Faculty of Business and Economics, Chair of Energy Economics, Prof. Dr. Möst
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Spannungshaltung und Blindleistungsmanagement bei zunehmend dezentraler Stromerzeugung
Fabian Hinz
Strommarkttreffen: VerteilnetzeBerlin, 22. September 2017
TU Dresden, Chair of Energy Economics, Fabian Hinz 2 / 1522.09.2017
Remuneration mechanisms4
Economics of voltage stability3
Model development2
Motivation1
TU Dresden, Chair of Energy Economics, Fabian Hinz 3 / 1522.09.2017
Flexible distribution gridConventional supply
Electricityfeed-inGermany
110 kVgrid
Medium / lowvoltage grid
Transmissiongrid
Reactive power has to be more flexible in the future
Reactive power supply: conventional and flexible scenario
Source: Kraftwerksliste BNetA 2015, Netzentwicklungsplan 2025
Reactive power supply
Conventional supply through large power plants and compensators
Availability in the transmission grid decreases
Supply can be replaced by RES in the distribution grid
Reactive power consumption
Reactive power consumption
38% 51% 59%
62% 42% 28%
13%
203520252014
8%
DSOOffshore TSOFlexible reactive powerIcons made by Freepik from www.flaticon.com
TU Dresden, Chair of Energy Economics, Fabian Hinz 4 / 1522.09.2017
Currently, reactive power remuneration does not incentivize flexibly supply
110 kVgrid
Medium / low voltage grid
Transmissiongrid
Usage and remuneration of reactive power in Germany
Final customers
Reactive power tariffs
No incentive for flexibility
Conventional power plants
Bilateral contracts for
reactive power
Renewable Energy Sources
Obligatory provision
No incentive for flexibility
Interface TSO / DSO
Reactive power tariffs
No incentive for flexibility
Remuneration
Reactive power tariffs exist in the form of penalties for excessive reactive power consumption and bilateral contracts.
Which are the benefits from a flexible supply and how can it be remunerated?
Usage
Voltage control Reactive power flows along a voltage
differential Voltage increase through feed-in of
inductive reactive power Voltage decrease through feed-in of
capacitive reactive power
Compensation of transmission equipment Transmission lines show a reactive power
behavior dependent on their load
Reactive power consumption of customers
0% 20% 40% 60% 80% 100%-10
0
2
-12
4
6
Utilization [%]
380 kV line
380 kV cable
Rea
ctiv
e p
ow
er c
on
sum
-p
tio
n[M
var/
km]
Icons made by Freepik from www.flaticon.com
TU Dresden, Chair of Energy Economics, Fabian Hinz 5 / 1522.09.2017
Remuneration mechanisms4
Economics of voltage stability3
Model development2
Motivation1
TU Dresden, Chair of Energy Economics, Fabian Hinz 6 / 1522.09.2017
Model developed in order to assess the benefits of flexible reactive power
Simplified model formulation of ELMOD AC and ELMOD LinAC
Target function: 𝐌𝐢𝐧 𝒏∈𝑵 𝒄𝒐𝒔𝒕𝒏𝒎𝒂𝒓𝒈∙ 𝑮𝒆𝒏𝒏
𝑷
Thermal limit: 𝑳𝒊𝒏𝒆𝑪𝒖𝒓𝒓𝒆𝒏𝒕𝒍 ≤ 𝑻𝒉𝒆𝒓𝒎𝒂𝒍𝒍𝒊𝒎𝒊𝒕𝒍Voltage range TS: 𝟎, 𝟗𝟕 𝒑. 𝒖.≤ 𝑼𝒏 ≤ 𝟏, 𝟎𝟑 𝒑. 𝒖.Voltage range DS: 𝟎, 𝟗𝟒 𝒑. 𝒖.≤ 𝑼𝒏 ≤ 𝟏, 𝟎𝟔 𝒑. 𝒖.
Generator capability curve: 𝑮𝒆𝒏𝒏𝑷,
𝑮𝒆𝒏𝒏𝑸 ∈
ELMOD ACELMOD LinAC
1) Un / Um... Voltage magnitude at node n / m Θn / Θm... Voltage angle at node n / m gn,m / bn,m... Conductance / susceptance between node n and m
GenP
GenQ
Gen𝑛𝑃 − Dem𝑛
𝑃
=
𝑚∈𝑁
𝑈𝑛𝑈𝑚 ∙ 𝑔𝑛,𝑚𝑐𝑜𝑠(𝜃𝑛−𝜃𝑚)
Gen𝑛𝑄− Dem𝑛
𝑄
=
𝑚∈𝑁
𝑈𝑛𝑈𝑚 ∙ 𝑔𝑛,𝑚𝑠𝑖𝑛(𝜃𝑛−𝜃𝑚)
Real power:
Reactive power:Non-linearities
Gen𝑛𝑃 − Dem𝑛
𝑃 − Loss𝑛𝑃
=
𝑚∈𝑁
𝑔𝑛,𝑚 𝑈𝑛 − 𝑈𝑚
Gen𝑛𝑄− Dem𝑛
𝑄− Loss𝑛
𝑄
=
𝑚∈𝑁
−𝑏𝑛,𝑚 𝑈𝑛 − 𝑈𝑚
Real power:
Reactive power:
Iterativecalculation
Gri
d b
alan
ce
Nodal 110 kV potentials
TU Dresden, Chair of Energy Economics, Fabian Hinz 7 / 1522.09.2017
Model applied to 110 kV grid set based on OSM data and other public sources
Data set for grid model
Power plants / RES
Attribution to nodes
Plants: based on addresses and coordinates
RES: based on OSM data / RES database
Load
Attribution based on GDP and population of surrounding area
Nodes: ~5700Lines: ~6500Substations: ~370
380 kV220 kV110 kV
OSM data
Substations380 / 220 / 110 kV
Electricity lines380 / 220 / 110 kV
Nodes with generation and demand
Auxiliary nodes
Lines start / end, technical parametersupdated with TSO static grid models
Transformers 380 / 110 kV220 / 110 kV
TU Dresden, Chair of Energy Economics, Fabian Hinz 8 / 1522.09.2017
Remuneration mechanisms4
Economics of voltage stability3
Model development2
Motivation1
TU Dresden, Chair of Energy Economics, Fabian Hinz 9 / 1522.09.2017
High wind, high loadLow wind, low load
Availability and usage of reactive power depends on grid situation
Potentials estimated with ELMOD LinAC and usage calculated with ELMOD AC
Large potentials from 110 kV grid Potential mostly capacitive due to inductive load Usage of inductive potential due to loaded grid
Small potentials from 110 kV grid (conv. plants) Potential inductive due to inductive MV behavior Usage of capacitive potential due to idle grid
Legend
Used poten-tial inductive
Unused poten-tial inductive
Used poten-tial capacitive
Unused poten-tial capacitive
Size of circles proportional to control range
Re
sult
s
TU Dresden, Chair of Energy Economics, Fabian Hinz 10 / 1522.09.2017
2014 2025 2035
Reactive power supply from decentralized sources can save operational cost
Annual savings potential in operational cost through decentralized reactive power sources, in mio. EUR
19,93,9
5,6
5,6
3,3
3,5
0
5
10
15
20
25
30
35
40
31,2
14,8
Full grid extension
2,2
Delayed grid extension
1,9
RedispatchCurtailmentLosses TSLosses DS
8,614,0 16,4
12,82,9
2,66,2
4,7
4,5
4,9
15,1
10,6
0
5
10
15
20
25
30
35
40
Full grid extension
36,3
40,3
Green -no lignite
Delayed grid extension
26,8
0
5
10
15
20
25
30
35
40
Status Quo
9,3
2,9
Co
st s
avin
gs p
ote
nti
al [
mio
. EU
R]
4,40,2
1,8
Increasing savings potential in delayed grid scenario
Large savings in redispatch Significance of reactive power
concept increases with delays in grid extension
Higher saving potential when grid extension is delayed, especially in combination with lignite phase-out
Savings in redispatch and curtailment
Certain cost saving potential already in the status quo
Savings potential mainly from loss reductions
Re
sult
s
TU Dresden, Chair of Energy Economics, Fabian Hinz 11 / 1522.09.2017
High savings potential in situations with a low residual load
Comparison of reactive power and savings potential per grid situation
Reactive power potential Cost savings potential
Which situations lead to a high need for reactive power from the distribution grid?
Highest potential between 20% and 40% wind feed-in Potential around 0% wind feed-in results from conventional power
plants in the 110 kV grid Above 50% wind feed-in reduced potential due to congestions and
reaching of voltage limits
Moderate savings potential in areas of low and medium wind feed-in as well as medium and high load
Largest savings potential at high wind feed-in and low load Due to low residual load, only a few conventional power plants are
dispatched Wind turbines provide a sufficient reactive power potential
TU Dresden, Chair of Energy Economics, Fabian Hinz 12 / 1522.09.2017
Only a small share of potential reactive power sources has to be made available
Reactive power control ranges and cost savings under different shares of wind power inclusion
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
10
-15
0
-10
-5
5
-20
3.0
-2.4
-3.7-4.4
4.63.8
-16.4-11.6
1.0
-10.5
2.05.2-0.1-1.2
-15.9-15.3
-14.8-13.5
-12.3 -12.9-14.1
-10.9
Inductive
Capacitive
0
2
4
6
8
10
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
6.86.6
8.0
5.3
0.9
7.3
1.8
8.3
6.3
7.8
3.6
8.78.7
Share of wind power plants with reactive power control
Re
acti
ve p
ow
er
con
tro
l ran
ge [
Gva
r]Sy
ste
m c
ost
re
du
ctio
n[m
io. E
UR
p.a
.] → System cost reductions show limited growth
→ 72% of cost reductions achieved with a 20% share of wind power plants
Increasing share of wind power plants with reactive power control
→ Aggregated control range in Germany 2025 increases slightly less than proportional
How many reactive power sources should be made available?
TU Dresden, Chair of Energy Economics, Fabian Hinz 13 / 1522.09.2017
Remuneration mechanisms4
Economics of voltage stability3
Model development2
Motivation1
TU Dresden, Chair of Energy Economics, Fabian Hinz 14 / 1522.09.2017
Alternative remuneration mechanisms could leverage reactive power flexibilities
Alternative remuneration concepts for reactive power
Regulatory
Reactive power obligations and / or tariff
calculations fixed on a regulatory basis
Obligatory provision
Regulated tariffs1)
DSOs and large customers can choosebetween active and passive participation
Active participants receive a premium for conform and pay a penalty for non-conform behavior
Scheme for active participants:
U
conform,premium
non-conform,penalty
QindQcap
non-conform,penalty
conform,premium
Uschedule Tolerance +/- 2 kV
Voltage-based premium
Market-based
Prices are an outcome of an open competition between
suppliers and demander(s), regulation only determines
the framework
Bilateral agreement
Long-term tenders2)
Constitution of short-term markets for reactive power similar to electricity markets
Zonal or nodal market design due to the the local nature of reactive power
TSO could act as auctioneer in a monopsonicmarket environment to cover system requirements
Volatile sources can bid based on their actual reactive power potential
Zonal layout:
Zone A
Zone B
Zone C
Nodal / zonal spot markets
1) For reactive power reserve or dispatch 2) Only for reserve premium or for reserve premium and dispatch prices
TU Dresden, Chair of Energy Economics, Fabian Hinz 15 / 1522.09.2017
Conclusions
Benefits
Additional reactive power mostly required in low residual load situations
Flexible reactive power from 110 kV RES can reduce operational cost up to 40 mio. EUR, especially if grid extension is delayed
Large part of savings can be generated with a small amount of sources
Remuneration
Current mechanisms not sufficient to incentivize flexibility
Regulatory or market-based concepts exist
Faculty of Business and Economics, Chair of Energy Economics, Prof. Dr. Möst
www.ee2.biz
Thank you for your attention!
Dipl.-Wi.-Ing. Fabian HinzChair of Energy EconomicsFaculty of Business and EconomicsTU DresdenEmail: [email protected]: +49 351 463 39896
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