TY - JOUR

T1 - Two-Timescale Stochastic Dispatch of Smart Distribution Grids

AU - Lopez-Ramos, Luis M.

AU - Kekatos, Vassilis

AU - Marques, Antonio G.

AU - Giannakis, Georgios B.

N1 - Publisher Copyright:
© 2017 IEEE.

PY - 2018/9

Y1 - 2018/9

N2 - Smart grids should efficiently integrate stochastic renewable resources while effecting voltage regulation. Energy management is challenging since it is a multistage problem where decisions are not all made at the same timescale and must account for the variability during real-time operation. The joint dispatch of slow- and fast-timescale controls in a smart distribution grid is considered here. The substation voltage, the energy exchanged with a main grid, and the generation schedules for small diesel generators have to be decided on a slow timescale; whereas optimal photovoltaic inverter setpoints are found on a more frequent basis. While inverter and looser voltage regulation limits are imposed at all times, tighter bus voltage constraints are enforced on the average or in probability, thus enabling more efficient renewable integration. Upon reformulating the two-stage grid dispatch as a stochastic convex-concave problem, two distribution-free schemes are put forth. An average dispatch algorithm converges provably to the optimal two-stage decisions via a sequence of convex quadratic programs. Its non-convex probabilistic alternative entails solving two slightly different convex problems and is numerically shown to converge. Numerical tests on real-world distribution feeders verify that both schemes yield lower costs over competing alternatives.

AB - Smart grids should efficiently integrate stochastic renewable resources while effecting voltage regulation. Energy management is challenging since it is a multistage problem where decisions are not all made at the same timescale and must account for the variability during real-time operation. The joint dispatch of slow- and fast-timescale controls in a smart distribution grid is considered here. The substation voltage, the energy exchanged with a main grid, and the generation schedules for small diesel generators have to be decided on a slow timescale; whereas optimal photovoltaic inverter setpoints are found on a more frequent basis. While inverter and looser voltage regulation limits are imposed at all times, tighter bus voltage constraints are enforced on the average or in probability, thus enabling more efficient renewable integration. Upon reformulating the two-stage grid dispatch as a stochastic convex-concave problem, two distribution-free schemes are put forth. An average dispatch algorithm converges provably to the optimal two-stage decisions via a sequence of convex quadratic programs. Its non-convex probabilistic alternative entails solving two slightly different convex problems and is numerically shown to converge. Numerical tests on real-world distribution feeders verify that both schemes yield lower costs over competing alternatives.

KW - Multistage economic dispatch

KW - convex-concave problem

KW - stochastic approximation

KW - voltage regulation

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U2 - 10.1109/TSG.2017.2654220

DO - 10.1109/TSG.2017.2654220

M3 - Article

AN - SCOPUS:85052678521

SN - 1949-3053

VL - 9

SP - 4282

EP - 4292

JO - IEEE Transactions on Smart Grid

JF - IEEE Transactions on Smart Grid

IS - 5

M1 - 7820228

ER -