IEEE Power & Energy Magazine - May/June 2019 - 96

one key constraint for network expansion is tight urban land
resources, often making expansions requiring the construction
of new circuits or new substations very difficult. Favorable system improvements use advanced transmission technologies to
effectively increase the delivery capability operation flexibility,
and utilization of the existing network infrastructure. another
challenge is the need for optimized expansion solutions to
address multiple issues. as shown in Figure 2, expansion needs
may require load-area tie line capacity expansion and dynamic
reactive power compensation at critical locations for compliance with n-1 or n-1-1 contingency criteria. Power flow control
devices may be needed to mitigate loop flow issues, especially
between the transmission and subtransmission networks.

Technology Options
for Network Expansion
to address network expansion issues, electric utilities have
the option of installing the following:
✔ new circuits or upgrade existing ones to mitigate circuit overloads
✔ new transformers or upgrade existing ones to mitigate
substation overloads
✔ phase-shifting transformers (Psts), also known as phase
angle regulators (Pars), sen transformers (sts), and
variable-frequency transformers (VFts), for controlling
active power flow in meshed networks
✔ reactive power-compensation devices, such as shunt
reactors or capacitor banks, and static var compensators (sVcs) or static synchronous compensators

(statcoms) for voltage regulation and power quality improvement.
Psts contain on-load tap-changers to insert an extra voltage in series with the normal transformer ratio. Psts have
been widely used in urban transmission and subtransmission
networks for controlling power flows to avoid congestion or
maintain desired power flows between adjacent load areas or
substations. similar to Psts, the newly invented st promises control of real power flows on transmission circuits, but
it also has the unique ability to control reactive power flow.
sVcs or statcoms use power semiconductors to control
the amount of reactive power compensation at critical locations.
Under normal system operating conditions, they continuously
control reactive power injection or absorption, maintaining an
optimal grid voltage profile. during system disturbances, they
can rapidly counteract voltage transients, reducing the risk of
serious voltage depressions or voltage collapse.
a VFt consists of a rotary transformer for controllable
phase shift together with a drive system and control that
adjust the angle and speed of the rotary transformer to regulate the active power flow. For example, an urban grid application installed a 3 × 100 mw VFt substation in linden,
new Jersey, in 2009, connecting the power systems of PJm
interconnection with new York iso. this was installed in
parallel with ties using phase-shifting transformers to regulate synchronous power flow in both directions for economic
energy exchanges between the two regions.
high-temperature superconductor (hts) power devices
can enable high-capacity power delivery on transmission and

Loop Flow Issues
Thermal Overload
Load Area B

External System
Load Area A

Load Area B

Load Area A
External
System

~

Voltage
Violations

~

~

~

~

External
System

~

~
Load Area C

~
~
Load Area D
External System

Load Area C

~
~
Load Area D

Transmission Substation

EHVac Circuit

Transmission Substation

EHVac Circuit

Distribution Substation

HVac Circuit

Distribution Substation

HVac Circuit

~ Local Generation

figure 1. The urban power grids are typically divided into
multiple load areas (also known as load zones or load districts) by electric utilities for convenience in planning and
operating the system.
96

~

ieee power & energy magazine

~ Local Generation

figure 2. The optimized network expansion solutions are
needed to address multiple network enhancements (capacity expansion, dynamic voltage support, and network power
flow control).
may/june 2019



IEEE Power & Energy Magazine - May/June 2019

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - May/June 2019

Contents
IEEE Power & Energy Magazine - May/June 2019 - Cover1
IEEE Power & Energy Magazine - May/June 2019 - Cover2
IEEE Power & Energy Magazine - May/June 2019 - Contents
IEEE Power & Energy Magazine - May/June 2019 - 2
IEEE Power & Energy Magazine - May/June 2019 - 3
IEEE Power & Energy Magazine - May/June 2019 - 4
IEEE Power & Energy Magazine - May/June 2019 - 5
IEEE Power & Energy Magazine - May/June 2019 - 6
IEEE Power & Energy Magazine - May/June 2019 - 7
IEEE Power & Energy Magazine - May/June 2019 - 8
IEEE Power & Energy Magazine - May/June 2019 - 9
IEEE Power & Energy Magazine - May/June 2019 - 10
IEEE Power & Energy Magazine - May/June 2019 - 11
IEEE Power & Energy Magazine - May/June 2019 - 12
IEEE Power & Energy Magazine - May/June 2019 - 13
IEEE Power & Energy Magazine - May/June 2019 - 14
IEEE Power & Energy Magazine - May/June 2019 - 15
IEEE Power & Energy Magazine - May/June 2019 - 16
IEEE Power & Energy Magazine - May/June 2019 - 17
IEEE Power & Energy Magazine - May/June 2019 - 18
IEEE Power & Energy Magazine - May/June 2019 - 19
IEEE Power & Energy Magazine - May/June 2019 - 20
IEEE Power & Energy Magazine - May/June 2019 - 21
IEEE Power & Energy Magazine - May/June 2019 - 22
IEEE Power & Energy Magazine - May/June 2019 - 23
IEEE Power & Energy Magazine - May/June 2019 - 24
IEEE Power & Energy Magazine - May/June 2019 - 25
IEEE Power & Energy Magazine - May/June 2019 - 26
IEEE Power & Energy Magazine - May/June 2019 - 27
IEEE Power & Energy Magazine - May/June 2019 - 28
IEEE Power & Energy Magazine - May/June 2019 - 29
IEEE Power & Energy Magazine - May/June 2019 - 30
IEEE Power & Energy Magazine - May/June 2019 - 31
IEEE Power & Energy Magazine - May/June 2019 - 32
IEEE Power & Energy Magazine - May/June 2019 - 33
IEEE Power & Energy Magazine - May/June 2019 - 34
IEEE Power & Energy Magazine - May/June 2019 - 35
IEEE Power & Energy Magazine - May/June 2019 - 36
IEEE Power & Energy Magazine - May/June 2019 - 37
IEEE Power & Energy Magazine - May/June 2019 - 38
IEEE Power & Energy Magazine - May/June 2019 - 39
IEEE Power & Energy Magazine - May/June 2019 - 40
IEEE Power & Energy Magazine - May/June 2019 - 41
IEEE Power & Energy Magazine - May/June 2019 - 42
IEEE Power & Energy Magazine - May/June 2019 - 43
IEEE Power & Energy Magazine - May/June 2019 - 44
IEEE Power & Energy Magazine - May/June 2019 - 45
IEEE Power & Energy Magazine - May/June 2019 - 46
IEEE Power & Energy Magazine - May/June 2019 - 47
IEEE Power & Energy Magazine - May/June 2019 - 48
IEEE Power & Energy Magazine - May/June 2019 - 49
IEEE Power & Energy Magazine - May/June 2019 - 50
IEEE Power & Energy Magazine - May/June 2019 - 51
IEEE Power & Energy Magazine - May/June 2019 - 52
IEEE Power & Energy Magazine - May/June 2019 - 53
IEEE Power & Energy Magazine - May/June 2019 - 54
IEEE Power & Energy Magazine - May/June 2019 - 55
IEEE Power & Energy Magazine - May/June 2019 - 56
IEEE Power & Energy Magazine - May/June 2019 - 57
IEEE Power & Energy Magazine - May/June 2019 - 58
IEEE Power & Energy Magazine - May/June 2019 - 59
IEEE Power & Energy Magazine - May/June 2019 - 60
IEEE Power & Energy Magazine - May/June 2019 - 61
IEEE Power & Energy Magazine - May/June 2019 - 62
IEEE Power & Energy Magazine - May/June 2019 - 63
IEEE Power & Energy Magazine - May/June 2019 - 64
IEEE Power & Energy Magazine - May/June 2019 - 65
IEEE Power & Energy Magazine - May/June 2019 - 66
IEEE Power & Energy Magazine - May/June 2019 - 67
IEEE Power & Energy Magazine - May/June 2019 - 68
IEEE Power & Energy Magazine - May/June 2019 - 69
IEEE Power & Energy Magazine - May/June 2019 - 70
IEEE Power & Energy Magazine - May/June 2019 - 71
IEEE Power & Energy Magazine - May/June 2019 - 72
IEEE Power & Energy Magazine - May/June 2019 - 73
IEEE Power & Energy Magazine - May/June 2019 - 74
IEEE Power & Energy Magazine - May/June 2019 - 75
IEEE Power & Energy Magazine - May/June 2019 - 76
IEEE Power & Energy Magazine - May/June 2019 - 77
IEEE Power & Energy Magazine - May/June 2019 - 78
IEEE Power & Energy Magazine - May/June 2019 - 79
IEEE Power & Energy Magazine - May/June 2019 - 80
IEEE Power & Energy Magazine - May/June 2019 - 81
IEEE Power & Energy Magazine - May/June 2019 - 82
IEEE Power & Energy Magazine - May/June 2019 - 83
IEEE Power & Energy Magazine - May/June 2019 - 84
IEEE Power & Energy Magazine - May/June 2019 - 85
IEEE Power & Energy Magazine - May/June 2019 - 86
IEEE Power & Energy Magazine - May/June 2019 - 87
IEEE Power & Energy Magazine - May/June 2019 - 88
IEEE Power & Energy Magazine - May/June 2019 - 89
IEEE Power & Energy Magazine - May/June 2019 - 90
IEEE Power & Energy Magazine - May/June 2019 - 91
IEEE Power & Energy Magazine - May/June 2019 - 92
IEEE Power & Energy Magazine - May/June 2019 - 93
IEEE Power & Energy Magazine - May/June 2019 - 94
IEEE Power & Energy Magazine - May/June 2019 - 95
IEEE Power & Energy Magazine - May/June 2019 - 96
IEEE Power & Energy Magazine - May/June 2019 - 97
IEEE Power & Energy Magazine - May/June 2019 - 98
IEEE Power & Energy Magazine - May/June 2019 - 99
IEEE Power & Energy Magazine - May/June 2019 - 100
IEEE Power & Energy Magazine - May/June 2019 - 101
IEEE Power & Energy Magazine - May/June 2019 - 102
IEEE Power & Energy Magazine - May/June 2019 - 103
IEEE Power & Energy Magazine - May/June 2019 - 104
IEEE Power & Energy Magazine - May/June 2019 - 105
IEEE Power & Energy Magazine - May/June 2019 - 106
IEEE Power & Energy Magazine - May/June 2019 - 107
IEEE Power & Energy Magazine - May/June 2019 - 108
IEEE Power & Energy Magazine - May/June 2019 - 109
IEEE Power & Energy Magazine - May/June 2019 - 110
IEEE Power & Energy Magazine - May/June 2019 - 111
IEEE Power & Energy Magazine - May/June 2019 - 112
IEEE Power & Energy Magazine - May/June 2019 - 113
IEEE Power & Energy Magazine - May/June 2019 - 114
IEEE Power & Energy Magazine - May/June 2019 - 115
IEEE Power & Energy Magazine - May/June 2019 - 116
IEEE Power & Energy Magazine - May/June 2019 - 117
IEEE Power & Energy Magazine - May/June 2019 - 118
IEEE Power & Energy Magazine - May/June 2019 - 119
IEEE Power & Energy Magazine - May/June 2019 - 120
IEEE Power & Energy Magazine - May/June 2019 - Cover3
IEEE Power & Energy Magazine - May/June 2019 - Cover4
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070821
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050621
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030421
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010221
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111220
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091020
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070820
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050620
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030420
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010220
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111219
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091019
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070819
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050619
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030419
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010219
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111218
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091018
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070818
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050618
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030418
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010218
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111217
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091017
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070817
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050617
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030417
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010217
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111216
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091016
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070816
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050616
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030416
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010216
https://www.nxtbook.com/nxtbooks/ieee/powerenergy_010216
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111215
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091015
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070815
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050615
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030415
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010215
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111214
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091014
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070814
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050614
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030414
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010214
https://www.nxtbookmedia.com