DC FLC variable frequency dead zone control method and system based on Prony online analysis

Abstract

The present invention discloses a direct current FLC variable frequency dead zone control method and system based on Prony online analysis, and relates to the technical field of power grid frequency control. The present invention collects the frequency of an alternating current power grid in real time, and performs Prony analysis on the frequency of the alternating current power grid; and judges in real time whether there is ultra-low frequency frequency fluctuation in the power grid according to the result of Prony analysis, wherein the ultra-low frequency refers to a frequency less than 0.05 Hz, wherein, if the alternating current power grid is continuously monitored to have a frequency fluctuation with a fluctuation period greater than a set time within a T time, it is judged that there is ultra-low frequency frequency fluctuation in the power grid, otherwise, it is judged that there is no ultra-low frequency frequency fluctuation in the alternating current power grid; if there is no ultra-low frequency frequency fluctuation in the alternating current power grid, the dead zone of the FLC controller of the high voltage direct current is selected as the dead zone frequency f 1 ; If there is ultra-low frequency fluctuation in the AC power grid, the dead zone of the FLC controller of the high-voltage DC is selected as the new dead zone frequency f 2 The present invention is used to suppress the ultra-low frequency fluctuation problem of the power grid frequency.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid frequency control, and in particular to a direct current FLC variable frequency dead zone control method and system based on Prony online analysis. Background Art

[0002] With the continuous advancement of the "West-to-East Power Transmission" strategy and the development of power grids in the future, high-voltage direct current transmission projects are becoming more and more widely used. DC frequency limit control (FLC) is a power debugging control function of the high-voltage direct current transmission system. It is an important means of stable control of power grid frequency and plays an important role in the stability of power grid frequency. In the case of large disturbances such as unit tripping and DC blocking in the power grid, DC FLC control has the advantages of wide adjustment range and fast adjustment speed. It can quickly suppress the increase and decrease of power grid frequency and ensure the stable operation of power grid frequency by coordinating the unit's primary frequency regulation, stabilization control and high-frequency cutting measures.

[0003] However, with the vigorous development of hydropower clean energy, the proportion of hydropower installed capacity has increased significantly, and the frequency ultra-low frequency fluctuation caused by hydropower units has become prominent. At present, the FLC dead zone of high-voltage direct current is generally set to be greater than 0.1Hz (fixed dead zone), which cannot respond to the frequency fluctuation of the ultra-low frequency of the power grid with a frequency less than 0.05Hz. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a DC FLC variable frequency dead zone control method and system based on Prony online analysis, which are used to suppress the problem of ultra-low frequency fluctuation of power grid frequency.

[0005] To achieve the above object, the present invention can be carried out by adopting the following technical solutions:

[0006] A DC FLC variable frequency dead zone control method based on Prony online analysis, comprising:

[0007] Collect the frequency of the AC power grid in real time and perform Prony analysis on the frequency of the AC power grid;

[0008] According to the results of Prony analysis, it is judged in real time whether there is ultra-low frequency fluctuation in the power grid, where ultra-low frequency refers to a frequency less than 0.05 Hz. If the AC power grid is continuously monitored to have a frequency fluctuation with a fluctuation period greater than the set time within T time, it is judged that there is ultra-low frequency fluctuation in the power grid; otherwise, it is judged that there is no ultra-low frequency fluctuation in the AC power grid;

[0009] If there is no ultra-low frequency fluctuation in the AC power grid, the dead zone of the FLC controller of the high voltage DC is selected as the dead zone frequency f1;

[0010] If there is ultra-low frequency fluctuation in the AC power grid, the dead zone of the high voltage DC FLC controller is selected as the new dead zone frequency f2. In the DC FLC variable frequency dead zone control method based on Prony online analysis as described above, further, the fluctuation period is not less than 20 seconds.

[0011] As described above, the DC FLC variable frequency dead zone control method based on Prony online analysis, further, the T time is not less than 40 seconds.

[0012] As described above, the DC FLC variable frequency dead zone control method based on Prony online analysis, further, in the conventional high voltage DC FLC dead zone, the dead zone frequency f1 is set to ±0.14 Hz, and in the UHV DC FLC dead zone, the dead zone frequency f1 is set to ±0.15 Hz.

[0013] As described above, in the DC FLC variable frequency dead-zone control method based on Prony online analysis, further, the dead-zone frequency f2 is set to a value less than 0.05 Hz.

[0014] A DC FLC variable frequency dead zone control system based on Prony online analysis, comprising:

[0015] A frequency acquisition module, which is used to acquire the frequency of the AC power grid in real time;

[0016] A Prony analysis module is used to perform Prony analysis on the frequency of the AC power grid, and determine in real time whether the power grid has ultra-low frequency fluctuations according to the results of the Prony analysis, wherein the ultra-low frequency refers to a frequency less than 0.05 Hz, wherein if the AC power grid is continuously monitored to have frequency fluctuations with a fluctuation period greater than a set time within a T time, it is determined that the power grid has ultra-low frequency fluctuations, otherwise, it is determined that the AC power grid does not have ultra-low frequency fluctuations; and,

[0017] The frequency selection module is used to select the dead zone frequency f1 of the FLC controller of the high voltage direct current if there is no ultra-low frequency fluctuation in the AC power grid; if there is ultra-low frequency fluctuation in the AC power grid, the dead zone frequency f2 of the FLC controller of the high voltage direct current is selected.

[0018] As described above, in the DC FLC variable frequency dead zone control system based on Prony online analysis, further, the fluctuation period is not less than 20 seconds.

[0019] As described above, in the DC FLC variable frequency dead zone control system based on Prony online analysis, further, the T time is not less than 40 seconds.

[0020] As described above, the DC FLC variable frequency dead zone control system based on Prony online analysis, further, in the conventional high voltage DC FLC dead zone, the dead zone frequency f1 is set to ±0.14 Hz, and in the UHV DC FLC dead zone, the dead zone frequency f1 is set to ±0.15 Hz.

[0021] As described above, in the DC FLC variable frequency dead-band control system based on Prony online analysis, further, the dead-band frequency f2 is set to a value less than 0.05 Hz.

[0022] Compared with the prior art, the present invention has the beneficial effect that: the present invention can solve the problem that the FLC dead zone of the current high voltage direct current is a fixed dead zone, and the fixed dead zone frequency setting is generally set to be greater than 0.1 Hz, thereby achieving the problem of suppressing the ultra-low frequency fluctuation of the power grid frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 The figure is a flow chart of a DC FLC variable frequency dead zone control method based on Prony online analysis according to an embodiment of the present invention.

[0025] Figure 2 It is a structural schematic diagram of a system for direct current FLC variable frequency dead zone control based on Prony online analysis according to an embodiment of the present invention;

[0026] Figure 3 The figure is a structural diagram of an example of a practical application in engineering of an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0028] Example:

[0029] It should be noted that the terms "including" and "having" and any variations of the embodiments of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0030] See also Figure 1 The present invention proposes a DC FLC variable frequency dead zone control method based on Prony online analysis, which is used to suppress the ultra-low frequency fluctuation problem of the power grid frequency. The specific implementation method is as follows:

[0031] (1) Real-time acquisition of AC grid frequency and frequency Prony analysis;

[0032] (2) Based on the Prony analysis results, it is determined in real time whether there is ultra-low frequency fluctuation in the power grid: if the power grid is continuously monitored to have frequency fluctuations with a fluctuation period greater than 20 seconds within the time T, it is determined that there is ultra-low frequency fluctuation in the power grid; otherwise, there is no ultra-low frequency fluctuation in the power grid. T is generally set to be no less than 40 seconds.

[0033] (3) If there is no ultra-low frequency fluctuation in the power grid, the dead zone of the high-voltage DC FLC controller is selected as the dead zone f1

[0034] (In engineering, the conventional high-voltage DC FLC dead zone is generally set to ±0.14Hz, and the UHV DC FLC dead zone is generally set to ±

[0035] 0.15Hz);

[0036] (4) If there is ultra-low frequency fluctuation in the power grid, the dead zone of the high-voltage DC FLC controller is selected as the new dead zone f2

[0037] (The new dead zone can be set to a value less than 0.05 Hz according to system research needs, such as 0.02 Hz), quickly smoothing out ultra-low frequency oscillations of frequency deviation.

[0038] See also Figure 2 At the same time, the present invention also provides a DC FLC variable frequency dead zone control system based on Prony online analysis, which includes: a frequency acquisition module, a Prony analysis module and a frequency selection module, wherein:

[0039] The frequency acquisition module is used to collect the frequency of the AC power grid in real time.

[0040] The Prony analysis module is used to perform the following work: Prony analysis is performed on the frequency of the AC power grid, and the results of the Prony analysis are used to determine in real time whether the power grid has ultra-low frequency fluctuations, where the ultra-low frequency refers to a frequency less than 0.05 Hz. If the AC power grid is continuously monitored to have frequency fluctuations with a fluctuation period greater than the set time within the T time, it is determined that the power grid has ultra-low frequency fluctuations, otherwise, it is determined that the AC power grid does not have ultra-low frequency fluctuations. Specifically, the fluctuation period is not less than 20 seconds. The T time is not less than 40 seconds.

[0041] The frequency selection module is used to perform the following operations: if there is no ultra-low frequency fluctuation in the AC power grid, the dead zone selection of the FLC controller of the high-voltage DC is the dead zone frequency f1; if there is ultra-low frequency fluctuation in the AC power grid, the dead zone selection of the FLC controller of the high-voltage DC is the new dead zone frequency f2. Specifically, in the conventional high-voltage DC FLC dead zone, the dead zone frequency f1 is set to ±0.14Hz, and in the ultra-high voltage DC FLC dead zone, the dead zone frequency f1 is set to ±0.15Hz. The dead zone frequency f2 is set to a value less than 0.05Hz.

[0042] See also Figure 3 The method and system can be applied to variable dead-drive control to suppress the ultra-low frequency fluctuation problem of power grid frequency.

[0043] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0044] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable ordinary technicians in the field to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made based on the essence of the content of the present invention should be included in the protection scope of the present invention.

Claims

1. A DC FLC variable frequency dead zone control method based on Prony online analysis, characterized in that: include: Collect the frequency of the AC power grid in real time and perform Prony analysis on the frequency of the AC power grid; According to the results of Prony analysis, it is judged in real time whether there is ultra-low frequency fluctuation in the power grid, where the ultra-low frequency refers to a frequency less than 0.05 Hz. If the AC power grid is continuously monitored to have a frequency fluctuation with a fluctuation period greater than the set time within the T time, it is judged that the power grid has ultra-low frequency fluctuation, otherwise, it is judged that the AC power grid does not have ultra-low frequency fluctuation; the fluctuation period is not less than 20 seconds, and the T time is not less than 40 seconds; If there is no ultra-low frequency fluctuation in the AC power grid, the dead zone of the HVDC FLC controller is selected as the dead zone frequency f1. In the conventional HVDC FLC dead zone, the dead zone frequency f1 is set to ±0.14 Hz, and in the UHVDC FLC dead zone, the dead zone frequency f1 is set to ±0.15 Hz. If there is ultra-low frequency fluctuation in the AC power grid, the dead zone of the FLC controller of the high voltage DC is selected as the new dead zone frequency f2, and the dead zone frequency f2 is set to a value less than 0.05 Hz.

2. A DC FLC variable frequency dead zone control system based on Prony online analysis, characterized in that: include: A frequency acquisition module, which is used to acquire the frequency of the AC power grid in real time; A Prony analysis module is used to perform Prony analysis on the frequency of the AC power grid, and determine in real time whether the power grid has ultra-low frequency fluctuations according to the results of the Prony analysis, wherein the ultra-low frequency refers to a frequency less than 0.05 Hz, wherein if the AC power grid is continuously monitored to have frequency fluctuations with a fluctuation period greater than a set time within a T time, it is determined that the power grid has ultra-low frequency fluctuations, otherwise, it is determined that the AC power grid does not have ultra-low frequency fluctuations; the fluctuation period is not less than 20 seconds, and the T time is not less than 40 seconds; and, The frequency selection module is used to select the dead zone frequency f1 of the high-voltage direct current FLC controller if there is no ultra-low frequency fluctuation in the alternating current grid, and the dead zone frequency f1 is set to ±0.14 Hz in the conventional high-voltage direct current FLC dead zone, and the dead zone frequency f1 is set to ±0.15 Hz in the ultra-high voltage direct current FLC dead zone; if there is ultra-low frequency fluctuation in the alternating current grid, the dead zone frequency f2 of the high-voltage direct current FLC controller is selected as the new dead zone frequency f2, and the dead zone frequency f2 is set to a value less than 0.05 Hz.

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