Online analysis and early warning method for low-frequency oscillation of electric power system

A low-frequency oscillation and power system technology, applied to electrical components, circuit devices, AC network circuits, etc., can solve the problems of difficult to distinguish the change law of the carrier signal at the symbol flip point, large processing errors, complex calculations, etc., to achieve rapid response capability And robustness, calculation accuracy, avoiding the effect of integral operation

Active Publication Date: 2013-03-27
CENT CHINA GRID +1
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Problems solved by technology

The disadvantage of this method is that the process of solving the damping ratio involves a large number of integrals, and the calculation is complicated
This method has reference significance in low-frequency oscillation early warning, but its shortcoming is that the frequency detection adopts the zero-crossing detection method, which only takes into account the number of positive and negative changes of the value at the sampling point, and the amplitude of the carrier signal attenuates to zero at the symbol flip. Signal, in the case of limited quantization accuracy, it is difficult to distinguish the change law of the carrier signal at the symbol flip point, and the frequency identification accuracy is limited; in addition, the Prony algorithm is a spectrum analysis method suitable for linear systems. Data processing errors are large

Method used

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  • Online analysis and early warning method for low-frequency oscillation of electric power system
  • Online analysis and early warning method for low-frequency oscillation of electric power system
  • Online analysis and early warning method for low-frequency oscillation of electric power system

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Experimental program
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Effect test

Embodiment 1

[0042]An on-line analysis and early warning method of low-frequency oscillation in a power system, the method comprising the following steps:

[0043] a. The relative power angle is collected from the phase angle measurement unit (PMU) of the UHV synchronous power grid wide-area measurement system, and the relative power angle and the time of collecting the relative power angle are taken as a sample point data to Acquire sample point data for the sampling frequency where 8 Hz ≤ ≤15Hz;

[0044] b. According to the chronological order of the sample data, N sample data are continuously taken, and the N sample data constitute a WAMS data group, among which 150≤N≤2000;

[0045] c. Perform k-point median filtering or k-point mean filtering on the WAMS data set, where 3≤k≤9, and the filtered relative power angle signal is recorded as ;

[0046] d. Use Teagar energy operator to process relative power angle signal :

[0047] d1. Calculate the relative power angle signal The...

Embodiment 2

[0069] An on-line analysis and early warning method of low-frequency oscillation in a power system, the steps of which are the same as those in Embodiment 1, taking the relative power angle signal of No. 7 unit relative to No. 1 unit in the 8-unit system in the PSASP as an example, wherein in step a, Pick =15Hz, take N=150 in step b, take k=7 in step c, take H=75 in step i, and see the EMD decomposition results of the relative power angle signal of G7-G1 in the appendix figure 2 , the energy statistics of the G7-G1 relative power angle signal and its EMD component are shown in Table 1. In Table 1, E0 is the energy of the original signal, and E1, E2, E3, E4, Er are the components c1, c2, c3, c4, The energy of r, among the intrinsic mode components c1~c4, the IMF component c1 with the largest energy weight is the dominant oscillation mode.

[0070] The Q-R eigenvalue analysis results of the 8-machine system are shown in Table 2. 0.77Hz is the mode with the weakest damping and...

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Abstract

The invention discloses an online analysis and early warning method for low-frequency oscillation of electric power system, relating to the safe operation of electric power system. The method comprises the steps that: oscillation frequency is obtained by carrying out K point median filtering over collected relative power angle in a power grid wide-area measurement system and via Teagar energy operator; and when power oscillation with the oscillation frequency between 0.1-0.2 Hz exists in power grid, the damping ratio dominating oscillation mode can be worked out through a signal energy analysis method based on EMD, thus to realize online analysis and early warning for low-frequency oscillation. The advantages of the invention include that the Teagar energy operator can rapidly work out the frequency of the relative power angle in the power grid; the algorithm of the damping ratio is simplified; large amount of integral operation can be avoided; the calculation is much simpler and more rapid; and the online analysis and early warning for low-frequency oscillation in power grid is realized.

Description

technical field [0001] The invention relates to the safe operation of the electric power system, and more particularly relates to the measurement and analysis of the medium and low frequency oscillation of the power grid in the wide area measurement system (WAMS) of the power grid. Background technique [0002] The low-frequency oscillations that occur in power systems originate from the relative swing between the rotors of generators or generator groups. It is the continuous oscillation of active power in the system caused by the lack of damping when there is a local surplus or lack of active power in the system, and the relevant generators or generator groups are accelerated and decelerated to achieve active power balance. Power oscillation with an oscillation frequency between 0.1 and 2.5Hz is called low-frequency oscillation or electromechanical oscillation. Low-frequency oscillations often occur on long-distance, heavy-duty transmission lines, especially in excitation ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/00
Inventor 徐友平党杰刘涤尘廖清芬李勇刘天斌王娜娜董飞飞
Owner CENT CHINA GRID
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