Centralized oscillation suppression method and system based on multi-band impedance remodeling

Abstract

The invention discloses a centralized oscillation suppression method and system based on multi-frequency-band impedance remodeling, and relates to the technical field of oscillation suppression of a power system, and the method comprises the steps: obtaining an impedance curve of a controlled power electronic device cluster, dividing frequency bands according to the characteristics of the impedance curve, and respectively listing impedance formulas and constraint conditions according to different frequency bands; and determining strategies and parameter configuration of an oscillation suppression link of the suppressor under different frequency bands, and completing centralized oscillation suppression of multi-frequency-band impedance remodeling. The method can be used for solving the problem of sub-hyper-synchronous oscillation in power electronic device gathering areas such as a wind power plant, a photovoltaic power station and a port, treatment can be carried out according to the impedance curve of the treated device in a frequency band division mode, and improvement of multi-frequency-band damping is achieved. Along with gradual increase of power electronic equipment in the power system, the risk of oscillation of the system is gradually increased, and the method is wide in application scene and has good popularization value.

Description

Technical Field

[0001] The present invention relates to the technical field of power system oscillation suppression, and in particular to a centralized oscillation suppression method and system based on frequency-band impedance reshaping. Background Art

[0002] At present, with the widespread application and rapid development of new energy power generation represented by wind power and photovoltaic power generation, as well as reactive compensation devices and AC transmission technology, the converters of new energy stations and the frequency converters of port hoists have oscillation problems in the sub / super synchronous frequency band. This oscillation phenomenon is mainly caused by the interaction between the grid-connected inverter control and the weak AC power grid. The active oscillation suppression method is still in the research stage at home and abroad. Summary of the invention

[0003] In view of the problems existing in the existing centralized oscillation suppression method, system and device, the present invention is proposed.

[0004] Therefore, the problem to be solved by the present invention is that conventional methods cannot achieve multi-band damping improvement based on the impedance curve of the device to be treated by frequency band treatment.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] In a first aspect, an embodiment of the present invention provides a centralized oscillation suppression method based on frequency-band impedance reshaping, which includes obtaining an impedance curve of a power electronic device cluster to be governed, and dividing the frequency bands according to the impedance curve characteristics;

[0007] Determine the constraint formulas for different frequency bands, and determine the strategies and parameter configurations for the oscillation suppression link of the suppressor under different frequency bands.

[0008] As a preferred solution of the centralized oscillation suppression method based on frequency band impedance reshaping of the present invention, obtaining the impedance curve of the power electronic device group under control includes extracting the impedance characteristic curve of the power electronic group under control, dividing the impedance characteristic curve into 2 to 4 key frequency bands, and expressing the impedance of different frequency bands as follows:

[0009]

[0010] Among them, Z w (jω i ) represents the impedance characteristic of the i-th frequency band, ω1≤ω i ≤ω2, ω1 and ω2 are the start and end ranges of the frequency band, A w (ω i ) represents Z w (jω i ), θ w (ω i ) represents Zw (jω i ) phase.

[0011] As a preferred solution of the centralized oscillation suppression method based on frequency-band impedance reshaping of the present invention,

[0012] Among them: The constraint formulas for determining different frequency bands include:

[0013] The equivalent impedance of the centralized active oscillation suppression equipment in the ith frequency band can be expressed as:

[0014]

[0015] Among them, θ D (ω i ) represents Z D (jω i ) compared to Z w (jω i ) phase shift angle, K D (ω i ) represents the gain link of the centralized oscillation suppression device.

[0016] Based on the cost of the capacity of the centralized oscillation suppression equipment, the gain link K D (ω i ) constraint can be expressed as:

[0017] K D (ω i )≤1.2

[0018] After the governed power electronic group and the centralized oscillation suppression device are connected in parallel, the impedance characteristics of the i-th frequency band can be expressed as:

[0019]

[0020] In order to avoid negative resistance in the impedance characteristics of the ith frequency band, Z(jω i ) are all greater than zero, that is, the damping constraint of the i-th frequency band can be expressed as:

[0021] real(Z(jω i ))>0

[0022] As a preferred solution of the centralized oscillation suppression method based on frequency band impedance reshaping of the present invention, the strategy configuration of the oscillation suppression link of the suppressor under different frequency bands is determined, including:

[0023] According to the gain constraint and the real impedance constraint, the active oscillation suppression device strategy is obtained, including K D (ω i ) and θ D (ω i);

[0024] Determining the current command of the active oscillation suppression device includes measuring the current I of the power electronic device group to be governed w , will I w Divided into i frequency bands, each frequency band goes through the signal extraction link and the phase shift link Post-multiplication gain link K D (ω i ), and obtain the corresponding frequency band suppression current calculation value I Damp_i , the suppression current command I of the active oscillation suppressor is obtained Damp_ref It is the sum of the calculated values ​​of the suppression current of each frequency band. The specific formula is:

[0025]

[0026] Among them, I Damp_ref Indicates the suppression current instruction of the oscillation suppressor, n indicates the quantity, I Damp_i Indicates the calculated value of the current command corresponding to the frequency band suppression.

[0027] In a second aspect, an embodiment of the present invention provides a centralized oscillation suppression system based on frequency-band impedance reshaping, which includes:

[0028] An acquisition module, which acquires the impedance curve of the power electronic device group to be managed and divides the frequency band according to the characteristics of the impedance curve;

[0029] The suppression module determines the constraint formulas for different frequency bands and determines the strategies and parameter configurations for the oscillation suppression link of the suppressor under different frequency bands.

[0030] In a third aspect, an embodiment of the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein: when the processor executes the computer program, any step of the above-mentioned centralized oscillation suppression method based on frequency-band impedance reshaping is implemented.

[0031] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, any step of the above-mentioned centralized oscillation suppression method based on frequency-band impedance reshaping is implemented.

[0032] The beneficial effects of the present invention are as follows: the present invention accurately divides the impedance curve frequency bands to ensure that the impedance characteristics of each frequency band are accurately expressed; negative resistance characteristics are avoided through an active oscillation suppression scheme to improve the stability and reliability of the system; and the safe operation of the power electronic cluster is guaranteed to ensure the stability and safety of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0034] Figure 1 A flow chart of strategy parameter configuration of a centralized oscillation suppression method and system based on frequency-band impedance reshaping provided by an embodiment of the present invention.

[0035] Figure 2 A control block diagram of a centralized oscillation suppression method and system based on frequency-band impedance reshaping provided by an embodiment of the present invention.

[0036] Figure 3 A Bode diagram of impedance characteristics of a governed power electronic machine group in a centralized oscillation suppression method and system based on frequency-band impedance reshaping provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0038] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0039] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0040] Example 1

[0041] Reference Figure 1 to Figure 3 , which is the first embodiment of the present invention, provides a centralized oscillation suppression method based on frequency-band impedance reshaping, including:

[0042] S1: Obtain the impedance curve of the power electronic device group to be managed and divide the frequency bands according to the characteristics of the impedance curve.

[0043] Among them, obtaining the impedance curve of the controlled power electronic device group includes extracting the impedance characteristic curve of the controlled power electronic device group, dividing the impedance characteristic curve into 2 to 4 key frequency bands, and expressing the impedance of different frequency bands as follows:

[0044]

[0045] Among them, Z w (jω i ) represents the impedance characteristic of the i-th frequency band, ω1≤ω i ≤ω2, ω1 and ω2 are the start and end ranges of the frequency band, A w (ω i ) represents Z w (jω i ), θ w (ω i ) represents Z w (jω i ) phase.

[0046] S2: Determine the constraint formulas for different frequency bands, and determine the strategies and parameter configurations for the oscillation suppression link of the suppressor under different frequency bands.

[0047] Among them, the constraint formulas for determining different frequency bands include:

[0048] The equivalent impedance of the centralized active oscillation suppression equipment in the ith frequency band can be expressed as:

[0049]

[0050] Among them, θ D (ω i ) represents Z D (jω i ) compared to Z w (jω i ) phase shift angle, K D (ω i ) represents the gain link of the centralized oscillation suppression device.

[0051] Based on the cost of the capacity of the centralized oscillation suppression equipment, the gain link K D (ω i ) constraint can be expressed as:

[0052] K D (ω i )≤1.2

[0053] After the governed power electronic group and the centralized oscillation suppression device are connected in parallel, the impedance characteristics of the i-th frequency band can be expressed as:

[0054]

[0055] In order to avoid negative resistance in the impedance characteristics of the ith frequency band, Z(jω i ) are all greater than zero, that is, the damping constraint of the i-th frequency band can be expressed as:

[0056] real(Z(jω i ))>0

[0057] As a preferred solution of the centralized oscillation suppression method based on frequency band impedance reshaping of the present invention, the strategy configuration of the oscillation suppression link of the suppressor under different frequency bands is determined, including:

[0058] According to the gain constraint and the real impedance constraint, the active oscillation suppression device strategy is obtained, including K D (ω i ) and θ D (ω i );

[0059] Determining the current command of the active oscillation suppression device includes measuring the current I of the power electronic device group to be governed w , will I w Divided into i frequency bands, each frequency band goes through the signal extraction link and the phase shift link Post-multiplication gain link K D (ω i ), and obtain the corresponding frequency band suppression current calculation value I Damp_i , the suppression current command I of the active oscillation suppressor is obtained Damp_ref It is the sum of the calculated values ​​of the suppression current of each frequency band. The specific formula is:

[0060]

[0061] Among them, I Damp_ref Indicates the suppression current instruction of the oscillation suppressor, n indicates the quantity, I Damp_i Indicates the calculated value of the current command corresponding to the frequency band suppression.

[0062] like Figure 3As shown, after the centralized oscillation suppressor 1 of the suppression method of the present invention was put into use in the controlled station, the impedance of the station was improved between 2 and 95 Hz. After the centralized oscillation suppressor 2 of the ordinary suppression method was put into use in the controlled station, the impedance of the station deteriorated between 55 and 70 Hz. In a preferred embodiment, a centralized oscillation suppression system based on frequency-band impedance reshaping includes an acquisition module, which acquires the impedance curve of the controlled power electronic device cluster, divides the frequency band according to the characteristics of the impedance curve, and lists the impedance formula and constraint conditions according to different frequency bands; a suppression module, which determines the constraint formulas of different frequency bands, determines the strategy and parameter configuration of the suppressor oscillation suppression link under different frequency bands, and completes the centralized oscillation suppression with frequency-band impedance reshaping.

[0063] The above-mentioned unit modules may be embedded in or independent of a processor in a computer device in the form of hardware, or may be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above-mentioned modules.

[0064] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0065] In summary, the present invention accurately divides the impedance curve frequency bands to ensure that the impedance characteristics of each frequency band are accurately expressed; avoids negative resistance characteristics through an active oscillation suppression scheme to improve the stability and reliability of the system; ensures the safe operation of the power electronic cluster and ensures the stability and safety of the power system.

Claims

1. A centralized oscillation suppression method based on frequency-band impedance reshaping, characterized in that: include, Obtain the impedance curve of the power electronic device group being managed and divide the frequency bands according to the characteristics of the impedance curve; Determine the constraint formulas for different frequency bands, and determine the strategies and parameter configurations for the oscillation suppression link of the suppressor under different frequency bands.

2. The centralized oscillation suppression method based on frequency-band impedance reshaping as claimed in claim 1, characterized in that: Obtaining the impedance curve of the controlled power electronic device group includes extracting the impedance characteristic curve of the controlled power electronic device group, dividing the impedance characteristic curve into 2 to 4 key frequency bands, and expressing the impedance of different frequency bands as follows: Among them, Z w (jω i ) represents the impedance characteristic of the i-th frequency band, ω1≤ω i ≤ω2, ω1 and ω2 are the start and end ranges of the frequency band, A w (ω i ) represents Z w (jω i ), θ w (ω i ) represents Z w (jω i ) phase.

3. The centralized oscillation suppression method based on frequency-band impedance reshaping as claimed in claim 2, characterized in that: The constraint formulas for determining different frequency bands include: The equivalent impedance of the centralized oscillation suppression equipment in the ith frequency band can be expressed as: Among them, θ D (ω i ) represents Z D (jω i ) compared to Z w (jω i ) phase shift angle, K D (ω i ) represents the gain link of the centralized oscillation suppression device; Based on the cost of the capacity of the centralized oscillation suppression equipment, the gain link K D (ω i ) constraint can be expressed as: K D (oh i )≤1.2 After the governed power electronic group and the centralized oscillation suppression device are connected in parallel, the impedance characteristics of the i-th frequency band can be expressed as: In order to avoid negative resistance in the impedance characteristics of the ith frequency band, Z(jω i ) are all greater than zero, that is, the damping constraint of the i-th frequency band can be expressed as: real(Z(jω i ))>0。 4. The centralized oscillation suppression method based on frequency-band impedance reshaping as claimed in claim 3, characterized in that: The strategy configuration for determining the oscillation suppression link of the suppressor in different frequency bands includes: According to the gain constraint and the real impedance constraint, the active oscillation suppression device strategy is obtained, including K D (ω i ) and θ D (ω i ); Determining the current command of the active oscillation suppression device includes measuring the current I of the power electronic device group to be governed w , will I w Divided into i frequency bands, each frequency band goes through the signal extraction link and the phase shift link Post-multiplication gain link K D (ω i ), and obtain the corresponding frequency band suppression current calculation value I Damp_i , the suppression current command I of the active oscillation suppressor is obtained Damp_ref It is the sum of the calculated values ​​of the suppression current of each frequency band. The specific formula is: Among them, I Damp_ref Indicates the suppression current instruction of the oscillation suppressor, n indicates the quantity, I Damp_i Indicates the calculated value of the current command corresponding to the frequency band suppression.

5. A centralized oscillation suppression system based on frequency-band impedance reshaping, characterized by: include, An acquisition module, which acquires the impedance curve of the power electronic device group to be managed and divides the frequency band according to the characteristics of the impedance curve; The suppression module determines the constraint formulas for different frequency bands and determines the strategies and parameter configurations for the oscillation suppression link of the suppressor under different frequency bands.

6. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the centralized oscillation suppression method based on frequency-band impedance reshaping according to any one of claims 1 to 4 are implemented.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the centralized oscillation suppression method based on frequency-band impedance reshaping according to any one of claims 1 to 4 are implemented.

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