1 - Composition, operation and maintenace GTU 101 - RevGB FF

DL GTU101 S

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ContentPREFACE Pag. VII

1. Composition, operation and maintenance Pag. 11. Introduction Pag. 1

2. Hardware layout and description Pag. 3

3. Communication between hardware and software Pag. 5

4. Wiring diagram Pag. 6

5. Operation Pag. 9

6. Maintenance and repair Pag. 9

2. Installation of the trainer Pag. 111. Description and layout Pag. 11

2. Hardware Installation Pag. 13

3. Communication network installation Pag. 15

4. Software installation Pag. 16

3. Theoretical section Pag. 393.1 Introduction Pag. 39

3.2 Response of the alternator in isolated operation Pag. 43

3.3 Synchronization issues of the generators Pag. 53

3.4 Response on a constant voltage constant frequency system Pag. 67

Preface

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4. Experimental Section Pag. 73

4.1 Generator winding resistance measurement Pag. 73

1. Introduction. Description of the experiment Pag. 73

2. Objectives Pag. 76

3. Components list Pag. 76

4. Procedure outline Pag. 77

5. Conclusions Pag. 86

4.2 Generator Open Circuit Test (OCC) Pag. 87






4.3 Generator Short Circuit Test (SCC) Pag. 103






4.4 Generator Load Characteristics Pag. 119






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4.5 Generator Regulation Characteristics Pag. 139






4.6 Generator Manual Synchronization Pag. 159






4.7 Alternator and Synchronous Motor Pag. 179





5. Questions Pag. 195

4.8 Generator Automatic Synchronization Pag. 197






Preface

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4.9 Dynamic cos control Pag. 215






4.10 Pumped storage hydropower (PSH) Pag. 233






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3. Theoretical section

3.1 Introduction

In the area of public power supply, the three phase current has emerged as thesimplest form of power, in terms of both transmission and universal application.

The three phase current can be transformed to a voltage level appropriate for thedistance it has to be transmitted and can be used in the manner ideally suited forthe consumer, e.g. for drive purposes.

However, electric power cannot be stored in large quantities. Consequently, it hasto be generated at the same time the consumer needs it.

As a result, over the course of time, large interconnected networks have evolved tosatisfy the requirements of a nearly continuous and cost efficient electric powersupply.

The basic structure and components (with guiding values) of a typical chain: thegeneration transmission distribution utilization system is shown in the next figure(1 step up transformer for high voltage transmission, 2,3 transformers that delimitthe sub transmission system (or step up), 3 step down transformer for electricpower distribution, 4 step down transformers for end customers).

Notice that, in many books, transmission and distribution networks follow the sameregulations and are integrated in the same diagram. Also, the illustration is notdrawn to scale.

This schematic diagram is a one line diagram, which does not show the threephases for each circuit.

The interconnected network operation offers several advantages. The generation ofelectric power from the various primary energy sources (coal, gas, oil, nuclearpower, water) can take place where the resources are located. The transmission ofelectric power is generally more economical than the transport of primary energysources.

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Furthermore, the interconnected network permits power generation to occur inlarge units, which operates at a greater degree of efficiency. In addition to this,power stations can be employed with varying loads, thus always being able toexploit fully those units with the lowest specific fuel costs.

Also, the interconnected system provides for an economical reserve capacity ofgenerated power and transmission power. This is equally true for power plants andtransmission lines. The consumer can also expect to receive the desired power atany time and at a reasonable cost, while at the same time the voltage and thefrequency can be also kept almost constant, even under a fluctuating load due tothe multitude of feeding generators. This is referred to in this context as a constantvoltage constant frequency system (also stiff system).

The generation of electric energy is performed almost exclusively using high powersynchronous machines, or alternators, whose construction design depends on thetype of drive normally steam, gas or water. The name synchronous machine(which can be used both as a generator and as a motor) stems from the fact thatthe rotor runs at a constant speed, which is synchronous with the speed of themagnetic field in a constant voltage constant frequency system.

The rotor contains a DC winding (exciter winding or field) which in the case ofgenerators produces the desired three phase voltage in the three phase winding(stator winding or armature), which is evenly staggered along the circumference ofthe stator. This design is referred to as a stationary armature machine.

In addition to this, there are also stationary field machines, in which the exciterwinding is arranged on the stator and the three phase winding is attached to therotor. Here, however, it is not the exciter power, but the far greater three phasepower that has to be supplied or transferred via brushes. As a result, this design islimited to smaller scales.

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Thermal power plants heated by coal, oil, gas or nuclear reactors use steamturbines and occasionally gas turbines as well for converting energy. Forconstruction reasons, these are designed for a high rotating speed (3000 or 1500min 1) for networks with a frequency of 50 Hz).

Because of this high rotating speed and the associated centrifugal forces, the rotorhas to be solid and may only have a small diameter. The exciter winding is insertedinto grooves, which have been machined longitudinally into the rotor. Since thepower output of a generator is dependent on, among other things, its size, when ithas a small diameter a longer length has to be selected, in order to achieve a highpower level.

Machines of this type are called non salient pole or turbo alternators. Thegenerators in water driven power plants are designed differently. The turbinesavailable for driving these plants demonstrate considerably lower rotating speeds,in the range of approx.. 100 750 min 1. The rotor used here is equipped with manyleg types salient poles, which accommodate the exciter winding.

In extreme cases, a machine of this type can have up to 60 individual poles.

The larger diameter permits the machine to have a considerably shorter rotorlength, despite the high power being generated. Machines of this type are calledsalient pole alternators.

The largest synchronous generators are found in nuclear power stations and arecapable today of producing power up to 1300 MW at a nominal stator voltage of 27kV. In spite of the high degree of efficiency over 98% the power losses involved(above all, current heat dissipation in the windings) are considerable in large scalemachines and require expensive cooling facilities, for example, water cooling for thestator as well as the rotor.

In contrast to asynchronous machines, a synchronous machine cannot startindependently (if a damper winding is present in the rotor, there is the possibility ofa so called asynchronous start up, at least in smaller machines; however, this is notmade of in the area of power generation and supply).

If a synchronous generator is supposed to be connected in parallel with theconstant voltage constant frequency system, it first has to be brought up to thenominal speed via the turbine. At the same time, the exciter voltage has to beincreased from zero until the stator voltage reaches the same level as that of thenetwork. However, connection is then only possible when the magnitude, phaserelation and rotational direction of the two voltages are in agreement.

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The described procedure is called synchronization. This operation is carried outautomatically in modern power stations, in which a synchronizing device (alsoreferred to as a paralleling device) is responsible for controlling and monitoring theabove mentioned procedure.

After the synchronous machine has been connected to a constant voltage constantfrequency system, the active power to be produced and consumed and also thereactive power can be adjusted as desired, independently of each other (only thepower limits of the machine have to be adhered to).

As a result, it can be universally put into operation, and in addition to its mainapplication the generation of active and lagging reactive power – it can be used fordriving the pumps in pumped storage power stations or as a rotating phase shifterfor the improvement of a system's power factor.

Due to the unrivalled importance of turbo alternators for power generation and tosimplify mathematical investigation, especially in comparison to the salient polemachine, we wish to limit the following considerations to the former machine type.

However, the conclusions drawn from this machine can generally be applied tomachines with salient poles.

In the present experiments, a two pole alternator is investigated; a DC shunt woundmachine performs the drive function.

To determine some of the characteristic features of the synchronous machine usedhere, this machine is operated in a so called isolated operation. This is an operatingmode in which the generator supplies just one single consumer.

Voltage magnitude and frequency are determined here by the alternator.

Then, in the second part of the experiments, various synchronisation circuits areassembled and the response of the machine is investigated in a constant voltageconstant frequency system.

In contrast to the isolated network, here voltage and frequency are predeterminedby the system and have constant values.

If the synchronous machine is driven mechanically here, then it operates as agenerator. If its excitation is altered, it can then generate as well as consumereactive power.

It is precisely this function that, in addition to generating active power, is also ableto influence the reactive power content of a system, providing the synchronousmachine with its varied application options.

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4. Experimental Section

4.1 Generator winding resistance measurement

1. Introduction. Description of the experiment

This experiment studies the winding resistance and provides information about theresistance of stator and rotor windings of the synchronous generator.

Three phase synchronous generators are the primary source of the electric energy.The stator contains a three phase armature winding. The rotor contains a fieldwinding that is excited by DC voltage.

For describing the concept, a very simplified schematic is presented in figure 1.a,where the generator (GS) is shown as a part of the power grid.

The simplified equivalent schematic diagram from figure 1.b can be used as areference for this experiment, if the experiment is performed while thesynchronous generator is kept stationary.

Figure 1

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The voltage drop across the internal resistance can be calculated by using theOhm’s law. In order to calculate the winding voltage, students will measure thecurrent through the armature and rotor windings.

The rotor and stator windings resistance will be calculated with the measuredvalues of the DC current (A1 and A2) and the measured values of the DC voltage (V1

and V2).

The values of the winding resistance in the synchronous machine are useful tocalculate the synchronous impedance and the voltage variation between no loadand full load.

Using the SCADA software, students will adjust the voltage level of the DC powersupply that will be applied to the phases of the stator and rotor windings.

The resistance per phase is the armature resistance of an alternator. The resistanceof a winding, depending on the resistivity of the winding material, the length andthe area of the cross section, is called DC resistance of the winding.

The actual or AC resistance is nearly 1.25 to 1.75 times the DC resistance. This isbecause of the unequal distribution of the alternating current (skin effect) over thecross section of the conductor.

Voltage drop occurs in the winding because of this resistance, which is in phasewith the current phasor.

However, the value of this resistance is very small as compared to the synchronousreactance of the machine, which is why, many times, its voltage drop effect isneglected.

Heavy copper losses occur in the machine because of the armature resistance.

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Characteristics curves

The internal resistance of the synchronous machine characteristics refers to thefollowing curves presented in figure 2.

The method uses a DC power source to supply the motor windings and measuresthe voltage and the current flowing through them.

Figure 2

The rating of the electric machines is influenced by the temperature rise caused bythe internal losses of the machine.

The copper loss (I2Ra) in the armature depends on the magnitude of the currentpassing through the armature conductors and the core loss depends on theoperating voltage. Both these losses are independent on the power factor.


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2. Objectives

Students are expected to learn about the measurement of the armature andexcitation windings resistance for synchronous machines. By running thisexperiment, students will face some main objectives:

To understand the schematic diagram corresponding to the measurement ofthe armature and excitation windings resistance for synchronous machines.

To learn which are the conditions to perform the winding resistancemeasurement of the synchronous generator.

To learn the synchronous machine wiring connections, in order to measure thewinding resistance.

To obtain the characteristic curves related to the measurement of the internalresistance for the excitation winding and the field winding of the machine:

3. Components list

According to the formulated objectives, for running this experiment the followingmodules are needed:

A. Software and communications:

PC with Windows OS

SCADA software (GTU 101 S)

Interface Converter: Moxa UPort 1130 USB to RS485 (4 wires for channel 1)

Interface Converter: USB to RS485 Adapter (2 wires for channel 2)


B. Hardware:

DL 1026P4 Three Phase Synchronous Machine

DL 1067S Motor Driven Power Supply

DL 10065N Electric Power Digital Measuring Module

DL HUBRS485F Communication MODBUS HUB

U = f(I) and Ra = f(I)

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4. Procedure outline

Schematic diagram

The circuit diagram for measuring the electric winding resistance of the

synchronous machine is presented in figure 3. The measurement of the excitation

and armature windings characteristic essentially describes how the current changes

by modifying the applied voltage.

Figure 3

The winding resistance can be directly measured with an ohmmeter. Another

method is to calculate the resistance by measuring the current trough every

winding, using an ammeter A, when a voltage is applied and measured with a

voltmeter V. In figure 3.a, the general circuit diagram for measuring the current

through the armature winding is presented. Figure 3.b shows the circuit diagram

correlated with the synchronous machine used in this experiment. In figure 3.c, the

general circuit diagram for measuring the current through the field winding is

presented. Figure 3.d shows the circuit diagram correlated to the synchronous

machine used in this experiment.


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Schematic diagram

Figure 4 shows the schematic diagram where the armature winding of the

synchronous generator DL 1026P4 will be supplied from the DC part (variable) of

the power supply DL 1067S.

The electric parameters of the generator DL 1026P4 will be measured with the

measuring device DL 10065N.

Supply the generator windings separately. First, connect the DC supply to the field

winding and then to the armature winding (dotted line).

Figure 4

The schematic diagram from figure 4 is close to the student’s theoretical knowledge (it uses the classical electrical symbols). Use this diagram while performing the experiment, having as reference the wiring diagram from figure 5.

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Follow the diagram from the next figure and connect the power cables accordingly:

Figure 5

We use for this experiment the analog output 1 of the communication MODBUS

HUB. The electric parameters of the generator DL 1026P4 will be measured with

the measuring device DL 10065N.


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Experimental procedure and learning plan

Once we have understood all these preparatory aspects, we can proceed with the

experiment.

Before starting any wiring activity, check all power connections: all switches must be OFF. Do not miss the ground-connecting terminal! All equipment must be connected to the protective network by specific connector and cable.

1) Perform the circuit configuration shown in the wiring diagram presented in

figure 5. Operate the network power switch (I/O) that can be found on the

front panel of the laboratory modules. On the DL 10065N, the power switch

(I/O) is on the back of the module.

2) Enter in the SCADA software and select EXERCISE 1 – Winding Resistance

Measurement.

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3) A general power grid schematic diagram is shown in the main window of the

SCADA. The windings of the alternator are supplied with DC voltage. The

voltage is gradually increased and the current is recorded for every change.

Click on “Experiments” to proceed with the SCADA application.

4) Increase the voltage of the motor driven power supply DL 1067S, using the

Analog Output Voltage from SCADA (related to the DC power supply). From

SCADA, you can observe the DC voltage, the current trough the generator field

winding (F1 F2) and the calculated winding resistance.


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On SCADA, by clicking on “Records”, you will be able to see the acquired values

related to the experiment. The recorded data can be saved in a comma

separated values (CSV) format for further processing.

5) Fill the next table with real measured data, while gradually increasing the

voltage and measuring the current through the excitation winding. The table

presents the correlation between I and U. This table can be filled with the real

data from SCADA.

Consider the values from the software interface as a reference.

Based on your laboratory conditions, the actual measurements

values might be slightly different. The values obtained in the

table below were read at the ambient temperature. Fill the

ambient temperature from your laboratory:

a = ............ °C

Table 1

Rcalculated

F1 F2

Ie (A) Ua (V) Re ( ) R(F1 F2)( )

Rmeasured ( )

0.06 6.9 115

129 135

0.09 11.1 123.3

0.12 15.3 127.5

0.14 19.7 140.7

0.17 23.6 138.8

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6) Continue to increase the current (I) until you obtain about five readings of the

voltage drop. The voltage and current are read from the measuring device DL

10065N using address 65, as shown in the figure below.

When you reach the last value of the current, decrease the DC power supply DL

1067S, using the Analog Output Voltage from SCADA, by pressing the

decrementing button.

Calculate the mean value of the resistances between the terminals:

e(F1-F2)

RR = =129

5

For copper winding, to relate the resistance at 75 °C, use the coefficient:

( )R = 309.5 =1.14234.5+ a

The resistances at the conventional temperature of 75 °C are:

(75) Re=135.6 (Re = C )


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7) Follow the figure 3.a,b for measuring the armature winding resistance. Increase

the voltage of the motor driven power supply DL 1067S using the Analog

Output Voltage from SCADA. From SCADA, you can observe the DC voltage, the

current through the generator armature winding (U W) and the calculated

winding resistance. The voltage and current are read as in the previous test

using the DL 10065N (address 65).

8) Fill the next table with real measured data, while gradually increasing the

voltage and measuring the current through the armature winding. The table

presents the correlation between I and U. This table can be filled with the real

data from SCADA.

Table 2

Rcalculated

W U

Ie (A) Ua (V) R(W U) ( ) Ra ( ) Rmeasured ( )

0.1 2.9 26.3

14.2 16.3

0.24 6.8 28.3

0.38 11 28.9

0.52 15.3 29.4

0.65 19 29.2

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Plot the characteristic curves related to the measurement of the internal

resistance for the excitation (Re) and armature (Ra) windings of the machine.

The mean value of the resistances between the armature terminals (W U):

e(W-U)

RR = = 28.42

5

As the stator is star connected, the phase resistance of the armature is:

W-URa = 1 R =14.22

The resistances at the conventional temperature of 75 °C are:

(75) Re=16.2 (Re = C )


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9) When the experiment is complete, press the emergency stop button from

SCADA that will stop the power supply.

5. Conclusions

The test was carried out in direct current with the volt ammetric method and itaims to obtain the winding resistance of the synchronous generator.

Students will compare the calculated resistance winding values with the valuesmeasured using an ohmmeter.

The value of a test current should be selected according to the nominal windingcurrent. The information about the nominal winding current can be found on theplate of the synchronous generator (DL 1026P4).

The test current must not exceed 10% of the nominal winding current. Because ofcables heating, higher values of test current will significantly increase the windingresistance.

In practical real situations, the winding resistance of three phase AC machines ismeasured between their terminals (all three combinations).

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4.8 Generator Automatic Synchronization

1. Introduction. Description of the experiment

This experiment provides the knowledge about an operation that is frequently

performed in power grids. Synchronizing a generator is very important before

paralleling it with another generator, because that ensures quality, reliability and

optimum efficiency within the system.

The fundamentals about generator synchronization were described in detail in

experiment 6 (if necessary, review the fundamentals regarding the conditions for

the synchronizing systems). The automatic synchronization is made based on the

diagram shown in figure 1.

Figure 1


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An automatic synchronization can be performed using an automatic relay (ANSI

Code 25). This relay is a device that can perform all the functions required to

synchronize a generator. It can measure the parameters needed for synchronization

and it can close the breaker.

The generator G (the generator to be put in parallel with the mains) has a prime

mover.

Once the prime mover is up to its rated speed and the generator is producing

voltage at the nominal frequency, the relay (25) will make decisions in the

synchronization process and will give the “switch on” command to the proper

circuit breaker CB3 (52).

During this experiment, the student manually adjusts the prime mover speed or the

frequency control set point (of the motor driven power supply) to match the

generator frequency to the mains frequency.

The student manually adjusts, using SCADA, the excitation level or the voltage

regulator set point to match the generator voltage to the mains voltage.

Characteristics curves

The automatic synchronization relay (25) can be programmed to operate in

different systems conditions (programmed using the software MSCom2). The

synchronization of generators in a power plant is done in two different ways:

the classic method named "live bus synchronization". In the relay programmed

software, this method is named

the advanced method named "dead bus synchronization". In the relay

programmed software, this method is named

DL GTU101 S


Dead Bus not allowed (DB = OFF) – the relay will control the voltage difference, the

frequency difference and the phase displacement.

In this configuration, closing of the circuit breaker (CB3 from figure 1) can take place

if:

Bus voltage UB within the set limits [U <] < UB < [U >]

Voltage difference below the set limit U < [ U]

Frequency difference below the set limit f < [ f]

Phase displacement below the set limit < [ ]

Dead Bus allowed (DB = ON) – if UB < 5%Un is detected, the generator input is

compared with the rated voltage (Un) and the rated frequency (fn).

The angle where the circuit breaker closing command is issued (energization of the

output relay R1 of DL 2108T25) can be different according to the programming of

the parameter [tCB = 0,05 0,50 / Dis.] which represents the closing time of the

circuit breaker for automatic selection of the closing angle.

If the closing time of the circuit breaker is disabled tCB = DIS, then the closing

command is issued as soon as the phase difference between the generator

voltage (UG) and the bus voltage (UB), while decreasing, is below the set value

[ ], as shown in figure 2a.

Figure 2 Phase angle characteristic for closing the synchronization relay

If the closing time of the circuit breaker is set tCB Dis, then the closing

command is issued as soon as the phase difference , while decreasing, comes

within the limits 1.1 S > > 0.9 S, as shown in figure 2b.



2. Objectives

Students are expected to learn about the automatic synchronization of the

synchronous generator with the mains. By running this experiment, students will

face some main objectives:

To understand the single line diagram corresponding to the automatic

synchronization of synchronous generators.

Based on the schematic diagram, to learn how to connect the laboratory

modules accordingly.

To learn how to adjust the automatic synchronization relay (using the

dedicated software MSCom2).

To understand the generator automatic synchronization characteristic related

to the experiment (control of the voltage difference, of the frequency

difference and of the phase displacement).

3. Components list

According to the formulated objectives, for running this experiment the following

modules are needed:

A. Software and communications:

PC with Windows OS

SCADA software (GTU 101 S)

MSCom2 software

Interface Converter: Moxa UPort 1130 USB to RS485 (4 wires for channel 1)



DL GTU101 S


B. Hardware:

DL 2102AL Three phase Power Supply

DL 2108T26 Brushless Motor Controller

DL 2108T26BR Braking resistance

DL 1026P4 Three Phase Synchronous Machine

DL 1067S Motor Driven Power Supply

DL 10065N Electric Power Digital Measuring Module

DL 2109T29 Three Phase Power Meter

DL 2108T02 Power Circuit Breaker

DL 2108T02A Power Circuit Breaker

DL 2108T25 Generator Synchronizing Relay

DL 1017R Resistive Load

DL 1017L Inductive Load

DL 1017C Capacitive Load

DL HUBRS485F Communication MODBUS HUB

4. Procedure outline

Schematic diagram

Figure 3 shows the schematic diagram related to the experiment, where the prime

mover (M brushless motor) will be controlled by the students using the SCADA.

The generator stator configuration can be in star/delta, but for this experiment we

have selected the star connection (the parallel coupling will be with the power

network). The electric parameters of the generator DL 1026P4 will be measured

with the measuring device DL 10065N. The generator excitation will be provided

from a DC power supply DL 1067S.

For the live bus synchronization, the synchronization relay will supervise the closing

to operate the breaker at a point when the waveforms are in sync. The busbar is

then directly connected to the load, the local grid for example.

For the automatic synchronization, as shown in figure 3, using the three phase

power meter (DL 2109T29), the user will measure the BUS parameters and using the

DL 10065N – AC part, will measure the GENERATOR parameters.



The generator field excitation will be measured with the DC part of the

measurement module DL 10065N.

Figure 3

We use for this experiment the output R1 (normally close) and R2 (normally open)

of the communication MODBUS HUB. The motor driven power supply (DL 1067S)

must be switched to the automatic (“auto”) function in order to be controlled from

SCADA.

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The testing will be made to understand the live line - live bus

practical situation, where the breaker can only be closed, if both

the bus and line voltage are at acceptable voltage and frequency,

and the AC waveforms are synchronized within a specified

number of degrees of the phase angle (less than 30°).

Follow the diagram from the next figure and connect the power cables accordingly:

Figure 4



Experimental procedure and learning plan

Once we have understood all these preparatory aspects, we can proceed with the

experiment.

Before starting any wiring activity, check all power connections: all switches must be OFF. Do not miss the ground-connecting terminal! All equipment must be connected to the protective network by specific connector and cable.

1) Perform the circuit configuration shown in the wiring diagram presented in

figure 4. First, connect the modules to the network and then operate the power

switch (I/O) that can be found on the front panel of the laboratory modules.

On the DL 10065N, the power switch (I/O) is on the back of the module. On the

DL 2108T26, press the “Torque and Enable” button to enable the brushless

driver.

2) ENABLE the DL 2108T02 and DL 2108T02A circuit breakers by following the

enclosed figure. By pressing the “Green”, button the circuit breakers are

. Remember that the switch ON and OFF commands will be given using

the SCADA.

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As shown in the wiring diagram from figure 4, the

(synchronising) circuit breaker is enabled (1) by connecting it

with the normally closed relay (R1) of the HUB. The switch ON

and OFF (2) will be given from SCADA via the HUB

communication relay R2 (normally open).

The relay R1 of the generator is energized when the conditions

for the closing of the generator’s circuit breaker are satisfied.

The R1 is connected with the digital input (BR) that blocks the

operation of the regulator relay.

The second circuit breaker (that connects the load) is enabled by

manually pressing the button (3). The switch ON and OFF (2)

will be given from SCADA via the HUB communication relay R2

(normally open).



3) Open MSCom2 (the software that controls the relay). Then, when you have the

list of the specific COM, click on the Scan button and, when you have found the

device, click on the Connect option.

4) Click on the “relay icon” to enter in the Setting menu to program the relay.

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5) Enter the limits for amplitude, frequency and displacement angle. See the dU

(maximum permissible voltage difference for the closing of the circuit breaker),

dF (maximum permissible frequency difference for the closing of the circuit

breaker) and the alpha (maximum permissible displacement angle UG/UB for

the closing of the circuit breaker). Send all parameters to the device (PW:

blank).

6) Enter in the SCADA and select EXERCISE 8 – Automatic Synchronization.

7) A general power grid schematic diagram is shown in the main window of the

SCADA. The main interface shows the characteristics and the requirements for

the parallel operation of the mains with the generator, using the automatic

synchronisation method:

Frequency: the frequencies must be the same (mains and generator)

Voltage: the generators should produce or be set to produce the same

voltage amplitude

Phase number: the two systems should have the same number of phases

and the same sequence.



Voltage phase angle: the waveforms should be matched such that they rise

and fall together. The angle difference should be in a maximum permissible

displacement angle UG/UB.

Click on “Experiments” to proceed with the SCADA application.

8) Switch on the power supply DL 2102AL shown in the wiring diagram presented

in figure 4. Turn the key of the three phase power supply to start. If you open

the virtual power meter DL 2109T29 from SCADA (but also on the real module),

you can see the electric parameters related to the mains.

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9) Before making any further step, it is very important to verify the correct phase

sequence of the mains (check the wiring between the power supply and the

power meter). If the phase sequence is not correct, a message will pop up in

SCADA (Pay attention, mains phase sequence wrong).

If the phase sequence is not correct, change two wirings between the power

supply (DL 2120AL) and the power meter (DL 2109T29).

10) Close the circuit breaker that interconnects the load by clicking on the HR2

switch from SCADA. This will close the circuit breaker (DL 2108T02) that

connects the power network with the load. In this step, make sure that the RLC

loads are on zero position.



11) Turn the switches of the resistive load from R0 to R4 in steps of one (from DL

1017R). In this way, after sinchronisation the generator will be connected to

the power grid and (that is connected to the load). The load current can be

measured and seen in SCADA, if you click on the power meter (DL 2109T29).

Also the active power (P) is measured and can be directly seen in SCADA.

12) Control the brushless motor (M) until the rated speed of the alternator is

reached. You can do this automatically by pressing the “Auto” button in SCADA

(1). The brushless diver DL 2108T26 will control the motor until approximatively

1500 rpm. Verify the correct phase sequence (2) of the generator side (check

the wiring between the generator terminals and the power meter). Click on the

relay (DL 2108T25) and its graphical interface (3) will pop up showing the

generator and mains parameters for synchronization.

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13) Slowly increase the excitation voltage (1) corresponding to the DC voltage of

the module DL 1067S, until you can read on the digital measuring module the

armature voltage of the generator (2).

14) The measured values of the armature voltage (UG) and of the mains voltage

(UB) can be seen in the SCADA software (2). The voltage values are indicated on

every line from the schematic diagram. Press INC/DEC (1) from SCADA to

increase (decrease) the excitation current, until the generator voltage

amplitude (UG) is as close as possible to the mains voltage amplitude (UB).



15) Slowly increase/decrease the speed of the generator (1) by pressing INC/DEC

from the prime mover control. Adjust the speed until the frequency of the

generator (2) is as close as possible to the mains frequency.

During this time, observe the LEDs of the relay front panel, that provide

information on the relay actual status.

Check the relay DL 2108T25 front

panel. When you see the red LEDs

flashing, that means that the associated

parameter is not yet matched ( U, f or the displacement

angle from the relay display). The LEDs will turn OFF one by one

when the synchronization conditions are according to the relay

program (MSCom2).

If you open the virtual synchronizing relay DL 2108T25 from SCADA (but also on

the real module), you can see the electric parameters related to the mains and

the generator side.

DL GTU101 S


When the voltage and frequency conditions are fulfilled, wait until the phase

displacement angle between UG UB will be <[ ] (see figure 2a).

16) After the three synchronization conditions have been fulfilled (phase sequence,

frequency and voltage amplitude), the automatic relay will CLOSE the circuit

breaker, and the generator will be synchronized with the mains.

17) When the experiment is complete, switch off the circuit breaker that

interconnects the generator with the mains.

18) Decrease the excitation of the generator. Press the DEC from SCADA. Observe

the output voltage of the generator and record the values through the software

facility for later processing.

19) Drive the brushless motor by pressing the DEC (related to the speed parameter)

from SCADA. This will decrease the speed of the prime mover.



20) Press again the “Torque and Enable” button from DL 2108T26.

21) Stop the experiment. Press the Exit button, from SCADA, to stop the power

supply of the prime mover.

22) Switch off the power supply DL 2102AL.

5. Conclusions

During this experiment, we have understood the importance of the automatic

method for synchronizing the synchronous generators.

The parallel operation of the generators is realized automatically when all the

parallel connection conditions are fulfilled.

The system does not require additional measuring tools for monitoring and control

processes.

The automatic synchronization relay is fast, cost effective, reliable and precise to be

used for monitoring, measurement and parallel operation of the synchronous

generators.

The knowledge learned in this experiment is very useful for understanding the

smart grid concept.

The synchronization of generators in parallel allows a greater efficiency of the

equipment, since in this type of installation it is possible to connect and disconnect

one or more of the synchronized generators according to the demand of the electric

network.

1 - Composition, operation and maintenace GTU 101 - RevGB FF

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Transcript of 1 - Composition, operation and maintenace GTU 101 - RevGB FF