IEEE Power & Energy Magazine - July/August 2019 - 45

Dynamic performance studies should be undertaken
to assess the condenser response and its effect on the
transient stability performance of the system.
reliability criteria. Dynamic performance studies should be
undertaken to assess the condenser response and its effect on
the transient stability performance of the system.
Dynamic Performance Requirements

The following is a summary of these requirements.
✔ Voltage ride-through requirements: The synchronous
condensers must be able to remain connected and in
service during any of the short-term excursions in
voltage in accordance with requirements by the Western Electricity Coordinating Council and NERC. In
the worst low-voltage scenario, when the voltage is at
zero for nine cycles, the synchronous condenser must
remain connected to the network.
✔ Voltage recovery requirements: One of the primary
requirements from SDG&E is that the synchronous
condenser, exciter, and regulator shall be coordinated
to restore the controlled voltage to within ±5% of the
set voltage within 1 s after either fault removal or line
energization. The maximum voltage overshoot during

a rapid change from faulted conditions to normal conditions shall not exceed ±20%.
✔ Frequency deviation requirements: Typical dynamic
frequency profiles due to an event on the transmission
network are shown in Table 3.
Dynamic Study Scenarios

To evaluate the synchronous condensers' dynamic response
and their effect on the system, a dynamic performance study
was performed with system models that include machine
parameters for the synchronous condenser and its excitation
system. The study scenarios typically reflect various operating conditions with different contingencies. In our study, two
power flow cases were used: peak and off-peak load operating conditions. Under each power flow case, two variations
with different numbers of synchronous condensers in service
were considered. For all of the study combinations of operating scenarios and the number of synchronous condensers
in service, a number of contingencies under different NERC
categories were simulated. Figure 8 shows results of a study

Protection Function Description

ANSI Code

Differential protection

Restricted earth fault protection

87N

Time overcurrent phase protection

50/51

Time overcurrent earth protection

50N/51N

Voltage (p.u.)

table 2. Step-up transformer activated
protection functions.

1.1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0

Voltages at TA 230, 138,17.5 Buses

17.5 kV
0

Frequency, F (Hz)

Length of Application

F < 55.5

Instantaneous

55.5 ≤ F < 56.5

0.5 s

56.5 ≤ F < 57.0

57.0 ≤ F < 57.5

10 s

57.5 ≤ F < 58.5

1.5 min

58.5 ≤ F < 59.5

10 min

59.5 ≤ F < 60.5

Steady state

60.5 ≤ F < 61.5

10 min

61.5 ≤ F < 62.0

45 s

F ≥ 62.0

Instantaneous

july/august 2019

Reactive Power (Mvar)

table 3. Frequency performance requirements.
600
500
400
300
200
100
0
-100
-200

138 kV

10 12
Time (s)
(a)

230 kV
16

Reactive Power at TA 17.5 Bus

SC Mvar
0

10 12
Time (s)
(b)

figure 8. (a) The TA bus voltages and (b) the TA synchronous condenser reactive power.
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IEEE Power & Energy Magazine - July/August 2019

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