Transient Motor Starting Lab Sheet

FACULTY OF ELECTRICAL ENGINEERING

POWER LAB

TRANSIENT MOTOR STARTING

EXPERIMENT 1

Analysis on Test System 1

EXPERIMENT 2

Analysis on Test System 2

EXPERIMENT 3

Analysis on IEEE Recommended Power System Analysis network

EXPERIMENTAL THEORY

1. INTRODUCTION

Basically, these experiments deals with simulation and analysis of three phase

induction motor in power system network. Load (induction motor) is one of the factors

contribute to unstable power systems. This is because, starting large induction motor will

produce voltage drop, draw high current and create high loss in active power. “SKM Power

Tools for Windows” is a simulation software package use for design and analysis of

electrical power systems. Manual calculation analysis is very tedious process for getting the

result, which open up into calculation error especially for complex system. This software is

suitable for analyze complex system which helps in time reduction and occurrence of

calculation error if compare to analysis by manual.

1.1 Objective

(i) Recognize the normal problems that always happen in industrial power system

when three phase induction motors are used;

(ii) To understand the behavior, characteristics and performance of three phase

induction motor in power system; and

(iii) To understand the effect of starting large three phase induction motors to the local

power system

1.2 Scope

(i) Analysis of transient motor starting base on manual calculation and software.

(ii) Simulation via “SKM Power Tools for Windows” software package.

(iii) Analysis of IEEE Industrial Power Systems.

1.3 Need for Motor Starting Study

Starting large three phase induction motor, especially across-the-line can cause

several disturbances to the motor and any locally connected load, and also to buses

electrically remote from the point of motor starting. A brief discussion of major problems

associated with starting large motors, and therefore of significant in power system design

and evaluation.

1.3.1 Voltage Dips

Probably the most widely recognize and studied effect of motor starting is the

voltage dip experienced throughout an industrial power system as a direct result of

starting large induction motors. Available accelerating torque drops appreciably at the

motor bus as voltage dips to a lower value, extending the starting interval and affecting,

some times adversely, overall motor starting performance. During motor starting, voltage

level at the motor terminals should be maintained at approximately 80 % of rated voltage.

This value result from examination of speed-torque characteristic of this type motor (150

% starting torque at full voltage) and the desire to successfully accelerate a fully loaded

motor at reduced voltage (that is, torque varies with the square of the voltage).

When other motors or lower shaft loading are involve, the speed torque

characteristic of both the motor and its load should be examined to specially determine

minimum acceptable voltage. Assuming reduced voltage permits adequate accelerating

torque, it should also be verified that the longer starting interval required at reduced

torque cause by a voltage dip does not result in the damage limit of the motor being

exceed.

1.3.2 Weak Source Generation

Smaller power systems are usually served by limited capacity sources, which

generally magnify voltage drop problems on motor starting, especially when large

induction motors are involve.

Small systems also often have limited on-site generation, which further

complicates normal problem since additional voltage drops occur in transient impedance

of local generators during the motor starting interval the type of voltage regulator system

applied with the generators can dramatically influence motor starting.

A motor starting study can be useful, even for analyzing the performance of small

system. SKM power tools can accurately model regulator response under motor starting

conditions necessary for meaningful result and conclusion.

1.3.3 Special Torque Requirement

Sometimes special load must be accelerated under carefully controlled condition

without exceeding specified torque limitation of the equipment. An example of this is

starting a motor connected to a load trough gearing. This application requires a special

period of low torque cushioned acceleration to allow slack the gear and coupling to be

picked up without damage to the equipment.

High inertia loads increase motor starting time, and heating in the motor due to

high current drawn during starting can be intolerable. In TMS study, allows accurate

values of motor acceleration current and time. This makes it possible to determine if

thermal limits of standard motor will be exceed for longer starting time intervals. Other

loads have special starting torque requirements or accelerating time limits that require

special high starting torque (and inrush) motors.

Additionally, the starting torque of the load or process may not permit low inrush

motors in situation where these motors might reduce the voltage dips cause by starting a

motor having standard inrush characteristics. A simple inspection of the motor and load

speed-torque curves is not sufficient to determine whether such problems exist. This is

another area where the motor torque and accelerating time study can be useful.

1.3.4 Analyzing Starting Requirement

A speed-torque and accelerating time study often in conjunction with the

previously discussed voltage dips study permits a means of exploring a variety of

possible motor speed torque characteristic.

This type of motor starting study confirms that starting time are within acceptable

limits. The accelerating study assists in establishing the necessary thermal damage

characteristic of motors or verifies that machines with locked rotor protection supervised

by speed switches will not experience nuisance tripping on starting. Speed-torque /

accelerating time motor starting study is also used to verify special torque or inrush

characteristics, specified to actually produce desire result.

Mechanical equipment requirement and special ratings necessary for motor

starting auxiliary equipments are bases on information developed from motor starting

study.

1.4 Type of Motor Starting Study

From the above discussion, it is clearly that depending on the factors of concern

in any specific motor starting situation, more type of motor starting study can be required.

1.4.1 The Voltage Drop Snapshot

One method of examining the effect of voltage dip during starting is to ensure the

maximum instantaneous drop that occurs, leaves bus voltage at acceptable levels

throughout the system. This is done by examining the power system that corresponds to

the worst case voltage. Through appropriate system modeling, this study can be

performed by various calculating methods using the digital computer. The snapshot

voltage drop study is useful only for finding system voltage. Except for the recognition of

generator transient impedances when appropriate, machine inertias, load characteristics

and other transient effect are usually ignored. This type of study, while certainly an

approximation is often sufficient for many applications.

1.4.2 The Motor Torque and Acceleration Time Analysis

Perhaps the most exciting analysis for motor starting for motor starting conditions

is the detailed speed-torque analysis. Similar to the transient stability study ( some can

also be used to accurately investigate motor starting ), speed-torque analysis provides

electrical and accelerating torque calculation for specified time intervals during the motor

starting period.

Motor slip, load and motor torque, terminal voltage magnitude and angle, and the

complex value of motor current drawn are values to be examined at time zero at the end

of each time interval. Under certain circumstances, even across-the line starting, the

motor may not be able to break away from standstill or it may stall at some speed before

acceleration is complete. A speed-torque analysis, especially when performed using a

computer program, and possibly in combination with one or more previously discuss

studies, can predict these problem areas and allow corrections to be made before

difficulties arise. When special starting techniques are necessary, such as auto-

transformer reduced voltage starting, speed-torque analysis can account for the auto-

transformer magnetizing current and it can determine the optimum time to switch the

transformer out of the circuit.

The starting performance of wound rotor motors is examined through this type. A

particular adaptation can require a slight modification of any of the above studies to be of

greatest usefulness. Often combinations of several types of studies described are required

to adequately evaluate system motor starting problems.

EXPERIMENT 1: TEST SYSTEM 1

Figure 1

Input data

ALL PU VALUES ARE EXPRESSED ON A 100 MVA BASE.

FEEDER INPUT DATA

NAME FROM TO QTY Kv LENGTH SIZE TYPE

CBL-0001 BUS-0002 BUS-0003 1 3300 1000.0m 25 Copper

Duct Material: Non-Magnetic Insulation Type: PLC Insulation Class:

+/- Impedance: 0.8989 + J 0.0781 Ohms/1000 m 8.25 + J 0.7170 PU

Z0 Impedance: 1.43 + J 0.1985 Ohms/1000 m 13.12 + J 1.82 PU

TRANSFORMER INPUT DATA

NAME NO NAME L-L (kV) NO NAME L-L (kV) KVA

XF2-0001 BUS-0001 D 69000.0 BUS-0002 YG 3300.00 10000.0

Pos. Seq. Z%: 0.710 + J 8.97 0.071 + j 0.897 PU

Zero Seq. Z%: 0.710 + J 8.97 0.071 + j 0.897 PU

Taps Pri. 0.000 % Sec. 0.000 % Phase Shift (Pri. Leading Sec.): 30.00 Deg.

NAME NO NAME L-L (kV) NO NAME L-L (kV) KVA KVA

XF2-0002 BUS-0001 D 69000.0 BUS-0003 YG 3300.00 10000.0 10000.0

Pos. Seq. Z%: 0.710 + J 8.97 0.071 + j 0.897 PU

Zero Seq. Z%: 0.710 + J 8.97 0.071 + j 0.897 PU


GENERATION DATA

BUS NAME GENERATION VOLT SIZE InitKW MaxKVAR TYPE

BUS-0001 GEN-0003 1 pu 100 MVA 0.00000 0.00000 SB

ENERGY AUDIT LOADS

BUS LOAD NAME VOLTS SIZE LOADTYPE PF LAG/LEAD

BUS-0002 LOAD-0001 3300 0.8*1.00MVA KVA 0.80 LAG

BUS-0003 LOAD-0002 3300 0.4*1.00MVA KVA 0.80 LAG

MOTOR LOAD DATA

BUS LOAD NAME VOLT SIZE # TYPE EFF PF

BUS-0002 MTRI-0001 3300 500.0* 1 HP KVA 0.80 0.80 LAG


Method

1. Draw Figure 1 using “SKM Power Tools for Windows” software.

2. Simulate Figure 1 and determine the voltage drop at each busbar.

3. Any problems to draw and simulate, please refer to the manual in appendix.

4. By manual calculation, determine the voltage drop at each busbar. Use Gauss

Siedel Method.

5. Compare the result obtained from step 2 and step 4.

6. For motor starting result, display each motor starting curves from the TMS

(Transient Motor Starting) module.

Load Flow Solution (Gauss-Siedel Method)

Impedance between buses;

For admittance between buses;

The admittance (Y) matrix of the system;

Y =

Iteration for ;

Iteration for ;

Iteration for ;

Power generates;

Summary of manual calculation

P Q |V|

Slack Bus 0.01988 0.06502 1.0 0

Bus 2 -0.01783 -0.09008 0.9881 0.104

Bus 3 -0.00948 -0.03566 0.9545 0.04

Bus 4 -0.00800 -0.05043 0.9396 -0.03

Comparison of manual calculation and skm result

|V|

Bus

Slack Bus 1.0 1.0 - 0 0

Bus 0002 0.9862 0.9881 0.0019 1.4 1.19

Bus 0003 0.9510 0.9545 0.0035 4.9 4.55

Bus 0004 0.9381 0.9396 0.0015 6.2 6.04

Example of motor starting result

EXPERIMENT 2: TEST SYSTEM 2

Figure 2

Input data

ALL PU VALUES ARE EXPRESSED ON A 100 MVA BASE.

FEEDER INPUT DATA

NAME FROM TO QTY Kv LENGTH SIZE TYPE

CBL-0001 BUS-0001 BUS-0002 1 69000 1000.0 m 120 Copper

Duct Material: Non-Magnetic Insulation Type: XLPE Insulation Class:

+/- Impedance: 0.1951 + J 0.1539 Ohms/1000 m 0.0041 + J 0.0032 PU

Z0 Impedance: 0.3101 + J 0.3917 Ohms/1000 m 0.0065 + J 0.0082 PU


NAME NO NAME L-L (kV) NO NAME L-L (kV) KVA

XF2-0001 BUS-0002 D 69000.0 BUS-0003 YG 3300.00 20000.0

Pos. Seq. Z%: 0.575 + J 9.48 0.028 + j 0.474 PU

Zero Seq. Z%: 0.575 + J 9.48 0.028 + j 0.474 PU


GENERATION DATA


BUS-0001 GEN-0001 69000.0 100.0 MVA 0 0 SB

KG: 1.03 xdsat: 1.60 Excitation Limit: 1.30 Ik - ON

Pos Sequence Impedance (100 MVA Base) 0.0100 + J 0.1500 PU

Neg Sequence Impedance (100 MVA Base) 0.0103 + J 0.1549 PU

Zero Sequence Impedance (100 MVA Base) 0.0103 + J 0.1549 PU

MOTOR CONTRIBUTION DATA

BUS CONTRIBUTION VOLTAGE BASE Motor

NAME NAME L-L kVA X"d X/R Number

BUS-0003 MTRI-0001 3300 932.5 0.17 10.0 1.00

Pos Sequence Impedance (100 MVA Base) 1.82 + j 18.23 PU

BUS-0003 MTRI-0002 3300 233.1 0.17 10.0 1.00

Pos Sequence Impedance (100 MVA Base) 7.29 + j 72.93 PU

Method




4. By manual calculation, determine the voltage drop at each busbar. Use Gauss

Siedel Method.

5. Compare the result obtained from step 2 and step 4.

6. For motor starting result, display each motor starting curve from the TMS


Load flow solution – Gauss Siedel Method

Impedance between buses;

Admittance between buses;

Admittance matrix (Y) of the systems;

Iteration for ;

Iteration for ;

Iteration for ;

Power generates;

Summary of manual calculation

P Q V

Slack bus 0.01300 0.070039 1.0 0

Bus 0002 0.012795 0.069500 0.9897 0.12

Bus 0003 0.012774 0.069492 0.9880 -0.01

Bus 0004 0.012677 0.067073 0.9556 -0.17

Comparison of manual calculation and skm result

|V| Bus

Slack Bus 1.0 1.0 - 0 0

Bus 0001 0.9893 0.9897 0.0004 1.1 1.03

Bus 0002 0.9891 0.9886 0.0005 1.1 1.1

Bus 0003 0.9554 0.9556 0.0002 4.5 4.4

Example of motor starting result

EXPERIMENT 3 : IEEE RECOMMENDED POWER SYSTEM ANALYSIS

NETWORK

Method




4. For motor starting result, display each motor starting curve from the TMS


5. Compare result in experiment 1,2 and 3

6. Make your assumption regarding experiment 1, 2 and 3.

Input data

ALL PU VALUES ARE EXPRESSED ON A 100 MVA BASE

FEEDER INPUT DATA

NAME NAME NAME /PH L-L SIZE TYPE

CBL-0001 BUS-0001 BUS-0002 1 69000 10000 FEET 120 Copper


+/- Impedance: 0.0595 + J 0.0563 Ohms/1000 ft 0.0125 + J 0.0118 PU

Z0 Impedance: 0.0945 + J 0.1433 Ohms/1000 ft 0.0199 + J 0.0301 PU

CBL-0002 BUS-0001 BUS-0003 1 69000 10000. FEET 120 Copper





Duct Material: Non-Magnetic Insulation Type: PILS Insulation Class:




CBL-0005 BUS-0006 BUS-0007 1 11000 650.0 FEET 50 Copper









Duct Material: Non-Magnetic Insulation Type: Insulation Class:

THWN












Duct Material: Non-Magnetic Insulation Type: Insulation Class:THWN













Duct Material: Non-Magnetic Insulation Type: Insulation Class: THWN
































CBL-0038 BUS-0002 BUS-0051 1 69000 10000. FEET 120 Copper





NAME NO NAME L-L NO NAME L-L KVA

XF2-0001 BUS-0002 D 69000.0 BUS-0006 Y 11000.0 20000.0

Pos. Seq. Z%: 0.575 + J 9.48 0.028 + j 0.474 PU

Zero Seq. Z%: 0.575 + J 9.48 0.028 + j 0.474 PU


XF2-0002 BUS-0003 D 69000.0 BUS-0014 Y 11000.0 20000.0

Pos. Seq. Z%: 0.575 + J 9.48 0.028 + j 0.474 PU

Zero Seq. Z%: 0.575 + J 9.48 0.028 + j 0.474 PU


XF2-0003 BUS-0004 D 11000 BUS-0005 Y 3300.00 1600.00

Pos. Seq. Z%: 1.13 + J 5.89 0.707 + j 3.68 PU

Zero Seq. Z%: 1.13 + J 5.89 0.707 + j 3.68 PU


XF2-0004 BUS-0008 D 11000.0 BUS-0009 Y 480.00 2000.00

Pos. Seq. Z%: 1.31 + J 5.89 0.820 + j 3.68 PU

Zero Seq. Z%: 1.31 + J 5.89 0.820 + j 3.68 PU


XF2-0005 BUS-0011 D 11000.0 BUS-0013 Y 3300.00 5000.00

Pos. Seq. Z%: 0.828 + J 8.96 0.165 + j 1.79 PU

Zero Seq. Z%: 0.828 + J 8.96 0.165 + j 1.79 PU


XF2-0006 BUS-0016 D 11000.0 BUS-0017 YG 480.00 2000.00

Pos. Seq. Z%: 1.31 + J 5.89 0.820 + j 3.68 PU

Zero Seq. Z%: 1.31 + J 5.89 0.820 + j 3.68 PU



XF2-0007 BUS-0019 D 11000.0 BUS-0020 Y 3300.00 2500.00

2000.00

Pos. Seq. Z%: 1.31 + J 5.89 0.656 + j 2.95 PU

Zero Seq. Z%: 1.31 + J 5.89 0.656 + j 2.95 PU


XF2-0008 BUS-0019 D 11000.0 BUS-0021 Y 3300.00 2500.00

Pos. Seq. Z%: 1.31 + J 5.89 0.656 + j 2.95 PU

Zero Seq. Z%: 1.31 + J 5.89 0.656 + j 2.95 PU


XF2-0009 BUS-0022 D 11000.0 BUS-0023 Y 480.00 2000.00

Pos. Seq. Z%: 1.31 + J 5.89 0.820 + j 3.68 PU

Zero Seq. Z%: 1.31 + J 5.89 0.820 + j 3.68 PU


XF2-0010 BUS-0026 D 11000.0 BUS-0027 Y 3300.00 2000.00

Pos. Seq. Z%: 1.31 + J 5.89 0.820 + j 3.68 PU

Zero Seq. Z%: 1.31 + J 5.89 0.820 + j 3.68 PU


XF2-0011 BUS-0026 D 11000.0 BUS-0028 Y 3300.00 4000.00

Pos. Seq. Z%: 1.000 + J 7.08 0.250 + j 1.77 PU

Zero Seq. Z%: 1.000 + J 7.08 0.250 + j 1.77 PU


XF2-0012 BUS-0029 D 11000.0 BUS-0030 YG 3300.00 5000.00

Pos. Seq. Z%: 1.000 + J 7.08 0.250 + j 1.77 PU

Zero Seq. Z%: 1.000 + J 7.08 0.250 + j 1.77 PU



XF2-0013 BUS-0032 D 11000.0 BUS-0033 YG 480.00 2000.00

Pos. Seq. Z%: 1.31 + J 5.89 0.820 + j 3.68 PU

Zero Seq. Z%: 1.31 + J 5.89 0.820 + j 3.68 PU


XF2-0014 BUS-0035 D 11000.0 BUS-0036 YG 480.00 800.00

Pos. Seq. Z%: 1.27 + J 4.32 1.59 + j 5.39 PU

Zero Seq. Z%: 1.27 + J 4.32 1.59 + j 5.39 PU


XF2-0015 BUS-0038 D 11000.0 BUS-0039 YG 600.00 2500.00

Pos. Seq. Z%: 0.980 + J 6.43 0.392 + j 2.57 PU

Zero Seq. Z%: 0.980 + J 6.43 0.392 + j 2.57 PU


XF2-0016 BUS-0040 D 11000.0 BUS-0041 YG 600.00 1000.00

Pos. Seq. Z%: 1.21 + J 4.85 1.21 + j 4.85 PU

Zero Seq. Z%: 1.21 + J 4.85 1.21 + j 4.85 PU


GENERATION DATA


BUS-0001 UTIL-0001 1 pu SB

Three Phase Contribution: 1000.30 MVA X/R : 2.20

Line to Earth Contribution: 75.00 MVA X/R : 9.90

Pos sequence impedance (100 MVA base) 0.1515 + J 0.3330 PU

Zero sequence impedance (100 MVA base) 0.1874 + J 4.19 PU


BUS-0004 GEN-0001 1 pu 15.60 MVA 14062.5 6810.30 PV

BUS-0014 GEN-0002 1 pu 15.60 MVA 14040.2 6799.40 PV

ENERGY AUDIT LOADS

BUS-0025 LOAD-0002 480 100.0*1.00kVA KVA 0.91 LAG

MOTOR LOAD DATA

BUS NAME LOAD NAME VOLT SIZE # TYPE EFF PF



BUS-0009 MTRI-0003 480 100.0* 1 HP Z 0.80 0.80 LAG

BUS-0009 MTRI-0004 480 110.0* 1 KW KVA 0.80 0.80 LAG

























Transient Motor Starting Lab Sheet

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