generation system adequacy for the republic of south africa · generation resources and demand-side...
TRANSCRIPT
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Generation System Adequacy for the Republic of South Africa SYSTEM OPERATOR | CORNER REFINERY ROAD AND POWER STREET, GERMISTON, 1401
2018 to 2023
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IMPORTANT NOTICE
While the System Operator has taken all reasonable care in the collection and analysis of data available,
the System Operator is not responsible for any loss that may be attributed to the use of this information.
The changing environment in the South African energy industry means continually changing data that
might not have been included in the modelling of this study.
The study is not intended to be used as a plan, but rather to explore how possible different futures might
test the adequacy of a generation system. Prior to taking business decisions, interested parties are advised
to seek separate and independent opinion in relation to the matters covered by this report and should
not rely solely on data and information contained here. Information in this document does not amount to
a recommendation in respect of any possible investment.
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Table of contents 1 Introduction .......................................................................................................................................... 5
2 Methodology ......................................................................................................................................... 5
3 Assumptions .......................................................................................................................................... 6
3.1 Demand forecast ........................................................................................................................... 7
3.2 Eskom existing and committed supply resources ......................................................................... 7
3.2.1 Eskom committed build schedule ......................................................................................... 8
3.2.2 Shutdown of coal stations ..................................................................................................... 8
3.2.3 Eskom existing and committed sent-out capacity ................................................................ 9
3.3 Non-Eskom existing installed capacity ........................................................................................ 10
3.4 Renewable energy independent power producers contracted by Eskom ................................. 10
3.5 Small- to medium-scale embedded generation (solar PV) ......................................................... 11
3.6 Demand response ....................................................................................................................... 11
3.7 Plant performance ...................................................................................................................... 12
3.7.1 Modelling of plant performance ......................................................................................... 12
3.7.1.1 Planned outages .............................................................................................................. 12
3.7.1.2 Forced outages ................................................................................................................ 12
3.7.1.3 Partial load losses ............................................................................................................ 13
3.8 Air quality retrofitting ................................................................................................................. 13
4 Study cases .......................................................................................................................................... 14
5 Results ................................................................................................................................................. 15
5.1 Results of adequacy study .......................................................................................................... 15
5.2 Plant required to restore adequacy ............................................................................................ 15
6 Risks to system adequacy ................................................................................................................... 15
7 Conclusion ........................................................................................................................................... 16
8 Appendix: System Operator Statistics................................................................................................. 17
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List of figures
Figure 1: MTSAO methodology ..................................................................................................................... 6
Figure 2: Energy demand forecast ................................................................................................................ 7
Figure 4: Shutdown of Eskom coal station units ........................................................................................... 9
Figure 3: Eskom installed sent-out capacity (MW) ....................................................................................... 9
Figure 5: Non-Eskom installed capacity ...................................................................................................... 10
Figure 6: Estimated and forecasted small- to medium-scale embedded generation (solar PV) ................ 11
Figure 7: Eskom plant performance ............................................................................................................ 12
Figure 8: Capacity reduction due to air quality non-compliance ................................................................ 13
Figure 9: MTSAO 2018 scenarios ................................................................................................................ 14
Figure 10: Year-to-date OCGT utilisation .................................................................................................... 17
Figure 11: Number of frequency incidents ................................................................................................. 18
List of tables
Table 1: MTSAO adequacy metrics ............................................................................................................... 5
Table 2: Eskom committed build capacity .................................................................................................... 8
Table 3: REIPP cumulative installed capacity .............................................................................................. 11
Table 4: MTSAO 2018 system adequacy levers required to close gaps in MW .......................................... 15
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Glossary of terms Term Definition
Adequacy metrics The output parameters that are tracked in order to determine whether the power system is within acceptable thresholds
Base-load The plant capable of generating all day, when available
Capacity factor The ratio of the actual generated energy against the nominal energy (sent-out energy capability), representing the extent to which the installed capacity is utilised
CSP Concentrated solar power
EL1 Unit output above its maximum continuous rating maximum that could be produced for a short period on specific request of the System Operator
Energy availability factor (EAF) Ratio of the available energy generation over a given time period to the maximum amount of energy that could be produced over the same time period, expressed as a percentage
Mid-merit The plant that usually generates before the morning and evening peak demand and has a typical capacity factor range of 10% to 40%
National Energy Regulator of South Africa (NERSA)
The regulator of the electricity industry in terms of the Electricity Regulation Act 4 of 2006
Non-Eskom capacity Generation capacity from a third party (external source) not necessarily connected to the utility’s grid
Other capability load factor
The ratio of other unplanned energy losses (not under plant management’s control, including internal non-engineering constraints) to the maximum amount of energy that could be produced over the same time period, expressed as a percentage
Partial load losses Partial capacity reduction due to unplanned events
Peaking The plant generating only during the peak demand or emergency hours
Planned capability load factor The ratio of planned energy losses during a given period of time to the maximum amount of energy that could be produced over the same time period, expressed as a percentage
PV Solar photovoltaic
SO The System Operator who is responsible for dispatch of power
Unplanned capability load factor The ratio of unplanned energy losses during a given period of time to the maximum amount of energy that could be produced over the same time period, expressed as a percentage
Unserved energy The amount of energy that cannot be supplied to consumers, resulting in involuntary loss of supply to customers due to insufficient generation capacity, demand-side participation, or network capability
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1 Introduction
The South African Grid Code (SAGC, Version 9 July 2014) requires that the System Operator
(SO) publish a review (called the Medium-Term System Adequacy Outlook) on or before 30
October of each year of the adequacy of the integrated power system to meet the medium-term
(five-year future) requirements of electricity consumers.
In preparing the MTSAO, the SO considers the most recent information provided by Eskom
generators, independent power producers, other non-Eskom generators, the national
transmission company, transmission network service providers, and distributors such as:
possible scenarios for growth in the demand of electricity consumers;
possible scenarios for growth in generation available to meet that demand;
committed projects for additional generation;
demand management programmes; and
reasonable assumptions on imports and exports and any other information that the SO may
reasonably deem appropriate.
This Medium-term System Adequacy Outlook (MTSAO) provides a statement of generation
adequacy to meet the expected electricity demand for the next five years (calendar years 2018 to
2023). The adequacy to transmit and distribute electricity does not form part of this MTSAO.
2 Methodology
Generation adequacy studies are carried out to assess the balance between supply and demand,
without taking into account any limitations imposed by the transmission or distribution systems.
Based on South Africa’s load-shedding experience in year 2008, four metrics shown in Table 1
below were chosen to reflect risk associated with supply shortages to avoid the unreasonably
high cost associated with reducing this risk to a negligible level. The adequacy metrics provide
information on the operational, capacity, and energy adequacy of the generation system to meet
expected demand. The system is deemed adequate if all four system adequacy metrics are
satisfied.
Table 1: MTSAO adequacy metrics
Adequacy metric Threshold Details
Unserved energy < 20 GWh per annum Energy not supplied
OCCGT load factor < 6% per annum Gross load factor of all OCGT plant
Emergency Level 1 < 133 GWh per annum
Energy supplied by generators operating above their continuous rating. EL1 above the 133 GWh threshold is adjusted against the OCGT energy production.
Expensive baseload stations
< 50% per annum Gross load factor of the expensive coal-fired base-load stations
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The MTSAO assesses system risks using a Monte Carlo simulation technique, with the PLEXOS®
Simulation Software, on an hourly unit commitment and economic dispatch problem that does an
optimisation under uncertainties of the load, renewable generation production (particularly wind
and solar), and plant outages. The simulation results are tested against the four adequacy metrics
discussed above. Should any of the adequacy metrics not be met, additional capacity is then
added as per the iterative process shown in Figure 1 until all the adequacy metrics have been
met. The capacity options added to get to an adequate system are quantified per year and
classified as base-load, mid-merit, or peaking capacity in MW, depending on the capacity factor
required by the system for this resource.
Figure 1: MTSAO methodology
3 Assumptions
The assumptions with the largest impact on system adequacy are the demand forecast, the
available resources to meet demand, the performance of the plant, and the commercial operation
dates of plant under construction. These assumptions are outlined in the following subsections.
For the purposes of this assessment, it was assumed that the transient stability scheme (TSS)
currently under construction would not affect the dispatch of units at Medupi or Matimba. The TSS
would provide protection against the loss of rotor stability at Matimba and/or Medupi in the event
of a fault close to or at Matimba or Medupi. Furthermore, the load-shedding events of June to July
2018 due to labour-related strike action and possible future events were not specifically included
in the assessment.
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3.1 Demand forecast
Stats SA reported that South Africa’s energy consumption increased from 244.8 TWh in the 2016
calendar year to 244.5 TWh in the 20171 calendar year, a decrease of 0.1%.
The System Operator envisages energy demand growth to be conservative in the medium term
and has derived two energy demand trajectories for the country based on the moderate- and low-
growth scenarios as shown in Figure 2 below. The moderate energy forecast has an annual
average growth rate (AAGR) of 1.9%, while the low energy forecast is based on a 0.64% AAGR.
Figure 2: Energy demand forecast
3.2 Eskom existing and committed supply resources
Generation resources and demand-side initiatives are both used to meet the forecast demand.
The South African power system is made up of Eskom plant, which currently forms the bulk of
existing plant, non-Eskom generation resources licensed by NERSA, peaking and renewable
independent power producers (IPPs) contracted by Eskom, imports, and demand-side
management resources. Capacities of generation resources are grouped in terms of existing and
committed Eskom plant, existing non-Eskom plant, existing and committed Eskom-contracted
IPPs, and small- to medium-scale embedded generation.
1 Source: Statistics South Africa “Electricity generated and available for distribution”, March 2018
-1.00
-0.50
0.00
0.50
1.00
1.50
2.00
2.50
3.00
240
245
250
255
260
265
270
275
2017 2018 2019 2020 2021 2022 2023
Gro
wth
Rat
e [
%]
Ene
rgy
[TW
h]
Year
Energy Demand Forecast & Growth Rate
Low Growth Rate Moderate Growth RateLow Forecast Moderate Forecast
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Outlined below are details of the existing installed capacity, new capacity (in terms of quantity and
timing) to be commissioned during the period of study, and capacity expected to be shut down
during the period of study.
3.2.1 Eskom committed build schedule
The commercial operation dates (CoDs) of Eskom committed new build used in the assessment
are shown in Table 2 below for Medupi and Kusile Power Stations, respectively. The impact of
the possible early commercial operation of Medupi Unit 2, which was synchronised to the national
grid during October 2018 ahead of schedule, was not assessed in the study.
Table 2: Eskom committed build capacity
MEDUPI KUSILE
Unit 6 Commercial Unit 1 Commercial
Unit 5 Commercial Unit 2 31-Mar-2019
Unit 4 Commercial Unit 3 31-Dec-2019
Unit 3 31-Dec-2018 Unit 4 31-Dec-2020
Unit 2 31-May-2019 Unit 5 31-Aug-2021
Unit 1 30-Nov-2019 Unit 6 30-Jun-2022
Eskom new build programmes will add an additional 5 721 MW between 2019 and 2023.
3.2.2 Shutdown of coal stations
Capacity from Duvha Unit 3 was assumed not to be available for the purposes of the study. The
study further assumed that the units at Grootvlei, Hendrina, and Komati would be shut down when
it was no longer economical to carry out maintenance required in terms of the Occupational Health
and Safety Act (OHS Act) or turbine running hours. As at September 2018, 10 units had already
been shut down at these stations, removing 1 389 MW from the Eskom generation installed base.
It was assumed that the remaining units at these stations would be shut down when it is no longer
economical to carry out this maintenance.
Shut down refers to a unit brought down to zero power, but may be restarted in the future if the
necessary maintenance work is performed. However, for the purpose of this study, it was
assumed that these units would not be returned to service during the study period. This should
not be confused with decommissioning, which takes a unit out of service permanently or leaves it
dismantled partly or wholly, or closure of a facility to the extent that it cannot be readily returned
to service.
For the purposes of the assessment, other Eskom coal-fired units reaching their 50-year life were
also shut down, similar to the draft IRP 2018. This resulted in the shutdown of a single unit at
Arnot in 2021 and all the units of Camden between 2021 and 2023. The cumulative capacity shut
down during the study period is depicted in Figure 3.
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Figure 3: Shutdown of Eskom coal station units
This study then effectively assumed that 3 880 MW would be shut down at Hendrina, Grootvlei,
and Komati by the end of the study period. In addition, one unit at Arnot Power Station (372 MW)
would be shut down in 2021 and all the units at Camden Power Station (1 481 MW), starting in
2021 and completed in 2023. A total of 5 731 MW would have been removed from the system by
2023.
3.2.3 Eskom existing and committed sent-out capacity
The total Eskom installed capacity consists of coal, nuclear, pumped storage, diesel, hydro, and
wind as shown in Figure 4. The assumed timing of commissioning of new build stations and
shutting down of some units from older stations is as outlined in the following subsections.
Tech 2018 2019 2020 2021 2022 2023
Coal 36822 37839 39087 38690 38996 38074
Nuclear 1860 1860 1860 1860 1860 1860
Pump Storage 2732 2732 2732 2732 2732 2732
Hydro 600 600 600 600 600 600
Gas 2405 2405 2405 2405 2405 2405
Wind 100 100 100 100 100 100
Total 44519 45536 46784 46387 46693 45771
Figure 4: Eskom installed sent-out capacity (MW)
-
1 000
2 000
3 000
4 000
5 000
6 000
7 000
8 000
Jan
-18
Ap
r-1
8
Jul-
18
Oct
-18
Jan
-19
Ap
r-1
9
Jul-
19
Oct
-19
Jan
-20
Ap
r-2
0
Jul-
20
Oct
-20
Jan
-21
Ap
r-2
1
Jul-
21
Oct
-21
Jan
-22
Ap
r-2
2
Jul-
22
Oct
-22
Jan
-23
Ap
r-2
3
Jul-
23
Oct
-23
Cap
acit
y [M
W]
Month
Capacity Shutdown of Eskom Coal Stations
Arnot Camden Hendrina Grootvlei Komati
20000
30000
40000
50000
2018 2019 2020 2021 2022 2023
Cap
acit
y [M
W]
Year
Eskom Installed Capacity
Coal Nuclear Pumped Storage Hydro Gas Wind
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3.3 Non-Eskom existing installed capacity
Installed sent-out capacity of non-Eskom generation in South Africa is shown in Figure 5 below,
excluding the Renewable Energy Independent Power Producer (REIPP) Programme. The
capacity from Cahora Bassa (imported hydropower from Mozambique) is also reflected in the
figure. For the purposes of the study, it was assumed that one generation unit of the five installed
was on indefinite standby for contingencies, reducing the total capacity from Cahora Bassa
available to the South African system to 1 100 MW.
The study, furthermore, assumed that, although short-term contracts between Eskom and some
of the non-Eskom generators expired before or on 31 March 2017 (and had not been renewed),
those generators would continue generating for own use. The energy produced by non-Eskom
plant, excluding Cahora Bassa, was limited to 11 TWh2 per year throughout the study horizon.
Any reduction in this production would negatively affect the system adequacy outlook.
Figure 5: Non-Eskom installed capacity, excluding REIPP
Due to unavailability of non-Eskom plant performance data, the MTSAO modelled typical plant
performance based on plant of similar size and age. The actual generation profile of the above
stations is not well understood; hence, there was a risk of overestimating their production, which
would increase the demand required to be met by Eskom.
3.4 Renewable energy independent power producers contracted by Eskom
The capacity available from the REIPP (contracted by Eskom under Bid Windows 1 to 4) is shown
in Table 3 below.
2 Source: NERSA 2017 actuals net energy sent out
324 125
600
175
250
1 100
1 005
144
174
180
140 140 12
Non Eskom Installed CapacityKelvin
Sasol Infrachem Coal
Sasol Synfuel Coal
Sasol Infrachem Gas
Sasol Synfuel Gas
CahoraBassa
DoE Gas
Mondi
SappiNgodwana
Steenbras
Other Gas
Other CoGen
Other Hydro
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Table 3: REIPP cumulative installed capacity, including commercially connected plants
Technology 2018 2019 2020 2021 2022 2023
Wind 1 980 2 012 2 616 3 343 3 343 3 343
PV 1 474 1 964 2 287 2 287 2 287 2 287
CSP 500 500 600 600 600 600
Hydro 14 14 19 19 19 19
Landfill 8 8 8 8 8 8
Other 25 25 25 25
Total 3 976 4 498 5 555 6 282 6 282 6 282
The timing of the commercial operation dates for Bid Window 3.5 and 4 projects signed in April
2018 was derived from the contractual dates and is different from those assumed in the October
2017 MTSAO due to delays in contracting. As at October 2018, REIPP capacity currently in
commercial operation includes 1980 MW wind, 1474 MW solar PV, 300MW CSP, 14 MW landfill
and 5 MW hydro.
3.5 Small- to medium-scale embedded generation (solar PV)
The installed capacity of rooftop photovoltaic (PV) was assumed to be 285 MW (as at December
2017)3. Estimated and forecasted capacities are shown in Figure 6 below, showing a more
aggressive growth pattern into the future.
2013 2014 2015 2016 2017
Total Installed Capacity (MW)
18 33 96 186 285
Energy Generated (GWh)
18.5 41.5 109.3 241.1 370.84
Figure 6: Estimated and forecasted small- to medium-scale embedded generation (solar PV)
The inclusion of these estimates did not materially change the outcome of the adequacy
assessment, as the associated energy production was equivalent to less than 0.17% of the total
system energy in 2017, and the technology had no impact on the peak requirements of the
system.
3.6 Demand response
Demand response refers to loads that can be reduced on instruction of the SO. The MTSAO
assumed that the contracted interrupted loads due to expire from 2020 would not be renewed and
would, therefore, not be available as emergency resources to be deployed by the SO when
needed. An additional 350 MW of supplementary demand response is contracted up to March
3 Based on an April 2018 report by Eskom Research, Testing, and Development entitled “Trends and statistics of solar PV
distributed generation in South Africa” 4 This amounts to 0.17% of Eskom’s 2017 energy sent out
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2018. There is no certainty regarding renewal of this option, and therefore, these options were
not considered beyond this date.
3.7 Plant performance
Four scenarios for Eskom generation fleet performance were considered in the MTSAO,
specifically for energy availability factors (EAFs) of 80%, 75%, 73%, and 71% as reflected in
Figure 7 below.
Figure 7: Eskom plant performance
These numbers are averages over the study period and may vary from year to year. Different
combinations of planned and forced outage rates5 resulted in different annual average system
EAFs, ranging from 71% to 80%. On 8 October 2018, current financial year EAF was 74.86%,
while calendar year EAF was 73.6%.
For the purposes of the assessment, it was assumed that there would be sufficient coal of the
correct quality available.
3.7.1 Modelling of plant performance
3.7.1.1 Planned outages
Planned outages were optimised by the Projected Assessment of System Adequacy (PASA)
model of PLEXOS®, which is an algorithm used to shape required maintenance events into
periods of time with high capacity reserve margin. PLEXOS® enables the same pattern to be
applied across scenarios with the same planned outage rate, thereby enabling a balanced
comparison.
3.7.1.2 Forced outages
Forced outages were modelled as independent events; that is, one generator failing does not
influence the failure of another. Also, there was no certainty of forced outage at any particular
time; that is, several units may fail simultaneously, or there may be no failures at all. Reasons for
forced outage of a generator, such as system voltage disturbance that, in turn, causes another
5 Forced outage rate is a combination of Unplanned Capability Load Factor (UCLF) and Other Capability Load Factor (OCLF)
65
70
75
80
85
2018 2019 2020 2021 2022 2023
EAF
[%]
Year
Eskom Plant Energy Availability Factor
80% EAF 75% EAF 73% EAF 71% EAF
0
5
10
15
20
2018 2019 2020 2021 2022 2023
FOR
[%
]Year
Eskom Plant Forced Outage Rate
80% EAF 75% EAF 73% EAF 71% EAF
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generator to trip, were considered a matter for system security and, therefore, outside the scope
of this system adequacy study.
3.7.1.3 Partial load losses
The System Operator observed a trend of partial load losses typically increasing during peaking
hours and decreasing during periods of low demand.
Since load losses are categorised as capacity on forced outage in plant performance reporting,
an explicit modelling of the pattern of partial load losses improved the assessment of system
adequacy during the peak period. Historical data from 2015 to 2018 year-to-date was used to
predict the pattern of partial load losses used in the study.
3.8 Air quality retrofitting
Eskom is legally bound to comply with the minimum emission standards (MES)6 at all power
stations. The MES were promulgated in 2010 and required Eskom to comply with existing plant
standards by 2015 and for existing plant to comply with new plant standards by 2020. Most of the
power stations do not comply with one or more of the standards. A postponement application to
delay compliance by five years was granted to Eskom in 2015. Eskom is in the process of applying
for further postponements for the full implementation of the MES.
For the purposes of the assessment, it was assumed that the MES would not have an impact on
the availability of generation plant and that sufficient provision was made for planned outages to
complete the required retrofits. If additional planned outages were to be required to do the retrofits,
EAF might be negatively impacted.
Should all emission projects not be concluded and the DEA not allow additional postponements,
a number of units would be impacted and might be de-rated or shut down. That scenario would
lead to a reduction of the total Eskom system capacity as shown in Figure 8 below.
, Figure 8: Capacity reduction due to air quality non-compliance
6 Air quality refers to sulphur oxides (SOx), nitrogen oxides (NOx) and particulate matter (PM)
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4 Study cases
The scenarios considered in this assessment are shown in
Figure 9 below. Common parameters for all scenarios were the 50-year life of plant for coal power
stations, shutdown dates for Grootvlei, Hendrina, and Komati, forecasted commercial operation
dates for Eskom new build plants, and contracted REIPP capacity and timing.
A total of six scenarios as shown in Figure 9 were tested in the study. Two demand forecasts
were used, where the low demand forecast was tested against two plant performance scenarios
and the moderate forecast tested against four Eskom plant performance scenarios.
Figure 9: MTSAO 2018 scenarios
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5 Results
5.1 Results of adequacy study
Based on the assumptions used, the results of the MTSAO 2018 can be summarised as follows:
At an EAF of 71%, the system is inadequate, regardless of demand growth.
At an EAF of 73%, the system is inadequate for moderate demand growth.
At an EAF of 75%, the system is adequate for all demand forecast scenarios considered.
At an EAF of 80%, the system is adequate for all demand forecast scenarios considered.
5.2 Plant required to restore adequacy
Simulations were carried out on all the scenarios that violated the adequacy metrics to estimate
the additional supply needed to restore system adequacy. The supply required to close the gaps
was characterised as baseload, mid-merit, or peaking plant, depending on the capacity factor
required by the system for this supply.
Table 4 approximates capacity needed to restore the system to adequacy. The optimal investment
(in terms of quantity and timing) in capacity should be informed by a long-term planning study,
such as the Integrated Resource Plan.
Table 4: MTSAO 2018 system adequacy levers required to close gaps in MW
Scenario Lever 2018 2019 2020 2021 2022 2023
Moderate demand + 71% EAF Baseload 1 000 2 100 1 000 1 500 1 500 2 100
Mid-merit - - 800 - 700 700
Peaking - - 1 500 1 500 900 600
Low demand + 71% EAF Baseload 200 400 400 400 400 400
Moderate demand + 73% EAF Baseload - 300 - - 600 1 500
Peaking - - - 300 - 900
Increasing the capacity available to the system by either increasing EAF or delaying the shutdown
of units as well as demand side initiatives would increase the adequacy of the system.
6 Risks to system adequacy
The MTSAO identified the following risks that could result in the deterioration of system adequacy:
Insufficient plant maintenance due to either funding constraints or unavailability of space to
do maintenance would cause deterioration of plant performance.
Earlier shutdown for economic or other reasons of Eskom and non-Eskom units. Such events
would further reduce capacity available to meet the demand.
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Insufficient coal at power stations due to the low coal stockpile levels currently experienced at
some power stations. This could be exacerbated by unavailability of suitable coal and/or
excessive rain in the Mpumalanga area.
Failure to comply with air quality standards might lead to load losses or shutdown of
generation units or stations. Currently, some of the Eskom power stations do not comply with
one or more of the minimum emission standards required by the National Environmental
Management: Air Quality Act 39 of 2004. Projects to ensure compliance might be hindered by
funding constraints or other logistical impediments such as compatibility of new technologies
with aging Eskom plant.
Retrofitting of plant to comply with environmental legislation might require additional PCLF;
this might increase the system’s planned outage days to affect retrofits and, consequently,
reduce EAF, thus having an impact on the availability of generators.
The switching back to using Eskom supply by non-Eskom generators would increase demand
on the system.
A further risk is a delay in the assumed Eskom and IPP commissioning dates.
7 Conclusion
The assessment indicated that the system would be adequate for the two demand scenarios
studied with an EAF at 75% and above. A deteriorating EAF or increase in demand would have
an impact on adequacy and could be further exacerbated if one or more of the identified risks
were to materialise.
Increasing the capacity available to the system by either increasing EAF or delaying the shutdown
of units as well as demand side initiatives would increase the adequacy of the system.
Care must be taken to mitigate the risks of a shortage of coal and potential impacts of the MES
on the available capacity on the systems. Should these risks materialise, it would have severe
negative implications for the adequacy of the system.
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8 Appendix: System Operator Statistics
Some of the monitored system reliability indices deemed relevant are reported this section based
on actual System Operator year-to-date data, as at end September 2018:
a. Usage of open cycle gas turbine (OCGT) load factor includes Ankerlig (1 327 MW), Gourikwa
(740 MW) and Department of Energy (DoE) OCGTs at Dedisa (335 MW) and Avon (670 MW).
The contractual load factor for the DoE OCGTs is 1% every half year. Figure 10 shows a
weighted total OCGT utilisation of 2.15% year to date, well below the adequacy metric of 6%.
Figure 10: Year-to-date OCGT utilisation
b. Frequency incidents reveal cases where reserves were deployed. Paragraph 9 of the
South African Grid Code: Version 9 stipulates the type (instantaneous, regulating) and
capacity in MW required to restore the system depending on the level of frequency drop. The
actual incidents in Figure 11 below show that the system had sufficient reserves to recover
from the disturbances. There were no incidences of frequency dropping less than 49.2Hz;
such an incident would automatically activate under-frequency load shedding.
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
Jan Feb Mar Apr May Jun Jul Aug Sep
Load
Fac
tor
[%]
Month
OCGT Load Factor 2018 YTD
Ankerlig Gourikwa Avon Dedisa System
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Figure 11: Number of frequency incidents
0
10
20
30
40
50
60
Jan Feb Mar Apr May Jun Jul Aug Sep
No
of
inci
dem
ts
Month
Frequency Incidents Count 2018 YTD
49.5 < f < 49.7 f < 49.5 f > 50.4 f > 50.5