Operational Constraints (operational + constraint)

Distribution by Scientific Domains


Selected Abstracts


Computation of locational and hourly maximum output of a distributed generator connected to a distribution feeder

ELECTRICAL ENGINEERING IN JAPAN, Issue 2 2009
Yasuhiro Hayashi
Abstract Recently, the total number of distributed generation such as photovoltaic generation systems and wind turbine generation systems connected to a distribution network has drastically increased. Distributed generation using renewable energy can reduce the distribution loss and emission of CO2. However, the distribution network with the distributed generators must be operated while maintaining the reliability of the power supply and power quality. In this paper, the authors propose a computational method to determine the maximum output of a distributed generator under operational constraints [(1) voltage limit, (2) line current capacity, and (3) no reverse flow to bank] at arbitrary connection points and hourly periods. In the proposed method, a three-phase iterative load flow calculation is applied to evaluate the above operational constraints. The three-phase iterative load flow calculation has two simple procedures: (Procedure 1) addition of load currents from the terminal node of the feeder to root one, and (Procedure 2) subtraction of voltage drop from the root node of the feeder to terminal one. In order to check the validity of the proposed method, numerical simulations are performed for a distribution system model. Furthermore, the characteristics of locational and hourly maximum output of a distributed generator connected to a distribution feeder are analyzed using several numerical examples. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(2): 38,47, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20610 [source]


Service restoration method considering simultaneous disconnection of distributed generators by one-bank fault of distribution system

ELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 8 2008
Hirotaka Takano
Abstract Distributed generators (DGs) such as fuel cells and solar cells are going to be installed in the demand side of distribution systems. The DGs can reduce distribution loss by appropriate allocation. However, there are several problems installing DGs such as service restoration of distribution system with DGs and so on. When one bank fault of distribution substation occurs in distribution system, since DGs are simultaneously disconnected from the system, it is not easy to restore isolated load by one bank switching in distribution substation. Therefore, a service restoration method to determine restoration configuration and restoration procedures (switching procedure from normal configuration to restoration configuration) taking into account simultaneous disconnection of DGs is needed. In this paper, the authors propose a computation method to determine the optimal restoration configuration and the restoration procedure considering simultaneous disconnection of DGs by one bank fault of distribution system. In the proposed algorithm, after all of the restoration configuration candidates are effectively enumerated under the operational constraints, the optimal configuration to restore the isolated load is selected among enumerated configuration candidates. After determining the optimal restoration configuration, the optimal restoration procedures are obtained by greedy algorithm. Numerical simulations are carried out for a real scale system model with 237 sectionalizing switches (configuration candidates are 2237) and 21 DGs (total output is 5250 kW which is 3% of total load) in order to examine the validity of the proposed algorithm. © 2008 Wiley Periodicals, Inc. Electron Comm Jpn, 91(8): 44,55, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10133 [source]


A genetic algorithm multi-objective approach for efficient operational planning technique of distribution systems

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 2 2009
C. Lakshminarayana
Abstract This paper presents a genetic algorithm multi-objective approach for efficient operational planning technique for electrical power distribution systems (EPDS). Service restoration is a non-linear, combinatorial, non-differential and multi-objective optimization problem that often has a great number of candidate solutions to be evaluated by the operators. To tackle the problem of service restoration with multiple objectives, the weighted sum strategy is employed to convert these objectives into a single objective function by giving equal weighting values. The transformer/feeders capacity in the post-fault distribution network creates a major problem for the electrical power distribution engineers and distribution system substation operators to satisfy the operational constraints at the consumer localities while restoring power supply. The feasibility of the developed algorithm for service restoration demonstrated on several distribution networks with fast and effective convergence of the results of this technique helps to find the efficient operational planning of the EPDS. Copyright © 2007 John Wiley & Sons, Ltd. [source]


Enhanced ac power-flow solutions for reliability analyses

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 2 2001
A. Sorg
The paper presents an advanced Newton-Raphson power-flow algorithm for reliability evaluation with special regard to the prevention of non-convergent situations. Remedial actions in order to relieve violations of operational constraints and some generation rescheduling functions are considered. Included is a reliability analysis for a sample power system in order to compare the resulting reliability indices using different power-flow algorithms. [source]


Integrated method of determining transmission and distribution loss-minimum network configurations

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 3 2006
Yasuhiro Hayashi Senior Member
Abstract In Japan, the secondary transmission system (66 kV, 77 kV) and distribution system (6.6 kV) with loop structures are operated using the radial configuration. The transmission and distribution network configurations must be determined so as to keep the radial configuration and satisfy the operational constraints such as line capacity, voltage drop, and so on. However, the configuration candidates are too many, and it is not easy to determine transmission and distribution loss-minimum network configurations comprehensively. In this paper, the authors propose an integrated method of determining the transmission and distribution loss-minimum network configurations under the operational constraints within practical computation time. In order to check the validity of the proposed method of determination, numerical simulations using the proposed method are carried out for a real-scale Japanese transmission and distribution network model with 22098 configuration candidates. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]


Three-level and mixed-level orthogonal arrays for lean designs

QUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 6 2010
Chang-Xing Ma
Abstract Orthogonal arrays (OA's) are widely used in design of experiments. Each OA has a specific number of rows that is fixed by the number of factors in the OA and the number of levels in each factor. In a practical application of an industrial experiment, however, because of various operational constraints it could happen that the number of runs of the experiment cannot be set exactly equal to the number of rows of an OA. In this case, a lean design can be used. A lean design is obtained by removing some specific rows and columns from the extended design matrix formed from an OA, so that the resulting sub-matrix still allows efficient estimation of the effects of some of the factors. Tables for 2-level lean designs are already available in the literature. In this paper, the authors will investigate 3-level lean designs and mixed-level lean designs, and construct tables for such designs for convenient use. Copyright © 2009 John Wiley & Sons, Ltd. [source]