Spannungshaltung und Blindleistungsmanagement bei

Faculty of Business and Economics, Chair of Energy Economics, Prof. Dr. Möst

www.ee2.biz

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


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

http://www.freepik.com/

http://www.flaticon.com/


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


Interface TSO / DSO

Reactive power tariffs


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

http://www.freepik.com/

http://www.flaticon.com/




Model development2

Motivation1


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


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




Model development2

Motivation1


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


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


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


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?




Model development2

Motivation1


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


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

mailto:[email protected]

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Spannungshaltung und Blindleistungsmanagement bei