CN112014631A - Oscillating power acquisition method and device under grid transient fault - Google Patents

Abstract

The invention discloses a method and a device for obtaining oscillating power under grid transient faults. When grid transient faults occur in power electronic equipment, the method first measures the inductance voltage and current of the network inductance branch, and measures the inductance voltage and current respectively. Perform Hilbert transform; then calculate the instantaneous resistance represented by the network inductance branch according to the inductor voltage, current, Hilbert transform voltage parameter, and Hilbert transform current parameter; and calculate the network inductance branch The instantaneous power of ; extract the power consumed by the instantaneous resistance related to the instantaneous resistance from the instantaneous power, and use the power consumed by the instantaneous resistance as the oscillation power. The invention can help to solve the existing problems that the amplitude frequency of the internal potential of the power electronic equipment changes with the imbalance of the input and output power of the equipment, and the change of the amplitude and frequency of the internal potential will adversely affect the input and output power imbalance of the equipment through the network. There are flaws in the technology.

Description

Oscillating power acquisition method and device under grid transient fault

technical field

The invention relates to the technical field of power electronics, and in particular, to a method and device for obtaining oscillating power under a transient fault of a power grid.

Background technique

With the rapid development of new energy power generation, new semiconductor materials and control technology, the penetration rate of power electronic converters on the power supply side, transmission network and load side of the power system is getting higher and higher. The continuous increase of power electronic equipment and its capacity in the power system has led to an obvious trend of power electronics in the power system. This trend makes the power system appear system oscillation problems related to power electronic equipment.

At present, the research on the oscillation mechanism mainly stays on the research on the characteristics of the equipment. The oscillation form mainly considers the oscillation inside the power electronic device, the oscillation between the power electronic device and the system, the oscillation between the converters when the multi-converter is running in parallel, and the Sub/supersynchronous oscillations between power electronics and motors, without considering the dynamics between equipment and the network (ie, lines).

However, when the power electronic equipment is disturbed, the amplitude frequency of the internal potential of the equipment changes with the imbalance of the input and output power of the equipment. Therefore, it is very necessary to incorporate the dynamic characteristics of the network under equipment voltage excitation into the oscillation mechanism analysis system. How to obtain the oscillation power under the transient fault of the power grid is a technical problem that needs to be solved urgently.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a method and device for obtaining oscillating power under transient faults of the power grid, aiming to solve the above-mentioned problems.

In order to achieve the above purpose, the present invention provides a method for obtaining oscillating power under a grid transient fault. When a grid transient fault occurs in a power electronic device, the following steps are performed:

Measure the inductance voltage of the network inductance branch, and perform Hilbert transform on the inductance voltage to obtain the Hilbert transform voltage parameter;

Measure the current flowing through the inductor in the inductance branch of the network, and perform Hilbert transform on the current to obtain the Hilbert transform current parameter;

Calculate the instantaneous resistance represented by the network inductance branch according to the inductor voltage, the current, the Hilbert transform voltage parameter, and the Hilbert transform current parameter;

Calculate the instantaneous power of the network inductance branch according to the inductance voltage and the current;

The power consumed by the instantaneous resistance related to the instantaneous resistance is extracted from the instantaneous power, and the power consumed by the instantaneous resistance is used as the oscillation power.

Preferably, the step of measuring the inductance voltage of the inductance branch of the network, and performing Hilbert transform on the inductance voltage to obtain the Hilbert transform voltage parameter, includes:

The analytical signal related to the inductance voltage of the network inductance branch is preset, and the inductance voltage u(t) is characterized by the following formula:

u(t)=A _u (t)∫ω _u (t)

where A _u (t) is the instantaneous amplitude of the inductor voltage u(t), ω _u (t) is the instantaneous angular frequency of the inductor voltage u(t), A _u (t) and ω _u (t) ) changes with time, and the analytical signal u _c (t) related to the inductor voltage u (t) is represented by the following formula:

u _c (t)=u(t)+ju _HT (t)

Wherein, j represents a virtual symbol, and u _HT (t) represents the Hilbert transform voltage parameter obtained by the inductance voltage u (t) after Hilbert transform;

Correspondingly, the step of measuring the current flowing through the inductor in the inductance branch of the network, and performing the Hilbert transform on the current to obtain the Hilbert transform current parameter, includes:

An analytical signal related to the current i(t) in the network inductance branch is preset, and the current i(t) is characterized by the following formula:

i(t)=A _i (t)∫ω _i (t)

where A _i (t) is the instantaneous amplitude of the current i(t), ω _i (t) is the instantaneous angular frequency of the current i(t), A _i (t) and ω _i (t) are both As a function of time, the analytical signal ic (t) associated with the current i( _t ) is represented by the following formula:

i _c (t)=i(t)+ji _HT (t)

Wherein, j represents a virtual symbol, and i _HT (t) is a Hilbert-transformed current parameter i _HT (t) obtained after the current i(t) is Hilbert-transformed.

Preferably, the instantaneous resistance r(t) characterized by the network inductance branch is calculated by the following formula:

Wherein, r(t) represents according to the inductor voltage u(t), the current i(t), the Hilbert transform voltage parameter u _HT (t), and the Hilbert transform current parameter i _HT (t) The instantaneous resistance of the network inductance branch obtained by calculation.

Preferably, the instantaneous power of the network inductance branch is calculated by the following formula;

p(t)= _u (t)i(t)= _pr (t)+px(t)

Wherein, pr (t) represents the power consumed by the instantaneous resistance of the network inductance branch, and p _x ( _t ) represents the power consumed by the instantaneous reactance of the network inductance branch.

Preferably, the step of extracting the power consumed by the instantaneous resistance related to the instantaneous resistance r(t) from the instantaneous power includes:

The power dissipated by the instantaneous resistance of the inductive branch of the network is calculated by the following formula:

p _r (t)=r(t)i ² (t)

where pr ( _t ) represents the power dissipated by the instantaneous resistance of the inductive branch of the network.

In addition, in order to achieve the above purpose, the present invention also proposes a device for obtaining oscillating power under a transient fault of a power grid, the device comprising:

The voltage processing module is used to measure the inductance voltage of the network inductance branch, and perform Hilbert transform on the inductance voltage to obtain the Hilbert transform voltage parameter;

a current processing module for measuring the current flowing through the inductor in the network inductor branch, and performing Hilbert transform on the current to obtain the Hilbert transform current parameter;

an instantaneous resistance calculation module, configured to calculate the instantaneous resistance represented by the network inductance branch according to the inductor voltage, the current, the Hilbert transform voltage parameter, and the Hilbert transform current parameter;

a power calculation module, configured to calculate the instantaneous power of the network inductance branch according to the inductance voltage and the current;

An oscillation power acquisition module, configured to extract the power consumed by the instantaneous resistance related to the instantaneous resistance from the instantaneous power, and use the power consumed by the instantaneous resistance as the oscillation power.

The beneficial effect of the present invention is that: when a power grid transient fault occurs in the power electronic equipment, the method firstly measures the inductance voltage and current of the network inductance branch, and performs Hilbert transform on the inductance voltage and current respectively; and then according to the inductance voltage, current, the Hilbert transform voltage parameter, and the Hilbert transform current parameter to calculate the instantaneous resistance characterized by the network inductance branch; and calculate the instantaneous power of the network inductance branch; extract and from the instantaneous power and The power consumed by the instantaneous resistance related to the instantaneous resistance is taken as the oscillation power. The invention can help to solve the existing problems that the amplitude frequency of the internal potential of the power electronic equipment changes with the imbalance of the input and output power of the equipment, and the change of the amplitude and frequency of the internal potential will adversely affect the input and output power imbalance of the equipment through the network. There are flaws in the technology.

Description of drawings

1 is a schematic flowchart of a method for obtaining oscillating power under grid transient faults according to the present invention;

2 is a schematic flowchart of an embodiment of a method for obtaining oscillating power under grid transient faults according to the present invention;

FIG. 3 is a schematic diagram of functional modules of an embodiment of an apparatus for obtaining oscillating power under grid transient faults according to the present invention.

The realization, functional characteristics and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments.

Detailed ways

The embodiments described herein are only used to explain the present invention, and are not intended to limit the present invention.

It is understandable that when the power system oscillates, the excitation acting on the network is essentially a voltage signal whose amplitude and frequency vary with time, and the current flowing through the network is also a signal whose amplitude and frequency vary with time. , then the power consumed on the network naturally contains the inherent reason for the oscillation of the system. Extracting the oscillation power is of great significance for the study of the oscillation mechanism of the power electronic power system.

Referring to FIGS. 1 and 2 , the first embodiment of the present invention provides a method for obtaining oscillating power under grid transient faults. When a grid transient fault occurs in power electronic equipment, the following oscillations under grid transient faults are performed. How to get power:

Step S10: measure the inductance voltage u(t) of the network inductance branch, and perform Hilbert transform on the inductance voltage u(t) to obtain the Hilbert transform voltage parameter u _HT (t);

Specifically, the implementation of step S10 specifically includes:

The analytical signal related to the inductance voltage u(t) of the network inductance branch is preset, and the inductance voltage u(t) is essentially a time-varying amplitude-frequency signal. The inductance voltage u(t) is characterized by formula 1:

u(t)=A _u (t)∫ω _u (t) (Equation 1)

where A _u (t) is the instantaneous amplitude of the inductor voltage u(t), ω _u (t) is the instantaneous angular frequency of the inductor voltage u(t), A _u (t) and ω _u (t) ) changes with time, and the analytical signal u _c (t) related to the inductor voltage u (t) is represented by formula 2:

u _c (t)=u(t)+ju _HT (t) (Equation 2)

Wherein, j represents a virtual symbol, and u _HT (t) represents the Hilbert-transformed voltage parameter obtained by the inductance voltage u(t) after Hilbert-transformation.

Step S20: measure the current i(t) flowing through the inductor in the network inductance branch, and perform Hilbert transform on the current i(t) to obtain the Hilbert transform current parameter i _HT (t);

Specifically, the implementation of step S20 specifically includes:

The analytical signal related to the current i(t) in the inductance branch of the network is preset, and the current i(t) flowing through the inductance is essentially a time-varying amplitude frequency signal; t) Characterize:

i(t)=A _i (t)∫ω _i (t) (Equation 3)

where A _i (t) is the instantaneous amplitude of the current i(t), ω _i (t) is the instantaneous angular frequency of the current i(t), A _i (t) and ω _i (t) are both As a function of time, the analytical signal ic (t) related to the current i( _t ) is represented by Equation 4:

i _c (t)=i(t)+ji _HT (t) (Equation 4)

Wherein, j represents a virtual symbol, and i _HT (t) is a Hilbert-transformed current parameter i _HT (t) obtained after the current i(t) is Hilbert-transformed.

Step S30: According to the inductor voltage u(t), the current i(t), the Hilbert transform voltage parameter u _HT (t), and the Hilbert transform current parameter i _HT (t ) calculate the instantaneous resistance r(t) characterized by the network inductance branch;

In a specific implementation, the instantaneous resistance r(t) represented by the network inductance branch is calculated by the following formula 5:

Among them, r(t) is the instantaneous resistance of the inductive branch under the excitation of the time-varying amplitude-frequency signal.

Step S40: Calculate the instantaneous power of the network inductance branch according to the inductance voltage u(t) and the current i(t);

In a specific implementation, the instantaneous power of the network inductance branch is calculated by the following formula 6;

p(t)= _u (t)i(t)= _pr (t)+px(t) (Equation 6);

Wherein, pr (t) represents the power consumed by the instantaneous resistance of the network inductance branch, and p _x ( _t ) represents the power consumed by the instantaneous reactance of the network inductance branch.

Step S50: extracting the power consumed by the instantaneous resistance related to the instantaneous resistance r(t) from the instantaneous power, and using the power consumed by the instantaneous resistance as the oscillating power;

In a specific implementation, the power consumed by the instantaneous resistance of the network inductance branch is directly calculated by the following formula 7, and the power pr ( _t ) consumed by the instantaneous resistance is used as the oscillation power:

p _r (t)=r(t)i ² (t) (Equation 7)

In addition, the instantaneous reactance x(t) characterized by the network inductance branch can also be calculated by the following formula 8:

Wherein, x(t) represents according to the inductor voltage u(t), the current i(t), the Hilbert transform voltage parameter u _HT (t), and the Hilbert transform current parameter The instantaneous reactance represented by the network inductance branch obtained by calculating i _HT (t); then calculate the instantaneous reactance consumption of the network inductance branch according to the current i(t) and the instantaneous reactance x(t) Power p _x (t).

The beneficial effects of this embodiment are: this embodiment incorporates the network dynamic characteristics under the voltage excitation of power electronic equipment into the oscillation mechanism analysis system for research, which is not involved in the current research on oscillation mechanism of power electronic power systems. The instantaneous resistance represented by the inductive branch is calculated by defining the analytical signal related to the voltage and current of the inductive branch of the network by Hilbert transform, and the oscillating power can be obtained by extracting the part of the instantaneous resistance in the power consumed by the network. The oscillating power acquisition method is of great significance for studying the formation of the oscillation mechanism of the power electronic power system considering the dynamic characteristics of the network, and the invention has good development potential and promotion space. In the prior art, it can help to solve the problem that the amplitude frequency of the internal potential of the power electronic equipment changes with the imbalance of the input and output power of the equipment, and the change of the amplitude and frequency of the internal potential will adversely affect the input and output power imbalance of the equipment through the network. Flawed.

Referring to FIG. 3, the first embodiment of the present invention provides an oscillating power acquisition device under grid transient faults, the device may be an entity device, and the entity device is used to perform calculation and measurement on power electronic equipment; The device may be a program, the program is implanted into the power electronic equipment, and the oscillating power acquisition device under the grid transient fault will perform corresponding work when the power electronic equipment has a grid transient fault; specifically, the device includes: :

The voltage processing module 10 is used for measuring the inductance voltage u(t) of the inductance branch of the network, and performing Hilbert transform on the inductance voltage u(t) to obtain the Hilbert transform voltage parameter u _HT (t);

Specifically, the implementation of the voltage processing module 10 specifically includes:

By manually presetting the analytical signal related to the inductance voltage u(t) of the network inductance branch, the inductance voltage u(t) is essentially a time-varying amplitude-frequency signal, and the inductance voltage u(t) is characterized by formula 1 :

u(t)=A _u (t)∫ω _u (t) (Equation 1)

where A _u (t) is the instantaneous amplitude of the inductor voltage u(t), ω _u (t) is the instantaneous angular frequency of the inductor voltage u(t), A _u (t) and ω _u (t) ) changes with time, and the analytical signal u _c (t) related to the inductor voltage u (t) is represented by formula 2:

u _c (t)=u(t)+ju _HT (t) (Equation 2)

Wherein, j represents a virtual symbol, and u _HT (t) represents the Hilbert-transformed voltage parameter obtained by the inductance voltage u(t) after Hilbert-transformation.

The current processing module 20 is used for measuring the current i(t) flowing through the inductor in the inductance branch of the network, and performing the Hilbert transform on the current i(t) to obtain the Hilbert transform current parameter i _HT (t );

Specifically, the implementation of the current processing module 20 specifically includes:

By manually presetting the analytical signal related to the current i(t) in the inductance branch of the network, the current i(t) flowing through the inductance is essentially a time-varying amplitude frequency signal; i(t) is characterized:

i(t)=A _i (t)∫ω _i (t) (Equation 3)

where A _i (t) is the instantaneous amplitude of the current i(t), ω _i (t) is the instantaneous angular frequency of the current i(t), A _i (t) and ω _i (t) are both As a function of time, the analytical signal ic (t) related to the current i( _t ) is represented by Equation 4:

i _c (t)=i(t)+ji _HT (t) (Equation 4)

Wherein, j represents a virtual symbol, and i _HT (t) is a Hilbert-transformed current parameter i _HT (t) obtained after the current i(t) is Hilbert-transformed.

The instantaneous resistance calculation module 30 is configured to calculate the current according to the inductor voltage u(t), the current i(t), the Hilbert transform voltage parameter u _HT (t), and the Hilbert transform current The parameter i _HT (t) calculates the instantaneous resistance r(t) characterized by the network inductance branch;

In a specific implementation, the instantaneous resistance r(t) represented by the network inductance branch is calculated by the following formula 5:

Among them, r(t) is the instantaneous resistance of the inductive branch under the excitation of the time-varying amplitude-frequency signal.

a power calculation module 40, configured to calculate the instantaneous power of the network inductance branch according to the inductance voltage u(t) and the current i(t);

In a specific implementation, the instantaneous power of the network inductance branch is calculated by the following formula 6;

p(t)= _u (t)i(t)= _pr (t)+px(t) (Equation 6);

Wherein, pr (t) represents the power consumed by the instantaneous resistance of the network inductance branch, and p _x ( _t ) represents the power consumed by the instantaneous reactance of the network inductance branch.

an oscillation power acquisition module 50, configured to extract the power consumed by the instantaneous resistance related to the instantaneous resistance r(t) from the instantaneous power, and use the power consumed by the instantaneous resistance as the oscillation power;

In a specific implementation, the power consumed by the instantaneous resistance of the network inductance branch is directly calculated by the following formula 7, and the power pr ( _t ) consumed by the instantaneous resistance is used as the oscillation power:

p _r (t)=r(t)i ² (t) (Equation 7)

The beneficial effects of this embodiment are: this embodiment incorporates the network dynamic characteristics under the voltage excitation of power electronic equipment into the oscillation mechanism analysis system for research, which is not involved in the current research on oscillation mechanism of power electronic power systems. The instantaneous resistance represented by the inductive branch is calculated by defining the analytical signal related to the voltage and current of the inductive branch of the network by Hilbert transform, and the oscillating power can be obtained by extracting the part of the instantaneous resistance in the power consumed by the network. The acquisition device of oscillating power is of great significance for studying the formation of the oscillation mechanism of the power electronic power system considering the dynamic characteristics of the network, and the device has good development potential and promotion space. In the prior art, it can help to solve the problem that the amplitude frequency of the internal potential of the power electronic equipment changes with the imbalance of the input and output power of the equipment, and the change of the amplitude and frequency of the internal potential will adversely affect the input and output power imbalance of the equipment through the network. Flawed.

From the description of the above embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus a necessary general hardware platform, and of course hardware can also be used, but in many cases the former is better implementation. Based on this understanding, the technical solutions of the present invention can be embodied in the form of software products in essence or the parts that make contributions to the prior art, and the computer software products are stored in a storage medium (such as ROM/RAM, magnetic disk, CD-ROM), including several instructions to make a terminal device (which may be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) execute the methods described in the various embodiments of the present invention.

The above are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the description and drawings of the present invention, or directly or indirectly applied in other related technical fields , are similarly included in the scope of patent protection of the present invention.

Claims (6)

1. A method for obtaining oscillating power under a grid transient fault, characterized in that, when a grid transient fault occurs in power electronic equipment, the following steps are performed: Measure the inductance voltage of the network inductance branch, and perform Hilbert transform on the inductance voltage to obtain the Hilbert transform voltage parameter; Measure the current flowing through the inductor in the inductance branch of the network, and perform Hilbert transform on the current to obtain the Hilbert transform current parameter; Calculate the instantaneous resistance represented by the network inductance branch according to the inductor voltage, the current, the Hilbert transform voltage parameter, and the Hilbert transform current parameter; Calculate the instantaneous power of the network inductance branch according to the inductance voltage and the current; The power consumed by the instantaneous resistance related to the instantaneous resistance is extracted from the instantaneous power, and the power consumed by the instantaneous resistance is used as the oscillation power. 2. The method according to claim 1, wherein the step of measuring the inductance voltage of the inductance branch of the network, and performing Hilbert transform on the inductance voltage to obtain the Hilbert transform voltage parameter, comprises: The analytical signal related to the inductance voltage of the network inductance branch is preset, and the inductance voltage u(t) is characterized by the following formula: u(t)=A _u (t)∫ω _u (t) where A _u (t) is the instantaneous amplitude of the inductor voltage u(t), ω _u (t) is the instantaneous angular frequency of the inductor voltage u(t), A _u (t) and ω _u (t) ) changes with time, and the analytical signal u _c (t) related to the inductor voltage u (t) is represented by the following formula: u _c (t)=u(t)+ju _HT (t) Wherein, j represents a virtual symbol, and u _HT (t) represents the Hilbert transform voltage parameter obtained by the inductance voltage u (t) after Hilbert transform; Correspondingly, the step of measuring the current flowing through the inductor in the inductance branch of the network, and performing the Hilbert transform on the current to obtain the Hilbert transform current parameter, includes: An analytical signal related to the current i(t) in the network inductance branch is preset, and the current i(t) is characterized by the following formula: i(t)=A _i (t)∫ω _i (t) where A _i (t) is the instantaneous amplitude of the current i(t), ω _i (t) is the instantaneous angular frequency of the current i(t), A _i (t) and ω _i (t) are both As a function of time, the analytical signal ic (t) associated with the current i( _t ) is represented by the following formula: i _c (t)=i(t)+ji _HT (t) Wherein, j represents a virtual symbol, and i _HT (t) is a Hilbert-transformed current parameter i _HT (t) obtained after the current i(t) is Hilbert-transformed. 3. The method of claim 2, wherein the instantaneous resistance r(t) characterized by the network inductance branch is calculated by the following formula:

Wherein, r(t) represents according to the inductor voltage u(t), the current i(t), the Hilbert transform voltage parameter u _HT (t), and the Hilbert transform current parameter i _HT (t) The instantaneous resistance of the network inductance branch obtained by calculation. 4. The method of claim 3, wherein the instantaneous power of the network inductance branch is calculated by the following formula; p(t)= _u (t)i(t)= _pr (t)+px(t) Wherein, pr (t) represents the power consumed by the instantaneous resistance of the network inductance branch, and p _x ( _t ) represents the power consumed by the instantaneous reactance of the network inductance branch. 5. The method according to any one of claims 3 or 4, wherein the step of extracting the power consumed by the instantaneous resistance related to the instantaneous resistance r(t) from the instantaneous power comprises: The power dissipated by the instantaneous resistance of the inductive branch of the network is calculated by the following formula: p _r (t)=r(t)i ² (t) where pr ( _t ) represents the power dissipated by the instantaneous resistance of the inductive branch of the network. 6. An oscillating power acquisition device under grid transient fault, characterized in that the device comprises: The voltage processing module is used for measuring the inductance voltage of the network inductance branch, and performing the Hilbert transform on the inductance voltage to obtain the Hilbert transform voltage parameter; a current processing module for measuring the current flowing through the inductor in the network inductor branch, and performing Hilbert transform on the current to obtain the Hilbert transform current parameter; an instantaneous resistance calculation module, configured to calculate the instantaneous resistance represented by the network inductance branch according to the inductor voltage, the current, the Hilbert transform voltage parameter, and the Hilbert transform current parameter; a power calculation module, configured to calculate the instantaneous power of the network inductance branch according to the inductance voltage and the current; An oscillation power acquisition module, configured to extract the power consumed by the instantaneous resistance related to the instantaneous resistance from the instantaneous power, and use the power consumed by the instantaneous resistance as the oscillation power.

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