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Distributed generation placement

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Voltage Stability-Based DG Placementin Distribution Networks

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Distributed generation placement

  1. 1. M. Ettehadi , H. Ghasemi , S. Vaez-Zadeh Electr. & Comput. Eng., Univ. of Tehran, IEEE Power & Energy society 2013 Student ; Reza Shahbazi 2014 December Voltage Stability-Based DG Placement in Distribution Networks 1
  2. 2. Power system stability Rotor angle stability Transient stability Small Disturbance Frequency stability Short term Long term Voltage stability Small Disturbance Large Disturbance 2 View on Stability :
  3. 3. I. Introduction  DG II. Voltage-stability Problem In Distribution Networks  Problem Identification  Modal Analysis  CPF : Continuous Power-Flow Methodology III. DG Placement Algorithm  DG Placement Process  DG Placement Evaluation Indices IV. Short-term Reactive Power Ranking  Qualified Load Index (QLI)  Ranking Process V. Case Study 3
  4. 4.  Introduction : DG 4
  5. 5. DG (Distributed Generation)  Distributed generation (DG) is any electricity generating technology installed by a customer.  Generating power on-site (close to the load), rather than centrally, eliminates the cost, complexity, interdependencies, and inefficiencies associated with transmission and distribution.  Since reactive power cannot travel over long distances, system operators/dispatchers should provide it locally. DG units are good local reactive power sources. 5
  6. 6.  Voltage-stability Problem In Distribution Networks  Problem Identification  Modal Analysis  CPF : Continuous Power-Flow Methodology 6
  7. 7. Problem Identification ‫ولتاژ‬‫پاشی‬‫و‬‫فر‬: ‫گر‬‫بدل‬ ‫کلی‬‫ولتاژ‬ ‫پاشی‬‫و‬‫فر‬‫ت‬‫ر‬‫بصو‬ ‫میتواند‬‫که‬ ،‫است‬ ‫ای‬‫ناحیه‬‫پدیده‬‫یک‬‫خود‬ ‫طبیعت‬‫در‬‫ولتاژ‬ ‫ی‬‫ناپایدار‬‫این‬‫ر‬‫بناب‬‫پاسخ‬‫هیچ‬‫بدون‬‫دد‬ ‫سریعی‬. 7 ‫ایش‬‫ز‬‫اف‬‫بار‬(‫بار‬ ‫تقاضای‬‫ایش‬‫ز‬‫اف‬)‫ناحی‬ ‫در‬‫ولتاژ‬ ‫شدن‬ ‫کنترل‬‫غیرقابل‬‫ه‬ ‫قدرت‬‫سیستم‬‫از‬‫مشخصی‬‫ولتاژ‬ ‫ی‬‫ناپایدار‬
  8. 8.  Voltage stability (IEEE ): refers to the ability of a power system to maintain steady voltages at all buses in the system after being subjected to a disturbance from a given initial operating condition  Voltage collapse : usually occurs in heavily loaded systems that do not have sufficient local reactive power sources. 8 This reactive power shortage may lead to wide-area Blackouts
  9. 9. Tools for voltage stability analysis Different methods exist in the literature for carrying out a steady state voltage stability analysis:  P-V curve method.  V-Q curve method and reactive power reserve.  Methods based on singularity of power flow Jacobian matrix at the point of voltage collapse.  Continuation power flow method. 9
  10. 10. Modal analysis : ‫ی‬‫پایدار‬ ‫د‬‫ر‬‫مو‬‫در‬ ‫بینی‬‫پیش‬‫و‬ ‫سی‬‫ر‬‫بر‬‫ای‬‫ر‬‫ب‬ ‫ریاضی‬‫شهای‬‫و‬‫ر‬‫از‬ ‫یکی‬/‫ولتاژ‬ ‫ی‬‫ناپایدار‬.  A modal analysis can discover the instability characteristics and can be used to find the best sites for reactive power compensation  For a (n*n) square matrix A, left and right eigenvectors are defined as follows: A.x = λx y.A = λy λ = eigenvalue of the matrix A x (n*1) = right eigenvector y (1*n) = left eigenvector 10
  11. 11. The characteristic equation of both equations det (A-λ*I) = 0 The solution of this equation: [ λ1 , λ2,…. , λn] are the eigenvalues of A if λi > 0 The system is voltage stable if λi < 0 The system is voltage unstable if λi > 0, then the variation of Vi and Qi are in the same direction. 11
  12. 12. Continuous Power-Flow ( CPF ( Methodology  VSM : Voltage Security Margin The higher the VSM ,the more secure the system Near the voltage collapse point It is difficult to obtain a power flow solution Continuation power flow is a technique by which the power flow solutions can be obtained near or at the voltage collapse point According to the proposed algorithm, a CPF is executed on the system under study In this step we use CPF to identify the most sensitive bus to voltage collapse. 12
  13. 13.  DG Placement Algorithm  DG Placement Process  DG Placement Evaluation Indices 13
  14. 14. DG Placement Process The DG placement problem can be formulated by many objective Functions including  Loss Minimization  Voltage Profile Improvement  Economical Revenue  Environmental Impact Reduction  Improvement On Reliability Aspects  Voltage security margin enhancement and loss reduction 14
  15. 15. the modal analysis is used concurrently to determine the critical modes and their associated buses. The CPF can be used for the determination of the VSM and the bus voltages at collapse points. 15  bus with a minimum voltage at the collapse point is defined as the most sensitive bus to voltage collapse.  This bus is selected as a candidate for DG placement.
  16. 16. 16start Receive the network data Execute the CPF and determine the most sensitive bus to voltage collapse as a candidate Execute the modal analysis and determinate the worst modes Determine the most participating bus in each mode as a candidate Add a DG to the candidate bus Execute CPF and calculate the maximum loading Is it the last candidate? Next candidate Select the candidate bus with the highest loading Do we want to place another DG ? Print the result Locate a DG at the bus which has the maximum loading 16
  17. 17. DG Placement Evaluation Indices 17 The higher the VSM, the more secure the system. ALR and RLR show active and reactive loss reduction after installing DG/DGs. Higher values of and indicate better performance of ALR and RLR DGs in loss reduction. The lower the VI, the better the performance of DG units.
  18. 18. • Application of the Placement Algorithm CASE STUDY 18
  19. 19. 19 Application of the placement method and the corresponding indices are examined on the well-known 33-bus radial distribution Network. Single-line diagram of the 33-bus radial distribution network The system total apparent load is 4.3694 MVA and DG penetration is considered to be 40% (i.e., 1.7477 MVA).
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  23. 23. I. Voltage Stability-Based DG Placement in Distribution Networks M. Ettehadi , H. Ghasemi , S. Vaez-Zadeh : Electr. & Comput. Eng., Univ. of Tehran, IEEE Power & Energy society 2013 II. Voltage Stability Evaluation of The Khuzestan Power System in Iran Using CPF Method and Modal Analysis(2010) Farbod Larki-Ahvaz, Iran ; Mahmood Joorabian-Ahvaz, Iran ; Homayoun Meshgin Kelk, Mojtaba Pishvaei- Tafresh, Iran III. Notes on Power System Voltage Stability By S. Chakrabarti, Dept. of EE, IIT, Kanpur Refrences 23
  24. 24. I Really Appreciate Your Concern. 24

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