66 research outputs found
Optimal Ensemble Control of Loads in Distribution Grids with Network Constraints
Flexible loads, e.g. thermostatically controlled loads (TCLs), are
technically feasible to participate in demand response (DR) programs. On the
other hand, there is a number of challenges that need to be resolved before it
can be implemented in practice en masse. First, individual TCLs must be
aggregated and operated in sync to scale DR benefits. Second, the uncertainty
of TCLs needs to be accounted for. Third, exercising the flexibility of TCLs
needs to be coordinated with distribution system operations to avoid
unnecessary power losses and compliance with power flow and voltage limits.
This paper addresses these challenges. We propose a network-constrained,
open-loop, stochastic optimal control formulation. The first part of this
formulation represents ensembles of collocated TCLs modelled by an aggregated
Markov Process (MP), where each MP state is associated with a given power
consumption or production level. The second part extends MPs to a multi-period
distribution power flow optimization. In this optimization, the control of TCL
ensembles is regulated by transition probability matrices and physically
enabled by local active and reactive power controls at TCL locations. The
optimization is solved with a Spatio-Temporal Dual Decomposition (ST-D2)
algorithm. The performance of the proposed formulation and algorithm is
demonstrated on the IEEE 33-bus distribution model.Comment: 7 pages, 6 figures, accepted PSCC 201
One Breaker is Enough: Hidden Topology Attacks on Power Grids
A coordinated cyber-attack on grid meter readings and breaker statuses can
lead to incorrect state estimation that can subsequently destabilize the grid.
This paper studies cyber-attacks by an adversary that changes breaker statuses
on transmission lines to affect the estimation of the grid topology. The
adversary, however, is incapable of changing the value of any meter data and
can only block recorded measurements on certain lines from being transmitted to
the control center. The proposed framework, with limited resource requirements
as compared to standard data attacks, thus extends the scope of cyber-attacks
to grids secure from meter corruption. We discuss necessary and sufficient
conditions for feasible attacks using a novel graph-coloring based analysis and
show that an optimal attack requires breaker status change at only ONE
transmission line. The potency of our attack regime is demonstrated through
simulations on IEEE test cases.Comment: 5 pages, 5 figures, Accepted to the IEEE PES General Meeting 201
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