Design method of low-frequency multi-sine signal for power system

A sinusoidal signal and power system technology, which is applied in the cross-field of power system identification and signal processing, can solve problems such as the reduction of the signal-to-noise ratio of the response signal, the insufficient concentration of input signal energy, and the impact on the identification accuracy of the state space model of the power system. small effect

CN109726490BActive Publication Date: 2020-09-22SOUTH CHINA UNIV OF TECH
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2020-09-22

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Abstract

The invention discloses a low-frequency-band multi-sine signal design method for electric power system state space model identification. The method comprises the following steps of determining each harmonic component amplitude, each harmonic component frequency and a sampling length of a low-frequency-band multi-sine signal x (t); Then, defining a wave crest factor of the low-frequency-band multi-sine signal x (t); converting a wave crest factor minimization problem into a wave crest factor minimization problem; gradually increasing the p value of the lp norm, and solving a column vector pp composed of the harmonic wave phases (please see the formula in the specification), so as to minimize the lp norm of the low-frequency band multi-sine signal x (t); And finally, solving the problem by adopting an algorithm, wherein p is set as 4, 8, 16, 32, 64, 128, 256, 512 ... in sequence. For each set p value, adopting a Gauss Newton method in combination with Levenberg-Marquardt algorithm to solve a column vector pp, so that the lp norm of x (t) is minimum; And when p is set to be 512, the approximation requirement can be met, so that the low-frequency-band multi-sine signal x (t) meeting the requirement is solved. The input signal designed by the method disclosed by the invention simultaneously meets the time domain waveform amplitude limiting requirement and the frequency domain energyconcentration requirement.
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Description

technical field

[0001] The invention relates to the intersecting technical fields of power system identification and signal processing, in particular to a design method for low-frequency band multi-sine signals used in power systems.

[0002] technical background

[0003] With the development of the interconnected power grid, the problem of low-frequency oscillation in the power system in the frequency range of 0.1 to 2.5 Hz is prominent, which needs to be solved by installing a power system low-frequency oscillation controller. The design of power system low-frequency oscillation controller depends on the power system state-space model. In the actual power system engineering design, the problem of state-space model identification needs to be solved first. In order to ensure the safe and stable operation of the power system during the identification process, practical projects usually use small disturbance signals to excite the power system, then collect the power system exci...

Examples

Embodiment

[0035] In this embodiment, the time-domain expression of the low-frequency multi-sine signal is: where t is time, a u , ω u and are the amplitude, frequency and phase of the uth sine harmonic component, N u is the number of sine harmonic frequency components.

[0036] Define the crest factor of the multi-sine signal in the low frequency band as: Among them, t is the sampling time, N is the total number of samples of the low-frequency multi-sine signal (that is, the total length of the signal), and max() represents the maximum value of the array in parentheses; obviously, C r The magnitude of reflects the fluctuation of the signal in the time domain: given the frequency domain characteristics of the signal x(t), the smaller the time domain fluctuation of the signal x(t), the C r smaller.

[0037] Low-frequency multi-sine signal design refers to the a u , ω u , N u And the sampling length N, use the algorithm to solve to obtain a set of parameters of the signal whe...