Report on the completion of HPP POBREG RAIFFEISEN BANK SH.A. ALBANIA. Evaluation and Business Plan Supervision of Hydropower Plants

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1 Head Office Augustaanlage D Mannheim Germany Reinhold Metzler Project manager Tel: RAIFFEISEN BANK SH.A. ALBANIA entecag Consulting & Engineering Bahnhofstr. 4 CH-9000 St. Gallen Switzerland Hedi Feibel Hydrologist Tel: hedi.feibel@entec.ch Evaluation and Business Plan Supervision of Hydropower Plants intec - GOPA International Energy Consultants GmbH Leopoldsweg Bad Homburg v.d.h. Germany Anja Lassonczyk Energy Economist Tel:: +49 (6172) anja.lassonczyk@gopaintec.de Report on the completion of HPP POBREG Submitted: 29 August

2 1. Objective This completion report: Presents the work and related expenses done to complete the power plant s realisation in June 30, 2013 based on a plausibility check of the information provided by the investor, compares the total expenditures done with the re-allocated budget as of Aug. 12, aims at giving an account on the degree of completion of the works based on: Visual inspection of the components of the plant and functional tests conducted during the site visits of the Consultant on 2 nd July 2013 Evaluation of the documents on commissioning provided by the developer 2. Certification of work The investor provided us with his claim of work, executed from 1 st February up to 30 April 2013, with the remark, that no more work will be claimed after this time. Based on a check against the plans and the work inspected during the site visit this claim appears to be plausible. This statement is made under the condition that a signed copy from the supervisor would be provided after his return from holidays. (3 Sept.) The bank has provided its LC payments up to 30 June 2013, which are include in the assessment. The result of this assessment is reflected in the Table below. Based on the information provided and found plausible, the following can be stated: For the period 1st February up to 30 June 2013 an amount of Euro 740,797 can be certified. Up to the end of June 2013 a total of Mio. Euro or 93.6%% of the agreed budget has been spent. Description Budget March 12 Re-allocated Budget Aug.12 Total expenditure up to 31 Jan 2013 Spent 01 Feb March 2013 Spent 16 March - 30 June 2013 Total Expenditures up to 30 June 2013 Remaining budget as of June 30, 2013 Euro Euro Euro Euro Euro % Euro Headworks(Intake & Desander) Civil works 1,369,183 1,369,183 1,369,183 17,779 5,967 1,392, % -23,746 Hydromechanic equipment 130, ,250 89,275 89,275 80% 21,975 Headrace 0 0 Civil works & Hydromechanic equipment 4,928,029 4,928,029 4,928, ,057 84,853 5,121, % -193, Forebay and Spillway Cascade 0 0 Civil works 146, , ,653 22, , % -22,436 Hydromechanic equipment 66,920 60,510 38,044 38,044 63% 22,466 Penstock 0 0 Civil works 344, , , , , % -113,353 Pipework 445, , , , % -5,614 Powerhouse 0 0 Civil works 225, , ,483 15, , % -15,306 Electromechanical equipment 2,196,957 2,251,772 1,633, ,491 1,998,884 89% 252,888 Tailrace channel 335, , ,000 4,298 2, , % -6,500 Transmission line and connection 369, , , ,726 54% 97,846 Access roads 100, , , , % 452 Infrastructural expenses 145, , , , % -4,492 Planning and construction supervision 1,270,429 1,270,429 1,237,206 1,237,206 97% 33,223 Savings from items 229, , , % 0 Contigiencies 1,207,502 1,207, , ,919 33% 807,583 Project Insurance during construction 8,160 8,160 8,160 8, % 0 Total investment 13,290,684 13,290,684 11,698, ,075 Expenses claimed by Client 153, ,680 14,488, % Expenses certified by Consultant 153, ,171 12,439, % 2

3 3. Degree of completion of the civil works 3.1 Weir, intake and desander Figure 3-1 Weir, intake and desander completed and in operation Weir, intake and desander appear to be completed. Whether the design is functional has bee tested: During the time of high river discharges the structure performed as foreseen. The flush gates together with the weir crown as spillway seem to be sufficiently dimensioned The flushing channel in front of the intake has a good performance. The dividing wall has the right slope and height to create a perpendicular flow towards the intake when the flush gate is closed and changes into a parallel flow for effective flushing when the gate is open (see Fehler! Verweisquelle konnte nicht gefunden werden.) The only open issue regarding the weir is the leakage between the two sections of the weir (Figure 3-2). The engineers are aware of the problem and the consequences it could have if this leakage is not stopped. Their plan is, to seal the joint from the upstream side of the weir once the river water is low enough to allow to open the weir s backside. 3

4 Figure 3-3 Dividing wall correctly dimensioned: perpendicular flow if gate is closed (left), parallel flow during flushing (right) Figure 3-2 Leakage between the two sections of the weir 4

5 The desander has been checked regarding its desilting efficiency and the effectiveness of flushing out the settled sediment. As the river was already relatively low in discharge it did not carry too much sand. Hence it was difficult to actually test the function of the structure. The incoming water flow was relatively turbulent up to half of the chamber length which would lower the effectiveness of the desander significantly. By partially closing the inlet gates and observing the velocity distribution in the individual chamber it could be shown that the flow can be well distributed. It will be the task of the gate operators to find the best position of the gates to achieve a well distributed flow as shown in Figure 3-4 Figure 3-4 Desander under operation: the flow distribution between the chambers can be well adjusted by the inlet gates After a full day of operation, not too much sediment had settled in the chamber and hence the effectiveness of the flushing could not be tested. However, opening the flush gates in the evening of the site visit, released flush water which was loaded with silt (Figure 3-5) which can be taken as an indication that the flushing arrangement is working. Whether further refinement is required will be found out in the next rainy season. 5

6 Figure 3-5 Sediment settled in the chambers is flushed out 3.2 Tunnel and spillway During previous visits the tunnel work had been already inspected and found to be done in a professional way. As the plant was in operation the tunnel the final work on the tunnel was not inspected. Driving along its alignment no leakage could be detected. Hence, this part of the headrace can be considered to be completed. In contrast to previous discussions and plans, the spillway has not been placed close to the forebay but rather at the end of the tunnel. As it leads the water over a solid rock face, no stepped channel part was realised. Instead a chute was constructed. The spillway s capacity appears to be sufficient as it was tested during the emergency shutdown, described further below. The height of the headrace channel walls is sufficient to provide enough freeboard to avoid overtopping during shutdown(figure 3-6, Figure 3-7). 6

7 Figure 3-6 Spillway at the end of the tunnel to release excess water during shutdown Figure 3-7 The chute leading the water to a rock face, from where it drops down into the river 3.3 Forebay and irrigation water release The construction of the forebay is completed and its functions are assured. During the visit a significant amount of water was released into the irrigation scheme. The members of the irrigation committee where present and at first look they seem to be content with the solution. An open issue is still the manual cleaning of the trashrack, which is quite cumbersome. The future will 7

8 show whether the amount of trash arriving at the rack requires a mechanical cleaning device or whether manual cleaning is sufficient. Figure 3-8 Headrace seen from the forebay. Gate (green) for releasing the irrigation water in the foreground Figure 3-9 Forebay with irrigation gate (left) and penstock inlet gate (blue, right) and trashrack 8

9 Figure 3-10 Manual trashrack cleaning Figure 3-11 Discussion with members of the irrigation committee next to the channel leading from the forebay to the irrigation system 3.4 Penstock, powerhouse and tailrace channel The construction of the penstock is completed. This pipeline is made up of buried GRP pipe sections. As documented in previous reports the pipe has been installed under the supervision of the supplier (SUBOR). No problem with this component was apparent. Apart from final touches, the powerhouse and tailrace channel construction is completed and its design has proven to be appropriate. No problem with these components was apparent. 9

10 Figure 3-12 Last part of the burried penstock leading to the powerhouse. Tailrace exiting to the right discharging into the lake Figure 3-13 Turbine water discharging into the tailrace channel at the powerhouse 10

11 Figure 3-14 Tailrace channel leading to the lake 11

12 4. Degree of completion of the electro-mechanical equipment 4.1 Status of the generating units The two generating units with turbines from Gugler and generators from Gamesa are commissioned and operating. Before that a bearing problem on unit 1 was experienced damaging the bearing pads. With the help of local workshops the pads could be restored and since then the unit operates with no bearing problem anymore. The units started commercial operation on the 1st June Figure 4-1The two Gugler/Gamesa generating units under operation Figure 4-2The automatic control, transformer and medium voltage switchgear (back) 12

13 Figure 4-3 Typical display regarding the operational status of the units at the monitor Figure 4-4 Detailed information available on display 13

14 Figure 4-5 Damaged bearing pads on unit 1 Figure 4-6 Dismantled bearing of unit 1 14

15 4.2 Performance of the plant For the following assessment data recorded each minute by the SCADA system in the time 7 th June to 10 th July 2013 have been made available. Further, the daily readings of the electricity meter from 14 June to 12 Aug 2013 were given for the overview of the generation values Performance unit 1 Plotting the active power values recorded by the SCADA system for unit 1 the following graph results: Figure 4-7 Output of unit 1 in the time between 7 June and 10 July 2013 The plot shows that the unit is running in a continuous mode and is performing reliably since its commissioning, which was verbally confirmed by the engineers. The maximum value was recorded on 13 th June during the commissioning with 9.2 MW Performance unit 2 Plotting the active power values recorded each minute by the SCADA system in the time 7 th June to 10 th July 2013 for unit 2 the following graph results: Figure 4-8 Output of unit 2 in the time between 7 June and 10 July 2013 Also this plot shows a continuous and reliable operation from 26 June onwards which was verbally confirmed by the engineers. This unit was running most of its time on its full opening with a recorded maximum output of 3.6 MW 15

16 4.2.3 Output of the entire plant Adding up the output data of the individual units recorded for the same time slot results in the combined output power of both units at one time and therefore the entire plant output can be shown. The graph below shows the result: Figure 4-9 Output of the plant in the time between 7 June and 10 July 2013 It can be seen that the plant reached several days an output > 12 MW. The maximum output of the plant was recorded on 28 June and 4 July with 12.6 MW. This value is just 2% lower than the sum of each unit running on its own i.e 12.8 MW. This small difference is caused by the increased loss in the penstock with the increased flow and indicates that the penstock is sufficiently dimensioned. According to the Gugler supply contract a maximum generator output of 8.5 MW and 3.4 MW was guaranteed (contract page 2+6). Hence it can be concluded that Gugler has fulfilled the condition of output power according to the contract ( 17.2 clause 1, 2 and 3) Electricity generation Using the daily readings from the grid operator s sealed meter and plotting it versus time results in the following graph showing the accumulated generation of the plant: Figure 4-10 Accumulated generation from 14 June up to 12 Aug

17 In the 60 days of reading, the plant has generated some 4.2 GWh. The decreasing daily generation must be attributed to the approaching dry season with decreasing river discharge. This fact is also indicated by the following graph, which plots the average daily output of the plant (calculated from the daily generation). During the planning phase of the project, discharge values were developed by the hydrological study, to forecast an average generation. If the average discharge values for the respective days are used and a 1.5 m³/s reduction for irrigation is considered, the black line in the graph results, depicting the potential generation (not considering part load efficiencies) which would have been forecasted for the respective period. The graph shows that the generation is quite close to what has been forecasted. The difference towards the low levels can be explained by the decreasing efficiency of the units under part load. Figure 4-11 Actual generation vs. predicted values Summarising the issues related to performance it can be said, that in general the units perform reliably and as expected. Whether the units show the efficiency guaranteed by the supply contract (page 2+6), especially under part load, can only be established by a performance test as described in the standard IEC 6004 and mentioned in the contract ( 17.2 clause 4). 4.3 Checking the surge during emergency shut down Apart from the performance under normal conditions it is important that the plant does not create a too strong water hammer during the most severe operating condition: the emergency shut down under full load. The degree of surge pressure (water hammer) is determined mainly by the closing speed of the turbines. To see whether this speed has been adjusted correctly the plant was run on full power with both units open for a short moment and then dripped from the grid by the emergency button. The raise of water was observed in the air tube just next to the penstock inlet valve (Figure 4-12) while the whole test was recorded by the SCADA system (Figure 4-13 through Figure 4-15) 17

18 The observation during the test can be summarised as follows: the rise of the water level in the air tube stayed well below the end of the pipe the pressure raise measured at the turbine is less than 8% and hence the surge is acceptable the available flow in the channel was less than maximum and hence the wave development in the headrace channel could not be simulated good enough. The test showed that the pressure surge due to emergency closing is acceptable. Figure 4-12 Air tube (with black cover) next to the turbine inlet valve (blue steel structure) Figure 4-13 Plot of the opening and frequency of unit 2 during surge test. Closing time of the 18

19 turbine is 85 s Figure 4-14 Plot of the opening and frequency of unit 1 during surge test. Closing time of the turbine is 15 s Figure 4-15 Plot of the pressure raise (0.8 bar) during the surge test 19

20 4.4 Checking the vibration level over the operating range Even so both units run without problem at full load there is a marked increase of vibration at part load in unit 1. At certain power levels this vibration is so strong that the deflection of the turbine shaft can be seen with the naked eye. The vibration can be influenced to some extend by closing the bypass valve for the leakage water and with it increase the backpressure on the runner. However, at certain points of openings this measure is not reducing the vibration anymore. To determine this point of operation unit 1 was opened in steps, the influence of operating the valve on the vibration and the pressure was recorded. The observation is documented in the following table: Output (MW) Valve position Open/closed Pressure at runner back (bar) Observed vibration 0.75 CLOSED 2 Low OPEN 1.5 Low 1.5 CLOSED 2.0 Low OPEN 1.5 Low 2.5 CLOSED 2.5 Low OPEN 1.8 Vibration 3 CLOSED 3.0 strong shaft vibration OPEN 2 strong shaft vibration 5 CLOSED 3.5 Low OPEN 2.0 Vibration 6 CLOSED 4 Low OPEN 2.5 Low 8.5 CLOSED 4.5 Low OPEN 3.2 Low Table 4-1 Observation of vibration at various output levels of unit 1 The observed vibration is so strong that the opening of the turbine between 3 and 5 MW need to be avoided. The investor s engineers are aware of this fact and Gugler needs to be approached regarding this case of warrantee. 4.5 Documentation of the commissioning Asked for the documentation of the commissioning tests the consultant was given only two commissioning test records from GAMES for the two generators. These documents contain the standard onsite tests for generators: Standstill Tests No load tests Load tests The generators have past these tests without complaint. Both documents are signed by the supplier and the investor on 30 May However, the last page of unit 2 was signed later (2 June 2013) and carries a note that.the Generator is not ready to work without supervision under warranty condition (Figure 4-16). It is not clear whether this remark on the bearings has been already dealt with and the note on restriction been withdrawn by GAMESA already. Regarding the commissioning test of the turbines and their control no documentation has been submitted. The information given was, that the investor has not signed the required provisional certificate of commissioning yet, as the delivery and installation of the replacements for the damaged bearing pads and the check valves at the generator ends was still outstanding. Hence it must be stated that the 20

21 equipment has not yet been accepted by the investor. It needs to be noted that according to the contract 17.1 clause 8 The seller is discharged from executing any warranty obligations for the time where the equipment has not been taken over with a signed provisional or final Certificate of Commissioning.. Despite of this, the seller can claim that the warrantee period for the equipment of 27 months has started with the date of readiness of shipment (contract 11.1) which was in Nov So care needs to be taken not to lose time of the warrantee period by prolonging the period of acceptance for too long. Figure 4-16 Note on last page of commissioning test record unit 2 5. Statement of the Consultant on the completion After the visual inspection of the works and the test done as described in more details in the previous chapters, it can be stated that the realization of HPP Pobreg has been generally completed with only minor finishing work left on the civil works side. Regarding the Gugler supply the final and official taking over of the equipment is still outstanding. 21