H. A. Mangalvedekar

Cascading Failure Analysis for Indian Power Grid

Major power grid blackouts in various parts of the world are characterized by voltage collapse. This paper studies the blackout case in the Indian power grid due to voltage collapse in the inter-regional corridor. First, the computer simulation models are tuned to match responses from the phasor measurement units at various locations in the grid. The inter-area mode with the frequency of 0.3 and 0.5 Hz with reduced damping were observed and resulted due to switching actions that occurred during the disturbance. This paper simulates the complex power grid network for various loading conditions of Northern region using power system simulator for engineering. Further, the system variables are analyzed using Prony method to estimate the inter-area mode for different NR loading conditions. The eigen values associated with the 0.3 Hz mode depict the movement from open left half plane into open right half plane with a slight increase in the parameter indicating “hopf bifurcation.” This paper also discusses the maximum loading capacity for the inter-regional lines in-order avoid loss of small signal stability, and highlights the use of real time phasor measurement unit measurements in-order to estimate and track the oscillatory modes.

Mathematical Modeling of Steam-Water-Vapor-Space with Mfact-Vfact Approach Using Combined Steam Properties

Computational complexity of a software model is directly related to its mathematical model. Mathematical modeling of Saturated Steam and Water Spaces is a challenging problem due to the involvement of complicated equations and steam tables. A simple modeling technique results in better turnaround time. This paper proposes a simple and quick approach for modeling steam water vapor spaces by efficiently combining suitable steam and water properties. This approach is computationally efficient and reduces the model development time considerably. It enables easy integration of steam water vapor space models with other models and easy deployment in parallel processing and other high performance computing environments.

Synchrophasor Based Oscillatory Mode Source Identification: A Case Study Indian Grid

Power grid is one of the complex networks and is subjected to disturbances which manifest in the form of oscillations in system. The presence of unstable oscillations in the system sustained for a longer time period may disrupt the grid operation. Thus monitoring and detecting unstable oscillations is necessary for reliable, stable and secure operation of the system. Identifying the source of these oscillatory modes is also necessary in-order to damp them. This paper reports a case study of an event leading to loss of generation in the Northern Region of the Indian power grid and identifying the source of oscillations using measurement based methods. With the availability of synchrophasor measurements the ability to locate the source of the disturbance by performing modal analysis in real time will help the grid operator to take quicker actions for stable operation of power system.

Analysis of HTEM Horn-Type Antenna for High-Power Impulse Radiation Applications

High-power microwaves are generated using high voltage (HV) pulses, which are generated using a Marx generator connected to a peaking stage. The output of the peaking stage is the input to the half transverse electromagnetic (HTEM) horn-type antenna. This paper discusses the effect of isolation distance between HV tapered arm and the grounded reflector on the variation of characteristic impedance and gain with respect to the length, flair angle, and tapering angle of the antenna. This paper also discusses the radiation loss on the side and back of antenna. An experiment has been described using an available Marx generator and HTEM antenna. Using the experimental and simulation results, the optimal design parameters of antenna are obtained.

Analysis of half TEM horn antenna for high power UWB system

This paper discusses the UWB system consisting of a high voltage low rise time pulse generator feeding the pulse to an antenna. The modeling and analysis of half transverse electromagnetic (HTEM) horn type antenna with an input feed of 25 ns and 5 ns rise time and voltage of 113.75 kV is studied. The electrodynamic modeling is done using CST microwave studio software. The E far field intensity is simulated and compared with experimental result. A mathematical model is developed in MATLAB Simulink to calculate response of step input on E far field radiation.

Development of Transfer Function Model and Analysis of the Peaking Capacitor and Switch

This paper discusses the development and analysis of a transfer function model of the peaking capacitor and peaking switch for an input from Marx generator and an output across load. The effect of variations of gap distance, pressure, peaking capacitor, and the input pulse rise time on the rise time of the output pulse is simulated using this model. For a given geometry, the modeling gives an optimum input pulse rise time and the effect of variation of peaking capacitor on various output parameters. The results obtained from modeling are validated with the experimental results.

Modelling of a spark gap switch

High voltage Marx generator along with a high pressure spark gap switch is a key component in systems that generate high power microwaves. This paper presents modelling and analysis of high pressure spark gap switch. In this paper, the three-dimensional static and dynamic electromagnetic spark gap model is simulated using computer simulation technology (CST) electromagnetic studio and microwave studio. The resistance and inductance model of the switch is developed and analysed to study the peak voltage of the output pulse generated by the switch for gases under different pressure.

Mathematical modeling of unbounded spaces using single-equation-based point saturated steam water spaces

Purpose Industries, especially power plants, using steam as power fluid employ many equipment and systems using saturated steam. Mathematical modeling of this saturated steam water space (SSWS) equipment is important for simulators catering to these industries and power plants. Single-equation-based modeling approach and its optimized version, mass factor–volume factor approach, are very efficient in modeling SSWS with bounded volumes, where the volume of the space is fixed. In unbounded volumes, the volume may be changing or is unbounded because of expansion, contraction or pressure control. The purpose of this paper is to propose a single equation based modeling approach for unbounded SSWS. Such unbounded volumes are encountered in coolant channels of pressurized heavy water reactor (PHWR)-type nuclear power plants (NPPs). Design/methodology/approach This paper proposes an extension of a single-equation approach by considering a subsection of the volume as miniature Point SSWS. In the proposed Point SSWS, the total heat, mass and volume of the SSWS are delinked and overall density and heat density are introduced in place. With this extension, Point SSWS can be applied to unbounded volumes. Findings In this study, 392 coolant channels of proposed 680 MWe PHWR have been simulated to ascertain the overall coolant density when coolant boils partially on nuclear heating. The simulation results have been compared with simulation results available from previous researchers and it has been found that the values are in line with previous researchers with maximum deviation of 1.2 per cent. Originality/value From the simulation results and their low value of deviation, it is clear that point space approach can be effectively used in modeling Point SSWS. Moreover, theoretically, it has been proved that the density of homogenous steam–water mixture is dependent only on the bulk heat density and temperature of the mixture.

Particle in cell simulation of peaking switch for breakdown evaluation

Marx generator connected to peaking capacitor and peaking switch can generate Ultra-Wideband (UWB) radiation. A new peaking switch is designed for converting the existing nanosecond Marx generator to a UWB source. The paper explains the particle in cell (PIC) simulation for this peaking switch, using MAGIC 3D software. This peaking switch electrode is made up of copper tungsten material and is fixed inside the hermitically sealed derlin material. The switch can withstand a gas pressure up to 13.5 kg/cm2. The lower electrode of the switch is connected to the last stage of the Marx generator. Initially Marx generator (without peaking stage) in air; gives the output pulse with peak amplitude of 113.75 kV and pulse rise time of 25 ns. Thus, we design a new peaking switch to improve the rise time of output pulse and to pressurize this peaking switch separately (i.e. Marx and peaking switch is at different pressure). The PIC simulation gives the particle charge density, current density, E counter plot, emitted electron current, and particle energy along the axis of gap between electrodes. The charge injection and electric field dependence on ionic dissociation phenomenon are briefly analyzed using this simulation. The model is simulated with different gases (N2, H2, and Air) under different pressure (2kg/cm2, 5kg/cm2, 10kg/cm2).

PPPS-2013: Abstract: Analysis of half TEM horn antenna for high power UWB system

Ultra Wideband (UWB) system has many applications such as target object detection, transient radar, mine clearing, detection of crack on underground pipeline, water purification, electronic effects testing, and jamming. This system consists of Marx generator, peaking capacitor, peaking switch and radiating element (antenna). The complete transient analysis of half transverse electromagnetic (HTEM) horn antenna integrated to the peaking stage is modeled in CST microwave studio. The simulation model has triangular excitation input pulse feed to the peaking stage with 25 ns rise time, 150 ns pulse width and 113.75 kV peak amplitude. The radiated E far field is measured at 15 m distance gives the rise time 232 ps, pulse length 25 ns, and peak amplitude 14.886kV/m. The experiment for the same has been conducted and the E field is measured up to 50 m distance. The radiated field in the experiment is measured in open air. The amplitude of the maximum radiated far field, measured by using B dot sensor probe at different distance is match with the modeling results. The mathematical model is developed in MATLAB Simulink to calculate effect of step input on E far field radiation.