http://hdl.handle.net/20.500.12228/57 Tue, 21 Apr 2026 10:20:00 GMT 2026-04-21T10:20:00Z http://hdl.handle.net/20.500.12228/449 Some Aspects of Generation Expansion Planning Azad, Dr. Md. Abul Kalam The primary objective of generation expansion planning is to meet the electrical energy needs of the customers as economically as possible with an acceptable degree of safety, reliability, and quality. Power system planning involves studies to determine the resources required to meet the growth in demand at the lowest possible cost considering environmental and financial constraints. A power utility should meet the demand under a wide range of normal, abnormal, and emergency conditions including the reasonable foreseeable failures and maintenance outages of facilities. This requires some generation system capacity reserve in excess of forecasted demand. The uncertainty associated with future demand projections could make the system facilities inadequate, or excessive and uneconomical, both cases being unacceptable. Purchasing cheaper power from other utility through interconnection is another alternative which improves system reliability. in this thesis, some studies have been made on generation expansion planning taking into account the above important criteria. The thesis contains a brief research background, motivation and objective to the modelling and analysis of some important requirements of generation expansion planning. The proposed techniques are implemented to an existing electric utility for generation expansion. The key to all generation expansion planning is a good forecast of load that reflects current and future trends, tempered with good judgment. This is quite important for financial success. Undoubtedly, the most obvious deficiency in any expansion plan is and eventually is seen to be, the accuracy of the demand forecasts. Four modules of Artificial Neural Network have been studied in detail, to forecast peak load of two distribution substations. It is observed from the sensitivity analysis that all modules are not valid for all systems. In other words, for a specific system only a particular module is suitable for load forecasting. It is also found that the predicted results of minimum mean absolute error (MAE) is dependent on learning rate and learning momentum. Using the findings of the sensitivity analysis, various modules of ANN are studied and the most suitable module found is used to forecast yearly peak load of an existing electric utility for fifteen years choosing an appropriate module for the system. Reliability criterion, the next aspect, is primarily used to determine the required S stein generating capacity reserve, to operate the system under equipment failures, equipment maintenance, and load variations. Probabilistic methods are used to evaluate reliability of generation expansion plans using stochastic representation of the generating unit failure-repair process, load variability and emergency help from interconnections. A modified FFT method has been proposed to evaluate the loss of load probability (LOLP) of a power generating system consisting of different types and sizes of unit. This approach uses hourly loads, or any suitable time interval for system demand, for a given period. Out of several properties of FFT scheme, some properties have been used for the reduction of computational complexity. The accuracy of the method has been illustrated using an example. This modified FFT algorithm is applied to IEEE Reliability Test System (IEEE-RTS). The modified approach improves the efficiency in comparison to the conventional FFT method. Further, another new approach has also been developed to evaluate the LOLP of a power generating system. This approach uses joint probability density function (PDF) concepts to convolve the unit outages and loads of the system. The reduction of computational effort for identical generating units is obtained using the binomial distribution. The method has been illustrated through an example and is applied to IEEE-RTS. This method is found efficient and easy to use as compared to other existing methods. In addition, the proposed approach can simulate multistate representations of generating units at less computational efforts. Exploiting these advantages of the proposed approach, generation expansion planning of an existing utility has been made based on levelized LOLP for projected future demand. In generation expansion planning, interconnected system may play an important role on system reliability. Reliability evaluation methodology of interconnected systems is different from that of a single area system. If the available capacity in one geographical region can be transmitted to other regions whenever it is needed without tie line restrictions then and only then, this system may be treated as a single area. Though it is possible to evaluate interconnected systems as a single system with some approximation, but, it is not in practice due to many obvious reasons. The improved modified FFT scheme, developed for single area, has been extended to evaluate LOLP of two area interconnected power systems. A stochastic procedure for interconnected systems is presented using improved two dimensional FF'T IMSL subroutine of Cyber 180/840A mainframe. This method can simulate multi-state generating units without affecting the computational complexity, whereas the computational complexity of other existing methods increases with the increase of number of outage states of generating units. The joint PDF approach, developed for single area, has also been applied to evaluate LOLP of two area interconnected power system consisting of different types and sizes of generating units considering independent as well as correlated system demands. The Probability Density Function (PDF) of equivalent load is obtained by convolving the PDF of generating unit outages with the PDF of system demands using the proposed approach. The LOLP values of each system are obtained from the PDF of equivalent load. The accuracy of the proposed method has been illustrated using a simple example. The results obtained for IEEE-RTS are compared with existing methods. In addition, the above approach is also implemented to an existing utility for which expansion planning studies were carried out. The system under study is considered to be interconnected with a hypothetical system. The benefits desired due to interconnection are evaluated and the impact of interconnection on expansion planning is studied. An efficient approach has been developed to evaluate the expected energy generation, expected unserved energy, production costs (in the thesis production cost is used for fuel cost) and loss of load probability of a power generating system. The expected energy generation of a given generating unit is obtained by evaluating the difference of unserved energy before and after the commitment of the unit. The method can evaluate expected energy generation and production costs of identical generating units at a time. This is not restricted to load duration curves and unit outage density function of any shapes, or size of the systems with a large number of generation units. Multiple generating units with same outage behavior can be committed with system demand efficiently. The new developed approach has been extended to evaluate the expected energy generation, expected unserved energy and production costs for two area interconnected power generating system. An example and IEEE-RTS have been used for illustration. Further, the proposed method has been used to evaluate expected energy generation, unserved energy and production cost of the generation expansion plan developed for existing utility under study. Based on the detailed study, addition of generating units for the existing utility has been recommended for the period under consideration. Reliability index is derived from the estimates of availabilities of generating units, forecasted loads and unit incremental costs. Uncertainty which results in an unacceptable estimates of system reliability is implicit in the estimates of availability of units and forecasted loads. The uncertainty in the availability of generating units is due to the variation of failure data for different reporting sources and fluctuation in environmental conditions. Fuzzy set theory provides optimistic and pessimistic values of the derived quantities, corresponding to the assumptions of the highest and lowest possibilities of concerned events. In many cases, these bounds provide excellent guidelines to the generation expansion planners. A model has been developed for fuzzy reliability to quantify the effect of uncertainty associated with unit capacity, FORs and the forecast loads on the LOLP of a power generating system. The model has been explained with the help of a simple generation system. Studies are also conducted on the IEEE-RTS to demonstrate effect of uncertainty on system parameters. Effects on the system reliability index due to variation in the amount of uncertainty of the parameters is studied. This proposed model has also been applied to a practical system to predict fuzzy LOLP. This thesis is submitted to the Department of Mechanical Engineering, Indian Institute of Technology in partial fulfillment of the requirements for the degree of Doctor of Philosophy.; Cataloged from PDF Version of Thesis.; Includes bibliographical references (pages 225-243). Mon, 01 Apr 1996 00:00:00 GMT http://hdl.handle.net/20.500.12228/449 1996-04-01T00:00:00Z http://hdl.handle.net/20.500.12228/448 Parameter Adaptive Vector Controller for CSI-fed Induction Motor Drive and Generalized Approaches for Simulation of CSI-IM System Ghosh, Dr. Bashudeb Chandra The main subject matter of this dissertation is to develop parameter adaptive rotor flux oriented current fed induction motor drive systems for controlled speed operation. The parameter adaptive approaches do not require special test signals and softwares in a big way. Three easy-to-implement schemes are suggested. One scheme is based on airgap power estimation method and takes into account of the non-linear magnetic state while tracking the actual rotor resistance. The other two methods constitute model reference adaptive controllers. They are based on the inverter input voltage and torque producing component of the stator current. The effectiveness of these methods is examined by extensive simulation and experimentation with two laboratory type induction machines. The experimental set up makes use of two microcomputers (i-8006 with i-6007) and a PC/AT with Burr Brown's PCI system having multi-channel 12 bit data acquisition modules for implementing the control algorithms. Prior to the description of parameter corrective algorithms, a control system suitable for a CSI-fed induction motor under rotor flux orientation is designed and tested by suitable simulation model. Then the influence of rotor resistance variation in the presence of magnetizing flux saturation has been extensively investigated. A two-parameter saturation model (two-term quintic non-linearity) is used in all these studies. It is further shown how the machine performances under field oriented condition are affected inclusion of saturation characteristics. Analytic expressions as well as digital simulation procedures are presented to study the performance of the drive system. Robustness of the drive system has been studied applying the concept of Kharitonov's theorem and then justified from the simulation results of the system for both parametric and torque disturbances. 'Bond Graph' and 'Nodal method' provide an organised way to write equations for a dynamic system. Tedious way of writing equations and their arrangement and re-arrangement for framing state equations can be avoided in the proposed simulation techniques. Simulation studies based on systematic modelling and framing of the system equations using the above two methods for the operation of a speed controlled CSI-IM system under normal and abnormal conditions have also been provided. This thesis is submitted to the Department of Electrical Engineering, Indian Institute of Technology in partial fulfillment of the requirements for the degree of Doctor of Philosophy, July 1992.; Cataloged from PDF Version of Thesis.; Includes bibliographical references (pages 281-295). Wed, 01 Jul 1992 00:00:00 GMT http://hdl.handle.net/20.500.12228/448 1992-07-01T00:00:00Z http://hdl.handle.net/20.500.12228/272 Planar Electromagnetic Bandgap Structures and Applications Mollah, Md. Nurunnabi With the emergence of novel wireless technologies, the demands for larger bandwidth, high efficiency and high capacity RF and microwave devices have been growing tremendously. To satisfy the demand novel materials, new processing techniques and refinement of existing devices have been evolving. Using electromagnetic bandgap (EBG) is a new technology to improve the performances of existing RF active and passive devices. EBG structures (EBGSs) are periodic structures, which exhibit distinct passband and stopband characteristics. The passband can be used as phase shifters and slow wave structures. The stopband characteristics can be used to suppress surface waves in dielectric media. Due to these unique properties, EBGSs find potential applications in many active and passive RF and microwave devices including antennas, filters, amplifiers and oscillators. Recently, the dispersion properties in passband of EBGSs are used in the phased array antennas for wide angle beam steering. Among various EBG configurations, planar EBGSs become most popular due to their low profile, ease of fabrication and integration with monolithic microwave integrated circuits (MMICs). The thesis concerns the planar EBG structures in the forms of conventional circular and rectangular photonic bandgap structures (PBGSs) and defected ground structures (DGSs). Novel PBGSs in the form of non-uniform Binomial and Chebyshev distributions of unit PBG cells have been proposed. This novel PBGSs yield ripple free passband and wide stopband properties, which are very useful to suppress higher order harmonics in the bandpass filters. Next the chirped PBGSs are investigated that yield better passband return loss, low ripples and wider stopband than those for conventional PBGSs as well as non-uniform PBGSs mentioned earlier. The parametric study of dumbbell shaped DGSs has been conducted with the gap width and length and the size of dumbbell slots. Three novel designs are proposed: non-uniform dumbbell shaped DGSs with Chebyshev distribution, hybrid DGS and PBG and modified hybrid DGS and PBG configurations. The novel designs outperform the conventional DGSs reported in the literature. The DGSs yield perfect LPF responses with negligible passband ripples and extremely wide stopband. The modified hybrid DGS and PBG configuration yields dual stopbands that can be used as a dual stopband filter. The novel design are used in asymmetric coupled line bandpass filters, aperture coupled single band and dual-band patch antennas and finally in 4-element conventional and reconfigurable phased array antennas. For filters, PBGSs suppress second and third harmonics by about 40 dB, A comprehensive investigation of the number, filling factor and position of the PBGS under the filter has been conducted. The frequency response of the filter has been observed. This investigation is novel and illustrates the significance of PBGSs in suppression of higher order harmonics of the bandpass filters. It has been found that non-uniform distribution of PBGSs is more effective to suppress higher order harmonics than the conventional uniform PBGSs. DGSs are very effective for simultaneous suppression of both 2nd and 3rd harmonics due to their very wide stopband performances. This phenomenon of DGSs has been demonstrated in various designs of asymmetric coupled line bandpass filters. Finally, the passband phase properties of the PBG and DGS have been investigated. The comprehensive investigations of relative phase delays of PBGS and DGS assisted microstrip transmission lines have been performed. Such investigation is not found in the open literature. It is observed that DGSs yield much larger phase delay compared to a similar size PBG structure. Therefore, DGS assisted feed network can scan the beam over a wide angle. After thorough and satisfactory investigation of phase delays for PBGSs and DGSs, phased array theory is studied. The required phase delays for a 4-element phased array are calculated based on the element spacing and number of elements. A wide beam scanning up to approximately 60° is achieved with 0-8-16-24 DGS assisted corporate feed network for the 4-element patch antenna array. So far such wide angle scanning using DGS assisted beamforming network has not been reported in the open literature. This thesis is submitted to the Nanyang Technological University in fulfillment of the requirement for the degree of Doctor of Philosophy in Electrical & Electronic Engineering, March 2005.; Cataloged from PDF Version of Thesis.; Includes bibliographical references (pages 265-278). Tue, 01 Mar 2005 00:00:00 GMT http://hdl.handle.net/20.500.12228/272 2005-03-01T00:00:00Z http://hdl.handle.net/20.500.12228/271 Protection of the Inter-Tie between an Industrial Cogenerator and a Utility Mollah, Abdur Rahim The work presented in this thesis is concerned with the development of a microprocessor based technique to detect and locate symmetrical and unsymmetrical faults on the interfacing network of a utility interconnected industrial cogenerator system; and to identify the type of the detected fault. In order to provide operational flexibility and supply security to such an interconnected industrial cogenerator plant, fault location is regarded as being of prime importance. Current protection practices using conventional technology for this sort of interconnected cogeneration system were reviewed. A relay coordination study was carried out on a simulated utility interconnected cogeneration system. This resulted in identification of the problems and limitations of the application of standard IDMT relays for overcurrent protection of such a system. A review of digital protection, and its various algorithms, was undertaken. This provided the basis for a rational choice of algorithm for the proposed new technique. The sequence of functions of the protection scheme's algorithm, based on the proposed technique, can be presented in brief as follows: First, phase currents at selected positions on the system are sampled. The positive phase sequence (pps) currents at those positions are then obtained in digitised form from the sampled phase currents. Then, these pps currents, containing fundamentals along with other harmonics and dc offsets, are used in a Fourier filtering algorithm to extract only fundamental components in rectangular forms. Signs of imaginary parts of these components are then used to determine the directions of pps currents at the selected positions. The industrial bus voltage is used as the polarising reference. Finally these directions are based in a fault detection aridlocat1on subroutine to determine the location of any fault under such conditions. After detecting a fault and locating its position, the type of fault is determined from off-line analysis of the postfault phase currents. The analysis is based on identifying the phases carrying the maximum fault current and checking the presence of zero sequence current. The proposed protection scheme has been tested on a computer simulated system which consists of a utility interconnected to an industrial plant with cogeneration. The performance has been found to be satisfactory for all kinds of solid and low are resistance faults anywhere on the interfacing network between the systems. This thesis is submitted in partial fulfilment of the requirements of the Council for National Academic Awards for the degree of Doctor of Philosophy in Electronic and Electrical Engineering, November 1990.; Cataloged from PDF Version of Thesis.; Includes bibliographical references (pages 173-180). Thu, 01 Nov 1990 00:00:00 GMT http://hdl.handle.net/20.500.12228/271 1990-11-01T00:00:00Z