This paper concerns frequency regulation performance in power systems with a high level of wind generation penetration. As wind generation becomes a significant portion of total energy production, wind power variability will cause system frequency to deviate from nominal value. Short-term wind power fluctuations are characterized by frequency spectra. This information is used together with robust control, specifically the H∞ method, to synthesize new governors for conventional plants in order to better attenuate frequency deviation caused by wind power fluctuations. A reduced-order controller is obtained based on Hankel singular values. Simulation results show the effectiveness of the H∞ controller. This work suggests several directions for further research.
"However, due to the disadvantages of standard H ∞ methods, it produces a high-order dynamic controller which is generally undesirable in practice. Therefore, the approach in  is only applicable to small-scale power systems. For large-scale power systems, reduced-order model are often used. "
[Show abstract][Hide abstract] ABSTRACT: As wind generation becomes a significant portion of total energy production, wind power variability will introduce more variability in system frequency. This paper presents a method to improve primary control for frequency regulation in large-scale power systems with high wind power penetration. To assure system stability, a passivity-based framework is developed for power systems by introducing a storage function derived from the entropy of individual generators. Tellegen's theorem is invoked to derive the storage function for the entire power network. Given the network parameters and the point of interconnection of the wind farm, a single generator is selected to balance wind power fluctuations. A passive H<sub>∞</sub> controller is synthesized for the selected generator by using a passive reduced-order model of the large-scale power system. Simulation results of a 9-bus test system show the effectiveness of the passive H<sub>∞</sub> controller. This work also suggests several directions for further research.
[Show abstract][Hide abstract] ABSTRACT: This paper surveys major technical challenges for power system operations in support of large-scale wind energy integration. The fundamental difficulties of integrating wind power arise from its high inter-temporal variation and limited predictability. The impact of wind power integration is manifested in, but not limited to, scheduling, frequency regulations, and system stabilization requirements. Possible alternatives are suggested for a more reliable and cost-effective power system operation. New computationally efficient methods for improving system performances by using prediction and operational interdependencies over different time horizons remain critical open research problems.
Proceedings of the IEEE 02/2011; 99(1-99):214 - 232. DOI:10.1109/JPROC.2010.2070051 · 4.93 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This paper deals with fault-tolerant controller design for linear time-invariant (LTI) systems with multiple actuators. Given some critical subsets of the actuators, it is assumed that every combination of actuators can fail as long as the set of the remaining actuators includes one of these subsets. Motivated by electric power systems and biological systems, the goal is to design a controller so that the closed-loop system satisfies two properties: (i) stability under all permissible sets of faults and (ii) better performance after clearing every subset of the existing faults in the system. It is shown that a state-feedback controller satisfying these properties exists if and only if a linear matrix inequality (LMI) problem is feasible. This LMI condition is then transformed into an optimal-control condition, which has a useful interpretation. The results are also generalized to output-feedback and decentralized control cases. The efficacy of this work is demonstrated by designing fault-tolerant speed governors for a power system. The results developed here can be extended to more general types of faults, where each fault can possibly affect all state-space matrices of the system.
Proceedings of the American Control Conference 06/2011; DOI:10.1109/ACC.2011.5991381
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