sources (“APS”), “such as static power converters
`
`(‘SPC’),” with a power grid. See e.g., Ex. 1009, Abstract, 1:16-24. Generally,
`
`static power converters on their own are small-scale, supplemental power sources.
`
`While wind turbine generators do include static power conversion components,
`
`they are just one piece of a larger wind turbine generator system.
`
`40.
`
`I note that there is also a Deng ’650 patent introduced in this case,
`
`which is not materially different from Deng ’988 other than its introduction of a
`
`basic PLL. This is notable because Deng ’650 provides more insight into its static
`
`power converters than Deng ’988. In particular, Deng ’650 explains that “AC
`
`power sources, such as static power converters (SPCs) draw[] power from
`
`batteries, fuel cells, and the like, [and] have been used as low cost power
`
`
`
`22
`
`
`
`IPR2018-01015
`Declaration of Dr. William Mack Grady
`generators to provide added power capacity to power grids during peak periods.”
`
`Ex. 1012, 1:44-48. Professor Blaabjerg also identified several examples of static
`
`power converters during his deposition, including a fuel cell, a photovoltaic power
`
`converter, or a DC-DC converter. Ex. 2020, 128:14-129:1.
`
`41. Static power converters are mechanically and operationally very
`
`different than large scale electrical machines like wind turbines or power plants
`
`like wind farms. In fact, Deng ’650 expressly distinguishes its static power
`
`converters: “An alternative to large power plants is the use of small low cost power
`
`generators connected in parallel to power grids to provide added power capacity
`
`during peak power consumption periods in order to reduce the strain on power
`
`grids.” Id., 1:38-42. This distinction in Deng ’650 alone would discourage a
`
`POSITA from looking to either Deng reference in solving a problem in large scale
`
`power plant consisting of wind turbines.
`
`42.
`
`In setting out its alleged motivation to combine Janssen and Deng
`
`’988, I note that Petitioner relies on the grid codes (i.e., EON and FERC) as the
`
`ba
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