8 research outputs found
Improving power grid transient stability by plug-in electric vehicles
Plug-in electric vehicles (PEVs) can serve in discharge mode as distributed
energy and power resources operating as vehicle-to-grid (V2G) devices and in
charge mode as loads or grid-to-vehicle (G2V) devices. It has been documented
that PEVs serving as V2G systems can offer possible backup for renewable power
sources, can provide reactive power support, active power regulation, load
balancing, peak load shaving,% and current harmonic filtering, can provide
ancillary services as frequency control and spinning reserves, can improve grid
efficiency, stability, reliability, and generation dispatch, can reduce utility
operating costs and can generate revenue. Here we show that PEVs can even
improve power grid transient stability, that is, stability when the power grid
is subjected to large disturbances, including bus faults, generator and branch
tripping, and sudden large load changes. A control strategy that regulates the
power output of a fleet of PEVs based on the speed of generator turbines is
proposed and tested on the New England 10-unit 39-bus power system. By
regulating the power output of the PEVs we show that (1) speed and voltage
fluctuations resulting from large disturbances can be significantly reduced up
to 5 times, and (2) the critical clearing time can be extended by 20-40%.
Overall, the PEVs control strategy makes the power grid more robust.Comment: 15 pages, 4 figures, submitted to New Journal of Physic
Energy-efficiency in decentralized wireless networks: A game-theoretic approach inspired by evolutionary biology
Energy efficiency is gaining importance in wireless communication networks which have nodes with limited energy supply and signal processing capabilities. We present a numerical study of cooperative communication scenarios based on simple local rules. This is in contrast to most of the approaches in the literature which enforce cooperation by using complex algorithms and require strategic complexity of the network nodes. The approach is motivated by recent results in evolutionary biology which suggest that, if certain mechanism is at work, cooperation can be favored by natural selection, i. e. even selfish actions of the individual nodes can lead to emergence of cooperative behavior in the network. The results of the simulations in the context of wireless communication networks verify these observations and indicate that uncomplicated local rules, followed by simple fitness evaluation, can generate network behavior which yields global energy efficiency
Stability of power grids: An overview
Transient stability and steady-state (small signal) stability in power girds are reviewed. Transient stability concepts are illustrated with simple examples; in particular, we consider three methods for computing region of attraction: time-simulations, extended Lyapunov function, and sum of squares optimization method. We discuss steady state stability in power systems, and present an example of a feedback control via a communication network for the 10 Unit 39 Bus New England Test system