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Damping Controller Design for Inter-area Oscillations Using Wide-area Measurements

Beiraghi, Mojtaba | 2016

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 49122 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Ranjbar, Ali Mohammad
  7. Abstract:
  8. The wide-area damping controller (WADC) has been proposed to enhance the damping of inter-area oscillations. The most challenging deficiencies to make this controller practical are the power system operating condition changes and the inherent time delay of remote signals. They can deteriorate the controller performance and the whole system stability if not properly accounted for in the design procedure. This thesis presents an adaptive delay compensator (ADC) on the basis of the latest development in the wide-area measurement system (WAMS) to cater to varying latencies. The proposed compensator can effectively reciprocate the phase deviation resulting from varying delays to improve the performance of central WADC. The greatest challenge to continuous delay compensation is the uncertainty regarding the inherent robustness of the central controller. The proposed technique provides an opportunity to epitomize the uncertainty retrieved from phase compensated delay. Next, taking the uncertainty into consideration, the mixed synthesis technique is adopted for the robust design of WADC. The comprehensive case studies are conducted including small signal analysis and nonlinear time domain simulation and it is confirmed that the proposed scheme accomplishes the desired performance, both in terms of robustness and satisfactory damping action despite the presence of system nonlinearities and time varying delays.
    Additionally, to account for the operating condition changes, an adaptive WADC scheme based on gain scheduling (GS) technique and decision tree (DT) approach is presented. For the predefined operating scenarios, several robust controllers are designed, so that each controller performs well within certain range of load /generation variation and contingencies. Considering the best acting controller in each operating condition as the target of classification, several DTs are trained using stage-wise additive modeling by multi-class exponential loss function (SAMME). The weighted combination of DTs is referred to as additive model DT (AMDT), which is used to interpolate the controller coefficients from phasor measurement unit (PMU) signals. Afterwards, the combined controller is applied to damp the inter-area oscillations. Case studies on the IEEE 39-bus 10-machine and 68-bus 16-machine test systems demonstrate the effectiveness of the proposed controller in a wide range of operating conditions as well as its robustness in the presence of uncertainty in the predicted scenarios
  9. Keywords:
  10. Adaptive Control ; Power Systems ; Time Delay ; Robust Controller ; Gain Scheduling ; Decision Tree Learning ; Inter-Area Mode Oscillations ; Damping Controller ; Delay Compensator

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