Security-constrained Optimal Rescheduling of Real Power using Hopfield Neural Network

A new method for security-constrained corrective rescheduling of real power using the Hopfield neural network is presented. The proposed method is based on solution of a set of differential equations obtained from transformation of an energy function. Results from this work are compared with the results from a method based on dual linear programming formulation of the optimal corrective rescheduling. The minimum deviations in real power generations and loads at buses are combined to form the objective function for optimization. Inclusion of inequality constraints on active line flow limits and equality constraint on real power generation load balance assures a solution representing a secure system. Transmission losses are also taken into account in the constraint function

A Review of Recent Advances in Economic Dispatch

A survey is presented of papers and reports that address various aspects of economic dispatch. The time period considered is 1977-88. Four related areas of economic dispatch are identified and papers published in the general areas of economic dispatch are classified into these. These areas are: optimal power flow, economic dispatch in relation to AGC, dynamic dispatch, and economic dispatch with nonconventional generation sources

Analysis of Interrelationships Between Photovoltaic Power and Battery Storage for Electric Utility Load Management

The impact of photovoltaic power generation on an electric utility\u27s load shape under supply-side peak load management conditions is explored. Results show that some utilities utilizing battery storage for peak load shaving might benefit from use of photovoltaic (PV) power, the extent of its usefulness being dependent on the specific load shapes as well as the photovoltaic array orientations. Typical utility load shapes both in the eastern (at Rayleigh, NC) and in the western (at Hesperia, CA) parts of the USA are examined for this purpose. It is concluded that while photovoltaic power generation seems to present a bigger impact on the load of the western utility, both utilities will experience considerable savings on the size of the battery system required to shave the peak loads as well as in the night-time base capacity required to charge the batter

Input Dimension Reduction in Neural Network Training-Case Study in Transient Stability Assessment of Large Systems

The problem in modeling large systems by artificial neural networks (ANN) is that the size of the input vector can become excessively large. This condition can potentially increase the likelihood of convergence problems for the training algorithm adopted. Besides, the memory requirement and the processing time also increase. This paper addresses the issue of ANN input dimension reduction. Two different methods are discussed and compared for efficiency and accuracy when applied to transient stability assessment

Simulation of Photovoltaic Power Systems and Their Performance Prediction

A number of photovoltaic (PV) performance-analysis models are tested for their ability to estimate the AC power output and validated against historical observations from a PV test facility. A method to estimate meteorological parameters is developed for use in PV performance models for predicting future AC power output from a PV test site. Twelve such PV performance models are examined, and the PVFORM system analysis program and lifetime cost and performance models are extensively tested. These two models are tested using the typical meteorological year and the VPI model-generated estimates of long-term data. Performance prediction results are compared against actual observations at a 4 kW PV test facility. Results show that the VPI model-generated data, when used with the PVFORM model, provide the best predictions for AC power output from this 4 kW PV test facility

Superconducting Magnetic Energy Storage System (SMES) for Improved Dynamic System Performance

A Superconducting Magnetic Energy Storage System (SMES) consists of a high inductance coil emulating a constant current source. Such a SMES system, when connected to a power system, is able to inject/absorb active and reactive power into or from a system. The active power injected into the system is controlled by varying the duty cycle of the switches in the dc-dc chopper while the SMES coil is discharging into the system. The reactive power is controlled by the magnitude of the converter output voltage. The storage setup is tested on a WSCC 3 machine 9 bus system. The behavior of the system is tested for a three phase fault on the network at different locations. The transient behavior of the system is observed with and without the SMES unit. The SMES unit is able to damp out the post-fault oscillations within a short tim

Modeling LHP in carbon steel-1045 during quenching

The modelling of an axisymmetric industrial quenched carbon steel-1045 based on finite element method has been produced to investigate the impact of process history on metallurgical and material properties. Mathematical modelling of 1-Dimensional line (radius) element axisymmetric model has been adopted to predict temperature history and consequently the hardness of the quenched steel bar at any point (node). The lowest hardness point (LHP) is determined. In this paper hardness in specimen points was calculated by the conversion of calculated characteristic cooling time for phase transformation t8/5 to hardness. The model can be employed as a guideline to design cooling approach to achieve desired microstructure and mechanical properties such as hardness. The developed mathematical model converted to a computer program. This program can be used independently or incorporated into a temperature history software which named LHP-software to continuously calculate and display temperature history of the industrial quenched steel bar and thereby calculate LHP. The developed program from the mathematical model has been verified and validated by comparing its hardness results with experimental work results. The comparison indicates reliability of the proposed model. Keywords:, Heat Treatment; Quenching; Axisymmetric Chromium Steel Bar; Finite Element; Mathematical Modeling; Unsteady State Heat Transfer

Determination LHP of axisymmetric transient Molybdenum steel-4037H quenched in sea water by developing 1-d mathematical model

The modelling of an axisymmetric industrial quenched molybdenum steel bar AISI-SAE 4037H quenched in sea water based on finite element method has been produced to investigate the impact of process history on metallurgical and material properties. Mathematical modelling of 1-dimensional line (radius) element axisymmetric model has been adopted to predict temperature history and consequently the hardness of the quenched steel bar at any point (node). The lowest hardness point (LHP) is determined. In this paper hardness in specimen points was calculated by the conversion of calculated characteristic cooling time for phase transformation t8/5 to hardness. The model can be employed as a guideline to design cooling approach to achieve desired microstructure and mechanical properties such as hardness. The developed mathematical model was converted to a computer program. This program can be used independently or incorporated into a temperature history calculator to continuously calculate and display temperature history of the industrially quenched steel bar and thereby calculate LHP. The developed program from the mathematical model has been verified and validated by comparing its hardness results with commercial finite element software results. The comparison indicates reliability of the proposed model