This paper presents the application of a new genetic algorithm for the optimal design of large distribution systems, solving the optimal sizing and locating problems of feeders and substations using the corresponding fixed costs as well as the true nonlinear variable costs. It can be also applied to single stage or multistage distribution designs. The genetic algorithm has been tested with real size distribution systems achieving optimal designs in reasonable CPU times compared with respect to the dimensions of such distribution systems. On the other hand, these distribution systems present significantly larger sizes than the ones frequently found in the technical literature about the optimal distribution planning. Furthermore, original operators of the genetic algorithm have been developed in order to obtain global optimal solutions, or very close ones to them. An integer codification of the genetic algorithm has also been used to include several relevant design aspects in the distribution network optimization.

Genetic algorithms applied to the design of large power distribution systems

The planning problem of electrical power distribution networks, stated as a mixed nonlinear integer optimization problem, is solved using the ant colony system algorithm (ACS). The behavior of real ants has inspired the development of the ACS algorithm, an improved version of the ant system (AS) algorithm, which reproduces the technique used by ants to construct their food recollection routes from their nest, and where a set of artificial ants cooperate to find the best solution through the interchange of the information contained in the pheromone deposits of the different trajectories. This metaheuristic approach has proven to be very robust when applied to global optimization problems of a combinatorial nature, such as the traveling salesman and the quadratic assignment problem, and is favorably compared to other solution approaches such as genetic algorithms (GAs) and simulated annealing techniques. In this work, the ACS methodology is coupled with a conventional distribution system load-flow algorithm and adapted to solve the primary distribution system planning problem. The application of the proposed methodology to two real cases is presented: a 34.5-kV system with 23 nodes from the oil industry and a more complex 10-kV electrical distribution system with 201 nodes that feeds an urban area. The performance of the proposed approach outstands positively when compared to GAs, obtaining improved results with significant reductions in the solution time. The technique is shown as a flexible and powerful tool for the distribution system planning engineers.

Ant colony system algorithm for the planning of primary distribution circuits

Part I: Electrical Design and Analysis Transmission System Planning Introduction Aging Transmission System Benefits of Transmission Power Pools Transmission Planning Traditional Transmission System Planning Techniques Models Used in Transmission System Planning Transmission Route Identification and Selection Traditional Transmission System Expansion Planning Traditional Concerns for Transmission System Planning New Technical Challenges Transmission Planning After Open Access Possible Future Actions by FERC References Transmission Line Structures and Equipment Introduction The Decision Process to Build a Transmission Line Design Tradeoffs Traditional Line Design Practice Transmission Line Structures Subtransmission Lines Transmission Substations SF6-Insulated Substations Transmission Line Conductors Insulators Substation Grounding Ground Conductor Sizing Factors Mesh Voltage Design Calculations Step Voltage Design Calculations Types of Ground Faults Ground Potential Rise Transmission Line Grounds Types of Grounding Transformer Classifications Environmental Impact of Transmission Lines Transformer Connections Autotransformers in Transmission Substations Transformer Selection Transformer Classifications References Fundamental Concepts Introduction Factors Affecting Transmission Growth Stability Considerations Power Transmission Capability of a Transmission Line Surge Impedance and Surge Impedance Loading (SIL) of a Transmission Line Loadability Curves Compensation Shunt Compensation Series Compensation Flexible AC Transmission Systems (FACTS) Static Var Control (SVC) Static Var Systems Thyristor Controlled Series Compensator (TCSC) Static Compensator Thyristor-Controlled Braking Resistor Superconducting Magnetic Energy Systems (SMES) Subsynchronous Resonance Use of Static Compensation to Prevent Voltage Collapse or Instability Energy Management System Supervisory Control and Data Acquisition (SCADA) Advanced SCADA Concepts Substation Controllers Six-Phase Transmission Lines References Overhead Power Transmission Introduction Review of Basics Constant Impedance Representation of Loads Three-Winding Transformers Autotransformers Delta-Wye and Wye-Delta Transformations Transmission Line Constants Tables of Line Constants Equivalent Circuits for Transmission Lines Short Transmission Lines (up to 50 mi or 80 km) Medium-Length Transmission Lines (up to 150 mi or 240 km) Long Transmission Lines (above 150 mi or 240 km) General Circuit Constants Bundled Conductors Effect of Ground on Capacitance of Three-Phase Lines Environmental Effects of Overhead Transmission Lines Additional Solved Numerical Examples for the Transmission Line Calculations References Problems Underground Power Transmission and Gas Insulated Transmission Lines Introduction Underground Cables Underground Cable Installation Techniques Electrical Characteristics of Insulated Cables Sheath Currents in Cables Positive- and Negative-Sequence Reactance Zero-Sequence Resistance and Reactance Shunt Capacitive Reactance Current-Carrying Capacity of Cables Calculation of Impedances of Cables in Parallel EHV Underground Cable Transmission Gas-Insulated Transmission Lines Location of Faults in Underground Cables References Problems Direct Current Power Transmission Basic Definitions Introduction Overhead High Voltage DC Transmission Comparison of Power Transmission Capacity of High Voltage DC and AC High Voltage DC Transmission Line Insulation Three-Phase Bridge Converter Rectification Per-Unit Systems and Normalizing Inversion Multibridge (B-Bridge) Converter Stations Per-Unit Representation of B-Bridge Converter Stations Operation of Direct Current Transmission Link Stability of Control Use of FACTS and HVDC to Solve Bottleneck Problems in the Transmission Networks High Voltage Power Electronic Substations Additional Commends on HVDC Converter Stations References Problems Transient Overvoltages and Insulation Coordination Introduction Traveling Waves Effects of Line Terminations Junction of Two Lines Junction of Several Lines Termination in Capacitance and Inductance Bewley Lattice Diagram Surge Attenuation and Distortion Traveling Waves on Three-Phase Lines Lightning and Lightning Surges Shielding Failures of Transmission Lines Lightning Performance of UHV Lines Stroke Current Magnitude Shielding Design Methods Switching and Switching Surges Overvoltage Protection Insulation Coordination Geomagnetic Disturbances and Their Effects on Power System Operations References Problems Limiting Factors for Extra-High and Ultra-High Voltage Transmission Introduction Corona Radio Noise Audible Noise Conductor Size Selection References Problems Symmetrical Components and Fault Analysis Introduction Symmetrical Components The Operator "a" Resolution of Three-Phase Unbalanced System of Phasors into its Symmetrical Components Power in Symmetrical Components Sequence Impedances of Transmission Lines Sequence Capacitances of Transmission Line Sequence Impedances of Synchronous Machines Zero-Sequence Networks Sequence Impedances of Transformers Analysis of Unbalanced Faults Shunt Faults Series Faults Determination of Sequence Network Equivalents for Series Faults System Grounding Elimination of SLG Fault Current by Using Peterson Coils Six-Phase Systems References Problems Protective Equipment and Transmission System Protection Introduction Interruption of Fault Current High Voltage Circuit Breakers Circuit Breaker Selection Disconnect Switches Load-Break Switches Switchgear The Purpose of Transmission Line Protection Design Criteria for Transmission Line Protection Zones of Protection Primary and Backup Protection Reclosing Typical Relays Used on Transmission Lines Computer Applications in Protective Relaying References Problems Transmission System Reliability Basic Definitions National Electric Reliability Council Index of Reliability Section 209 of PURPA of 1978 Basic Probability Theory Combinational Analysis Probability Distributions Basic Reliability Concepts Systems with Repairable Components Reliability Evaluation of Complex Systems Markov Processes Transmission System Reliability Methods References Problems Part II: Mechanical Design and Analysis Construction of Overhead Lines Introduction Factors Affecting Mechanical Design of Overhead Lines Character of Line Route Right-of-Way Mechanical Loading Required Clearances Type of Supporting Structures Mechanical Calculations Grade of Construction Line Conductors Insulator Types Joint Use by Other Utilities Conductor Vibration Conductor Motion Caused by Fault Currents References Problems Sag and Tension Analysis Introduction Effect of Change in Temperature Line Sag and Tension Calculations Spans of Unequal Length: Ruling Span Effects of Ice and Wind Loading National Electric Safety Code Line Location Construction Techniques References Problems Appendix A: Impedance Tables for Overhead Lines, Transformers, and Underground Cables Appendix B: Methods for Allocating Transmission Line Fixed Charges Among Joint Users Appendix C: New Trends and Regulation Appendix D: A Guide to the FERC Electric Transmission Facilities Permit Process Appendix E: Standard Device Numbers Used in Protection Systems Appendix F: Order No. 1000 of Federal Energy Regulatory Commission Appendix G: Unit Conversions from the English System to SI System Appendix H: Unit Conversions from the SI System to English System Appendix I: Classroom Example to Select Conductors for an EHV Transmission Line Design Appendix J: Additional Solved Examples of Shunt Faults Appendix K: Additional Solved Examples of Shunt Faults Using MATLAB(R) Appendix L: Glossary for Transmission System Engineering Terminology Index

Electric Power Transmission System Engineering: Analysis and Design

This paper presents a new possibilistic (fuzzy) model for the multiobjective optimal planning of power distribution networks that finds out the nondominated multiobjective solutions corresponding to the simultaneous optimization of the fuzzy economic cost, level of fuzzy reliability, and exposure (optimization of robustness) of such networks, using an original and powerful meta-heuristic algorithm based on Tabu Search. This model determines the optimal location and size of the future feeders and substations in distribution networks with dimensions significantly larger than the ones usually presented in papers on the matter. The model also allows to determine the optimal reserve feeders (location and size) that provide the best distribution network reliability at the lowest cost for a given level of robustness (exposure). The model and the algorithm have been intensively tested in real distribution networks, which proves their practical application to large power distribution systems.

Possibilistic model based on fuzzy sets for the multiobjective optimal planning of electric power distribution networks

This paper presents a multiobjective optimization methodology, using an evolutionary algorithm, for finding out the best distribution network reliability while simultaneously minimizing the system expansion costs. A nonlinear mixed integer optimization model, achieving the optimal sizing and location of future feeders (reserve feeders and operation feeders) and substations, has been used. The proposed methodology has been tested intensively for distribution systems with dimensions that are significantly larger than the ones frequently found in the papers about this issue. Furthermore, this methodology is general since it is suitable for the multiobjective optimization of n objectives simultaneously. The algorithm can determine the set of optimal nondominated solutions, allowing the planner to obtain the optimal locations and sizes of the reserve feeders that achieve the best system reliability with the lowest expansion costs. The model and the algorithm have been applied intensively to real life power systems showing its potential of applicability to large distribution networks in practice.

Reliability and Costs Optimization for Distribution Networks Expansion Using an Evolutionary Algorithm

The application of a branch-and-bound method to a heuristic circuit-optimisation algorithm for electricity distribution planning is described. The intention is to produce a family of near-optimal designs, to a given planning problem. The principal results of this approach are twofold. First, a clearer understanding of the complex network modelling problem is obtained, and secondly the imaginative development of branch-and-bound formulation for optimisation purposes is stimulated.

A Branch And Bound Formulation To An Electricity Distribution Planning Problem

This paper discusses and compares several synthesis methods for electricity distribution networks, assessing the validity of the feasibility constraints used in the various methods. Established methods, together with some original ideas, are explained; special reference is made to heuristics based on group-transfer concepts. The algorithms have been applied to data extracted from case studies to simulate a green-field synthesis of network configuration, thus results are comparable with existing network configurations. The results were produced using an interactive computing system.

C. C. Meckiff

Papers

A Branch And Bound Formulation To An Electricity Distribution Planning Problem

Comparative Analysis of Heuristic Synthesis Methods for Electricity Transmission Networks