IEEE Power & Energy Magazine - March/April 2017 - 65

Load (GW)

from concentrating solar power, VRE technologies interface
to the grid through power electronics devices called inverters
Synchronous
Generator-Dominated Inverter-Dominated
that convert native dc electricity into grid-compatible ac power.
System
System
Although it is common for a VRE resource, such as wind, to
70
utilize multiple ac-dc and dc-ac conversion stages before inter50% VRE
facing to the grid, we focus our attention on the final output
60
stage that converts dc to grid-compatible ac because that is
the circuit that directly interacts with the ac power system. In
50
100% VRE
future grids [Figure 5(b)], the number of inverter-based devices
may be more than 50% of the rated power at any time, thereby
40
forming an inverter-dominated grid.
30
The synchronous generators used in conventional power
plants are machines that have a stationary part (stator) and
20
rotating part (rotor) that produce a rotating magnetic field
inducing a voltage within the stator windings. This process
10
creates ac electricity at a specified frequency (typically 50 or
60 Hz). These machines have unique characteristics that have
0
0
20
30
40
50
60
70
10
dictated how power systems have been planned and operated
VRE Power (GW)
since the inception of electric machinery more than a century
ago. Once synchronized to the rest of the grid, the real power
figure 4. VRE compared to load for only the ERCOT sysof the machine can be controlled through the shaft torque, and
tem at the 80% VRE transmission-constrained scenario.
the reactive power is controlled through the field current. To
ensure the reliable operation of the interconnected power system, the system frequency and voltages are tightly regulated the system. Further, the total amount of system inertia (i.e., the
through a combination of fast-acting closed-loop controllers at net rotating mass across all interconnected machines) is proeach machine (primary frequency response through governor portional to the ability of a system to absorb variations across
controls) and slow, centralized controllers (automatic generator control, or AGC) that system operators
Present Grid
Future Grid
use to restore the system frequency
* Fewer Synchronous
to its nominal value. Ultimately,
Generators
frequency and voltages are the key
* More Variable,
variables that must be regulated
Inverter-Based
in the system and form the main
Generation
objectives of system control.
* More Distributed
From a physics standpoint, the
Generation and
Controllable Loads
turbine system and rotating components inside each machine exhibit
mechanical inertia, and as such they
are capable of storing kinetic energy
in this rotating mass. Because that
energy can be extracted from or
absorbed into these rotating masses
during system disturbances, an interconnected system of machines
is able to withstand fluctuations in
net load and generation. Specifically, a net excess (or deficiency) in
(a)
(b)
Generator
Inverter
generation delivers energy into (or
extracts energy from) the rotating
masses and subsequently leads to an
figure 5. The present grid is dominated by synchronous generators having large,
increased (or decreased) system fre- rotational inertia with a relatively small amount of inverter-interfaced VRE sources.
quency; hence, the direction of the The future grid will be realized as VRE penetration increases and conventional synfrequency deviation is an indicator chronous machines are gradually replaced with power electronics-based generation,
of net energy excess or deficiency on storage, and loads.
march/april 2017

ieee power & energy magazine

65



Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - March/April 2017

IEEE Power & Energy Magazine - March/April 2017 - Cover1
IEEE Power & Energy Magazine - March/April 2017 - Cover2
IEEE Power & Energy Magazine - March/April 2017 - 1
IEEE Power & Energy Magazine - March/April 2017 - 2
IEEE Power & Energy Magazine - March/April 2017 - 3
IEEE Power & Energy Magazine - March/April 2017 - 4
IEEE Power & Energy Magazine - March/April 2017 - 5
IEEE Power & Energy Magazine - March/April 2017 - 6
IEEE Power & Energy Magazine - March/April 2017 - 7
IEEE Power & Energy Magazine - March/April 2017 - 8
IEEE Power & Energy Magazine - March/April 2017 - 9
IEEE Power & Energy Magazine - March/April 2017 - 10
IEEE Power & Energy Magazine - March/April 2017 - 11
IEEE Power & Energy Magazine - March/April 2017 - 12
IEEE Power & Energy Magazine - March/April 2017 - 13
IEEE Power & Energy Magazine - March/April 2017 - 14
IEEE Power & Energy Magazine - March/April 2017 - 15
IEEE Power & Energy Magazine - March/April 2017 - 16
IEEE Power & Energy Magazine - March/April 2017 - 17
IEEE Power & Energy Magazine - March/April 2017 - 18
IEEE Power & Energy Magazine - March/April 2017 - 19
IEEE Power & Energy Magazine - March/April 2017 - 20
IEEE Power & Energy Magazine - March/April 2017 - 21
IEEE Power & Energy Magazine - March/April 2017 - 22
IEEE Power & Energy Magazine - March/April 2017 - 23
IEEE Power & Energy Magazine - March/April 2017 - 24
IEEE Power & Energy Magazine - March/April 2017 - 25
IEEE Power & Energy Magazine - March/April 2017 - 26
IEEE Power & Energy Magazine - March/April 2017 - 27
IEEE Power & Energy Magazine - March/April 2017 - 28
IEEE Power & Energy Magazine - March/April 2017 - 29
IEEE Power & Energy Magazine - March/April 2017 - 30
IEEE Power & Energy Magazine - March/April 2017 - 31
IEEE Power & Energy Magazine - March/April 2017 - 32
IEEE Power & Energy Magazine - March/April 2017 - 33
IEEE Power & Energy Magazine - March/April 2017 - 34
IEEE Power & Energy Magazine - March/April 2017 - 35
IEEE Power & Energy Magazine - March/April 2017 - 36
IEEE Power & Energy Magazine - March/April 2017 - 37
IEEE Power & Energy Magazine - March/April 2017 - 38
IEEE Power & Energy Magazine - March/April 2017 - 39
IEEE Power & Energy Magazine - March/April 2017 - 40
IEEE Power & Energy Magazine - March/April 2017 - 41
IEEE Power & Energy Magazine - March/April 2017 - 42
IEEE Power & Energy Magazine - March/April 2017 - 43
IEEE Power & Energy Magazine - March/April 2017 - 44
IEEE Power & Energy Magazine - March/April 2017 - 45
IEEE Power & Energy Magazine - March/April 2017 - 46
IEEE Power & Energy Magazine - March/April 2017 - 47
IEEE Power & Energy Magazine - March/April 2017 - 48
IEEE Power & Energy Magazine - March/April 2017 - 49
IEEE Power & Energy Magazine - March/April 2017 - 50
IEEE Power & Energy Magazine - March/April 2017 - 51
IEEE Power & Energy Magazine - March/April 2017 - 52
IEEE Power & Energy Magazine - March/April 2017 - 53
IEEE Power & Energy Magazine - March/April 2017 - 54
IEEE Power & Energy Magazine - March/April 2017 - 55
IEEE Power & Energy Magazine - March/April 2017 - 56
IEEE Power & Energy Magazine - March/April 2017 - 57
IEEE Power & Energy Magazine - March/April 2017 - 58
IEEE Power & Energy Magazine - March/April 2017 - 59
IEEE Power & Energy Magazine - March/April 2017 - 60
IEEE Power & Energy Magazine - March/April 2017 - 61
IEEE Power & Energy Magazine - March/April 2017 - 62
IEEE Power & Energy Magazine - March/April 2017 - 63
IEEE Power & Energy Magazine - March/April 2017 - 64
IEEE Power & Energy Magazine - March/April 2017 - 65
IEEE Power & Energy Magazine - March/April 2017 - 66
IEEE Power & Energy Magazine - March/April 2017 - 67
IEEE Power & Energy Magazine - March/April 2017 - 68
IEEE Power & Energy Magazine - March/April 2017 - 69
IEEE Power & Energy Magazine - March/April 2017 - 70
IEEE Power & Energy Magazine - March/April 2017 - 71
IEEE Power & Energy Magazine - March/April 2017 - 72
IEEE Power & Energy Magazine - March/April 2017 - 73
IEEE Power & Energy Magazine - March/April 2017 - 74
IEEE Power & Energy Magazine - March/April 2017 - 75
IEEE Power & Energy Magazine - March/April 2017 - 76
IEEE Power & Energy Magazine - March/April 2017 - 77
IEEE Power & Energy Magazine - March/April 2017 - 78
IEEE Power & Energy Magazine - March/April 2017 - 79
IEEE Power & Energy Magazine - March/April 2017 - 80
IEEE Power & Energy Magazine - March/April 2017 - 81
IEEE Power & Energy Magazine - March/April 2017 - 82
IEEE Power & Energy Magazine - March/April 2017 - 83
IEEE Power & Energy Magazine - March/April 2017 - 84
IEEE Power & Energy Magazine - March/April 2017 - 85
IEEE Power & Energy Magazine - March/April 2017 - 86
IEEE Power & Energy Magazine - March/April 2017 - 87
IEEE Power & Energy Magazine - March/April 2017 - 88
IEEE Power & Energy Magazine - March/April 2017 - 89
IEEE Power & Energy Magazine - March/April 2017 - 90
IEEE Power & Energy Magazine - March/April 2017 - 91
IEEE Power & Energy Magazine - March/April 2017 - 92
IEEE Power & Energy Magazine - March/April 2017 - 93
IEEE Power & Energy Magazine - March/April 2017 - 94
IEEE Power & Energy Magazine - March/April 2017 - 95
IEEE Power & Energy Magazine - March/April 2017 - 96
IEEE Power & Energy Magazine - March/April 2017 - Cover3
IEEE Power & Energy Magazine - March/April 2017 - Cover4
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