Load Flow Formulation Research Articles

Real-Time Decoupled Equivalent Models for Static Security Analysis

This paper presents some new decoupled external system equivalent models for use in system security evaluation. Three different models i.e., decoupled Tie-line power flow model, decoupled Boundary bus Impedance model and decoupled Impedance-Admittance model are developed based on P-δ and Q-V relations of fast decoupled load-flow formulation. The structure component of the models are then identified by processing real time data using Kalman filtering technique. Then the operating components of the decoupled equivalents are obtained from two new approaches. The performance of the various models with regard to contingency analysis has been presented using simulated data on a 25 bus test system. Persistency analysis of different input-output data is given to determine apriori choice of models. Also the bias conditions are derived to ascertain the accuracy of the models.

Decoupled Economic Dispatch Using the Participation Factors Load Flow

This paper presents the concept of the participation factors load flow and applies it to the economic dispatch problem. The participation factors load flow consists of a load flow model where the quantities specified or controlled at the NG generation buses are the NG participation factors instead of NG-1 real generations. This formulation permits us to more realistically model the closed loop mode of generation dispatch used by control centers today. In contrast most modern economic dispatch algorithms based on the conventional load flow produce an open loop dispatch which cannot be directly implemented in the closed loop participation factors dispatch mode without additional computations. The numeric and analytic properties of this new load flow formulation are very similar to those of the conventional load flow with one significant difference, a slack bus need not be defined, a property which has various advantages. The new model permits the development of a decoupled economic dispatch scheme which directly computes the participation factors and separates the dispatching of real power quantities quite naturally from reactive power, voltage variables and transformer parameters.

Decoupled Economic Dispatch Using the Participation Factors Load Flow

This paper presents the concept of the participation factors load flow and applies it to the economic dispatch problem. The participation factors load flow consists of a load flow model where the quantities specified or controlled at the NG generation buses are the NG participation factors instead of NG-1 real generations. This formulation permits us to more realistically model the closed loop mode of generation dispatch used by control centers today. In contrast most modern economic dispatch algorithms based on the conventional load flow produce an open loop dispatch which cannot be directly implemented in the closed loop participation factors dispatch mode without additional computations. The numeric and analytic properties of this new load flow formulation are very similar to those of the conventional load flow with one significant difference, a slack bus need not be defined, a property which has various advantages. The new model permits the development of a decoupled economic dispatch scheme which directly computes the participation factors and separates the dispatching of real power quantities quite naturally from reactive power, voltage variables and transformer parameters.

Static transmission capacity expansion planning under uncertainty

This paper presents a new formulation of the static optimization problem in long-range transmission capacity expansion planning. A quantitative reliability technique is used in conjunction with a stochastic load flow formulation in order to accommodate uncertainty in system component availability and demand projections. The problem is solved using chance-constrained programming. Application of the formulation is demonstrated using the IEEE five-bus test system.

A Modified Newton Raphson Load Flow Technique and Its Use in Simulating Line and Transformer Outages

This paper presents a modified formulation of the Newton-Raphson load flow using the Cartesian coordinates to represent the bus voltages and system parameters. The suggested modification reduces the computer storage required for the Jacobian matrix and the cpu time required for obtaining a load flow solution. The proposed load flow formulation is then used in a technique which simulates the outages of lines and transformers. The outage simulation technique determines the bus power injections whose effects are similar to the outage and uses this information to calculate, upto a prespecified accuracy, the voltages and power flows in the post outage states. Some results of line outage simulations are included.