2014018-20-1.0 Testing of Primary Response of Chamera I Unit 3

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C:\Temp\2014018 - INT, POSOCO, Testing of Primary Response\2014018-20-1.0 Testing of Primary Response of Chamera I Unit 3.docx

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CONTENTS

1 INTRODUCTION .......................................................................................... 4 1.1 Background ....................................................................................................... 4

1.2 Tests performed ................................................................................................ 4 2 DESCRIPTION OF TESTED UNIT ............................................................ 5 2.1 Basic unit data .................................................................................................. 5 2.2 Governor ........................................................................................................... 5 2.3 Actuator system ................................................................................................ 6 3 DESCRIPTION OF TESTS PERFORMED ................................................ 7 3.1 Definitions ........................................................................................................ 7 3.2 Method for island operation testing .................................................................. 8 3.3 Test procedure .................................................................................................. 9 3.3.1 Test equipment/function/signal check ............................................................... 9 3.3.2 Step response tests ............................................................................................ 9 3.3.3 Small island tests .............................................................................................. 9 3.3.4 Large island test ............................................................................................. 10 4 TEST RESULTS ........................................................................................... 11 4.1 Executive summary ........................................................................................ 11 4.1.1 Primary frequency response ........................................................................... 11 4.1.2 Island operation .............................................................................................. 11 4.2 Primary frequency response, step response tests ............................................ 11 4.2.1 Step response tests in FGMO mode ................................................................ 11 4.2.2 Step response tests in RGMO mode ................................................................ 19 4.3 Island operation tests Small island .............................................................. 27

4.3.1

Small island

generated load 10 %. .............................................................. 28

4.3.2 Small island generated load 75% ................................................................ 31 4.4 Island operation tests Large island .............................................................. 33 5 CONCLUSIONS ........................................................................................... 36 5.1 FGMO ............................................................................................................. 36 5.2 RGMO ............................................................................................................ 36 5.3 ISLAND OPERATION .................................................................................. 36 5.3.1 Small Island test: ............................................................................................ 36 5.3.2 Large island test ............................................................................................. 37 6 RECOMMENDATIONS ............................................................................. 38 6.1 Normal (grid connected) operation ................................................................ 38

6.2 Island operation .............................................................................................. 38 6.3 Mechanism ..................................................................................................... 38 7 REFERENCES ............................................................................................. 39


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REVISION RECORD

Rev.No.

Date Section Cause Revisedby

Distributed to

1.0 2014-11-23 All Draft report submitted NKr Nodal officers


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1 INTRODUCTION

1.1 Background

After the large disturbance/outage in northern India in July 2012 it was concludedthat there is a need to verify the primary response of generating units in India. InMarch 2013 it was decided that a pilot project to carry out primary frequencyresponse would be carried out, and this was then described in terms of referencedocument (annexure to contract agreement) [1].

Solvina International was awarded this pilot project after a global tender process andsigned a contract agreement with Power Grid PGCIL/POSOCO in August 2014 [1].

The purpose of these tests was to record and verify the following capabilities on thespecified generating units:

Primary Frequency Response in normal operation under Restricted governormode (RGMO) and Free governor mode (FGMO).

Primary Response of the machine to a simulated frequency signalcorresponding to islanded conditions in small island (one unit) and largeisland (2000MW system load).

The following units are included in the project:

490 MW thermal unit at Dadri NCTPS 210 MW thermal unit at Dadri NCTPS 216 MW gas turbine at Bawana GPS 180 MW hydro unit at Chamera-1 HPS 250 MW hydro unit at Tehri HPS

This report is for the tests at unit 3 (180MW) at Chamera, NHPC .

1.2 Tests performed

The following tests were carried out on Chamera-I unit 3 as per the test program [2]:

13 t Oct 2014 Test equipment/function/signal check

Connections completed with signal check and test equipmentfunction check.

14 t Oct 2014 Step Response tests

Step response tests at 10%, 75% and 100% of rated generated loadunder FGMO and RGMO mode.

15 t Oct 2014 Small Island test : 10% and 75% of rated generated load.

Large Island test: 75% of rated generated load.


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2 DESCRIPTION OF TESTED UNIT

Chamera hydro power station has three units of 180 MW each. The turbines are

Francis type.2.1 Basic unit data

Table 1: Basic data Chamera unit 3

Turbine Make BHEL

Age 1994

Size 180MW

Speed 214.3 rpm

Generator Make BHELAge 1994

Size 200MVA

Governor Make ALSTOM

Age 2011

Type Digital

2.2

GovernorThe governor is supplied by Alstom. It has two frequency control modes for normaloperation

1. FGMO (Free Governor Mode of Operation) is a linear power/frequencycontrol, based on a PI controller with droop. The feedback which is used forforming the droop response can be taken from either the measured generatedactive power (referred to as power feedback ON) or from the correspondingwicket gate position (referred to as power feedback OFF). This is selected bya switch in the control room. The normal condition is power feedback ON.FGMO is also suitable for islanding.

2. RGMO (Restricted Governor Mode of Operation) is a non-linear controlespecially adapted for the grid code requirements. Certain conditions ofdecreasing grid frequency within the RGMO frequency band will cause thegovernor to increase the generated load by 5 % of actual generated load for 5minutes. If the grid frequency goes above the limit of the RGMO, thegovernor will decrease the generated load by an amount calculated fromdroop (which is in this case referred to rated generated load).


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2.3 Actuator system

The wicket gate of each unit is controlled by a hydraulic actuator cylinder that rotatesa wicket gate ring in proportion to the governor output. The gate sections are linked

to this ring and are rotated by it, as indicated in the figure below. The sensor of thewicket gate position is placed on the actuator piston rod, which means that it cannotsense if there is any mechanical play or backlash in the link between the piston andthe ring or between the ring and the gate sections. The gate position in the figures inthis report is the position as measured by this sensor. The actual angle of the gatesections may differ from this measured position in case of mechanical play or

backlash.

The hydraulic actuator has a pressure reserve that enables rapid movement of thewicket gate. Repeated large movements could theoretically deplete this reserve fasterthan it can be refilled, but no such problems were seen during the tests.

Figure 1. Simplified diagram of the wicket gate control mechanism.

The results from the tests indicate that there is in fact a significant play or backlash inthe mechanism. This is the case for both the step response tests and the islandoperation tests, see section 5.

Sensor

ACTUATORCYLINDER

Piston rod

Ring

GatesectionsLinks


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3 DESCRIPTION OF TESTS PERFORMED

3.1 Definitions

Simulated frequency: This is the signal generated by the testequipment, SSPS.

It can be used as input to the frequency/speed controller instead of theactual speed from the frequency/speed

sensor.

Actual frequency: Signal from generator frequency/speed sensor.

Generated load: Active power of generating unit

[Active power (used in plots) ]

System load: Total active power consumption in the grid

Simulated system load System load simulated in the testequipment

System base load: Start value of simulated system load when starting the island simulation test.


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3.2 Method for island operation testing

Solvina has developed a test equipment to be used for evaluation of the islandoperation capability of power turbines. The equipment is called SolvSim Power

Station, SSPS.The test method uses the principle of HardWare In the Loop, i.e. a simulatorsimulating that a small power system is connected to the speed governor of a turbine.The speed controller will then act as if it is actually running in island operation. Theactive power produced by the turbine is measured and summed up with simulatedcontributions to calculate the active power balance of the simulated island.

Gen.

Grid

Turbine

M e a s u r e

d S i g n a

l s

Governor

Simulatedisland

Actual Frequency

SimulatedFrequency

SSPS

Relay

Figure 2. Hardware-in-the-loop simulation of island operation.

Models of loads as well as other power producers can be included in the model of theelectric island.

Using the active power balance and the total moment of inertia of the island, the

island frequency can be calculated and fed back to the speed controller of the turbinetested. In this way, the capability of running in island operation can be tested whilethe turbine is still synchronized to a strong grid.

SSPS is also used to inject simulated frequency steps for primary response tests.


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Simulated load steps were added to this base load as shown in section 4.3. After eachload step, the generated load and the simulated frequency were allowed to stabilize(near to 50 Hz).

The tests were repeated at 10% and 75% generated load with FGMO engaged ingovernor. The size of the acceptable system load steps was decided by increasing thestep size gradually until the simulated frequency limits or other limitations werereached.

3.3.4 L arge island test

This test was performed to assess the ability of the turbine to control the frequencytogether with other power plants on a local grid. All other power plants weresimulated to act according to power control. Simulated load steps of different sizeswere applied (see section 4.4) to determine the size of the load changes that the

power plant could handle.

The summary of the total simulated base load was 2000 MW. Table 3 belowsummarizes the grid model. The simulated load comprises frequency dependent andindependent loads.

Table 3 Simulator parameters for large island test

Totalsystem

base load

Ratedapparent

power (Sn) ofgenerator

System load withlinear frequency

characteristic

System loadwithout

frequencydependence,

no inertia

Additionalsimulated

powerplants

Largeisland:

2000 MW

200 MVA

(inertia 4,07 s)

1000 MW

(Inertia 0,70 s)1000 MW 2000 MVA(Inertia 4,0 s)

1800 MW


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4 TEST RESULTS

4.1 Executive summary

4.1.1 Pri mary f requency response

FGMO works as expected in both power feedback ON and power feedbackOFF . The magnitude of the response is as per the droop settings. However, the timeconstant varies vastly, mainly because of mechanical backlash in the actuator system.In power feedback OFF (meaning gate opening feedback), the gate openingresponds according to droop, but due to the mechanical backlash, the load respondsto various extent only. During the tests, both positive and negative frequency stepsup to 0.15 Hz were tested.

RGMO works as intended and in accordance with the Grid Code. Simulated

frequency steps were made to test functionality both within and outside the RGMOfrequency range 49.0-50.05 Hz.

4.1.2 I sland operation

The unit is very capable of controlling the frequency both in small island grids andlarge island grids. The capacity of handling load changes was tested up to 20MW(11%) with very moderate frequency variations (1,5Hz). It is believed that up to30MW should not be a problem in islanding.

Due to the mechanical backlash of the actuator there is a slow spontaneous frequencyoscillation of 0.3-0.4 Hz that however does not at all tend to cause instability.

4.2 Primary frequency response, step response tests

4.2.1 Step r esponse tests in F GM O mode

The step response tests are carried out to investigate how well the plant supports the power system at frequency changes of the grid. The speed droop is the parameter thatdecides the magnitude of response. The response has two characteristics that areinteresting to examine, the magnitude and the time constant (67% value, T 67).

For the tests in FGMO mode the droop setting during test was 6%. Both powerfeedback ON and power feedback OFF were tested.

Steps were carried out to give up to 5% load change, which is 9MW, and thefrequency step size giving that response would be 0.05*0.06*50 = 0.15 Hz.Consequently 9MW is the expected response for the steps to be carried out.Similarly, expressed in MW/Hz, the response is expected to be 60MW/Hz for anystep (9/0.15).


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4.2.1.1 Step response in FGMO, generated load 10%, power feedback ON

The step response tests were carried out at 10% generated load with power feedbackON.

Table 4 Frequency steps in FGMO, generated load 10 %, power feedback ON part 1

Simulatedfrequency (Hz)

Initialgeneratedload (MW)

Post stepgeneratedload (MW)

Gen. loadchange , P(MW)

MWcontribution(MW/Hz)

TimeconstantT 67 (s)

50 50,1 20 14 -6 60 48

50,1 50 14 20 +6 60 59

50 49,9

20 26 +6 60 25

49,9 50 26 20 -6 60 65

50 49,85 20 29 +9 60 42

49,85 50 30 20 -10 67 47

Figure 3. Frequency steps in FGMO, generated load 10 %, power feedback ON part 1.


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Table 5. Frequency steps in FGMO, generated load 10%, power feedback ON part 2

Simulatedfrequency (Hz)






Load setpoint changed from 20 25 MW @ 50 Hz

50 50,15 25 15 -10 67 30

50,15 50 15 25 +10 67 45

Figure 4. Frequency steps in FGMO, generated load 10%, power feedback ON part 2.

It can be concluded that the response is correct and in accordance with the droopsettings at all steps. The spread of time constant values mainly depends onmechanical backlash of the actuator linkage as explained in section 2.3 and 5.1. Itcan be seen from the above figure that the measured gate position opening variesdepending on step sequence whereas the load response is constant, which is expectedas power feedback is ON. The measured gate position is moved further tocompensate for the existing mechanical backlash (see section 5.1). For steps in thesame (decreasing) direction, the effect of mechanical backlash is reduced as the gate

position is already moving in upward direction so a shorter traveling distance isrequired by the actuator piston rod.


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4.2.1.2 Step response in FGMO, generated load 10%, power feedback OFF

The tests with power feedback OFF were carried at 10% generated load.

Table 6. Frequency steps in FGMO, generated load 10 %, power feedback OFF

Simulatedfrequency(Hz)

Initialgeneratedload(MW)

Post stepgeneratedload(MW)

Gen. loadchange ,P (MW)


Gatepositionchange(%)

Timeconstant,T 67 (s)

50 49,85 22 25 +3 20 5 57

49,85 50 25 23 -2 13 5 78

50 50,15 23 13 -10 67 5 27

50,15 50 13 14 +1 7 5 75

Figure 5. Frequency steps in FGMO, generated load 10 %, power feedback OFF.

The test shows that the gate opening response is according to the droop setting. Themeasured gate position change of 5% is in perfect accordance with the set droopvalue of 6%. However, looking at load response to frequency, steps have a varyingmagnitude. This is mainly because of the mechanical backlash, where certain gateopening value causes different values in real gate value and hence generated load.

The generated load change after a step is dependent on the direction of the previousstep. For example, for two steps in the same consecutive directio, the response of theactive load is immediate with frequency steps in increasing direction and the effect ofthe mechanical backlash is not there. This is because the movement of the gate

position is already in the downward direction and requires shorter piston travelingdistance.


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Tests were performed at 75% generated load with the same conditions as previoustests mentioned in above sections.

Table 8 Frequency steps in FGMO, generated load 75 %, power feedback OFF.Simulatedfrequency(Hz)







50 50,15 136 127 -9 60 5 47

50,15 50 127 133 +9 60 5 79


The test shows that the gate opening response is according to the droop setting. Themeasured gate position change of 5% is in perfect accordance with the set droopvalue of 6%.

However, the generated load response magnitude varies. This is mainly because ofthe mechanical backlash, where certain measured gate opening value causes differentvalues in real gate value and hence load.


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4.2.1.5 Step response in FGMO, generated load 100%, power feedback ON

Tests were performed at 100% generated load with the same conditions as for previous tests.

Table 9 Frequency steps in FGMO, generated load 100 %, power feedback ON.Simulatedfrequency (Hz)






50 49,85 180 189 +9 60 29

49,85 50 189 179 -10 67 26

50 50,15 179 169 -10 67 14

50,15 50 169 180 +10 67 30

Figure 8. Frequency steps in FGMO, generated load 100 %, power feedback ON.

The test shows that the generated load response to frequency steps has a consistentmagnitude in accordance with the droop setting. The response of the gate positionsignal is immediate. The response of the active load is immediate for some steps butdelayed by 7-10 seconds for some steps, due to the mechanical backlash as describedin sections 2.3 and 5.1.


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Tests were performed at 100% generated load with power feedback OFF and withsame conditions as for the previous tests.

Table 10 Frequency steps in FGMO, generated load 100 %, power feedback OFF.Simulatedfrequency(Hz)







50 50,15 179 170 -9 60 5 34

50,15 50 170 177 +7 47 5 38

50 49,85 177 190 +13 87 5 24

49,85 50 190 186 -4 27 5 52


The test shows that the gate opening response is according to the droop setting. Themeasured gate position change of 5% is in perfect accordance with the set droopvalue of 6%. However, looking at load response to frequency, steps have a varyingmagnitude. This is mainly because of the mechanical backlash, where certain gateopening value causes different values in real gate value and hence generated load.


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4.2.2 Step response tests in RGM O mode

The purpose of this test is to elaborate the function of RGMO. Frequency steps ofdifferent size and different levels are generated to excite the response of the RGMO.

The response in this mode should be in accordance with the grid code, which statesthat, There should not be any reduction in generation in case of improvement ingri d fr equency below 50.05 H z. Whereas for any fall in gri d fr equency, generati onfr om the unit should increase by 5 % limited to 105% of the M CR of th e un i tsubject to machine capability.

In Chamera, the RGMO frequency band is 49-50.05 Hz. The droop setting keptduring these tests in RGMO was 6%. The following sections give the results of thetests performed.


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4.2.2.1 Step response in RGMO, generated load 10%

For the tests at 10% generated load in RGMO mode, it is expected that for anydecrease in frequency below the RGMO upper band limit of 50.05 Hz, the generatedload should increase by 5%.

Table 11 Frequency steps in RGMO mode, generated load 10%, part 1of 2.

Simulated frequency(Hz)

Initial generatedload (MW)

Post step generatedload (MW)

Generated loadchange, P (MW)

50 49,95 24 22 -2

49,95 50 22 23 +1

50 50,10 23 16 -7

50,10 50 16 23 +7

50 50,15 23 13 -1050,15 50 13 23 +10

Figure 10. Frequency steps in RGMO mode, generated load 10%, part 1of 2


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Figure 11: Frequency steps in RGMO, generated load 10 % - part 2 of 2.

From the above figure, it can be seen that for a decrease in frequency, the generatedload increases by 5% of the actual value which is 1MW at that level. With increase infrequency to 50 Hz, no change in generated load is seen. For a step change in

frequency outside the RGMO frequency band 50.05 Hz, the generated load isdecreased in accordance with the droop setting referred to the rated load. The behavior is correct and in accordance with the grid code.


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4.2.2.3 Step response in RGMO, generated load 100%

The same procedure is repeated for tests carried out at 100% generated load. The behavior is expected to be according to grid code.

Table 14 Frequency steps in RGMO, generated load 100 % - part 1 of 2.Note: generated load changes after 5350 s are caused by water headoscillations due to starting of another unit.




Generated loadchange, P(MW)

50 49,85 Hz 179 188 +9

49,85 50Hz 188 179 -9

50 50,15 Hz 179 168 -11

50,15 50 Hz 168 187 +19 *)* )Simul ated fr equency going in and out of RGM O band, so resul t is not takeninto account.

Figure 14. Frequency steps in RGMO, generated load 100 % - part 1 of 2. Note:generated load changes after 5350 s are caused by water head oscillations dueto starting of another unit.

From the above figure, it can be seen that for a decrease in frequency, the generatedload increases by 5% of the actual generated load which is 9MW at that level. Withincrease in frequency to 50 Hz, no change in generated load is seen. The behavior is

in accordance with grid code.


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Table 15 Frequency steps in RGMO, generated load 100 % - part 2 of 2




Generated loadchange, P(MW)

50 50,10 Hz 178 171 -7

50,10 50 Hz 171 187 +16

50 50,2 Hz 178 164 -14

50,20 50 Hz 164 186 +22

50 49,98 Hz 178 178 0

49,98 50 Hz 178 178 0

50 50,02 Hz 178 178 0

50,02 50 Hz 178 178 050 49,99 Hz 178 178 0

49,99 50 Hz 178 178 0

50 50,04 Hz 178 178 0

50,04 50 Hz 176 186 +10

50 50,05 Hz 186 176* -10

50,05 50 Hz 176 186* +10* Simu lated fr equency going i n and out of RGM O band


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Figure 15. Frequency steps in RGMO, generated load 100 % - part 2 of 2

The test shows that when the frequency goes above 50.05 Hz, the generated load isdecreased in accordance with the droop setting. When the frequency decreases, thegenerated load is increased by 5 % of actual generated load.


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4.3 Island operation tests Small island

This test shows the ability of the plant to control the frequency when the tested unitis the only generating source of the system. By simulating system load changes of the

simulated island, the simulated frequency will change. The tested unit will try tocontrol the simulated frequency. This way, it can be seen if the unit is stable. Theisland operation tests were performed with power feedback off.Droop setting was 6 %.

It was decided that the testing would be made at 10% and 75% load.

For the following figures, the legend is as below:

Blue Simulated frequency. This denotes the grid frequency inreal Island operation.

Red Generated load (= measured active power). This denotesthe mechanical turbine load in real island operation.

Green Gate position feedback. Please note that this is measured onthe actuator piston, see section 2.3.

Purple Simulated system load. This denotes the actual system loadin real island operation.


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Figure 16. Simulated island operation, generated load 10 %, load step 16 MW.



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4.3.2 Small island generated load 75%

The tests were carried out at only 75% of rated generated load. Simulated systemload steps were applied and the frequency deviations were recorded.

Table 17 Simulated island operation, generated load 10 %, all applied load steps.

Total range ofgenerated load

(MW)

Simulated system load step(MW)

Max. frequency deviation, f(Hz)*

134-155 MW

+4 MW -0,4

-4 MW +0,6

+8 MW -0,5

-8 MW +0,7

+12 MW -0,5-12 MW +1,0

+16 MW -1,2

-16 MW +1,0

+20 MW -1,3

-20 MW +1,0


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Figure 19. Simulated island operation, generated load 75%, load step 16 MW.


The test shows that the unit is able to control the frequency in a stable way. There isa continuous slow oscillation while in island operation, due to mechanical backlashas earlier described, causing frequency deviations of around 0.3-0.4 Hz.

Nevertheless, the unit responds well to load steps and the frequency stabilizesquickly. The largest simulated load steps were 20 MW. It is likely that the unit can

handle even larger steps but the test was halted after 20 MW to avoid overstressingof the turbine.


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Figure 21. Simulated large island operation, generated load 75 %, load steps 25, 30MW. Simulated frequency and simulated system load are shown.

Figure 22. Simulated large island operation, generated load 75 %, load steps 25, 30MW. Generated load (active power) and gate position along with simulatedfrequency are shown.


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The test shows that the power plant responds well to load steps on a large grid. Thelargest simulated system load steps were 30 MW. It is likely that the unit canhandle even larger steps but the test was halted after 30 MW to avoid overstressingof the turbine.

From the above figure it can be seen that the load follows the same profile as thefrequency because of the inertia and linear frequency dependency characteristic ofthe load model described in section 3.3.4. Together with the inertia of the othersimulated power plants, this has a stabilizing effect of the grid frequency.


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5 CONCLUSIONS

5.1 FGMO

The results for step response tests in FGMO mode show a consistent behavior. Testswere performed both with power feedback ON and OFF.

Test performed with power feedback ON, show that response of load for a stepchange was as per droop, but with a variation in time constant.

Tests with power feedback OFF show that the response with regard to gate openingvalue was as per droop. However, a longer delay compared to power feedback ONwas noticed, as well as a varying response of the load magnitude depending on thecharacter of the step sequence.

The delay in response is attributed to mechanical backlash of the actuator system.

This cause shows in several ways. The measured gate position is seen to increase by3-4% before the load actually starts to increase. It was also observed that this phenomenon was not so pronounced when consecutive steps in frequency wereapplied in the same direction (either positive or negative), because the backlash at thesecond step then is zero.

In the case of power feedback is ON, the control compensates for this mechanical backlash by further moving the gate position. The tests with power feedback OFFshow a larger time delay for the response of the load. Here the delay is longer as thegovernor does not compensate for the existing mechanical backlash as there is nofeedback of generated load (active power).

5.2 RGMO

The grid code states that, There should not be any reduction in generation i n caseof improvement in gr id fr equency below 50.05 H z. Whereas for any fall in gri dfr equency, generation f rom the uni t shoul d increase by 5 % li mi ted to 105% of the

MCR of the unit subject to machine capability.

All tests show that the behavior is in accordance with the grid code. The time delayscaused by mechanical backlash has not been considered here because it is not part ofthe requirements, but the same variation in delay is present in RGMO.

5.3 ISLAND OPERATION

5.3.1 Small I sland test:

The unit could handle the 20MW system load steps very well, with very moderatefrequency variations. The tested load changes correspond to 11% of rated load, andthat is considered being very good.


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6 RECOMMENDATIONS

The results from the tests were analyzed to see what could further be done toimprove the performance. In this section some recommendations are presented.

6.1 Normal (grid connected) operation

FGMO is useful for providing frequency control to the national grid. Whileconnected to the national grid, the governor should be set to power feedback ON for

best accuracy of generated load and fastest possible response.

RGMO has a consistent response which is according to the settings. No actions arerecommended regarding this function.

6.2 Island operation

FGMO is also useful for frequency control while in island operation, either with oneunit as sole production on the grid or together with other units which may operate infrequency or load control. The unit responds well to load changes in the grid and canhandle load changes of at least 20 MW as sole production, and more if operatingtogether with other units. While operating on an island grid, the governor should beset to power feedback OFF for best stability.

While operating on a small island grid, there may be some slow continuousoscillations, caused by mechanical backlash in the wicket gate control mechanism.This oscillation does not impede the ability of the unit to respond to load changes inthe grid. It could however cause some difficulty or delay in the synchronization ofthe island grid to another grid.

RGMO should not be used while in island operation.

6.3 Mechanism

It is likely that a reduced mechanical backlash between the gate position sensor andthe angle of the gate sections will provide less continuous oscillations in islandoperation, as well as faster load control in grid connected operation.

One way of compensating for the backlash could be to move the gate positionfeedback sensor so that it senses the angle of the gate section rather than the positionof the piston that rotates the wicket gate ring.


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7 REFERENCES

[1] Contract Agreement No.: CC-CS/422-CC/CON-2241/3/G8/CA/5002 dated19/08/2014

[2] Test Program - Chamera : 2014 018-14-1.0

2014018-20-1.0 Testing of Primary Response of Chamera I Unit 3

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