With the wide application of synchronized phase measurement unit(PMU) in power system, the wide-area measurement system(WAMS) has enabled the use of a combination of measured information from remote location for global control purpose. However, the impact of time delays introduced by remote information's transmission in WAMS has to be considered, and the closed-loop power systems need be modeled as time-delay nonlinear systems. Moreover, the wide-area information is incomplete when not all generators in power system are equipped with the PMU. In order to eliminate the effects of power system model's nonlinearity and wide-area information's uncertainty including time delays and incomplete-ness, a novel approach based on inverse system algorithm and linear matrix inequality(LMI) technique is proposed to design a nonlinear robust integrated controller. Digital simulation demonstrates that the four-machine system under the nonlinear robust integrated control has less settling time, swing times, oscillatory peak value and more critical clear time and better voltage stability performance for various time delays of remote incomplete measured information than that under PID control or nonlinear decentralized integrated control.Index Terms-Center of inertia reference frame, inverse system method, integrated controller, linear matrix inequality (LMI), power system, wide-area measurement system (WAMS)

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Due to the fact that wide area information is easily disturbed, lost and distorted, while it is not fully considered in current wide area protection principle, a wide area backup protection algorithm with high fault-tolerance performance is proposed to implement the CSBPS(Centralized Substation Backup Protection System). After the fault-tolerance judgment, The CSBPS can locate the fault equipment according to the fault direction information and fault distance information which is calculated by currents and voltages measured from the electric equipments of local substation and collected from the adjacent substations. The results of case study show that CSBPS can't make the uncorrected judgment even when any one of the protection element operates incorrectly, fails to operate or its fault information lost. The proposed algorithm is simple and reliable with good fault-tolerance capability.

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In this paper, a Doubly Fed Induction Generator (DFIG) wind turbine controller which consists of two control loops is introduced. In steady state, the main control loop ensures that the wind power generators without wind speed measurement can perform active power control tasks below the nominal wind speed while the auxiliary stability control loop restraining the wind power system oscillations by eliminating the system unbalancing energy during system disturbances. The impacts of DFIG operation that limits on the controller are also discussed in this paper. In the simulation study, a testing system including a DFIG-based wind farm implemented in DIgSILENT/Power Factory is conducted to demonstrate the effectiveness of this strategy. The simulation results show that the control strategy can adjust the power of the DFIG wind generator accurately under wind speed fluctuation. In addition, when a disturbance occurs in the system, the strategy is effective in improving the power system transient stability in different operation statuses without deteriorating the system voltage stability. Index Terms--DFIG operation limits, DIgSILENT/PowerFactory, dynamic characteristic power control tasks, stability