Control of Distributed Energy Storage Devices for Power Grid Resiliency

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

David Copp, Felipe Wilches-Bernal, Raymond Byrne, David Schoenwald

Power system stability via wide-

area damping control

Current injections

Damping control with distributed Energy Storage (ES)

Two-area system: 4 generators, 6 ES devices.Subtransient Generator Models (6th order).Ground bus fault at bus 7.

Larger current injections: Diminishing improvement of damping performance w.r.t. 2-norm.

Controllability and Observability in western North American Power System (wNAPS)

Other research topics: Optimal Energy Management with ES [5], Energy storage valuation

Where to place ES and measurement devices for best damping of inter-area oscillations?4 modes of interest in the wNAPS. Use geometric measures of controllability/observability to determine where to inject power/current and where to collect measurements in linearized MiniWECC model [4].Use this information to site and size storage.

References:[1] F. Wilches-Bernal, D.A. Copp, I. Gravagne, D.A. Schoenwald. Stability Criteria for Power Systems with Damping Control and Asymmetric Feedback Delays. Submitted, 2017.[2] D.A. Copp, F. Wilches-Bernal, I. Gravagne, D.A. Schoenwald. Time-Domain Analysis of Power System Stability with Damping Control and Asymmetric Feedback Delays. 49th North American Power Symposium, 2017.[3] D.A. Copp, F. Wilches-Bernal, D.A. Schoenwald. Power Systems Damping Control via Current Injections from Distributed Energy Storage. 10th Electrical Energy Storage Applications and Technologies Conference, 2017.[4] D. Trudnowski, “The MinniWECC System Model,” Appendix 2 of J. Undrill and D. Trudnowski, “Oscillation Damping Controls,” Year 1 report of BPA contract 37508, 2008. [5] R.H. Byrne, T.A. Nguyen, D.A. Copp, B.R. Chalamala, I. Gyuk. Energy Management and Optimization Methods for Grid Energy Storage Systems. IEEE Access. In press, 2017.

Nonlinear Simulations: Power Systems Toolbox

ES response time# of injectionsProportional gainAvg angular velocity of gens in area

• Any injections are better than none. Figures show few combinations. • Location is important. Injections near ends and in area with lower inertia produce better damping (not shown).• Injections at all six locations perform almost as well as injections from only ES 1 and 6 with largest injection a third the size, allowing smaller (perhaps less expensive) ES devices to be installed.

Which/how many ES devices should provide current injections to produce best damping of inter-area oscillations? [3]

Period of oscillation ~2.73s

System oscillation (top) Power injections (bottom)

When time delays are equal, injections are zero-mean. When time delays are asymmetric, injections are not zero-mean.

Energy Storage Power Injections

Delay Differential Equations

Time-Domain SimulationsStable in black regions, unstable in white. Unstable regions grow as both gain and delays increase. Regions depend on frequency of oscillation and how close delays match that frequency. Measurement close to one period delayed may still be fairly accurate. Delayed measurement out-of-phase leads to incorrect feedback, and large gain will cause instability [2].

Stability Criterionstable

Lyapunov-Krasovskii ApproachGeneral delay-dependent sufficient conditions for asymptotic stability (conservative) [1].

In the presence of delays, increasing damping may lead to instability.Increasing damping

Regions of Stability

Linearized Dynamics:

right eigenvector of left eigenvector of

Measures of Controllability/ Observability:

Damping control with feedback delays

Electromechanical model of generator dynamics

Rotor angle

Rotor angular velocity

Funding for this work was provided by US DOE Energy Storage Program managed by Dr. Imre Gyuk of the DOE Office of Electricity Delivery and Energy Reliability.