Grid Integration Study Methodology, Scenarios & … · models in DIgSILENT PowerFactory ... Demand...

Project: Analysis of Indian distribution systems for the integration of high shares of rooftop PV

INTEGRATION OF RENEWABLE ENERGIES IN THE INDIAN ELECTRICITY SYSTEM (I-RE)

Final Workshop, 29 August 2017

Dr. Thomas Ackermann

Dr.-Ing. Eckehard Tröster

Grid Integration Study Methodology, Scenarios & Assumptions

Day 1, 10:45, 45 mins

Delhi Grid

• Introduction

• Scenarios investigated

Bhopal Grid

• Introduction

• Scenarios investigated

Solutions for enhancing the hosting capacity

CONTENT

2

3

INTRODUCTION TO THE DELHI GRID

Urban Feeder Characteristics:

• LV Network modelled with 2-5 400 V feeders per Distribution Transformer

• Min. length: 36 m

• Max. length: 719 m

• 8 Distribution Transformers (5.4 MVA total)

• Mostly of 630 kVA size

Rural Feeder Characteristics:

• Two 11kV feeders

• Feeder 1 length: 12.26 km

• Feeder 2 length: 12.3 km

• 40 Distribution Transformers in Feeder 1 (5.2 MVA total)


• 28 Distribution Transformers in Feeder 2 (4.6 MVA total)


FEEDERS INVESTIGATED

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Two networks from Delhi were investigated

• Urban Feeder

• Rural Feeder

GRID STRUCTURE – URBAN FEEDER

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033kV_Vasant..

011kV_Vasant..

External Grid

T01

_T

310

32

T01

_T

310

32

_2

0M

VA

_3

3/1

1kV

33/11kV Urban Feeder grid substation

11kV network Urban Feeder

400V Example networks

GRID STRUCTURE – RURAL FEEDER

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Feeder 2

Feeder 1

PV Connection

towards Rawta

PV Connection

towards JhulJhuli

~

3.5 MW PV plant

66/11 kV substation Rural Feeder

66/11 kV substation Rural Feeder

7

DELHI: SCENARIOS

• Load:

• Measurement at DT is available

• Divvied up based on loading information of feeders

• Equally distributed along the feeder every ca. 25m

• PV:

• Connected at every household

• Aggregated PV generation is proportional to DT’s rating

Example: 100 kVA DT

URBAN FEEDER SCENARIO 1: PV EQUALLY DISTRIBUTED ALONG THE FEEDER WITH NORMAL LOAD

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Load PV

Load PV

Load PV

Load PV

11 kV

400 V

PV equal distribution

Load PV

Load PV

Load PV

Load PV

Penetration Level PV(inverter) rating

30 % 30 kW

50 % 50 kW

75 % 75 kW

100 % 100 kW

150 % 150 kW

• Load:




• PV:

• Connected at every household starting at half of the line

• Aggregated PV generation is proportional to DT’s rating, but individual size doubles

URBAN FEEDER SCENARIO 2: PV WITH HIGHER PV PENETRATION AT THE END OF FEEDER WITH NORMAL LOAD

9

Load

Load

Load PV

Load PV

11 kV

400 V

PV at end of LV feeder

Load

Load

Load PV

Load PV

Larger individual

size

• Load:

• Additional AC load is added to every household

URBAN FEEDER SCENARIO 3: PV EQUALLY DISTRIBUTED ALONG THE FEEDER WITH ADAPTED LOAD

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Load PV

Load PV

Load PV

Load PV

11 kV

400 V

PV equal distribution

Load PV

Load PV

Load PV

Load PV

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load

in p

u

time of day

Additional AC Load

Exchange with

adapted load

SCENARIO 3: PV EQUALLY DISTRIBUTED ALONG THE FEEDER WITH ADAPTED LOAD

11

Nearly sinusoidal characteristic on aggregating household AC demand

A/C electricity demand of individual houses and their average in a low-income area with hot climate in Florida 1996. Source: Florida Solar Energy Center

• Load:

• Additional AC load is added to every household

• PV:



URBAN FEEDER SCENARIO 4: PV WITH HIGHER PV PENETRATION AT THE END OF FEEDER WITH ADAPTED LOAD

12

Load

Load

Load PV

Load PV

11 kV

400 V


Load

Load

Load PV

Load PV

Larger individual

size

Exchange with

adapted load

• Load:




• PV:



• Network:

• Cable cross section gets reduced from 300 mm² to 150 mm²

URBAN FEEDER SCENARIO 5: PV WITH CABLES CONVERTED TO CABLES WITH LOWER CROSS-SECTION

13

Load

Load

Load PV

Load PV

11 kV

400 V


Load

Load

Load PV

Load PV

Larger individual

size

Lower cable cross section

Lower cable cross section

Two feeders are included: Feeder 1 and

Feeder 2

• Load:

• Measurements known at some DT‘s, unknown data was taken from similar DT‘s

• PV:

• At 11 kV, aggregated PV Generation is proportional to DT’s rating and connected at every DT

RURAL FEEDER SCENARIO 1: PV EQUALLY DISTRIBUTED ALONG THE FEEDER WITH NORMAL LOAD

14


30 % 30 kW

50 % 50 kW

75 % 75 kW

100 % 100 kW

150 % 150 kW

Load PV

Load PV

Load PV

Load PV

66 kV

11kV Feeder 1

Load PV

Load PV

Load PV

Load PV

11kV

66 kV

Feeder 2

Additional AC load is added with the assumption that there would be a 25% energy consumption (kWh) increase in the load (5% per year for 5 years, 2016 to 2022), typically with regard to Air-Conditioning, where a high evening peak is considered

RURAL FEEDER SCENARIO 2: PV EQUALLY DISTRIBUTED ALONG THE FEEDER WITH ADAPTED LOAD

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Load PV

Load PV

Load PV

Load PV

66 kV

11kV Feeder 1

Load PV

Load PV

Load PV

Load PV

11kV Feeder 2

66 kV

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load

in p

u

time of day

Additional AC Load


Feeder 1

• Load:


• PV:


• 3.5 MW PV power plant gets connected to Feeder 2 (worst case)

RURAL FEEDER SCENARIO 3: PV ON ALL FEEDERS WITH A PV POWER PLANT CONNECTED

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Load PV

Load PV

Load PV

Load PV

66 kV

11kV Feeder 2

PV power plant

Switch on


Feeder 2

• Load:


• PV:


• 3.5 MW PV power plant not connected

• Network:

• Standard cables with cross-section close to the existing over-head-lines was chosen

RURAL FEEDER SCENARIO 4: PV WITH OVER-HEAD-LINES CONVERTED TO CABLES WITH SIMILAR CROSS-SECTION

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Load PV

Load PV

Load PV

Load PV

66 kV

11kV Feeder 2

Use cables instead of OHL

PV power plant

Switched off

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INTRODUCTION TO THE BHOPAL GRID

Two networks from Bhopal were investigated

• An Urban Feeder

• A Rural Feeder

Urban Feeder Characteristics:

• 11 Distribution Transformers


• Sum of all Distribution Transformer Ratings: 2.2 MVA

• Length of line (Longest line)

• 33 kV : 700 meters – from 132 kV Ss to 33 kV Ss

• 11 kV : 2.4 km – from 33 kV Ss to furthest DT

Rural Feeder Characteristics:

• 33 Distribution Transformers


• Sum of all Distribution Transformer Ratings:

3.7 MVA

• Length of Lines (Longest line)

• 33 kV : 10 km – from 132 kV Ss to 33 kV Ss

• 11 kV : 4.5 km – from 33 kV Ss to furthest DT

FEEDERS INVESTIGATED

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GRID STRUCTURE – URBAN FEEDER

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Upstream (33 kV Network)

Urban Feeder (11 kV Network)

33/11 kV Ss

GRID STRUCTURE – RURAL FEEDER

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Upstream (33 kV Network) Rural Feeder (11

kV Network)

33/11 kV Ss

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BHOPAL: SCENARIOS

SCENARIO 1: PV EQUALLY DISTRIBUTED ALONG FEEDER WITH NORMAL LOAD

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• At 33 kV, aggregated PV Generation is proportional to power transformer rating

• Example: PT rating = 5 MVA

• At 11 kV, aggregated PV Generation is proportional to DT’s rating

• Example: DT rating = 100 kVA

Load PV

Load PV

Load PV

Load PV

11 kV

33 kV

132 kV

33 kV

Load PV

Load PV


30 % 1.5 MW

50 % 2.5 MW

75 % 3.75 MW

100 % 5 MW

150 % 7.5 MW


30 % 30 kW

50 % 50 kW

75 % 75 kW

100 % 100 kW

150 % 150 kW

SCENARIO 2: PV EQUALLY DISTRIBUTED ALONG FEEDER WITH AC ADAPTED LOAD

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Load PV

Load PV

Load PV

Load PV

11 kV

33 kV

132 kV

33 kV

Load PV

Load PV

Exchange with adapted load

Exchange with adapted load

• Additional Load is added with the assumption that there would be a 25% energy consumption (kWh) increase in the load (5% per year for 5 years, 2016 to 2022), typically with regard to Air-Conditioning, where a high evening peak is considered

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load

in p

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time of day

Additional AC Load

SCENARIO 3 (URBAN): PV IN-FEED HIGHER AT THE END OF THE FEEDER

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• Only PV Generators are moved to the end of MV Feeder, NOT the loads

• The total rated PV in-feed remains the same i.e.

• In the Urban Feeder, sum of all Distribution Transformer Ratings is 2.2 MVA, total PV in-feed rating remains the same

• In the Rural Feeder, sum of all Distribution Transformer Ratings is 3.7 MVA, total PV in-feed rating remains the same

• The equivalent 33 kV network remains the same

Load

Load

Load PV

Load PV

11 kV

33 kV

132 kV

33 kV

Load PV

Load PV

Moved to the end of the feeder

Larger installed individual capacity

Installed sum stays the same

SCENARIO 3 (RURAL): PV EQUALLY DISTRIBUTED ALONG FEEDER WITH AN ADDITIONAL PV PLANT

26

• PV plant of 2.5 MWp rating is added to either:

• Start of Feeder

• Middle of Feeder

• End of Feeder

Load PV

Load PV

Load PV

Load PV

11 kV

33 kV

132 kV

33 kV

Load PV

Load PV

2.5 MW PV

SCENARIO 4 (RURAL) AND 5 (URBAN): NETWORK FULLY CABLED OR CABLED WITH LOWER CROSS-SECTION

27

• Both the 33 kV and the 11 kV network are fully cabled

• Cable diameters were chosen to be similar to the existing diameter

• In the case of the Urban feeder, the cable diameters were chosen to be the smallest available diameters available in the IEC standard cable models in DIgSILENT PowerFactory

• In the case of the Rural Feeder, standard cables with cross-section as close to the existing over-head-lines was chosen Load PV

Load PV

Load PV

Load PV

11 kV

33 kV

132 kV

33 kV

Load PV

Load PV

Fully cabled / lower cross-section

Fully cabled / lower cross-section

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SOLUTIONS FOR ENHANCING THE HOSTING CAPACITY

SOLUTION 1: ON LOAD TAP CHANGER WITH AUTOMATIC VOLTAGE REGULATION AT MV LEVEL

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Measure Abbreviation

No Solution/ Base case base

OLTC with automatic voltage

regulation at MV level mvoltc

Wide area control wide area control

Shunt compensators for voltage

control shuntvcontrol

PV inverters with fixed non-unity

power factor fixed PF

Active voltage control by PV

inverters (Q(U) characteristic) qvchar

On-load tap changing DT oltc

PV cap at certain percentage of

installed panel capacity cap pv

Reinforcements of lines, cables

transformers grid

reinforcement

PV storage battery deployment -

own consumption storage

ownConsumption


peak shaving storage

peakShaving

Demand side management dsm

Load PV

Load PV

Load PV

Load PV

OLTC

11 kV

33 kV 33 kV to 11 kV Transformers are controlled with discrete on load tap changers which control voltage at LT side between 1.02 and 0.98 pu

SOLUTION 2: WIDE AREA CONTROL

Load PV

Load PV

Load PV

Load PV

66/33 kV to 11 kV Transformer is controlled with discrete on load tap changers which control voltage at a specific node of the feeder. The node can be at 11 kV or 400 V level

OLTC

30
















transformers grid

reinforcement



ownConsumption



peakShaving


SOLUTION 3: SHUNT COMPENSATORS FOR VOLTAGE CONTROL

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transformers grid

reinforcement



ownConsumption



peakShaving


Load PV

Load PV

Load PV

Load PV

11 kV

33 kV

Shunts are voltage controlled to maintain 1.0 p.u. Voltage.
















transformers grid

reinforcement



ownConsumption



peakShaving


SOLUTION 4: FIXED POWER FACTOR

Load PV

Load PV

Load PV

Load PV

PV Units generate reactive power based on constant power factor

32
















transformers grid

reinforcement



ownConsumption



peakShaving


SOLUTION 5: ACTIVE VOLTAGE CONTROL BY PV INVERTERS (Q(U) CHARACTERISTIC)

Load PV

Load PV

Load PV

Load PV

PV Units generate reactive power based on voltage, to reduce voltage rise

33
















transformers grid

reinforcement



ownConsumption



peakShaving


SOLUTION 6: ON-LOAD TAP CHANGING DT

Load PV

Load PV

Load PV

Load PV

11 kV to 400 V Transformer is controlled with discrete on load tap changers which control voltage at a specific node of one of the 400 V feeders

OLTC

34
















transformers grid

reinforcement



ownConsumption



peakShaving


SOLUTION 7: PV CAP AT CERTAIN PERCENTAGE OF INSTALLED PANEL CAPACITY

Load PV

Load PV

Load PV

Load PV

PV Units cap active power generation

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SOLUTION 7: PV CAP AT CERTAIN PERCENTAGE OF INSTALLED PANEL CAPACITY

Load PV

Load PV

Load PV

Load PV

PV Units cap active power generation

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base

cap pv
















transformers grid

reinforcement



ownConsumption



peakShaving


SOLUTION 8: GRID REINFORCEMENT

Load PV

Load PV

Load PV

Load PV

Build new lines, reinforce existing ones and increase transformer size to compensate overloading and voltage problems

37
















transformers grid

reinforcement



ownConsumption



peakShaving


SOLUTION 9: PV STORAGE BATTERY DEPLOYMENT – OWN CONSUMPTION

Load PV &

Battery

Load PV &

Battery

Load PV &

Battery

Load PV &

Battery

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PV Battery optimized for own consumption gets added to every PV system

SOLUTION 9: PV STORAGE BATTERY DEPLOYMENT – OWN CONSUMPTION

Load PV &

Battery

Load PV &

Battery

Load PV &

Battery

Load PV &

Battery

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PV Battery optimized for own consumption gets added to every PV system

base

owncon

Storage charging

Storage discharging
















transformers grid

reinforcement



ownConsumption



peakShaving


SOLUTION 10: PV STORAGE BATTERY DEPLOYMENT - PEAK SHAVING

Load PV &

Battery

Load PV &

Battery

Load PV &

Battery

Load PV &

Battery

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Battery optimized for peak shaving gets added to every PV system

SOLUTION 10: PV STORAGE BATTERY DEPLOYMENT – PEAK SHAVING

Load PV &

Battery

Load PV &

Battery

Load PV &

Battery

Load PV &

Battery

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PV Battery optimized for peak shaving gets added to every PV system

peakshave

Storage charging

Storage discharging

base
















transformers grid

reinforcement



ownConsumption



peakShaving


SOLUTION 11: DEMAND SIDE MANAGEMENT

Load PV

Load PV

Load PV

Load PV

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AC loads shifted to mid-day peak

SOLUTION 11: DEMAND SIDE MANAGEMENT

Load PV

Load PV

Load PV

Load PV

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AC loads shifted to mid-day peak

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THANK YOU FOR YOUR ATTENTION!

Grid Integration Study Methodology, Scenarios & … · models in DIgSILENT PowerFactory ... Demand...

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