Sandoval Carneiro

A new heuristic reconfiguration algorithm for large distribution systems

Summary form only given. This paper presents a reconfiguration algorithm which is specially suited to large scale distribution systems. The algorithm uses a heuristic strategy that starts with the system in a meshed status, with all maneuverable switches closed. The choice of the switches to be opened is based on the calculation of the minimum total system losses, using a load-flow program. A refinement on this procedure, based on branch status exchange is described. The paper includes results and comparisons on test systems utilized in three classical papers published in the technical literature. Results obtained on a real large scale distribution system are also presented

A New Distribution System Reconfiguration Approach Using Optimum Power Flow and Sensitivity Analysis for Loss Reduction

This paper presents a new approach for distribution system reconfiguration (DSR) based on optimum power flow (OPF) in which the branch statuses (open/close) are represented by continuous functions. In the proposed approach, all branches are initially considered closed, and from the OPF results, a heuristic technique is used to determine the next loop to be broken by opening one switch. Then the list of switches that are candidates to be opened is updated, and the above process is repeated until all loops are broken, making the distribution system radial. This paper includes results and comparisons on test systems utilized in three classical papers published in the technical literature, as well as in a previous paper by the authors. Results obtained on a real large-scale distribution system are also presented

A Heuristic Constructive Algorithm for Capacitor Placement on Distribution Systems

This paper presents a heuristic constructive algorithm (HCA) for optimal capacitor placement on distribution systems. This is a nonlinear mixed integer optimization problem. In the proposed approach, the integer variables are represented using sigmoid function, thus interior point optimal power flow formulation can be applied to obtain sensitivity indexes based on Lagrange multipliers, reactive power, and bus voltage. The methodology is applied to two power distribution systems, and the results are compared with those obtained using a genetic algorithm approach.

Three-Phase Power Flow Based on Four-Conductor Current Injection Method for Unbalanced Distribution Networks

This work presents a new formulation for the power flow problem, with explicit representation of the neutral conductor and grounding. This methodology has been named the four-conductor current injection method (FCIM). The Newton-Raphson method is applied to solve the set of nonlinear current injection equations that are derived using phase coordinates, and the complex variables are written in rectangular form. The proposed algorithm can be used to analyze both balanced and unbalanced systems, meshed or radial, with controls and distributed generation, and is shown to be very efficient and robust for large scale systems.

Voltage control devices models for distribution power flow analysis

This paper presents the development of mathematical models for thyristor controlled series compensator (TCSC), for voltage regulator devices and for remote bus voltage control that are suitable to be used with the three-phase current injection method (TCIM) for power flow calculation. TCIM is a Newton method where the equations are written in rectangular coordinates resulting in a 6n/spl times/6n Jacobian matrix. The representation of a control device requires an augmented system of equations to incorporate the additional relationship between each control action and the controlled variable, resulting in an augmented Jacobian matrix. Practical distribution systems are tested and the effectiveness of the proposed formulation is demonstrated.

Transmission system expansion planning using a sigmoid function to handle integer investment variables

Summary form only given. This paper presents an optimum power flow (OPF) modeling algorithm that uses the primal-dual interior point technique to determine the best investment strategy in the transmission line expansion problem. In the proposed method the expansion decision (0 or 1) is mitigated by using a sigmoid function which is incorporated in the OPF problem through the modified DC power flow equations. The investment decision is taken using a new heuristic model based on enhanced sensitivity introduced by the OPF results. Additionally the transmission power losses are considered in the network model. The proposed methodology has been compared with methods available in the literature, using both a test system and an equivalent of the southeastern Brazilian system

Improvements in the representation of PV buses on three-phase distribution power flow

This letter describes a new voltage controlled bus (PV bus) representation in connection with the three-phase current injection method-TCIM of power flow analysis. This representation requires an augmented system of linearized equations to incorporate the reactive power as a dependent variable. Tests and comparisons between the former and the new approach are described and the improved stiffness of this new proposition is demonstrated.

A Comparative Study on the Performance of TCIM Full Newton versus Backward-Forward Power Flow Methods for Large Distribution Systems

This panel discussion summarizes performance comparisons between the well-known backward-forward sweep and a Newton load-flow algorithm when applied to large scale three-phase distribution systems. The three-phase current injection method-TCIM, applies the full Newton method to solve the nonlinear current injection equations which are derived using phase coordinates, and the complex variables are written in rectangular form. This summary intends to discuss simulation results obtained using some practical large scale distribution systems

A Three-Phase Optimal Power-Flow Algorithm to Mitigate Voltage Unbalance

This paper describes a new methodology for three-phase electrical system optimization, in which the phase unbalances are to be taken into account. A formulation for the three-phase optimal power-flow solution was developed using the primal-dual interior point method and the three-phase current injection method in rectangular coordinates. The Hessian matrix has a 6 × 6 blocked structure, where most of the elements are constant or equal to zero during the solution process. This characteristic brings computational efficiency when applied to three-phase systems.

Roadmap for the IEEE PES test feeders

The Distribution System Analysis Subcommittee (DSAS) of the IEEE PES Power System Analysis, Computing, and Economics Committee has been developing benchmarks for distribution system analysis tools. A number of test cases have already been developed may be easily downloaded on the Internet. Other test cases have been requested. This paper describes the purpose and planned direction for these test cases in the near future. Participation from the power industry is solicited.