Intelligent electrical quantity acquisition device for pumped storage unit

Abstract

The utility model discloses an electric quantity intelligent acquisition device for a pumped storage group, which relates to the technical field of relay protection devices, and comprises an alternating current sampling module electrically connected with the pumped storage group through a terminal strip input connecting wire and used for acquiring a first analog signal at the machine end side of the pumped storage group; the CPU module performs AD conversion on the analog signal, converts the analog signal into a digital signal, and calculates an electrical signal according to the digital signal; the direct current output module converts the electrical signal into a second analog signal of 4-20 mA through a DAC, and outputs the second analog signal through a terminal strip; the power supply module is arranged on the direct current output module and is an alternating current and direct current inverter power supply; the human-computer interface module comprises an LCD unit, and the LCD unit is used for displaying information. According to the utility model, voltage transformer slow melting detection, voltage transformer disconnection detection, voltage transformer switching, median selection and current transformer disconnection detection are carried out through the signal processing unit, so that the safety and reliability of signal processing are ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of relay protection devices, in particular to an intelligent electrical quantity acquisition device for pumped storage units. Background Technique

[0002] At present, traditional analog transmitters and AC sampling meters at home and abroad generally have problems such as complex component configuration, many wiring connections, long signal delay, poor anti-interference ability, and poor transient characteristics. Moreover, due to the poor transient characteristics of traditional transmitters, they cannot well reflect transient current, which easily leads to distortion of unit power sampling. They do not have the function of discriminating the disconnection of voltage transformers and current transformers, nor do they have the function of event recording, which is not conducive to post-event analysis. Currently, the speed governors of pumped storage power stations do not have the "three-value selection" function, and the current excitation regulators do not have the slow fuse criterion for voltage transformers, which is prone to mis-strong excitation problems. The traditional transmitters currently used do not have the functions of discriminating slow fusing of voltage transformers and disconnection of voltage transformers. When the voltage transformer is slowly fused, power transmission distortion is likely to occur, and accurate measurement cannot be achieved under low-frequency conditions. The influence of decaying DC components and harmonic components on measurement cannot be eliminated, resulting in inaccurate electrical quantities such as measured frequency, and cannot meet the requirements of anti-measurement and specifications. Content of the Utility Model

[0003] Based on the above-mentioned disadvantages of the prior art, the purpose of the utility model is to provide an intelligent electrical quantity acquisition device for pumped storage units to solve the technical problems.

[0004] To achieve the above purpose, the utility model provides the following technical solution: An intelligent electrical quantity acquisition device for pumped storage units, including an AC sampling module, a CPU module, a DC output module, a power supply module, and a human-machine interface module. The AC sampling module is electrically connected to the pumped storage unit through terminal block input wiring, and is used to collect the first analog signals on the machine side of the pumped storage unit. Among them, the first analog signals include current and voltage; the CPU module performs AD conversion on the analog signals, converts the analog signals into digital signals, and calculates electrical signals according to the digital signals; the DC output module converts the electrical signals into second analog signals of 4-20 mA through DAC conversion, and outputs the second analog signals through the terminal block; the power supply module is arranged on the DC output module, and the power supply module is an AC-DC inverter power supply; the human-machine interface module includes an LCD unit, and the LCD unit is used to display information.

[0005] The utility model is further set as follows. Calculating the electrical signals according to the digital signals includes: calculating the electrical signals according to the digital signals through a differential filtering algorithm and a full-wave Fourier algorithm, where the electrical signals include current, voltage, frequency, and power.

[0006] The present utility model is further configured such that the CPU module includes a signal processing unit; the signal processing unit is used to perform slow fuse detection of a voltage transformer, open-circuit detection of a voltage transformer, voltage transformer switching, median value selection, and open-circuit detection of a current transformer according to the electrical signal.

[0007] The present utility model is further configured such that two sets of voltage transformers are provided at the machine terminal of the pumped storage unit, and the line voltage and sequence components of the two sets of voltage transformers are obtained to perform the slow fuse detection of the voltage transformer.

[0008] The present utility model is further configured such that the device is also provided with three sets of intelligent transmitters, and the three sets of intelligent transmitters are used to perform median value selection on the electrical signal.

[0009] The present utility model is further configured such that one set of current transformer is also provided at the machine terminal of the pumped storage unit, and abnormal discrimination of electrical signal input is performed by comparing data of the two sets of voltage transformers and one set of current transformer.

[0010] The present utility model is further configured such that the signals output by the terminal block of the DC output module include: 4-way 4 - 20mA output, 1-way alarm signal relay circuit, 1-way RS485 communication circuit, and device power input circuit.

[0011] The present utility model is further configured such that the inputs of the terminal block of the AC sampling module include: voltage input and current input, 7-way AC voltage and 3-way measured current input channels. Among them, the 7-way AC voltage is the three-phase voltage at the machine terminal of two sets of machine-terminal PTs and the zero-sequence voltage of the generator neutral point.

[0012] The present utility model is further configured such that the differential filtering algorithm and the full-wave Fourier algorithm include: differential filtering algorithm, corrected frequency algorithm, full-cycle Fourier algorithm, and variable-frequency starting algorithm.

[0013] In summary, the present utility model mainly has the following beneficial effects:

[0014] 1. The present utility model performs slow fuse detection of a voltage transformer, open-circuit detection of a voltage transformer, voltage transformer switching, median value selection, and open-circuit detection of a current transformer through the signal processing unit in the CPU module, ensuring the safety and reliability of signal processing;

[0015] 2. The present utility model calculates power through differential filtering and Fourier algorithms, eliminating the influence of decaying DC components and harmonic components on power measurement;

[0016] 3. The present utility model simplifies equipment configuration and wiring through three sets of intelligent transmitters, and realizes median value selection of key signals for control.

[0017] The above description is only an overview of the technical solution of this application. In order to understand the technical means of this application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of this application more obvious and understandable, the following specific embodiments of this application are specifically given. Brief Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following will briefly introduce the drawings required for use in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. In the drawings:

[0019] Figure 1 is a structural schematic diagram of the present utility model;

[0020] Figure 2 is a wiring schematic diagram of the present utility model;

[0021] Figure 3 is a schematic diagram of the slow fuse criterion logic diagram of the voltage transformer of the present utility model;

[0022] Figure 4 is a schematic diagram of the open-circuit criterion logic diagram of the current transformer of the present utility model;

[0023] Figure 5 is a schematic diagram of the open-circuit criterion logic diagram of the voltage transformer of the present utility model;

[0024] Figure 6 is a schematic diagram of the voltage transformer switching logic diagram of the present utility model.

[0025] In the figure: 1. AC sampling module; 2. CPU module; 3. DC output module; 4. Power supply module; 5. Human-machine interface module. Detailed Embodiments

[0026] The following will describe the embodiments of the present utility model with reference to the drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in this specification. The present utility model can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present utility model. It should be understood that the preferred embodiments are only for explaining the present utility model, rather than for limiting the protection scope of the present utility model.

[0027] It should be noted that the illustrations provided in the following embodiments only schematically illustrate the basic concept of the present invention. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0028] In the following description, a large number of details are explored to provide a more thorough explanation of the embodiments of the present invention. However, it is obvious to those skilled in the art that the embodiments of the present invention can be implemented without these specific details. In other embodiments, well-known structures and devices are shown in the form of block diagrams rather than in detail to avoid making the embodiments of the present invention difficult to understand.

[0029] The following will describe the embodiments of the present invention according to its overall structure.

[0030] An intelligent electrical quantity acquisition device for a pumped-storage unit, as Figure 1 shown, includes an AC sampling module 1, a CPU module 2, a DC output module 3, a power supply module 4, and a human-machine interface module 5. The AC sampling module 1 is electrically connected to the pumped-storage unit through a terminal block input wiring for collecting a first analog signal on the machine side of the pumped-storage unit. Among them, the first analog signal includes current and voltage. The CPU module 2 performs AD conversion on the analog signal, converts the analog signal into a digital signal, and calculates an electrical signal according to the digital signal. The DC output module 3 converts the electrical signal into a second analog signal of 4 - 20 mA through DAC conversion and outputs the second analog signal through a terminal block. The power supply module 4 is arranged on the DC output module 3, and the power supply module 4 is an AC-DC inverter power supply. The human-machine interface module 5 includes an LCD unit, and the LCD unit is used to display information.

[0031] Please refer to Figure 2, the CPU module is used to perform AD conversion on the first analog signal collected by the AC sampling module, convert the first analog signal into a digital signal, and then use differential filtering and full-wave Fourier algorithm to calculate accurate electrical signals such as current, voltage, frequency, and power. Thus, it can sensitively judge the slow melting of the potential transformer (PT), complete the "three-out-of-three" function through median selection, judge the disconnection of the current transformer (CT) and PT, and PT switching. The AC sampling module is used to collect analog quantities such as current and voltage at the machine terminal side of the pumped-storage unit. The DC output module is used to convert the digital signal output by the CPU module into an analog quantity signal of 4-20mA through DAC conversion. The power supply module is used to input AC 220V, DC 220V / 110V, and DC 24V voltages, and after passing through an anti-interference filtering circuit, use the inverter principle to output two groups of direct currents to supply power to the device. The man-machine interface module (MMI) is used to display data such as system parameters, output settings, communication parameters, time synchronization mode, system time, output definition, event reports, and event records; Further, the AC sampling module obtains the machine terminal electrical quantities by ZMCT101D current transformer and ZMCT101B transformer, converts them into analog quantities and gives them to AD7616 for analog-to-digital signal conversion, and sends them to the GD32F407VGT6 chip. The GD32F407VGT6 chip calculates the power by combining the differential filtering algorithm and the Fourier algorithm to eliminate the influence of the decaying DC component and harmonic component on power measurement; The DC output module converts the digital signal output by the GD32F407VGT6 chip into an analog signal through DAC7552 and then outputs an analog quantity signal of 4-20mA and a pulse signal.

[0032] The power supply module consists of a KDYA-30NR03A switching power supply module and an anti-interference filtering circuit to form an AC-DC inverter power supply. AC 220V, DC 220V / 110V, and DC 24V power supplies are universal. Using the inverter principle, it outputs two groups of direct currents required by this device, namely 5V and 24V. The two groups of voltages are not grounded together and adopt a floating ground method and are not connected to the shell.

[0033] The GD32F407VGT6 chip can correct the frequency measurement under low-frequency working conditions, calculate the data window length based on the known frequency, and implement the recursive Fourier algorithm. To eliminate the cumulative error and the error caused by frequency change, non-recursive full-wave Fourier calculation is used for calibration every once in a while. To achieve accurate measurement under low-frequency working conditions.

[0034] The present utility model is further configured such that the electrical signal calculated according to the digital signal includes: calculating the electrical signal according to the digital signal through a differential filtering algorithm and a full-wave Fourier algorithm, wherein the electrical signal includes current, voltage, frequency, and power.

[0035] The present utility model is further configured such that the CPU module 2 includes a signal processing unit; the signal processing unit is used for performing slow fuse detection of a voltage transformer, open-circuit detection of a voltage transformer, switching of a voltage transformer, median selection, and open-circuit detection of a current transformer according to the electrical signal.

[0036] Please refer to Figure 3 , the present utility model is further configured such that two sets of voltage transformers are provided at the machine terminal of the pumped-storage unit, and the line voltage and sequence components of the two sets of voltage transformers are obtained for the slow fuse detection of the voltage transformer. Specifically, the PT slow fuse judgment function calculates the line voltage and sequence components of the two sets of PTs by the GD32F407VGT6 chip, and sets a specific difference to compare the positive-sequence voltage, negative-sequence voltage, and line voltage (U_PT) of PT1 and PT2. If the difference is greater than the specific difference (U_SET) and the neutral zero-sequence voltage is greater than 5V or the fitting phase voltage vector difference is less than 1V, it is determined as a PT slow fuse fault. And because the negative-sequence voltage is normally detected as zero under normal conditions, misjudgment may occur when the generator fails. Therefore, the present utility model adds a negative-sequence current criterion. When the negative-sequence current is greater than 3% of the secondary rated current, it is determined that the generator has a fault, which can effectively avoid the problem of misjudgment.

[0037] The present utility model is further configured such that the device is further provided with three sets of intelligent transmitters, and the three sets of intelligent transmitters are used for median selection of the electrical signal; specifically, the main function of the intelligent transmitter is to convert the physical quantities collected by the sensor, including current and voltage, into standardized signals, which is convenient for long-distance transmission and processing. Using three sets of intelligent transmitters helps to improve the accuracy and reliability of data acquisition. By independently collecting the same physical quantity three times, the median selection method (i.e., taking the middle value of three) can be used to eliminate the influence of a single sensor fault or noise, so as to obtain more accurate and reliable measurement data.

[0038] The present utility model is further configured such that a set of current transformers is further provided at the machine terminal of the pumped-storage unit, and the input abnormality of the electrical signal is discriminated by comparing the data of the two sets of voltage transformers and the set of current transformers.

[0039] Please refer to Figure 4 , the GD32F407VGT6 chip adopts Figure 4 the CT open-circuit discrimination logic shown, that is, when the self-produced zero-sequence current (3I0) of the three-phase CT is greater than 25% of the maximum phase current (I max), when the sum is with the secondary rated current (I n ) of the 5% three-phase CT, it is judged as CT disconnection.

[0040] Please refer to Figure 5 , the PT disconnection discrimination logic of the GD32F407VGT6 chip is as Figure 5 shown, that is, when the positive-sequence voltage is less than 20V and any phase current at the machine terminal is greater than, or the negative-sequence voltage is greater than 2.5V, it is discriminated as PT disconnection.

[0041] Please refer to Figure 6 , the PT switching logic adopted by the GD32F407VGT6 chip is as Figure 6 shown, that is, by comparing the maximum line voltage of PT2 ( ) with the maximum line voltage of PT1 ( ), and the positive-sequence voltage of PT2 ( ) with the positive-sequence voltage of PT1 ( ), when the difference between the two is greater than 2.5V, it is discriminated that PT1 is abnormal, and the power output is switched from the power calculated by PT1 to the power calculated by PT2.

[0042] The present utility model is further configured such that the output signals of the terminal block of the DC output module 3 include: 4-way 4 - 20mA output, 1-way alarm signal relay circuit, 1-way RS485 communication circuit, and device power input circuit.

[0043] The present utility model is further configured such that the input of the terminal block of the AC sampling module 1 includes: voltage input and current input, 7-way AC voltage and 3-way measured current input channels, wherein the 7-way AC voltage is the three-phase voltages at the machine terminal of two groups of machine-terminal PTs and the zero-sequence voltage of the generator neutral point.

[0044] The present utility model is further configured such that the differential filtering algorithm and the full-wave Fourier algorithm include: differential filtering algorithm, corrected frequency algorithm, full-cycle Fourier algorithm, and variable-frequency start algorithm, which are prior arts and will not be elaborated herein.

[0045] In summary, an intelligent electrical quantity acquisition device for a pumped-storage unit proposed by the present utility model can solve the problems existing in the above-mentioned traditional transmitters, such as complex component configuration, many wirings, long signal delay, poor anti-interference ability, poor transient characteristics; and it does not have the functions of PT and CT disconnection discrimination and event recording function, which is not conducive to post-event analysis; and the current speed governors of pumped-storage power stations do not have the "three-out-of-five" function, cannot sensitively detect the slow fuse fault of the machine-terminal PT, and cannot meet the requirements of anti-measures / norms.

[0046] Although embodiments of the present utility model have been shown and described, the specific embodiments are merely explanations of the present utility model and not limitations thereof. The specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. After reading this specification, those skilled in the art can make modifications, substitutions, and variations that do not make creative contributions to the embodiments as needed, but as long as they are within the scope of the claims of the present utility model, they are protected by the patent law.

Claims

1. An intelligent electrical quantity acquisition device for a pumped-storage unit, comprising an AC sampling module (1), a CPU module (2), a DC output module (3), a power supply module (4) and a human-machine interface module (5), characterized in that, The AC sampling module (1) is electrically connected to the pumped-storage unit through the input wiring of the terminal block, and is used to collect the first analog signals on the machine side of the pumped-storage unit. Among them, the first analog signals include current and voltage; the CPU module (2) performs AD conversion on the analog signals, converts the analog signals into digital signals, and calculates electrical signals according to the digital signals; the DC output module (3) converts the electrical signals into second analog signals of 4-20 mA through DAC and outputs the second analog signals through the terminal block; the power supply module (4) is arranged on the DC output module (3), and the power supply module (4) is an AC-DC inverter power supply; the human-machine interface module (5) includes an LCD unit, and the LCD unit is used to display information; calculating the electrical signals according to the digital signals includes: calculating the electrical signals according to the digital signals through a differential filtering algorithm and a full-wave Fourier algorithm, where the electrical signals include current, voltage, frequency and power; the CPU module (2) includes a signal processing unit; the signal processing unit is used to perform slow fuse detection of the voltage transformer, open-circuit detection of the voltage transformer, voltage transformer switching, median selection and open-circuit detection of the current transformer according to the electrical signals; two groups of voltage transformers are arranged at the machine side of the pumped-storage unit, and the line voltages and sequence components of the two groups of voltage transformers are obtained for the slow fuse detection of the voltage transformer; three groups of intelligent transmitters are also arranged in the device, and the three groups of intelligent transmitters are used to perform median selection on the electrical signals; one group of current transformers is also arranged at the machine side of the pumped-storage unit, and abnormal discrimination of electrical signal input is performed by comparing the data of the two groups of voltage transformers and one group of current transformers.

2. The intelligent electrical quantity acquisition device for a pumped storage unit according to claim 1, wherein The signals output by the terminal block of the DC output module (3) include: 4-way 4-20 mA output, 1-way alarm signal relay circuit, 1-way RS485 communication circuit, and device power input circuit.

3. The intelligent electrical quantity acquisition device for a pumped storage unit according to claim 1, characterized in that The terminal block input of the AC sampling module (1) includes: voltage input and current input, 7-way AC voltage and 3-way measured current input channels, where the 7-way AC voltage is the three-phase voltage at the machine side of two groups of machine-side PTs and the zero-sequence voltage of the generator neutral point.

4. The intelligent electrical quantity acquisition device for a pumped storage unit according to claim 1, characterized in that The differential filtering algorithm and the full-wave Fourier algorithm include: differential filtering algorithm, corrected frequency algorithm, full-cycle Fourier algorithm and variable-frequency start algorithm.

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