阅读说明：本技术 一种自适应电流源阻抗测量装置及测量方法 (Self-adaptive current source impedance measuring device and measuring method ) 是由 赵静波 孙蓉 马俊鹏 王伟淘 朱宇萌 杨文莉 刘天琪 李文博 于 2021-08-20 设计创作，主要内容包括：本申请提供了一种自适应电流源阻抗测量装置及测量方法,并联注入电流阻抗测量装置由三相不控整流、双向DC-DC和单相逆变器构成,其中三相不控整流器交流侧与电网连接,给后级双向DC-DC电路供电；DC-DC电路采用PI控制器实现恒压,为单相逆变器提供稳定的电压；单相逆变器控制部分包含基波控制器和扰动控制器,基波控制器用于防止待测系统与测量装置之间的基波信号交互,扰动控制器用于输出设定形式扰动电流。本申请可以实现阻抗测量装置在全频段内的稳定运行,无需规避待测系统谐振点。(The application provides a self-adaptive current source impedance measuring device and a measuring method, wherein the parallel injection current impedance measuring device consists of a three-phase uncontrolled rectifier, a bidirectional DC-DC and a single-phase inverter, wherein the alternating current side of the three-phase uncontrolled rectifier is connected with a power grid and supplies power to a post-stage bidirectional DC-DC circuit; the DC-DC circuit adopts a PI controller to realize constant voltage and provides stable voltage for the single-phase inverter; the single-phase inverter control part comprises a fundamental wave controller and a disturbance controller, the fundamental wave controller is used for preventing fundamental wave signal interaction between a system to be tested and the measuring device, and the disturbance controller is used for outputting disturbance current in a set form. The application can realize the stable operation of the impedance measuring device in the full frequency band, and the resonance point of the system to be measured does not need to be avoided.)

1. An adaptive current source impedance measuring device, comprising: the three-phase uncontrolled rectifier is connected with a power grid on the alternating current side, and the direct current side is connected with the bidirectional DC-DC circuit to supply power to the bidirectional DC-DC circuit on the later stage; the bidirectional DC-DC circuit provides a constant voltage to the single-phase inverter; the single-phase inverter outputs a disturbance current.

2. The adaptive current source impedance measuring device according to claim 1, wherein the bidirectional DC-DC circuit implements a constant voltage through a PI controller to provide a stable DC voltage for the three-phase inverter.

3. The adaptive current source impedance measuring device according to claim 2, wherein the three-phase inverter comprises a fundamental wave controller and a disturbance controller, the fundamental wave controller is used for preventing fundamental wave signal interaction between a system to be measured and the measuring device, and the disturbance controller is used for outputting a set form disturbance current.

4. An adaptive current source impedance measuring device according to claim 3, wherein the fundamental controller adopts a constant current control strategy oriented with the grid voltage of the system to be measured under the dq axis, and the dq axis current references are all set to 0.

5. The adaptive current source impedance measuring device according to claim 3, wherein the disturbance controller adopts a current control strategy oriented with disturbance voltage under dq axis, and the disturbance current amplitude is adaptively adjusted through feedforward disturbance voltage amplitude.

6. An adaptive current source impedance measuring method based on the measuring device according to any one of claims 1 to 5, characterized by comprising the steps of:

step 1: determining a direct-current side voltage reference value of a bidirectional DC-DC circuit according to the voltage grade of a system to be tested

Step 2: before impedance measurement, constant voltage control is carried out on the bidirectional DC-DC circuit;

and step 3: when receiving an impedance measurement signal, starting an inverter controller to control an inverter circuit, wherein the output frequency is f₁The disturbance current is adjusted in a self-adaptive mode, voltage and current data of a measuring point are collected at the same time, and f is calculated through the following formula₁The impedance of (a):

and 4, step 4: after a time of delta t, changeChanging the frequency of the disturbance current to f₁+ delta f, collecting voltage and current data of the measuring point;

and 5: and (4) repeating the step (4) until the disturbance current frequency covers the full measurement frequency band.

Technical Field

The invention belongs to the field of research and development of impedance actual measurement equipment, and particularly relates to a self-adaptive current source impedance measurement device and a measurement method.

Background

Under the large background of "carbon peaking", "carbon neutralization", the development and utilization of new energy is further accelerated, however, the interaction between power electronics and the grid often causes broadband oscillation accidents. The impedance analysis method is an important tool for analyzing the broadband oscillation phenomenon, the input/output impedance of the system can be obtained through a mathematical modeling means and an actual measurement means, however, when the internal parameters of the system are uncertain and the topology of the system has a time-varying characteristic, the accuracy of an impedance model obtained through the modeling means is reduced, and the impedance measurement becomes a research hotspot. At present, the research on impedance measurement at home and abroad is mainly focused on low-power occasions with medium and low voltages, and with the increasing scale of new energy stations, a high-power impedance measuring device needs to be developed urgently, so that the research on a control algorithm of the high-power impedance measuring device is very necessary.

The impedance measurement is divided into two categories, namely passive measurement and active measurement, wherein the passive measurement calculates the impedance value of the system to be measured by extracting the self background harmonic of the system to be measured, and the active measurement injects specific disturbance into the system to be measured through a disturbance injection circuit and extracts disturbance voltage and current response to calculate the impedance value. The active measurement method is controllable in disturbance and high in measurement accuracy, so that the method becomes a mainstream measurement method. According to the property of the injection disturbance signal, the active measurement method is further divided into a series injection voltage method and a parallel injection current method, wherein the parallel injection current method is strong in plug and play type and high in practical application value. However, because the impedance amplitude of the system to be measured is large in change and strong in uncertainty, in the process of injecting the broadband disturbance into the system to be measured through the disturbance injection circuit, the frequency of the disturbance current is easy to approach or even equal to the series resonance frequency of the system to be measured, the stable operation of the system to be measured is seriously disturbed when the disturbance injection circuit injects too large disturbance into the resonance frequency, and the adaptive adjustment of the disturbance intensity is very necessary.

Disclosure of Invention

Aiming at the characteristics of large change range and strong uncertainty of the impedance value of the system to be measured, the application provides a control method and a control device for adaptively adjusting the intensity of the injected disturbance current according to the impedance value of the system to be measured, so that the stable operation of the system to be measured is not disturbed, the high-impedance measurement precision is ensured, and the measurable impedance value range is expanded.

In a first aspect, the embodiment of the application discloses a self-adaptive current source impedance measuring device, which comprises a three-phase uncontrolled rectifier, a bidirectional DC-DC circuit and a three-phase inverter, wherein the AC side of the three-phase uncontrolled rectifier is connected with a power grid, and the DC side of the three-phase uncontrolled rectifier is connected with the bidirectional DC-DC circuit to supply power to the subsequent bidirectional DC-DC circuit; the bidirectional DC-DC circuit provides a constant voltage to the three-phase inverter; the single-phase inverter outputs a disturbance current.

Preferably, the bidirectional DC-DC circuit realizes a constant voltage through a PI controller, and provides a stable direct-current voltage for the single-phase inverter;

preferably, the single-phase inverter comprises a fundamental wave controller and a disturbance controller, the fundamental wave controller is used for preventing fundamental wave signal interaction between a system to be tested and the measuring device, and the disturbance controller realizes output of disturbance current in a set form;

preferably, the fundamental wave controller adopts a constant current control strategy oriented by the voltage of a system to be tested under the dq axis, and the dq axis current references are all set to be 0;

preferably, the disturbance controller adopts a current control strategy oriented by disturbance voltage under dq axis, and meanwhile, the disturbance current amplitude is adaptively adjusted through feedforward disturbance voltage amplitude.

In a second aspect, an embodiment of the present application discloses an adaptive current source impedance measuring method based on the above measuring apparatus, including the following steps:

step 1: determining a direct-current side voltage reference value of a bidirectional DC-DC circuit according to the voltage grade of a system to be tested

Step 2: before impedance measurement, constant voltage control is carried out on the bidirectional DC-DC circuit;

and step 3: when receiving an impedance measurement signal, starting an inverter controller to control an inverter circuit, wherein the output frequency is f₁The disturbance current is subjected to self-adaptive adjustment, voltage and current data of a measuring point are collected at the same time, and f is calculated through the formula (1)₁The impedance of (a):

and 4, step 4: after the time delta t, changing the frequency of the disturbance current into f₁+ delta f, collecting voltage and current data of the measuring point;

and 5: and (4) repeating the step (4) until the disturbance current frequency covers the full measurement frequency band.

According to the self-adaptive current source impedance measuring device and the self-adaptive current source impedance measuring method, by means of the technical scheme, the self-adaptive current source impedance measuring device has the beneficial effects that:

(1) according to the invention, a disturbance voltage directional control-based mode is adopted, so that saturation limitation can be conveniently selected, and further disturbance current intensity can be adaptively adjusted;

(2) the invention ensures the stable operation of the impedance measuring device in the full frequency band and ensures the high-precision measuring result by adaptively adjusting the disturbance current intensity.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of an adaptive current source impedance measuring apparatus according to an embodiment of the present disclosure;

FIG. 2 is a control block diagram of a bidirectional DC-DC circuit provided in an embodiment of the present application;

fig. 3 is a control block diagram of a single-phase inverter provided in an embodiment of the present application;

FIG. 4 is a control block diagram of a fundamental controller circuit provided in an embodiment of the present application;

fig. 5 is a circuit control block diagram of a fundamental wave controller according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In a first aspect, please refer to fig. 1, the adaptive current source impedance measuring apparatus provided in this embodiment includes a three-phase uncontrolled rectifier, a bidirectional DC-DC circuit, and a single-phase inverter, where an ac side of the single-phase uncontrolled rectifier is connected to a power grid, and a DC side of the single-phase uncontrolled rectifier is connected to the bidirectional DC-DC circuit to supply power to a post-stage bidirectional DC-DC circuit; the bidirectional DC-DC circuit provides a constant voltage to a single-phase inverter; the single-phase inverter outputs disturbance current.

Further, referring to fig. 2, the bidirectional DC-DC circuit in the parallel injection current impedance measuring apparatus provided in this embodiment adopts a PI controller to implement C₂The voltage on the inverter is constant, and stable direct-current voltage is provided for the single-phase inverter;

further, referring to fig. 3, the single-phase inverter provided in this embodiment includes a fundamental wave controller and a disturbance controller, which are respectively used for achieving a control target that the impedance measuring device and the system to be measured do not have fundamental wave signal interaction and the impedance measuring device outputs a disturbance current in a specific form;

further, referring to the control block diagram of the fundamental wave controller circuit provided in the embodiment of fig. 4, notch1 is centered on the frequency of the disturbance current ω_hThe wave trap filters disturbance frequency components in the voltage and current signals, so as to accurately control fundamental wave signals, and adopts a constant current control strategy oriented by the voltage of a system to be measured under the dq axis, and the dq axis current references are all set to be 0;

further, please refer to the circuit control block diagram of the disturbance controller provided in this embodiment of fig. 5, wherein notch2 is centered at the fundamental frequency ω_gThe wave trap filters the fundamental frequency component in the voltage and current signal, thereby accurately controlling the disturbance signal, wherein the expression of formula (1) is as follows:

when the impedance of the system to be tested is small, the disturbance controller works in a constant current mode, namely, a disturbance current with a constant amplitude is output; when the system to be measured exceeds the critical value, the disturbance voltage feedforward strategy acts, and the amplitude of the disturbance current is adjusted in a self-adaptive mode.

In the broadband impedance measurement process, the steady-state working point of the fundamental wave controller is unchanged, the steady-state working point of the disturbance controller changes along with the frequency of disturbance current, and in order to prevent the overmodulation phenomenon of the impedance measurement device caused by the saturation of the integrator in the measurement process, the anti-saturation strategy is added to the disturbanceIn the controller, the saturation limit u is set for better_msThe disturbance controller adopts a control strategy based on disturbance voltage orientation and adopts an anti-saturation coefficient K_AWThe feedforward disturbance voltage amplitude can adaptively adjust the disturbance current amplitude.

In a second aspect, the present application provides an adaptive current source impedance measuring method, including:

step 1: determining a direct-current side voltage reference value of a bidirectional DC-DC circuit according to the voltage grade of a system to be tested

Step 2: before impedance measurement, constant voltage control is carried out on the bidirectional DC-DC circuit;

and step 3: when receiving an impedance measurement signal, a switching signal is sent to the single-phase inverter circuit, the inverter controller is started, the inverter circuit is controlled, and the output frequency is f₁The disturbance current is subjected to self-adaptive adjustment, voltage and current data of a measuring point are collected at the same time, and f is calculated by the formula (2)₁The impedance of (a):

and 4, step 4: after the time delta t, changing the frequency of the disturbance current into f₁+ delta f, collecting voltage and current data of the measuring point;

and 5: and (4) repeating the step (4) until the disturbance current frequency covers the full measurement frequency band.

The technical scheme of the application can realize the stable operation of the impedance measuring device in the full frequency band, and the resonance point of the system to be measured does not need to be avoided.

In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. The meaning of "plurality" is two or more unless specifically limited otherwise.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.