Electric energy quality detection system

Abstract

The utility model discloses an electric energy quality detection system which comprises a voltage mutual inductance module, a current mutual inductance module, an operational amplification module, a data sampling module, an MCU processing chip, a storage unit EEPROM and a power management module. The voltage mutual inductance module and the current mutual inductance module are connected with the operational amplification module; the operational amplification module is connected with the data sampling module; the data sampling module and the MCU processing chip are in communication connection by using an FSMC protocol; and the power management module provides required power for the data sampling module, the operational amplification module and the MCU processing chip. According to the utility model, a plurality of voltage mutual inductance modules, current mutual inductance modules and operational amplification modules are arranged at the front end of the system, so that the problem that the error of a detection result suddenly rises due to obvious waveform distortion when the conventional detection device detects small voltage and small current is solved.

Description

Technical Field

[0001] The utility model relates to the field of power quality analysis, and in particular to a power quality detection system. Background Art

[0002] Power quality monitoring systems are widely used in industrial, commercial, public facilities, and critical infrastructure sectors to ensure safe and stable grid operation. Leveraging advanced electronic technology and signal processing algorithms, these systems provide real-time monitoring and analysis of various power quality indicators, including voltage, current, frequency, harmonics, and flicker.

[0003] During power transmission and distribution, various nonlinear loads, power supply fluctuations, and grid faults can all lead to degraded power quality, including voltage fluctuations, harmonic pollution, and three-phase imbalance. These issues not only affect the normal operation of power equipment but can also cause grid accidents and economic losses.

[0004] For example, the patent (CN206096293U) discloses an electric energy detection and metering system, which includes a mutual inductance module, a front-end voltage and current acquisition module, a power quality analysis module, an MCU processor, and a power management module; the mutual inductance module and the front-end voltage and current acquisition module are communicated with the power quality analysis module in turn; the power quality analysis module and the MCU processor are communicated with each other; the power management module is electrically connected to the power quality analysis module and the MCU processor; it includes multiple mutual inductance modules and front-end voltage and current acquisition modules, and the mutual inductance modules and the front-end voltage and current acquisition modules are arranged in a one-to-one correspondence, which simplifies the measurement system, reduces costs, and reduces the labor intensity of metering personnel.

[0005] While using the above technology, we discovered the following technical problem: existing detection devices exhibit significant waveform distortion when measuring low voltages (mV level) and currents (mA level), leading to significant errors in the detection results. To address this issue, we designed a new power quality detection system to provide an alternative solution. Utility Model Content

[0006] The purpose of the utility model is to provide a power quality detection system, which solves the problem that the existing detection device will obviously cause waveform distortion when detecting small voltage and small current, thereby causing a sudden increase in detection result errors.

[0007] To achieve the above-mentioned object, the utility model provides the following technical solution: a power quality detection system, comprising a voltage mutual induction module, a current mutual induction module, an operational amplifier module, a data sampling module, an MCU processing chip, and a power management module; the voltage mutual induction module and the current mutual induction module are connected to the operational amplifier module; the operational amplifier module is connected to the data sampling module; and the data sampling module is connected to the MCU processing chip via an FSMC;

[0008] The power management module is connected to the data sampling module, the operational amplifier module, the LCD serial port screen, and the MCU processing chip.

[0009] Furthermore, there are three voltage mutual induction modules and three current mutual induction modules. The voltage mutual induction module is a voltage transformer, and the model of the voltage transformer is Zeming Langxi ZMPT107-1. The current mutual induction module is a current transformer, and the model of the current transformer is Zeming Langxi ZEMCT1101.

[0010] Furthermore, the MCU processing chip uses the IIC protocol to connect to the storage unit EEPROM.

[0011] Furthermore, the MCU processing chip is also connected to a USB interface and a Bluetooth module.

[0012] Furthermore, the data sampling module uses chip AD7606, and chip AD7606 communicates with the MCU processing chip using FSMC protocol.

[0013] Furthermore, the MCU processing chip adopts STM32F407VET6 single chip microcomputer.

[0014] Furthermore, the operational amplifier module uses four dual-channel integrated operational amplifiers OP07.

[0015] Furthermore, the detection data is updated and displayed in real time via the LCD serial port screen.

[0016] One or more embodiments provided in this utility model have at least the following technical effects:

[0017] 1. The AD7606 power quality module is controlled by an MCU to acquire real-time power quality data. The ARM DSP soft core then performs FFT analysis to obtain information such as three-phase amplitude, phase, frequency, harmonics, three-term imbalance, and voltage sag. Real-time sampled data and analysis results are displayed via a graphical user interface (GUI) and stored in EEPROM, allowing the operator to record fault waveforms and power quality parameters. A preconditioning circuit combining a transformer and an operational amplifier amplifies small signals to a reasonable range before sampling the AD7606, avoiding waveform distortion caused by excessively small signals.

[0018] 2. This power quality detection system has small signal detection capabilities and an ARM architecture, enabling human-computer interaction. KEIL software is used to program and process received data. This system optimizes traditional measurement systems, expands the detection range, and improves detection accuracy.

[0019] 3. The voltage transformer adopts a transformation ratio of 1000:1000, can accommodate a linear voltage range of 0-1000V, has a rated output current of 2mA, and a maximum output phase difference of 45'. It has the characteristics of small size, high precision, and good consistency. The current transformer adopts a transformation ratio of 2000:1, can accommodate a linear current of 0-20A, has a rated output current of 2.5mA, and a maximum output phase difference of 20'. It also has the above characteristics.

[0020] 4. At the system's initial stage, the voltage and current sampling circuit completes initial data acquisition. The circuit then converts the 100V / 5A power-frequency signal from the transformer into an AC signal suitable for on-chip A / D acquisition by the AD7606. The AD7606 is an advanced high-speed sampling chip with eight 16-bit A / D converters. When used with the STM32F407VET6 microcontroller, it enables high-precision current and voltage acquisition, A / D conversion, digital signal processing, and parameter calculation. This includes measurements of active power, reactive power, apparent power, power factor, and other parameters, meeting national standards. The AD7606's low power consumption and strong anti-interference capabilities make it a reliable, low-power product suitable for power quality monitoring systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of a utility model power quality detection system;

[0022] Figure 2 This is a schematic diagram of a voltage acquisition circuit of the utility model;

[0023] Figure 3 This is a schematic diagram of a current collection circuit of the utility model;

[0024] Figure 4 This is a schematic diagram of the power supply of the utility model;

[0025] Figure 5 This is a schematic diagram of an operational amplifier circuit of the utility model.

[0026] In the figure: 1. Voltage transformer; 2. Current transformer; 3. Operational amplifier module; 4. MCU processing chip; 5. EEPROM cache; 6. USB interface; 7. Bluetooth module; 8. LCD serial port screen; 9. Power management module; 10. Data sampling module. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0029] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0030] In the description of the present invention, it should be noted that the terms "upper" and "lower" etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the present invention is usually placed when in use. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0031] It should also be noted that, in the description of this utility model, unless otherwise expressly specified or limited, the terms "disposed" and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0032] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0033] Please refer to Figure 1, which presents a schematic diagram of the structure of a utility model electric energy detection system provided by an embodiment of the present application. The system includes: a three-way voltage mutual inductance module 1 and a three-way current mutual inductance module 2, an operational amplifier module 3, a data sampling module 10, an MCU processing chip 4, an MCU peripheral module group, and a power management module 9. The mutual inductance module includes a three-way voltage mutual inductance module 1 and a three-way current mutual inductance module 2, both of which are connected to the operational amplifier module 3; the operational amplifier module 3 is connected to the data sampling module 10; the data sampling module 10 is also connected to the MCU processing chip 4 in communication; in addition to being connected to the data sampling module 10, the MCU processing chip 4 is also connected to the EEPROM cache 5, the USB interface 6, the Bluetooth module 7, and the LCD serial port screen 8. The power management module 9 is connected to the MCU processing chip 4, the operational amplifier module 3, the LCD serial port screen 8, and the data sampling module 10; the data sampling module 10 is a detection chip AD7606, and the MCU processing chip 4 is an STM32F407VET6 microcontroller.

[0034] Preferably, the operational amplifier module 3 uses four dual-channel integrated operational amplifiers OP07.

[0035] The current and voltage transformers (CVTs) transmit the current and voltage on the power lines through transformers for power isolation and proportional mutual induction. The 220V / 5A power-frequency voltage signal and the small power-frequency induced current signal obtained from the three-phase grid are converted via an operational amplifier into an AC voltage signal suitable for on-chip A / D acquisition by the AD7606. The AD7606 integrates eight 16-bit A / D converters, which primarily perform voltage and current acquisition, A / D conversion, and digital signal processing to calculate the required power quality parameters.

[0036] The three-phase data sampling module of data sampling module 10 uses the AD7606, with a maximum sampling rate of 200K, enabling high-precision acquisition and A / D conversion of current and voltage. The MCU processing chip 4 is the core of the entire system, primarily responsible for communicating with the AD7606. It controls the AD7606's operating mode, reads data from each channel, and calculates various parameters, including active power, reactive power, apparent power, and power factor. MCU processing chip 4 also analyzes electrical energy parameters and performs digital signal processing to obtain energy indicators such as three-phase imbalance. Furthermore, MCU processing chip 4 drives LCD serial port 8, stores indicator parameters in EEPROM 5, and provides USB and Bluetooth communication functions. The power management module provides power to power-consuming modules throughout the system, developing a specific power topology network based on each module's power requirements to provide the required power for each module. The LCD serial port 8 is used for human-computer interaction. The interface provides a real-time monitoring window for various indicators, allowing users to easily monitor the operating status of the three-phase power grid. Users can also manipulate the human-computer interaction interface to change the MCU's operating state by returning values, thereby controlling the entire system. The EEPROM buffer stores three-phase power grid waveforms. The USB port 6 and Bluetooth module 7 are used for communication with the host computer, enabling real-time data upload.

[0037] The current and voltage acquisition circuits primarily step down the 220V / 5A power frequency signal output from the power transformer's secondary side. The operational amplifier converts the reduced voltage signal into an AC signal suitable for acquisition by the AD7606. This process, combined with the voltage acquisition circuit, current acquisition circuit, and operational amplifier circuit, ensures that the AD7606's voltage channel maintains a linearity error of less than 0.5% within the 10mV to 1V range, while the current channel maintains a linearity error of less than 0.5% within the 2mV to 1V range. To ensure measurement accuracy and interference immunity, the AD7606's voltage input rating is 5V, and a pseudo-differential input is used. Three different sampling methods were considered for voltage signal sampling: the first was resistor division, which divided the input 220V power frequency signal and transmitted it to the detection chip's AD interface. The second method involved direct voltage transformation using a voltage transformer, ensuring signal isolation and accuracy. This approach employed a 220V / 0.4V enclosed voltage transformer module, followed by an operational amplifier to condition the signal to ±5V. This design was simple and precise. The third method involved first converting the voltage signal into a current signal, which was then restored to a voltage signal using current transformer 2 and a sampling resistor. After comprehensively considering the advantages and disadvantages of the three methods, option two was ultimately chosen: direct voltage transformation using a voltage transformer, followed by conversion to within ±5V using an operational amplifier, ensuring system stability and accuracy. To prevent spurious spectrum interference from the sampling circuit, an RC low-pass filter was designed before the signal input, effectively blocking high-frequency interference signals from entering the system.

[0038] According to the above analysis, the voltage acquisition circuit diagram is designed as follows: Figure 2 shown.

[0039] Similarly, the current signal passes through the current sampling circuit and current transformer 2, and becomes a voltage signal with an amplitude of 0.1V. After being amplified by operation, it is finally sent to the current A / D conversion port. The current acquisition circuit diagram is shown in the figure. Figure 3 shown.

[0040] Power quality monitoring typically relies on highly integrated modular power quality ICs. Commercially available power quality modules offer a comprehensive feature set, encompassing voltage and current acquisition, A / D conversion, digital signal processing, and calculation of various key power parameters. However, in real-world applications, data sampling modules often operate in complex and changing environments, often needing to capture minute signals. This places even more stringent demands on the power detection chips they employ. This not only requires high chip accuracy to determine the module's performance, but also requires robust interference immunity to ensure excellent stability in various power environments. Because the power supply for power quality analysis systems must be immune to interference from the power grid, a low-power power detection chip is a key consideration in system design. Based on the above analysis, the AD7606 was selected as the power quality module. It enables high-precision current and voltage acquisition, A / D conversion, digital signal processing, and parameter calculation, including active power, reactive power, apparent power, and power factor. It also enables precise measurement of key parameters such as phase current and voltage RMS, phase angle, and frequency. The AD7606, with its low power consumption and strong anti-interference performance, efficiently meets the various performance requirements of this solution.

[0041] In the data sampling module, power quality measurement values ​​are stored in the MCU's internal registers. However, internal data loss during an MCU reset or power failure requires a memory device with power-off retention to ensure that the energy measurement values ​​are constantly updated and saved. This design uses the 25LC1024, a serial EEPROM chip from the 25LC series with a 1Mbit (128KB) storage capacity. It is widely used in embedded systems, sensor nodes, and memory expansion. The 25LC1024 utilizes a serial communication interface and supports the SPI protocol, making data reading and writing more flexible and efficient. The SPI communication protocol offers high-speed transmission, a simple hardware interface, and a flexible master-slave architecture, making the 25LC1024 easily integrated into various embedded systems. Its 1Mbit storage capacity makes it suitable for scenarios requiring large-capacity data storage. Furthermore, its fast write and erase speeds and low power consumption facilitate efficient data management in resource-constrained systems. The 25LC1024 also offers reliability and durability, supporting approximately one million erase / write cycles, making it an excellent choice for applications requiring frequent data updates. It also features excellent radiation resistance and high-temperature stability, making it suitable for use in a variety of harsh environments.

[0042] To ensure stable operation, the design of a power quality monitoring system requires a sound power management solution that not only ensures the proper operation of the AD7606 monitoring module but also provides power for the MCU main control unit 4 and the LCD serial port display 8. Traditional power quality monitoring equipment typically uses two power supply methods: one is to connect to an external 220V industrial frequency power supply, which is converted into DC power for system operation through voltage transformation, rectification, and filtering. While this design ensures stable power supply and high measurement accuracy, it is bulky and requires an external power input point at the operating point, limiting the device's range of use.

[0043] Another approach is to use a 12V battery as power supply. A step-down module converts the 12V voltage into a suitable voltage for the operational amplifier module 3, data sampling module 10, LCD serial port display 8, and MCU main control unit 4. This design offers the advantage of increased portability and facilitates use in environments without a power source. However, its drawbacks are obvious: the battery requires regular replacement, and a drop in battery voltage can cause deviations in measurement results. To address this issue, the module's power supply cleverly draws power from the secondary output of the power transformer. This design not only expands the data sampling module's applicability but also minimizes the impact on the power transformer, reduces interference in the power supply design, and contributes to improved system stability. By selecting the 25LC1024 memory chip, which features power-loss retention, and utilizing a power supply derived from the power transformer, the data sampling module achieves efficient management and assurance of energy detection parameters.

[0044] The reliability and performance of an energy detection system hinges on precise power supply to the power voltage transformer. This power supply not only requires the voltage to remain within a ±5% fluctuation range to ensure measurement accuracy, but also requires minimal power consumption to minimize the detection module's reaction to the power voltage transformer.

[0045] There are two main challenges in choosing a power supply solution: choosing between a transformer and a switching power supply module. While the transformer solution offers the advantages of simplicity, ease of implementation, and relatively low cost, it is bulky, inefficient, and significantly affected by secondary voltage fluctuations in the power voltage transformer, potentially leading to unstable output voltage. This may not be the best choice for applications requiring high power supply stability. Switching power supply modules, in particular, offer superior adaptability and performance due to their compact size, high conversion efficiency (over 90%), and wide input voltage range. This offers significant advantages for ensuring stable system operation and reducing energy loss.

[0046] At the core of the system, the selection of the MCU processing chip 4 is particularly critical. As the information transfer station and command control center, the MCU's performance is directly related to the overall system efficiency. The STM32F407VET6 microcontroller was selected. It features high performance, low power consumption, a rich interface, and powerful communication capabilities. Its built-in peripherals, such as USB, UART, SPI, and FSMC, enable it to perform tasks such as programming calculations, command transmission, and FSMC communication.

[0047] The communication module, serving as the data transmission medium between the computer and the measurement module, also requires a satisfactory design. Two options are proposed: a UART interface and a USB interface. Both interfaces are native to the STM32F407VET6, ensuring ease of use while fully considering the required data volume and speed. This design can better adapt to the requirements of different application scenarios and enhance system flexibility.

[0048] The above is only an implementation scheme of the present invention. It should be pointed out that relevant changes can be made without departing from the design concept of the utility model, which also falls within the scope of protection of the present utility model.

Claims

1. A power quality detection system, characterized in that: It includes a voltage mutual induction module (1), a current mutual induction module (2), an operational amplifier module (3), an MCU processing chip (4), a storage unit EEPROM (5), a USB interface (6), a Bluetooth module (7), a power management module (9), and a data sampling module (10); The voltage mutual induction module (1) and the current mutual induction module (2) are connected to the operational amplifier module (3), and the operational amplifier module (3) is connected to the data sampling module (10); the data sampling module (10) is connected to the MCU processing chip (4) via the FSMC protocol; The power management module (9) is connected to the data sampling module (10), the LCD serial port screen (8), the MCU processing chip (4), and the operational amplifier module (3).

2. The power quality detection system according to claim 1, characterized in that: There are three voltage mutual induction modules and three current mutual induction modules. The voltage mutual induction modules are voltage mutual induction modules, and the current mutual induction modules are current mutual induction modules.

3. The power quality detection system according to claim 1, characterized in that: The MCU processing chip (4) is connected to the storage unit EEPROM using the IIC protocol.

4. The power quality detection system according to claim 1, characterized in that: The MCU processing chip (4) is also connected to a USB interface (6) and a Bluetooth module (7).

5. The power quality detection system according to claim 1, characterized in that: The data sampling module (10) uses a chip AD7606, and the chip AD7606 and the MCU processing chip (4) use the FSMC communication protocol.

6. The power quality detection system according to claim 1, characterized in that: The MCU processing chip (4) adopts an STM32F407VET6 single chip microcomputer.

7. The power quality detection system according to claim 1, characterized in that: The operational amplifier module (3) uses four dual-channel integrated operational amplifiers OP07.

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