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Coordinated Voltage Control of Power Systems in Normal and Emergency Operation States

Rabiee, Abbas | 2013

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 44162 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Parniani, Mostafa
  7. Abstract:
  8. One of the main objectives in operating a power system is to maintain the system voltage properly to avoid equipment damage and transfer power efficiently. Automatic control of transmission network voltage provides significant improvements in security, quality and efficiency of power system operation. This thesis investigates coordinated voltage control of power systems in normal, alert and emergency states. The aim is to propose a comprehensive framework for real-time operation of practical power systems, ensuring secure operation of the system in the normal state and after occurrence of sever contingencies.
    At the first, a new coordinated voltage control scheme is proposed to ensure voltage security of power systems in the normal operation state, based on the concept of model predictive control. The problem is treated as voltage security constrained multi-period optimal reactive power flow (VSC-MPORPF). To incorporate scheduling of both continuous and discrete VAR sources, the VSC-MPORPF is formulated as a mixed-integer nonlinear programming problem, and is solved using generalized Benders decomposition (GBD). Also, to make the proposed method applicable for large-scale power systems, optimality condition decomposition approach is utilized, along with the GBD.
    Then, a comprehensive control framework is presented to ensure desired loading margin (LM) while minimizing the corresponding control cost in the alert and emergency operation states. The proposed framework is divided into corrective control (CC) and preventive control (PC) subproblems. One of the features of the proposed methodology is to consider participation of demand-side resources (i.e. demand response (DR)) as an effective control facility that reduces control costs considerably.
    The recent trends toward smart grids and increasing share of renewable energy resources in many power systems have intensified the needs for powerful approaches for power system security enhancement. Noting the increasing penetration of wind power generation in nowadays power systems, scenario based approach is adopted for appropriate modeling of intermittent wind power generation in the proposed CC and PC models.
    Finally, the necessity for considering the effect of voltage on the load characteristic, especially in CC and PC problems, is explained. A general voltage dependent static model of loads, i.e. aggregated load model, is utilized in CC and PC problems, that comprises of residential, industrial and commercial loads together for any given load bus of system
  9. Keywords:
  10. Voltage Stability ; Voltage Security ; Demand Response ; Benders Decomposition ; Optimality Condition ; Coordinated Voltage Control ; Preventive Control ; Loading Margin ; Corrective Control

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