The data contained several inconsistencies and the following procedure was used to identify and rectify readings that appeared erroneous:

Transcription

1 4.0 LAO POWER MARKET 4.1 Load Analysis Analysis of System Load Data Load data from EdL substations was collected analyzed and, after some adjustments, used as a basis for the development of dimensionless load duration curves needed by Lahmeyer s generation planning model, SEXSI. The load analysis was carried out for the calendar year 2002 and used data from EdL s existing grids but not from its isolated load centers. Hourly substation load data was keyed into data files and converted to the Lahmeyer time series database. Hourly values of power sent out were processed for most of the main 22 kv substations covering more than 90% of the total power demand. This figure was brought to 100% by proportioning the predicted year 2002 values of all substations given in Tables and of the report, Study on Master Plan of Transmission Line and Substation System in Lao PDR (the JICA Report ) 3 against those from the substations for which data was available. The data contained several inconsistencies and the following procedure was used to identify and rectify readings that appeared erroneous: All readings with a rise or fall exceeding 70% compared with the previous hour were marked and checked, and those showing subsequent rebound of the same magnitude were specially marked as being highly suspicious. The time series were then inspected for the occasions marked and adjustments made where plausible. Program HCHEK was used to automatically suggest more reasonable values based on readings for the same hour in the previous and following week. All days that showed a total drop in generation of 30% compared with the previous week were also inspected (program HCHEC), and adjustments made as described above. The losses for the 115 kv system were taken as 4% at peak load and quadratically less for periods of lighter loads; i.e. the corresponding energy loss during any hour at half of peak load would be calculated as 4% x = 1.0%. The results of the load analysis are given in Table 4.1 and a summary of peak load and energy requirements is provided in Table 4.2. The values in Table 4.1 are for stations connected to the grid by the beginning of A small percentage of national electricity demand occurs in small EdL grids, provincial isolated systems and through off-grid generation in remote locations. The estimation of peak load takes load diversity into account using the diversity 3 Study on Master Plan of Transmission Line and Substation System in Lao PDR, Final Report, Nippon Koei, JICA, September 2002 Final Report Vol A: Main Report 36

2 found in the 2002 load data. The estimated peak for an interconnected system is therefore less than the aggregate of peak loads of the component systems. Table 4.1: Load Analysis Summary Comparison with EdL PDP 2003 PSDP Load Analysis Isolated Grids Code Peak Energy Load Factor Diversity Facor (MW) (GWh/a) (%) (%) Central 1 C Central 2.1 C Central 2.2 C South S Sum CS Aggregate Values Central 1 + Central 2.1 C Central 1 + Central C Central + South S Comparison with EdL PDP 2003 Isolated Grids Code Peak Energy Difference in Peak Difference in Energy (MW) (GWh/a) (MW) (GWh/a) Central 1 C % 1% Central 2 C21+C % -2% South S % 30% Sum CS % 3% Aggregate Values Central 1 + Central C % 0% Central + South S % 3% Table 4.2: Peak Load and Energy Requirements Grid Code Peak Load (MW) Energy Requirement (GWh) Annual System Load Factor Central 1 + Central 2.1 C Central 1 + Central 2.1 and 2.2 C Central 1 + Central 2 + South CS Central 2.2 C South S It can be seen from Table 4.2 that EdL estimates of peak demand (MW) for combined systems (assuming interconnection) appears to be about 10% higher than the values derived from the load analysis. This is largely because load diversity was not considered by EdL. EdL s estimate of overall energy requirement (GWh) is also higher, by about 3%. (%) Final Report Vol A: Main Report 37

3 4.1.2 Load Profiles Information on the average weekly load profile and seasonal distribution of peak loads for each of the grids were also generated (example of Grids C1/C2.1 provided as Figures 4.1 and 4.2). Final Report Vol A: Main Report 38

4 Figure 4.1: 2002 Average Weekly Load Profile Central 1 and 2.1 Final Report Vol A: Main Report 39

5 Figure 4.2: 2002 Annual Peak Load Profile Central 1 and 2.1 A number of features of the load profiles in Lao PDR are evident: Three distinct peaks occur within the daily load curve in the morning, afternoon and evening. The prominent evening peak extends from 6:00pm to 9:00pm and defines the system s installed capacity requirements the morning and afternoon peaks are only 80% of the evening peak. The EGAT system peak is in the afternoon and the lack of coincidence with the Lao peak may provide opportunities for mutual gain in power trading arrangements. The morning and afternoon peaks are attenuated on Saturdays and Sundays and the evening peak is about 10% less than the weekday peaks. The shape of the daily load curve does not vary between seasons but the capacity does. Loads during the cooler months of December and January are about 80% of the equivalent loads dung the hottest months. The system load factor 4 is relatively constant over the year (refer Figure 4.2) Load Duration Curves The load analysis of hourly loads produced dimensionless load duration curves (LDC) for each month of 2002 for use in the SEXSI power system expansion modeling. The SEXSI model employs the dimensionless curves to provide load duration patterns for future years by scaling them up to the predicted peak power and generation requirements of a given year. As an example, monthly load duration curves for C1/C2.1 are provided as Figure 4.3). The uniformity in their shape emphasizes the lack of variation in load patterns between months. 4 System load factor is defined as the ratio of energy (continuous power) to peak demand. Final Report Vol A: Main Report 40

6 The 2002 annual load duration, formed by aggregating the monthly figures for individual substations, is provided as Figure 4.4). Figure 4.3: 2002 Monthly Dimensionless Load Duration Curves Central 1 and 2.1 Figure 4.4: 2002 Annual Dimensionless Load Duration Curves Central 1 and 2.1 Final Report Vol A: Main Report 41

7 4.2 Demand Forecast for Lao PDR Basis of Forecast The reference point for the preparation of the demand forecast is the Government s goal to increase the national electrification ratio from the current level of 41% to 90% by This goal will be achieved by: (i) (ii) Off-grid development a successful but embryonic program of off-grid electrification employing state, donor and private resources is in place in Lao PDR. Villages chosen for off-grid electrification are currently beyond the reach of the EdL grids and are expected to remain so for the next 10 years (the time assumed for amortization of off-grid loans). Grid extension programs involving sub-transmission and distribution development. These programs will be scoped to achieve the 90% target after taking into account the contribution of off-grid household electrification. The basis of the demand forecast is the growth in demand in EdL s grids due to increasing demand of existing custiomers plus load associated with new connections. To the extent practicable, the PSDP demand forecast is based on the EdL forecast which was reviewed and adapted for the purpose. EdL s current forecast is described in EdL s recently updated Power Development Plan (the EdL PDP ). 5 EdL based its forecast on the methodology adopted in the JICA Report. The methodologies used in the JICA Report and EdL PDP have been reviewed and a summary of the reviews is contained in Annex Assumptions The key assumptions used in deriving the EdL demand forecast are described in Annex 8. These have been modified for the PSDP in the following areas. (i) Forecast of Electrification Ratio The planned household and village electrification ratios are a key input into the EdL and JICA demand forecast models. Accordingly the planned electrification ratios have been reviewed and the EdL targets modified as noted in Table 4.3 with the objective of electricity being introduced into of 90% of households by 2020 either through grid connections or off-grid supplies. The EdL electrification rates have been modified for PSDP forecasting purposes as indicated in Table 4.3. The modified EdL rates represent achievable interim targets. 5 Power Development Plan PDP (Updated Schedule of Committed Projects), System Planning Office, Development Division, Electricité du Laos, July Final Report Vol A: Main Report 42

8 Table 4.3: Electrification Targets Forecast Scenario PDP Low (%) PDP Medium (%) PDP High (%) Modified PDP (%) Pre-Grid (%) Grid Conversion (%) Off-Grid (%) Modified EdL (%) Total Households ( ) 915, ,449 1,071,383 1,183,863 1,295,799 Pre-Grid Households ( ) 310 1,325 50,000 86, ,000 The assumptions and sources of data behind the PSDP electrification targets in Table 4.3 are outlined: a) EdL PDP low, medium and high scenario - the source of this data is the EdL Power Development Plan for the period , July Although it is not explicitly stated, EdL s power development plan has been predicated on the high growth forecast scenario. This is the scenario that achieves GOL s intermediate and long-term electrification targets. b) Modifications to EdL PDP The EdL PDP s 2010, 2015 and 2020 targets may be achievable if funds for the necessary capital works are available. The 2005 PDP target, though, is ambitious from two perspectives; firstly, availability of funds for capital works and, secondly, capacity constraints within the Lao power transmission and distribution system. Consequently, the 2005 target was reviewed downwards from the EdL PDP high and medium case values. A 2005 household electrification target of 45% was adopted by interpolating between the EdL PDP s 2003 and 2010 PDP household electrification targets. c) Pre-Grid The EdL PDP does not take into account off-grid technologies (pre-grid) for electrifying households. There is currently a successful off-grid program in Lao PDR and the pre-grid household electrification targets have been deducted from the overall household electrification targets for the PSDP forecast. Targets of 50,000 households by 2010 and 150,000 households by 2020 were established for the pre-grid program in consultation with the off-grid unit of DOE and the World Bank. Though the contribution of the off-grid program to GOL s household electrification targets is significant, the effect on forecast demand for capacity and energy is slight. Final Report Vol A: Main Report 43

9 d) Grid Conversion - In combination with pre-grid targets, a rate at which off-grid villages convert to grid supplies was also estimated. This target takes into the account pre-grid households that change to grid-connected services as the grid extends further into rural areas. The grid conversion target was established in consultation with the off-grid unit of DOE. e) Off-Grid The off-grid scenario represents the households that will use off-grid technologies for the foreseeable future and is calculated by deducting the grid conversion target from the pre-grid target. f) Modified EdL The modified EdL scenario is calculated by deducting the off-grid households from the modified EdL PDP scenario. This is the demand forecast scenario that the PSDP study will use as a Base Case going forward. The household electrification rates from which the EdL PDP and modified EdL demand forecast scenarios are derived are shown in Figure 4.5. The modified EdL demand forecast scenario, together with the underlying assumptions, were discussed with the World Bank. Figure 4.5: Household Electrification Rates (ii) Non-Residential Demand Growth Non-residential demand growth is based in part on GDP growth targets. Should actual GDP growth be less than the GOL s targets, there will be lower than planned demand growth. The GDP growth targets assumed are the same for all scenarios and are based on the Socio-Economic Strategy of the GOL, repeated in Table 4.4. Final Report Vol A: Main Report 44

10 Table 4.4: GDP Growth Targets 2000 to to to 2020 GDP Total GDP Industry Sector GDP Service Sector The above GDP growth figures have been adopted; however, demand forecast should be reviewed in subsequent years and adjusted to reflect any changes in actual and forecast GDP figures. (iii) Household Electrification Rate Household electrification rates (number of electrified houses divided by the total number of houses in each village) are not specifically taken into account in the demand forecast. The implication of a low household electrification rate is that the grid must extend further to electrify the target number of households and this increases the cost per electrified household in newly electrified villages. Though household electrification rates may be low initially, household electrification rates are expected to increase rapidly to close to 100% within within 5 years of the grid arriving at a village. We therefore have not taken the household electrification rate into account in the demand forecast. (iv) Coincidence The following coincidence factors were allowed for when interconnecting EdL s grids: Central 1 + C 2.1 Grid 0.97 Central 1 + C2.1 + C2.2 Grid 0.94 Central 1 + C2.1 + C2.2 + S Grid 0.94 v) Industry Load in Central 2.1 Grid There is evidence of increasing economic activity in Lao PDR and the GMS region. A number of developments within the Central C2 supply area, in particular, is seeing a significant increase in demand. The improvement of the north-south and east-west (Thailand-Vietnam) road system will contribute to the general development of the area but, more significantly in the short term, a number of industrial point loads are being added in the Central 2.1 area including the following: Cement factory 20 MW 2005 Quarry 5 MW 2008 Gypsum & lead mine 5 MW 2006 Copper/Gold Mine 40 MW 2005 Final Report Vol A: Main Report 45

11 Nam Theun 2 construction 4-8 MW Irrigation 10 MW vi) Actual Energy Demand Data The 2002 value of demand was determined using load data obtained from EdL substations and processed using Lahmeyer s HCHEC and HDURM programs. The value so derived did not correspond to the EdL figure for the same year and the EdL forecast was therefore adjusted for PSDP purposes by anchoring the EdL growth forecasts to this known 2002 starting value PSDP Base Case Scenario Assumptions In summary, the PSDP base case demand forecast for grid-supplied electricity (domestic consumption) is formulated on the EdL PDP forecast with the following adjustments: (i) (ii) (iii) (iv) (v) The household electrification target (inclusive of off-grid households) for 2005 is reviewed downward to 45%; Pre-grid and off-grid households are taken into account in the projections of total households electrified; Coincidence has been allowed for when interconnecting isolated grids; Additional industrial load has been allowed for in the Central 2.1 grid (Khamouanne Province); The forecast has been adjusted to reflect actual 2002 energy demand data Comparison of PSDP and EdL Forecasts The aggregate EdL demand forecast is summarized in Table 4.5. The PSDP demand forecast, determined by making the adjustments to the EdL forecast described in the preceding section, is summarized in Table 4.6. The apparent anomaly between years 2002 and 2005 is caused by the copper/gold mine electro winning process in Central 2.1. This will be a load of about 40 MW with a load factor of 0.8. The electro winning plant is presently under construction, as is the 115 kv transmission line to feed the plant, with a planned commissioning date of December A graphical comparison of recent demand forecasts is provided in Figure 4.6. Final Report Vol A: Main Report 46

12 Table 4.5: Aggregate EdL Forecast Item Unit Energy Consumption GWh , , , ,834.2 Av. annual Growth Rate % 24% 9% 6% 5% Peak Load MW Av. annual Growth Rate % 22% 8% 6% 5% Load Factor % 55.3% 55.6% 60.0% 60.0% 60.0% (Source: Summary of Electricity Demand Forecast (High Case), EdL PDP Plan, EdL Power Development Plan PDP , July 2003) Table 4.6: PSDP Demand Forecast Item Unit Energy Consumption GWh , , , ,664.2 Av. annual Growth Rate % 23% 9% 6% 6% Peak Load MW Av. annual Growth Rate % 20% 7% 6% 5% Load Factor % 54% 58% 63% 63% 64% Final Report Vol A: Main Report 47

13 Figure 4.6: Comparison of Recent Demand Forecasts 1200 MAXIMUM DEMAND (MW) PSDP Demand Forecast (June 2004) EdL PDP (High Scenario, July 2003) JICA Study, (High Scenario, Sept 2002) JICA Study, (Low Scenario, Sept 2002) PSSS Study (High Scenario, March 2001) PSSS Study (Base Scenario,March 2001) HDSS Study (Base Scenario, Jan 2000) YEAR 6000 DEMAND (GWh) PSDP Demand Forecast (June 2004) EdL PDP (High Scenario, July 2003) JICA Study, (High Scenario, Sept 2002) JICA Study, (Low Scenario, Sept 2002) PSSS Study (High Scenario, March 2001) PSSS Study (Base Scenario,March 2001) HDSS Study (Base Scenario, Jan 2000) YEAR Final Report Vol A: Main Report 48