# US 10,374,427 B2 · Parameter tuning approach for bypass damping filter to suppress subsynchronous resonance in power systems

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- Number: US 10,374,427 B2
- Document ID: US10374427B2
- Status: Granted
- Kind: B2
- Application number: 15/523,135
- Filed: 2016-04-11
- Published: 2017-11-16
- Granted: 2019-08-06
- Earliest claimed: 2015-06-19
- Assignees: Zhejiang University
- Applicants: Zhejiang University
- Inventors: Zheng Xu; Shijia Wang
- Web page: https://patentgrep.com/patent/US10374427B2

## CPC

- H02J 3/0014: for preventing or reducing power oscillations in networks
- H02H 9/007: {avoiding or damping oscillations, e.g. fenoresonance or travelling waves}
- H02H 9/08: Limitation or suppression of earth fault currents, e.g. Petersen coil
- H02J 3/01: Arrangements for reducing harmonics or ripples
- H03J 3/22: of single resonant circuit by varying inductance and capacitance simultaneously
- H04B 15/02: Reducing interference from electric apparatus by means located at or near the interfering apparatus
- H04B 15/005: {Reducing noise, e.g. humm, from the supply}
- Y02E 40/40: Arrangements for reducing harmonics
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H)
- H03J: TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H04B: TRANSMISSION
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

The present invention discloses a parameter tuning approach for bypass damping filter to suppress subsynchronous resonance in power systems, namely determining the parameters of capacitor, inductor and damping resistor in BDF. Using this approach, the parameters of capacitor and inductor in BDF can be adjusted, so that the frequency where the negative electrical damping of generator reaches minimum can be away from the frequency range of low frequency oscillation mode and typical frequencies of each torsional mode; the parameter of damping resistor in BDF can be further adjusted so that the minimum value of negative electrical damping is in reasonable range. The application of BDF with parameters tuned by the present invention contributes to the suppression of both the torsional interaction effect and the transient torque amplification effect.

## Claims

### Claim 1

A parameter tuning method for a bypass damping filter (BDF) to suppress subsynchronous resonance in power systems, comprising the following steps:
(1) calculating typical frequencies of each torsional mode according to turbine-generator shaft parameters, and supposing a low frequency oscillation mode of the shaft is within a frequency range of 0˜2 Hz;
(2) choosing a per-unit frequency where negative electrical damping reaches minimum to be fm*, the fm* should be away from the frequency range of low frequency oscillation mode and typical frequencies of the each torsional mode mentioned in Step (1);
(3) according to the chosen fm* in Step (2), calculating a per-unit capacitance and reactance XBDF at system rated frequency using the equation below:
X
BDF
=
X
C
⁡
(
X
L
-
X
C
)
f
e
*
2
⁢
X
L
-
X
C
-
X
C
f
e
*
=
1
-
f
m
*
;
where XL is a system per-unit reactance at rated frequency, including generator subtransient reactance, line reactance and equivalent reactance of the receiving power grid; XC is capacitance of the series capacitor at rated frequency;
(4) calculating actual physical parameters of a capacitor and a inductor in BDF according to the above-mentioned XBDF in Step (3);
(5) calculating a minimum value of generator negative electrical damping De(min)0 without BDF applied;
(6) according to the fm* in Step (2) and the XBDF in Step (3), calculating the minimum value of generator negative electrical damping De(min)BDF with BDF applied; and
(7) adjusting a value of damping resistor in BDF to make De(min)BDF in a range;
wherein the range of De(min)BDF in Step (7) is chosen as
De(min)0<De(min)BDF<De(min)0/2
where De(min)0 is minimum value of generator negative electrical damping without BDF applied.

### Claim 2 (depends on 1)

The parameter tuning method for BDF to suppress subsynchronous resonance in power systems according to claim 1, characterized in that the per-unit frequency of fm* in Step (2) is chosen as a middle frequency between the frequency range from 2 Hz to the lowest typical frequency of the shaft torsional modes.

### Claim 3 (depends on 1)

The parameter tuning method for BDF to suppress subsynchronous resonance in power systems according to claim 1, characterized in that in Step (4) the actual physical parameters of the capacitor and the inductor in BDF are calculated using the following equations:
C
BDF
=
1
2
⁢
π
⁢
⁢
f
0
⁢
Z
B
⁢
X
BDF
×
10
6
⁢
⁢
μF
L
BDF
=
Z
B
⁢
X
BDF
2
⁢
π
⁢
⁢
f
0
×
10
3
⁢
⁢
mH
where f0 is the system rated frequency, ZB is the base value of system impedance, CBDF and LBDF are the capacitance and inductance of BDF, respectively.

### Claim 4 (depends on 1)

The parameter tuning method for BDF to suppress subsynchronous resonance in power systems according to claim 1, characterized in that in Step (5) the minimum value of generator negative electrical damping De(min)0 without BDF applied is calculated using the following equation:
D
e
⁡
(
min
)
0
=
-
ψ
0
2
⁢
1
-
f
m
0
2
⁢
f
m
0
⁢
1
R
f
m
0
=
1
-
X
C
/
X
L
where ψ0 is the per-unit air flux linkage of generator and can be chosen as 1.0 for simplification, R is the per-unit resistance of system.

### Claim 5 (depends on 1)

The parameter tuning method for BDF to suppress subsynchronous resonance in power systems according to claim 1, characterized in that in Step (6) the minimum value of generator negative electrical damping De(min)BDF with BDF applied is calculated using the following equation:
D
e
⁡
(
min
)
BDF
=
-
ψ
0
2
⁢
1
-
f
m
*
2
⁢
f
m
*
⁢
1
R
*
R
*
=
R
+
R
BDF
⁢
X
C
2
f
e
*
2
⁢
R
BDF
2
+
[
k
f
*
⁢
f
e
*
⁢
X
BDF
-
X
C
]
2
k
f
*
=
f
e
*
(
1
-
f
e
*
2
)
where ψ0 is the per-unit air flux linkage of generator and can be chosen as 1.0 for simplification, R is the per-unit resistance of system and RBDF is the resistance of the damping resistor in BDF.