ABSTRACT LIST

THE JOURNAL OF CPRI (Vol. 6, No. 2) September 2010

1. Investigation of Insulation Performance of High Voltage Rotating Machines using Intelligent Techniques

K.Sathiyasekar, K.Thyagarajah & A.Krishnan

The condition of insulation performance of a high voltage rotating machine has been

analyzed using Back Propagation Neural Network (BPN), Fuzzy logic and BPN network with Proportional Integral and Derivative (PID) controller concept along with slope

parameter. The economic aspects of its periodic maintenance, the loss in production due to breakdown, the investment cost due to frequent replacement with a new machine is huge. The insulation condition of the machine can be assessed by measuring the various

parameters like capacitance, leakage current, dissipation factor, polarization index, surge voltage withstanding strength and partial discharge magnitude. To assess these parameters of the insulations used in high voltage rotating machines, a number of

measurements have been made on actual stator coils of machines. For various test voltages, the capacitance, leakage current and dissipation factor are measured and correlated as a function of test voltages. It is observed from the simulation results that

BPN with PID techniques gives accurate results, predicting the performance of stator winding insulation.

2. A Low Cost Digitally Controlled Brushless DC Motor Drive

Designing

V. M. Takodia, J. J. Patel & M. A. Mulla

This paper presents a low cost, digitally controlled, closed loop BLDC motor drive.

Normally encoder feedback is required to get a speed feedback between two hall sensor status changes, for robust controller designing. With a view to reduce the cost, in this design an encoder feedback is avoided and moving average speed

estimation with variable Kp-Ki PI controller is realised. The digital controller Cortex M3 ARM microcontroller LM3S2616 is implemented with only hall-sensors feedback and variable Kp-Ki PI controller algorithm. The experimental setup is verified by

loading motor from no load to full load as well as with continuous and impact load. Serially, motor parameters like speed, current are gathered on PC and analysed, they confirmed the simulated results.

3. Development of Small Signal Analysis Package using FACTS Devices for Dynamic Stability Enhancement in Multi

machine Power Systems

J.Gokula Krishnan & N.Senthil Kumar

This paper presents a systematic method of developing the mathematical model for

small signal stability analysis of power system using different types of FACTS device namely (i) SVC (ii)STATCOM (iii) TCSC (iv) SSSC and (v) UPFC. In this paper, the two axis model of the synchronous machine is used for investigating the small signal

dynamic behavior of the multimachine power system. Local stabilizing signals such as real power perturbations, bus voltage deviations are used as control inputs for the damping controllers in FACTS devices. A nonlinear optimization model is developed

which tunes the gains, time constants of the FACTS based damping controllers in the stabilizing loop. Case studies are carried out on the standard WSCC 3 Machine 9 –

Bus system and the 10 Machine, 39 bus New England system. All computations are carried out using MATLAB v7.6.

4. Digital Real Time Simulator for Testing of Load Shedding

Controllers

Meera K.S., J.Sreedevi and R.S. Shivakumara Aradhya Load shedding is one the main actions that can be used to prevent complete black

out in industrial plants during grid disturbances. In case of grid disturbances it is essential to isolate the industrial plant units from the grid as quickly as possible to save the system. In importing mode of operation, it is essential that after grid

isolation the generators pick up additional power to meet the plant loads. If adequate generation is not available, loads have to be shed to achieve load-

generation balance. The load shedding schemes are designed based on various factors such as - power

import before isolation., excess margin available in inplant generators to pick up further load, response time of governors to changeover from constant power mode to isochronous mode, rate of change of frequency and actual frequency at the time

of isolation etc. Thus, such schemes are to be tested under realistic power system conditions including the protections used for islanding the system from Grid. Testing of load shedding schemes requires the use of advanced testing tools to ensure both

protection functions and control logic to be tested using dynamic simulations. In this paper, use of Real Time Digital Simulator (RTDS) at Central Power Research Institute, Bangalore for testing of intelligent load shedding controllers is discussed. It

is shown that these controllers can be pre-commissioned and tuned, while connected to the simulator in a closed loop.

5. A Novel Implementation Of Pspice Modeling For Reliability Analysis Of Distribution Systems

G.N.Sreenivas, P.Srividyadevi, M. Deepti Lavanya and V.Sankar

In this paper, Markov processes for determining the reliability indices of

distribution system are discussed. The continuous Markov modeling is applied to a complex radial distribution system and electrical equivalent circuits are developed for the modeling. In general PSPICE is being used for electrical and electronic circuits and various applications of power system like fault analysis, transient analysis etc. In this paper, the SPICE modeling equivalent circuits which are developed are applied in a novel way to Distribution System reliability analysis. These circuits are simulated using PSPICE software to obtain the state probabilities, the basic and performance indices. Thus the basic indices and the performance indices obtained by this method are compared with those obtained by FMEA technique. The application of the concepts presented in this paper are illustrated and analyzed for the IEEE -Roy Billinton Test System (RBTS)

6. Minimizing monsoon load dips in coal fired thermal power

plants

M.Siddhartha Bhatt and N.Rajkumar

Thermal power plants operating on low grade high ash coals experience capacity and performance drops during the rainy season. The parameters like plant load

factor (PLF), specific oil consumption (SOC), auxiliary power (AP), station load are affected. There are two types of effect: effect of heavy incessant rains for a period

of 1-3 days which result in capacity dips and continuous decrease in parameters over the 2-3 months monsoon season caused by decreased handling capacity and flow of coal. The effect of monsoons is quantified in terms of deviation in the

operating parameters by a study of several stations over a wide geographical range. Typically for a 1 to 3 GW station for short duration (1-3 days) peak load dips of the order of 25-35 %, SOC increase to 25-30 ml/kWh and AP increase by 2-3 % of gross

generation are experienced during heavy rainy periods. Instantaneous load dips (2 h duration) can be much higher. For the monsoon season the dips in monthly PLF can be 30-35 %, SOC can be 6-12 ml/kWh, auxiliary power increase is 1.5-3.0 % of

gross generation and forced outage % can increase to 4-5 times of the non-monsoon values. The stations need to gear up to the demands of the rainy season through several

preventive and control measures. A monsoon management plan needs to be in place for handling O & M in this period on the fuel front as well as on the boiler front. Well planned monsoon management can reduce severity of the power dips to less than

15 % of the peak load.

7. Energy efficiency improvement in coal fired thermal power plants through optimization of starts

M.Siddhartha Bhatt, Rajashekar P. Mandi and N.Rajkumar

This paper presents a review the impact of transient operations in coal fired thermal power plants on the unit heat rate (UHR). Once a tripping occurs, fuel oil, auxiliary

electric power, steam and coal is consumed to restore the unit back to its original plant level. From boiler light up to almost 20 % load, there is virtually no net generation from the unit. From 20 % load to 80 % load, the energy efficiency is

quite poor and uneconomical because of high auxiliary power and fuel oil support. The annual impact of transient operations is almost 40-50 kcal/kWh in many stations and this can be brought down to nearly 20 kcal/kWh by reducing the number of

trippings as well as the resource consumption during these operations. The outage period also need to be brought down from nearly 60-80 hours/outage down to 30-40

hours/outage

8. Least Cost Integration Of Solar Energy Technologies Into

Fossil Power Plants

M.Siddhartha Bhatt

This paper presents the optimal integration of solar energy into coal fired power

plants. The solar thermal energy can be integrated through augmentation of heating of make up water in the turbine cycle without any other additional equipment and without interfering with the primary process. Solar photovoltaic (PV) power can be

integrated through supplementing the DC emergency loads by charging the battery systems in the power plant. For a 250 MW coal fired plant, a solar flat plate collector area of ≈ 8,000 m2 would reduce heat rate by 0.26 %. A PV capacity of 2

MW would be able to provide a continuous capacity of 440 kW to meet the DC loads in normal course and emergency requirements (1 h of autonomy). The capital cost for solar thermal collectors would be around Rs. 7.9 crores and for solar PV it is

around Rs. 16 crores. The payback period is around 4.6 years for solar thermal and 10 years for solar PV systems.

9. Effect of Thermal Spraying & Plasma Nitriding Treatments

on Fatigue Life of En-24 Shafting Steel

U. N. Puntambekar, G. S. Grewal, P. B. Joshi, P. Sampathkumaran and T. P. Govindan

In the present work, the fatigue strength modification factors for a number of surface engineering treatments on EN-24 shafting alloy steels have been

investigated. The surface treatments include, thermal spraying with Alumina & Zirconia & Plasma nitriding with & without white layer. For this purpose, Basquin

type relationships for alternating stress versus cycles to failure have been developed. Based on these relationships, the surface treatment modification factors in terms of

power law relationships have been evolved.

10. Robust Three Phase Silicon Carbide Heaters Controller Designing

M. D. Raval, V. M. Takodia, J. J. Patel and M. A. Mulla

Silicon Carbide (SiC) is non-metallic high temperature heating element which is widely used in electric furnace and electric heating devices, but SiC heating elements

are very sensitive to thermal shock and offer negative temperature co-efficient of resistance which deteriorate its performances. This paper gives the novel solution of these problems, and discusses a complete design of an electronic heater controller

to feed the three-phase SiC elements. The controller enables soft starting, superior dynamic performance, reduce power losses, improves overall efficiency and high reliability with basic variable AC voltage control capability. A 36 kW three-phase SiC

heater controller is designed, developed and tested, which confirms the theoretical and simulated results.

11. Seismic Qualification Of Transformer Bushing

Srujana Nandam , Indrani Gogoi, R.Panneer Selvam and Ramesh Babu

In the past, Electric Power Substation equipment showed unreliable post-Earthquake

performance. The catastrophic failures of circuit breakers, transformer-bushings and disconnect switches at the substations are major causes of outages during past earthquakes. The satisfactory performance of Transformer Bushing system during

earthquake is very critical to ensure uninterrupted power supply for effective rescue operations. Many transformers damaged during earthquake were already undergone

seismic qualification in the laboratory under real time design Earthquake motion. Experimental test procedures recommended by the relevant Standards are being revised to remove the discrepancies identified. A case study on seismic qualification

of transformer bushing by Shake table testing is presented in this paper.