Method and device for monitoring and suppressing resonance

Patent metadata

Field	Value
Publication number	US-10003198-B2
Application number	US-201514850649-A
Country	US
Kind code	B2
Filing date	Sep 10, 2015
Priority date	Sep 12, 2014
Publication date	Jun 19, 2018
Grant date	Jun 19, 2018

Abstract

A method and device for monitoring and suppressing a resonance are provided, which are applied to a grid-connected generation system. A current sample voltage of a preset sample point of the grid-connected generation system is monitored in a real time manner; amplitudes of harmonics of the current sample voltage are acquired using a preset algorithm; it is verified whether a resonance occurs in the grid-connected generation system currently based on the acquired amplitudes of the harmonics; in a case that the resonance occurs in the grid-connected generation system, current corrections of parameters of inverters in the grid-connected generation system are acquired according to a preset rule and the parameters of the inverters are adjusted using the current corrections and a selected resonance suppressing algorithm.

First claim

The invention claimed is:

1. A method for monitoring and suppressing a resonance applied to a grid-connected generation system, wherein the method comprises:
monitoring a current sample voltage of a preset sample point of the grid-connected generation system;
acquiring amplitudes of harmonics of the current sample voltage using a preset algorithm;
verifying whether a resonance occurs in the grid-connected generation system based on the acquired amplitudes of the harmonics; and
in a case that the resonance occurs in the grid-connected generation system, acquiring current corrections of parameters of inverters in the grid-connected generation system according to a preset rule, and adjusting the parameters of the inverters using the current corrections and a selected resonance suppressing algorithm until the resonance disappears in the grid-connected generation system,
wherein the adjusting the parameters of the inverters using the current corrections and a preset resonance suppressing algorithm comprises:
adjusting bandwidths of the inverters using the current corrections and a preset adjustment formula, wherein the preset adjustment formula is:

{

k
p

=

k
p

+

Δ
⁢

⁢

U
out

k
p

<

k

p
⁢

⁢
min

k
p

=

k

p
⁢

⁢
min

,

where K p indicates a proportion control parameter, ΔU out indicates the current corrections and K pmin indicates minimum allowable adjustment values of the bandwidths of the inverters,
adjusting active damping coefficients of the inverters using a pre-stored active damping algorithm and the current corrections; and

transmitting the current corrections to the inverters to control an inactive damping resistor to be connected to a respective one of the inverters.

2. The method according to claim 1 , wherein the acquiring amplitudes of harmonics of the current sample voltage using a preset algorithm comprises:
calculating frequency domain values corresponding to the harmonics of the current sample voltage using an FFT algorithm formula, wherein the FFT algorithm formula is:

x
⁡

(
l
)

=

∑

n
=
0

N
-
1

⁢

⁢

U
x

⁡

(
n
)

×

w
N

l
⁢

⁢
n

w
N

l
⁢

⁢
n

=

e

-
j

⁢

⁢
2
⁢
π
⁢

⁢

nl
/
N

,

l
=
0

,
1
,
…
⁢

,

N
-
1

,

where U x (n) indicates a discrete signal of the current sample voltage, x(l) indicates a frequency domain value corresponding to the current sample voltage after an FFT transformation is performed on the current sample voltage, N indicates the total number of sample points, W N ln indicates a weight for the FFT algorithm; and
calculating the amplitudes of the harmonics using the frequency domain values and a preset harmonic extracting formula, wherein the preset harmonic extracting formula is:
U amp ( k )=√{square root over ( X (2 k ) 2 +X (2 k+ 1) 2 )} k= 0,1, . . . , N/ 2−1,

where U amp (k) indicates an amplitude of the k-th harmonic, X(2k) indicates a value of a rea

Assignees

• Sungrow Power Supply Co Ltd

Inventors

• Pan Nianan
• Cheng Lin
• Tao Lei

Classifications

• H02J3/381

  Dispersed generators · CPC title

• G01R23/20

  Measurement of non-linear distortion · CPC title

• H02J3/01

  Arrangements for reducing harmonics or ripples · CPC title

• Y02E40/40

  Arrangements for reducing harmonics · CPC title

• H02J3/38

  Arrangements for feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel · CPC title