Planning, Analysis and Assessment of Distribution Systems with Renewable Energy Sources

Guide for Planning, Analysis and Assessment of Distribution Systems with Renewable Energy Sources

1. PLANNING, ANALYSIS AND
ASSESSMENT OF DISTRIBUTION
SYSTEMS WITH RENEWABLE
ENERGY SOURCES









RODEL D. DOSANO
Distribution System Impact Study
Simulations – A Case Study

2. RATIONALE
Purpose of the presentation:
introduce simulation based assessment and
impact studies of DS considering the effect of
highly penetrated renewable distributed
generations (DG’s).

The research study was motivated by the recent
DS environment affected by the fast emerging
renewable resources technologies.

3. TABLE OF CONTENTS
I.Introduction
II.Objectives of the Study
III.Significance of the Study
IV.Issues Examined In Renewable Energy Impact
Studies
V.Distribution System Modeling and Load Flow
Analysis
VI.Important Software Capabilities Necessary for
Distribution System Studies
VII.Optimization Problem Applied to Distribution
System with Distributed Generations
VIII.Distribution System Case Studies
IX.Conclusions /Recommendations

4. I. INTRODUCTION
The simulations and verifications of DS are included
to the following but not limited to:

update availability of the measured data to fully
understand the impacts of DG’s and DS
sustainable development
investigate the impact of distributed generation
units on voltage regulation
determine the optimal size and location of the
static and dynamic compensation devices and
DG’s in order to enhance the system stability and
reduce losses

5. I. INTRODUCTION (CONTINUATION)
Motivations:

the global supplies of fossil fuels that are
depleting and the fear of its effects and the
damage to the environment.

Distributed Generations (DG’s) like photovoltaic
system (PV) and the wind turbines (WT), are
one of the promising alternatives

6. I. INTRODUCTION (CONTINUATION)
Some issues which should be
considered and analyzed before to
maximize these technical benefits.

Planning, analysis methods and
appropriate assessment softwares for
DS studies to mitigate the harmful
effects of DG’s prior to its connection to
grid.

7. OBJECTIVES OF THE STUDY

This study focuses on the modeling,
simulations and assessment of high penetrated
DG’s significant impacts on the Distribution
System.

8. SIGNIFICANCE OF THE STUDY
One aspect of the problems to be addressed is
the concern with the use of appropriate tool
which is the three-phase power flow
calculations in electric distribution systems.
Determine control variables like for the
optimum amount of reactive power (kVAr) of
capacitor bank and its respective locations,
optimization techniques were utilized for this
purpose.

9. SIGNIFICANCE OF THE STUDY
(CONTINUATION)
The following important issues concerning DG’s
integration in DS covered in this report are the
following;

Effects of unbalanced phase distribution of
DG’s on the distribution system which could be
resulted from uncoordinated massive
installations.

Voltage violations on some buses and impacts
of DG’s in system’s loss for different
penetration level.

10. SIGNIFICANCE OF THE STUDY
(CONTINUATION)
Effects of DG’s on transformer power factor
and protection devices setting and probable
contribution of this report as basis for
forming DS operational guidelines and RE
interconnection requirements.

11. ISSUES EXAMINED IN RENEWABLE ENERGY
IMPACT STUDIES

Basic Structure of Electric Grid

12. Restructured Electric Grid with RE Resources
Integration

13. ISSUES EXAMINED IN RENEWABLE ENERGY
IMPACT STUDIES
Harmonics
Effect of RE on Distribution Transformers
Effect of RE on Protection Device
Effects of Moving Clouds on Utilities with
Dispersed PV
Voltage Imbalance
Penetration Limits

14. ISSUES EXAMINED IN RENEWABLE ENERGY
IMPACT STUDIES
Harmonics
Inverters of the PV system convert DC
current to AC current but it will not be a
perfect sinusoidal wave.

The latest model inverters generate little
harmonics, but an older poor-quality inverter
may generate severe harmonics.

15. RELATED CODES AND STANDARDS
The Distributor shall design and operate its System to
assist the System Operator in maintaining the
Fundamental frequency within the limits of 59.7 Hz and
60.3 Hz during normal conditions (PDC 3.2.2.2).
A power Quality problem exist when at least one of the
following conditions is present and significantly affects
the normal operation of the system: (PDC 3.2.1.2)
•The system frequency has deviated from nominal
value of 60 Hz;
•Voltage magnitudes are outsides their allowable
range of variations;
•Harmonic Frequencies are present in the System;

16. At any User System, the THD of the voltage shall
not exceed five percent (5%) during normal
operating conditions (PDC 3.2.4.4).
d) The Distributor shall conduct Distribution
Impact Studies to evaluate the impact of the
proposed connection or modification to an
existing connection on the Distribution System.
The evaluation shall include the following:
•Impact of short-circuit infeed to the
Distribution Equipment;
•Coordination of Protection system; and
•Impact of User Development on Power
Quality. (PDC 5.3.3.2)

17. Limitation of dc injection (IEEE Std. 1547-2003
4.3.1) “The DR and its interconnection system
shall not inject dc current greater than 0.5% of
the full rated output current at the point of DR
connection.” (IEEE Std. 1547-2003 4.3)

18. ISSUES EXAMINED IN RENEWABLE ENERGY
IMPACT STUDIES

Effect of RE on Distribution Transformers

19. One problem of the RE integration is that the
PF at distribution transformer is reduced.
The benefit of this is the network losses are
reduced as transportation of power to a
distance is not needed.

20. ISSUES EXAMINED IN RENEWABLE ENERGY
IMPACT STUDIES

Effect of RE on Protection Device
Protection Device
Basis for Protection Device Rating

Original Rating > Required
Protection Device Rating

21. The fault can be cleared by the protection
device once the enough fault current is
detected based on this conventional setting.
With PV installed in the system, there will be
percentage of fault current contributed by PV
system.
The magnitude of this fault current may not
be enough to trip the protective device due
to the reduction.

22. ISSUES EXAMINED IN RENEWABLE ENERGY
IMPACT STUDIES

Effects of Moving Clouds on Utilities with
Dispersed PV

The power output of PV drops when shadow of
clouds passes above a PV system. Normal
generation capacity of PV system is resumed
once the blocking clouds moves away.

23. ISSUES EXAMINED IN RENEWABLE ENERGY
IMPACT STUDIES

The existence of large PV system, whose output
is intermittent and changes with area directly
exposed to sunlight.

 These systems produce large variations in the
voltage profile due to the reduction of the
amount of power generated from PV system.

24. ISSUES EXAMINED IN RENEWABLE ENERGY
IMPACT STUDIES
Voltage Imbalance
This condition commonly occurs for domestic
rooftop systems (PV and wind turbine
installations)

This is due to that fact that these installations
mostly comprise of single phase inverters and
thus disturb the equal voltage balance
condition for three-phase balanced power.

25. ISSUES EXAMINED IN RENEWABLE ENERGY
IMPACT STUDIES
Penetration Limits

26. “Penetration” is the ratio of capacity of the PV
to the overall generating capacity. Two kinds of
penetrations are defined here:

1) “Installed penetration” is the proportion of
PV capacity installed to the overall capacity of
generation installed on utility. It changes when
new generation is either removed or installed
from service.
2) “Operational penetration” is the proportion
of PV capacity installed (currently generating) to
the overall capacity at a definite time. It
changes continuously with the change in load
and insolation.

27. At the penetration level where generation from
PV becomes substantial their collective impact
should be considered.

This phenomenon is particularly essential
when broken moving clouds cause the output
of the PV system to change randomly over
time.

28. IMPORTANT SOFTWARE CAPABILITIES FOR
DISTRIBUTION SYSTEM STUDIES

The softwares must basically supports all RMS
steady-state (i.e., frequency domain) analyses
commonly performed for utility distribution systems.

It is designed to be indefinitely expandable so that it
can be easily modified to meet future needs in the
areas of studies like;

•Distribution Planning and Analysis
•General Multi-phase AC Circuit Analysis
•Analysis of Distributed Generation
Interconnections

29. • Annual Load and Generation Simulations
• Wind Plant Simulations
• Harmonics and Inter-harmonics Analysis
• Neutral-to-earth Voltage Simulations
• And more ….

30. The program has several built-in solution
modes, including:
• Snapshot Power Flow
• Daily Power Flow
• Yearly Power Flow
• Harmonics
• Dynamics
• Fault Study
• And others …

31. DISTRIBUTION SYSTEM CASE STUDIES
Case 1- Load Flow Analysis of Unbalanced Three-
Phase Distribution System
Case 2- Practical Distribution System Analysis and
Simulations
Case 3- Practical Solution of Distribution System
Optimal Reactive Power Dispatch Problem
Case 4- Power Flow Assessment of Highly
Penetrated Distributed Generation Distribution
System
Case 5- Real Distribution System Simulations and
Analyses

32. THREE-PHASE POWER FLOW ALL PHASES

33. CASE 2-PRACTICAL DISTRIBUTION SYSTEM
ANALYSIS AND SIMULATIONS
CIRCUIT ELEMENT CURRENTS

(Currents into element from indicated bus)

Power Delivery Elements

Bus Phase Magnitude, A
Angle

ELEMENT = "Vsource.SOURCE"
SOURCEBUS 1 17.976 /_ 179.1
SOURCEBUS 2 19.746 /_ 71.3
SOURCEBUS 3 22.285 /_ -58.5
------------
SOURCEBUS 0 17.976 /_ -0.9
SOURCEBUS 0 19.746 /_ -108.7
SOURCEBUS 0 22.285 /_ 121.5

ELEMENT = "Transformer.SUB"
SOURCEBUS 1 17.976 /_ -0.9
SOURCEBUS 2 19.746 /_ -108.7
SOURCEBUS 3 22.285 /_ 121.5
SOURCEBUS 0 0 /_ 0.0
------------
Results of the Simulation

34. CASE 2-PRACTICAL DISTRIBUTION SYSTEM
ANALYSIS AND SIMULATIONS
LINE LOSSES= 106.5 kW
TRANSFORMER LOSSES= 5.9 kW

TOTAL LOSSES= 112.5 kW

TOTAL LOAD POWER = 3454.7 kW
Percent Losses for Circuit = 3.2 6 %

Total Line and Equipment Losses

35. CASE 2-PRACTICAL DISTRIBUTION SYSTEM
ANALYSIS AND SIMULATIONS
NODE-GROUND VOLTAGES BY BUS & NODE

Bus Node V (kV) Angle p.u. Base kV

SOURCEBUS 1 66.394 /_ 30.0 0.99997 115.000
- 2 66.395 /_ -90.0 0.99999 115.000
- 3 66.392 /_ 150.0 0.99995 115.000
650 ..... 1 2.4016 /_ 0.0 0.99991 4.160
- 2 2.4017 /_ -120.0 0.99997 4.160
- 3 2.4016 /_ 120.0 0.99993 4.160
RG60 .... 1 2.536 4 /_ 0.0 1.056 4.160
- 2 2.4916 /_ -120.0 1.0374 4.160
- 3 2.5364 /_ 120.0 1.056 4.160
633 ..... 1 2.4289 /_ -2.6 1.0113 4.160
- 2 2.4667 /_ -121.8 1.027 4.160
- 3 2.4055 /_ 117.8 1.0015 4.160
Line to Neutral Voltages

36. CASE 2-PRACTICAL DISTRIBUTION SYSTEM
ANALYSIS AND SIMULATIONS
NODE-GROUND VOLTAGES BY BUS & NODE

Bus Node V (kV) Angle p.u. Base kV

SOURCEBUS 1 66.394 /_ 30.0 0.99997 115.000
- 2 66.395 /_ -90.0 0.99999 115.000
- 3 66.392 /_ 150.0 0.99995 115.000
650 ..... 1 2.4016 /_ 0.0 0.99991 4.160
- 2 2.4017 /_ -120.0 0.99997 4.160
- 3 2.4016 /_ 120.0 0.99993 4.160
RG60 .... 1 2.536 4 /_ 0.0 1.056 4.160
- 2 2.4916 /_ -120.0 1.0374 4.160
- 3 2.5364 /_ 120.0 1.056 4.160
633 ..... 1 2.4289 /_ -2.6 1.0113 4.160
- 2 2.4667 /_ -121.8 1.027 4.160
- 3 2.4055 /_ 117.8 1.0015 4.160
CONTROLLED TRANSFORMER TAP SETTINGS

Name Tap Min Max Step Position

reg1 1.05625 0.90000 1.10000 0.00625 9
reg2 1.03750 0. 90000 1.10000 0.00625 6
reg3 1.05625 0.90000 1.10000 0.00625 9

37. SOLUTION OF THE ORPD PROBLEM WITH
DIFFERENT DE TYPE Table 8.6 Solution of the ORPD Problem with Different DE Type
Type of
DE
No. of f(x)
Evaluated
Evaluation Time
(sec)
Param 1
(kVAr)
Param 2
Bus No.
1 17 63 90 76
2 16 60 90
76
3 17 63 90
76
4 17 63 90
76
5 17 63 90
76
6 17 63 90
76
7 17 63 90
76
8 17 59 90 76


Optimal Allocation (Capacity and Placement)
of Capacitor Bank Minimizing Total Active
Power Loss
Capacity Placement

38. CASE 4-POWER FLOW ASSESSMENT OF HIGHLY
PENETRATED DISTRIBUTED GENERATION
DISTRIBUTION SYSTEM
Step 1. Run base case 1 at daylight peak load to develop
normal circuit peak load baseline.
Step 2. Run base case 2 at daylight light load to develop
normal circuit minimum load baseline.
Step 3. Run base case 1 again with a high penetration of solar
generation and compare results with those from Study 1.
Step 4. Run base case 2 again with a high penetration of solar
generation and compare the results with those from Study 2.

39. CASE 4-POWER FLOW ASSESSMENT OF HIGHLY
PENETRATED DISTRIBUTED GENERATION
DISTRIBUTION SYSTEM
Step 5. Run base case 1 again with a high penetration of solar
with the solar output varying from maximum to minimum with
the circuit regulation frozen (remaining in its steady state
condition before the solar variation occurred) to determine
maximum circuit voltage variation. Compare results with those
from studies 1 and 3.

Step 6. Run base case 2 again with a high penetration of solar
with the solar output varying from maximum to minimum with
regulation frozen (remaining in its steady state condition
before the solar variation occurred) to determine maximum
circuit voltage variation. Compare results with those from
studies 2 and 4.

40. BUS VOLTAGE MAGNITUDE OF 123 BUS IEEE
TEST SYSTEM (BASE CASE)

41. BUS VOLTAGE MAGNITUDE OF 123 BUS IEEE
TEST SYSTEM (WITH LIGHT RE INTEGRATION)

42. BUS VOLTAGE MAGNITUDE OF 123 BUS IEEE
TEST SYSTEM (WITH HIGH RE PENETRATION)

43. THE IEEE 2400 BUS TEST SYSTEM
LOADSHAPE PROFILE

44. LOW VOLTAGE VARIATIONS OF BUS WITH PV
SYSTEM INSTALLED

45. REAL POWER INJECTION PROFILE AT PV SYSTEM
BUS

46. REACTIVE POWER INJECTION PROFILE AT PV
SYSTEM BUS

47. CASE 5-REAL DISTRIBUTION SYSTEM
SIMULATIONS AND ANALYSES
One-Line Diagram

48. One-Line Diagram with RE

49. COMPARISON FAULT CURRENT MAGNITUDE FOR
DIFFERENT FAULT CONDITIONS
Bus No. L-L 3Ф SLG
SOURCEBUS 122849 141856 161497
P1032 2681 3097 3064
P1033 2666 3080 3032
P1034 2657 3070 3014
P1035 2634 3043 2964
P1418 2620 3028 2937
P1418T 2619 3027 2935
P1193 2607 3013 2910
P1193T 2607 3012 2908
P1419 2585 2987 2864

50. X/R RATIO UNDER SHORT-CIRCUIT CONDITIONS FAULT STUDY REPORT
ALL-Node Fault Currents
Bus Node 1 X/R Node 2 X/R Node 3 X/R
"SOURCEBUS", 14.9, 14.9, 14.8,
"P1032", 9.3, 8.8, 4.1,
"P1433", 3.2, 6.4, 6.1,
"P1433REG", 4.0, 4.6,
"P1033", 9.0, 8.7, 4.0,
"P1034", 8.9, 8.5, 4.0,
"P1035", 8.4, 8.3, 3.9,
"P1418", 8.2, 8.1, 3.8,
"P1418T", 8.2, 8.1, 3.8,
"P1193", 8.0, 8.0, 3.8,
"P1193T", 8.0, 7.9, 3.8,
"P1419", 7.7, 7.7, 3.7,
"P1420", 7.3, 7.4, 3.6,

51. SCENARIO 1- 120 PERCENT LOAD INCREASE
0.9
0.92
0.94
0.96
0.98
1
1.02
1.04
1.06
1
11 21 31 41 51 61 71 81 91
101 111 121 131 141 151 161 171 181 191 201 211 221 231 241 251 261 271 281 291 301 311 321 331 341 351 361 371 381 391 401 411 421 431 441 451
13.2kV Distribution Line bus voltages profile

52. SCENARIO 2- 140 PERCENT LOAD INCREASE
0.88
0.9
0.92
0.94
0.96
0.98
1
1.02
1.04
1.06
1
11 21 31 41 51 61 71 81 91
101 111 121 131 141 151 161 171 181 191 201 211 221 231 241 251 261 271 281 291 301 311 321 331 341 351 361 371 381 391 401 411 421 431 441 451
230V line bus voltages profile

53. SCENARIO 3 - 160 PERCENT LOAD INCREASE
0.86
0.88
0.9
0.92
0.94
0.96
0.98
1
1.02
1.04
1.06
1
10 19 28 37 46 55 64 73 82 91
100 109 118 127 136 145 154 163 172 181 190 199 208 217 226 235 244 253 262 271 280 289 298 307 316 325 334 343 352 361 370 379 388 397 406 415 424 433 442 451 460

54. SCENARIO 4- 180 PERCENT LOAD INCREASE
0.8
0.85
0.9
0.95
1
1.05
1.1
1
11 21 31 41 51 61 71 81 91
101 111 121 131 141 151 161 171 181 191 201 211 221 231 241 251 261 271 281 291 301 311 321 331 341 351 361 371 381 391 401 411 421 431 441 451

55. SCENARIO 5- 200 PERCENT LOAD INCREASE
0.8
0.85
0.9
0.95
1
1.05
1.1
1
10 19 28 37 46 55 64 73 82 91
100 109 118 127 136 145 154 163 172 181 190 199 208 217 226 235 244 253 262 271 280 289 298 307 316 325 334 343 352 361 370 379 388 397 406 415 424 433 442 451 460

56. BUS VOLTAGE PROFILE WITH WT (LIGHT
PENETRATION LEVEL)
0.9
0.92
0.94
0.96
0.98
1
1.02
1.04
1.06
1
10 19 28 37 46 55 64 73 82 91
100 109 118 127 136 145 154 163 172 181 190 199 208 217 226 235 244 253 262 271 280 289 298 307 316 325 334 343 352 361 370 379 388 397 406 415 424 433 442 451 460

57. BUS VOLTAGE PROFILE WITH WT (MEDIUM
PENETRATION LEVEL)
0.9
0.92
0.94
0.96
0.98
1
1.02
1.04
1.06
1
10 19 28 37 46 55 64 73 82 91
100 109 118 127 136 145 154 163 172 181 190 199 208 217 226 235 244 253 262 271 280 289 298 307 316 325 334 343 352 361 370 379 388 397 406 415 424 433 442 451 460

58. BUS VOLTAGE PROFILE WITH WT (HIGH
PENETRATION LEVEL)
0.8
0.85
0.9
0.95
1
1.05
1.1
1
10 19 28 37 46 55 64 73 82 91
100 109 118 127 136 145 154 163 172 181 190 199 208 217 226 235 244 253 262 271 280 289 298 307 316 325 334 343 352 361 370 379 388 397 406 415 424 433 442 451 460

59. BUS VOLTAGE PROFILE WITH WT AND PV
SYSTEM (LIGHT PENETRATION LEVEL)
0.9
0.92
0.94
0.96
0.98
1
1.02
1.04
1.06
1
10 19 28 37 46 55 64 73 82 91
100 109 118 127 136 145 154 163 172 181 190 199 208 217 226 235 244 253 262 271 280 289 298 307 316 325 334 343 352 361 370 379 388 397 406 415 424 433 442 451 460

60. BUS VOLTAGE PROFILE WITH WT AND PV
SYSTEM (MEDIUM PENETRATION LEVEL)
0.86
0.88
0.9
0.92
0.94
0.96
0.98
1
1.02
1.04
1.06
1
11 21 31 41 51 61 71 81 91
101 111 121 131 141 151 161 171 181 191 201 211 221 231 241 251 261 271 281 291 301 311 321 331 341 351 361 371 381 391 401 411 421 431 441 451

61. BUS VOLTAGE PROFILE WITH WT AND PV
SYSTEM (HIGH PENETRATION LEVEL)
0.8
0.85
0.9
0.95
1
1.05
1.1
1
10 19 28 37 46 55 64 73 82 91
100 109 118 127 136 145 154 163 172 181 190 199 208 217 226 235 244 253 262 271 280 289 298 307 316 325 334 343 352 361 370 379 388 397 406 415 424 433 442 451 460

62. CONCLUSIONS
The electric distribution system has been
designed with traditionally central generation.
Historically, this design is a one-way power flow
and has proven to be safe, reliable, and least
cost.
However, the paradigm is quickly changing due
to price increases of traditional generations
and value shifts with awareness of climate
change.

63. The methodologies used DS Load Flow
analysis as primary tool for most of the
simulations.

The proposed methods are simulated off-line
and utilized efficient solution algorithm for
use in the distribution system environment
with renewable energy’s integration.

64. Verifications of its applicability and
robustness were tested using different sizes
of DS standard test systems.

Simulations of different case scenarios
using real distribution system show that the
proposed methodologies and approach have
promising applications to the current
distribution system needs.

65. RECOMMENDATIONS
The real implementations of this study have gone
through some difficult part not on the simulations
and analysis of the results but primarily on the
collection of accurate and actual data.

Based from these experiences the following
recommendations to facilitate ease of
implementations and future research in this field
are:

66. • Create a set of benchmark model data-
base of the distribution system to facilitate
actual valid data testing and simulations.
Upgraded and validated data base an
important component of offline simulations

67. • Since the simulations was been tested in a
single feeder for its applicability, robustness and
effectiveness, it is recommended to validate the
results with the actual data prior to the full
implementations of the whole distribution
system.

68. • Develop automated screening tools and the
associated software that will enable evaluation of
the impact RE on the distribution system. This
would help preserve low installation costs while
allowing for the more detailed assessment that
would be necessary at higher penetration levels
of distributed DG’s.

69. THANK YOU VERY MUCH!

70. Q & A