THE HYDRO-THERMAL OPTIMAL POWER FLOW PROBLEM IN RECTANGULAR COORDINATES

Abstract

This paper considers the formulation and computational solution of the optimal power flow problem in hydro-thermal electric system. The problem is formulated using the cartesian coordinate form of the power flow equations. Here the hydro generation is energy limited. As a result, a dynamic optimization problem involving the daily scheduling of the system is encountered. This dynamic optimal power flow problem requires the solution of a large scale set of non-linear simultaneous equations. In this paper, Newton's method is used to solve the problem. Due to the large scale nature of the problem, we have exploited the sparsity of the Jacobian and developed three different versions of the algorithms and implementation of these versions have been detailed in this paper. In all cases, the algorithm has been successfully tested with six standard IEEE test systems varying in size from 5 bus to 118 bus. Computational results and the CPU times required by all of the methods are given. Results are compared with the results obtained by the earlier version using polar form for load flow constraints and it is shown that the sparse implementation using rectangular coordinates offers superior computational speed.     

过渡金属氢化物TMH（TM=Mo、TC、RU）的显微组织、电子特性和力学性能的第一性原理研究

通过基于广义梯度近似密度泛函理论的第一性原理研究过渡金属氢化物 TMH(TM =Mo、TC、RU)的显微组织、电子特性和力学性能。在被研究的5个晶体结构中,立方结构比六方晶结构更稳定。预测了不同过渡金属氢化物在高压下的相结构转变,如：MoH中从ZB结构到WC结构的转变、在TcH中从NaCl结构到NiAs结构的转变以及在RuH中从NaCl结构到ZB结构再到NiAs结构的转变。弹性常数的计算表明：三种氢化物的力学性能在环境压力下是稳定的。     

Numerical analysis of grid plate melting after a severe accident in a Fast-Breeder Reactor (FBR)

Fast breeder reactors (FBRs) are provided with redundant and diverse plant protection systems with a very low failure probability (<?10^???6/reactor year), making core disruptive accident (CDA), a beyond design basis event (BDBE). Nevertheless, safety analysis is carried out even for such events with a view to mitigate their consequences by providing engineered safeguards like the in-vessel core catcher. During a CDA, a significant fraction of the hot molten fuel moves downwards and gets relocated to the lower plate of grid plate. The ability of this plate to resist or delay relocation of core melt further has been investigated by developing appropriate mathematical models and translating them into a computer code HEATRAN-1. The core melt is a time dependent volumetric heat source because of the radioactive decay of the fission products which it contains. The code solves the nonlinear heat conduction equation including phase change. The analysis reveals that if the bottom of grid plate is considered to be adiabatic, melt-through of grid plate (i.e., melting of the entire thickness of the plate) occurs between 800 s and 1000 s depending upon the initial conditions. Knowledge of this time estimate is essential for defining the initial thermal load on the core catcher plate. If heat transfer from the bottom of grid plate to the underlying sodium is taken into account, then melt-through does not take place, but the temperature of grid plate is high enough to cause creep failure.     

OPTIMAL ECONOMIC OPERATION OF THERMAL AND VARIABLE HEAD HYDRO SYSTEMS USING HAMILTON-LAMONT'S MODEL AND NEWTON-RAPHSON METHOD

ABSTRACT

In this paper, optimum scheduling of an integrated hydro-thermal electric power systems with variable head hydro plants, is treated. The scheduling problem is solved by the use of coordination equations developed by Ricard and Kron. There are many reported models to represent the performance of a hydro plant, and here Hamilton-Lamont's model is used to derive specific optimality conditions for the problem. Using Newton-Raphson method, an algorithm is developed for solving iteratively the problem of optimal power scheduling. The iterative method is implemented using a specially designed initial guess estimator based on the physical properties of the problem to generate a set of feasible initial estimates of the unknowns to speed up the process. A number of example systems are used to test the performance of the algorithm. Successful convergence of the algorithm is reported in this paper and results for one sample test system are given.     

INFLUENCE OF HYDROXYPROPYL METHYLCELLULOSE ON THE RHEOLOGICAL AND MICROSTRUCTURAL CHARACTERISTICS OF WHOLE WHEAT FLOUR DOUGH AND QUALITY OF PURI

Puri is a traditional unleavened fried product prepared from whole wheat flour. Hydroxypropyl methylcellulose (HPMC) was used to study its effect on rheological characteristics of whole wheat flour dough and puri making quality. Addition of HPMC at 0.5 and 1.0% w/w increased the water absorption and dough stability whereas the resistance to extension and extensibility decreased. Pasting temperature, peak viscosity and cold paste viscosity gradually decreased. The moisture and fat contents of puri increased marginally. Quality parameters and sensory acceptability were monitored after 0 and 8 h of storage. Addition of 0.5% HPMC gave higher sensory scores. Microscopic observations during puri processing showed that the starch granules in the control dough were clearly visible in the protein matrix, which reduced on frying due to partial gelatinization. Microstructure of puri with HPMC showed higher gelatinization of starch. It also helped in moisture retention and hence, resulted in highly pliable and soft-textured puri .

PRACTICAL APPLICATIONS

Puri is a traditional unleavened fried product that is prepared by mixing whole wheat flour and water, sheeted to a desirable thickness and fried. Use of hydroxypropyl methylcellulose (HPMC) affected the whole wheat flour dough and puri making quality. It helped in moisture retention and hence, resulted in highly pliable and soft-textured puri . Microstructure of puri with HPMC showed higher gelatinization of starch.     

Spectro-meteorological modelling of sorghum yield using single date IRS LISS-I and rainfall distribution data

The yield of grain Sorghum cultivated in dry-land regions in India fluctuates widely in relation to its critical growth phases depending on the weather conditions. Vegetation indices derived form remote sensing data acquired at the time of maximum vegetative growth are indicative of crop growth and vigour and consequent potential grain yields. In this paper we investigate rabi (winter) sorghum yields using Indian Remote Sensing Satellite's Linear Imaging and Self Scanning-I (IRS LISS-I) sensor data and monthly rainfall distribution data of the recent four seasons for the 37 tehsils (sub-units of districts) that constitute the three principal sorghum producing districts of the central Maharashtra state (India). The multiple linear regression yield models with both the spectral and spectro-meteorological parameters have been developed for tehsil, as well as the district yields, by identifying critical parameters with model estimation errors of about 22 per cent on tehsil yields and about 5 per cent on district yields. The yields are found to be correlated significantly with monsoon rainfall about 1 to 2 months before sowing. This study brings out the problems of yield modelling of the semi-arid tropical crop in a small region using remote sensing data only, and shows that the vegetation indices deduced from remote sensing data are found to be good indicators of the yield on large spatial scales, as the effects of varying rainfall on yields largely cancel out.