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Transcript of Assessing the maximum penetration of non-programmable RES generation in power systems with...
Assessing the maximum penetration of non-programmable RES generation in power systems with predominant thermal generation
Bruno CovaHead of Power Systems, Markets and RegulatoryDivision Consulting, Solutions & Services
Renewable Energy Seminar, Amman, 27th-28th March 2012
Source: AUE
Agenda
Trends towards a progressive decarbonisation of power systems
Increasing penetration of power generation from non-programmable RES
Problems to overcome to enhance generation from non-programmable RES
Possible solutions: Enhancing flexibility of the power system (generation / grid / demand) The role of transmission infrastructure (supergrids/electricity highways)
The CESI experience
2
Power generation in the world
Power Generation from main energy sources
Source: Enerdata Yearbook 2011 / CESI elaborationsWorld power production: ~21.240 TWh
40%
20%
7%
15%
16%2% COAL
GAS
OIL
NUCLEAR
HYDRO
RENEWABLE- Biomass- Solar- Wind- Geothermal
3
Power generation in the Arab Countries
Power Generation from main energy sources
Source: AUE statistical bulletin 2010 / CESI elaborations
Typical specific CO2 emissions (kg/MWh)95.9%
3.8%
0.2%
FOSSIL FUEL HYDRO RENEWABLE
750÷1000
750÷850
500÷700
350÷450
0
200
400
600
800
1000
1200
Coal Oil Gas OCGT Gas CCGTArab Countries power production: ~815 TWh
4
Trends towards a progressive decarbonisation of power systems: Europe
The EU 20-20-20 objectives to meet the goal of limiting the global surface warming to above pre-industrial level:
20% reduction of greenhouse gases (GHG) emissions in 2020 compared to 1990; 20% savings in energy consumption compared to baseline projections for 2020; 20% of overall energy mix from RES by the year 2020.
Long-term target (not binding yet) by 2050: decarbonisation up to 80-95% compared to 1990 level
Present trend of «carbon-free» generation in the EU power sector:
• 2010: 48%• 2020: 54% (2000 TWh)
5
China: announced in 2009 a target of CO2
emission reduction per unit of GDP between 40% and 45% compared to 2005 levels by 2020
US: Northeast’s Regional Greenhouse Gas Initiative (RGGI), the first cap-and-trade program in the United States (year 2009) to set mandatory CO2 limits for the power sector. RGGI caps power sector CO2 emissions at the 2009 levels and requires a 10% reduction by 2018
Trends towards a progressive decarbonisation of power systems: other regions
6
Trends towards a progressive decarbonisation of power systems: the Arab Countries
In the Arab Countries the share of RES power generation is limited to 4% out of which 3.8% from hydro (Egypt, Sudan, Iraq, Syria, Morocco)
…but Arab Countries are endowed with a huge potential of power generation from the sun and the wind
Source: TREC development group
Source: the Schott memorandum
From 1 sq km of desert one can obtain with CSP up to:
250 GWh/year of Electricity 60 Million m³/year of Desalted
Seawater
7
Increasing penetration of power generation from non-programmable RES
Which problems already
experienced in Europe ?
RES generating capacity in Europe [GW]
+46%
+149%
SolarWind
0
50
100
150
200
250
Hydro Wind SolarOthers
11478
2612
118194
38 32
2010
2020
8
Agenda
Trends towards a progressive decarbonisation of power systems
Increasing penetration of power generation from non-programmable RES
Problems to overcome to enhance generation from non-programmable RES
Possible solutions: Enhancing flexibility of the power system (generation / grid / demand) The role of transmission infrastructure (supergrids/electricity highways)
The CESI experience
9
Pag. 10
Additional reserve and balancing capability
Problems to overcome to enhance generation from non-programmable RES
Risk of overgeneration in low loading conditions
Voltage profile and reactive power management
Difficult transitions in the ramp up/down
hours
Network congestion
Critical behaviour of the system in dynamic conditions
Curtailed RES generation !!!
Pag. 11
Possible solutions
Maximisation of RES generation penetration while minimising the
risk of curtailment: a FOUR-LAYER TOP-DOWN APPROACH
1. Reserve Criterion
2. Network connection / Static analysis
3. Reliability analysis
4. Dynamic Analysis
Single Busbar model
Secondary and Tertiary reserves are sized to manage the frequency error and the largest generator tripping
Additional reserve to face the unpredictability of RES is estimated
Acceptable gradients of max power increase/decrease are taken into account to confirm the limit of non-dispatchable generation
RES energy feed points and network constraints are not considered yet
1. Reserve criterion – Part 1
Increase in reserve requirement
Source: IEA-Wind
12
Pag. 13
1. Reserve criterion – Part 2
Results
First evaluation of maximum RES penetration that can be accepted by the system
Secondaryincrease reserve
Tertiaryincreasereserve
Renewableproduction
Secondarydecrease reserve
Tertiarydecreasereserve
Additionalreserve forRESTraditional
generation
i iMINP
i iMAXP
Max{RES} = Demand - (∑i PMIN-i + Tertiary reserve + Additional reserve)
Pag. 14
2. Network connection / Static analysis
Load flow calculations in compliance with the N and N-1 security criteria (TSO rules)
The most significant load scenarios are considered (i.e. peak and low load conditions)
Check the congestions on transmission network Impact of wind production on the system’s voltage profile
Results
Distribution of RES energy production capacity
The best connection points of RES units on the network
Pag. 15
3. Reliability analysis – Part 1
Different scenarios of RES penetration are evaluated to highlight the effects of increased RES generation on the secure and reliable supply of electricity
Probabilistic analysis using Monte Carlo method and considering: The probabilistic nature of
generation-transmission system over a whole year of operation
The unavailability of all power system components
Possible optimal exploitation of hydro sources
A simplified or complete network model
9 657 130519532601324938974545519358416489713777858433
0
5,000
10,000
15,000
20,000
25,000Annual photovoltaic production [MW]
9 603 11971791238529793573416747615355594965437137773183250
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000Annual wind production [MW]
Pag. 16
3. Reliability analysis – Part 2
Results Three meaningful “Risk Indices”:
• Loss Of Load Expectation• Loss Of Load Probability• Expected Energy Not Supplied
Reliability of the system to fulfil power demand
The maximum RES penetration compliant with reliability standards
0
5
10
15
20
25LOLE [h/year]
LOLP[%]
EENS[p.u.]
Scenario AScenario BBound
Wind /solar curtailment due to network element overloads, lack of interconnection or minimum stable operation of conventional units in low load condition
Possible network reinforcements, new storage devices and reserve margins able to preserve the static reliability and the security of the system
Pag. 17
4. Dynamic Analysis – Part 1
Check the fluctuations due to RES production intermittency (mainly frequency due to wind)
Pag. 18
4. Dynamic Analysis – Part 2
Analysis of network response, voltages and frequency to major fault events
Results
Measures to avoid any RES production restriction due to dynamic constraints
&ĂƵůƚZŝĚĞdŚƌŽƵŐŚĐŚĂƌĂĐƚĞƌŝƐƟĐ
Pag. 19
Possible solutions
Energy storageTwo levels: small scale to smooth high frequency
low amplitude intermittency: batteries at s/s
large scale for systemwide stabilisation: hydro pumping / different policies for unit commitment : higher rate of start up/ shut down of unit : OC TG
Demand responsiveness Demand response from users……. including electric vehicles
Source EC
The role of transmission infrastructure: the electricity highways
20
The role of transmission infrastructure: electricity highways between Europe and the MENA region
21
Agenda
Trends towards a progressive decarbonisation of power systems
Increasing penetration of power generation from non-programmable RES
Problems to overcome to enhance generation from non-programmable RES
Possible solutions: Enhancing flexibility of the power system (generation / grid / demand) The role of transmission infrastructure (supergrids/electricity highways)
The CESI experience
22
Pag. 23
CESI experience
PREVISIONNEL AN 2016
HVDC to Europe
Max penetration of RES in Tunisia Max wind generation penetration in
Jordan
Renewable Integration Development Programme – Ireland
Max wind generation penetration in Italy
End of Presentation
24
Problems to overcome to enhance generation from non-programmable RES
Need for additional reserve to cope with the intermittency of non-programmable RES generation
Solar (PV) generation is treated like wind production with additional reserve equal to the half of wind one
Penetration: wind / solar production [MW] / demand
Additional reserve [%]: percentage of wind / solar generation
Generated power
Secondary increase reserve
i iMINP
i iMAXP
Tertiary increase reserve
Additional increase reserve
Renewable production Wind + solar
Secondary decrese reserve
Tertiary decrease reserve
Additional decrease reserve Traditional
generation
Increase in reserve requirement
Source: IEA-Wind
25
Problems to overcome to enhance generation from non-programmable RES
Wind generation in Spain on 4th and 5th March 2008 (source REE)
Excessive RES generation over the instantaneous demand: risk of overgeneration
Possible voltage problems
26
Downward wind modulation
Pag. 27
Example of SpainRamp rate up to 10% of installed wind capacity per hour
Situation 9th Mai 2005
Problems to overcome to enhance generation from non-programmable RES
Coping with sharp variations of RES generation
Difficult transitions during load ramp up/down
demand
windExample of Spain
Problems to overcome to enhance generation from non-programmable RES
Difficult upward/downward transitions
No correlation between wind/sun generation and demand !!!
Time (min)
Wind + Solar
Load Request
Gradient of generation
28
Pag. 29
Problems to overcome to enhance generation from non-programmable RES
Network congestions caused by RES generation: Sun and wind are location dependent – often remote locations w.r.t. the demand
centres No correlation between demand and non-programmable RES generation location
- power flowing on longer patterns through the network with risk of creating “scattered” congestions also relatively far away from RES generation areas
Expected congestion in the 150 kV of the Italian peninsular regions due to WF (year 2009) – (source: CIGRE, CESI-Terna paper)
Pag. 30
Problems to overcome to enhance generation from non-programmable RES
Critical dynamic behavior of the system caused by Intermittency in RES generation causing a higher stress
on the conventional units to balance the system
Risk of cascading effect leading to the
system collapse
Frequency (Hz)
Typical solar radiation
0.00
100.00
200.00
300.00
400.00
500.00
600.00
700.00
800.00
900.00
1000.00
1 3 5 7 9 11 13 15 17 19 21 23
Hours
Rad
iati
on
(W
/m^
2)
Winter
Summer
Solar Radiation (W/m2)
Faults (e.g.: short circuits on a network component)
Pag. 31
Problems to overcome to enhance generation from non-programmable RES
Risks of RES generation curtailment depending on:
(In)flexibility of power plants (in)adequacy of the transmission /distribution infrastructures (including
cross-border lines) Possibility of energy storage Demand responsiveness
Different feasible penetration levels of non-
programmable RES generation
5%10%
16%22%
28%
0%
5%
10%
15%
20%
25%
30%
35%
40%
1,000 2,000 3,000 4,000 5,000 RE
S p
enet
rati
on
fo
r ea
ch a
rea
Cu
rtai
led
no
n-p
rog
r. R
ES
gen
.
Installed RES capacity [MW]