HYXQT Intelligent Microcomputer Harmonic Elimination Device

1. Device overview

The HYXQT microcomputer resonance elimination device is an intelligent resonance elimination device developed by our company for the vicious accidents of voltage transformer (PT) burnout or even explosion that often occur due to ferromagnetic resonance in the power sector and users. The device uses the ARM processor as the core processing element of the device, and the device has the advantages of stable performance and strong anti-interference ability. It can not only eliminate ferromagnetic resonance, but also give an alarm indication for overvoltage and single-phase grounding.

   2. Model meaning

3. Technical indicators

(1) Working power supply: AC/DC80~250V, power consumption is less than 15W;

(2) Ambient temperature: -45℃~+50℃;

(3) Environmental humidity: not more than 90%RH;

(4) Resonant frequency can be eliminated: 17Hz (1/3 frequency division), 25Hz (1/2 frequency division), 50Hz power frequency, 150HzZ (3 times frequency), 300Hz (6 times frequency).

  4. Device features

(1) Suitable for various voltage levels, various resonance frequencies (1/3 frequency division, 1/2 frequency division, power frequency, 3 times frequency, 6 times) frequency range of application;

(2) There is no need for tuning and debugging, and it will automatically enter the running state after starting up, with little maintenance;

(3) It can distinguish between ferromagnetic resonance, overvoltage, and single-phase grounding;

(4) Automatic display, record the occurrence time of single-phase grounding, ferromagnetic resonance and related parameters (resonance frequency, amplitude);

(5) 100 fault information can be stored for recall and display, and the data will not be lost after 100 years of power failure;

(6) RS485 communication interface can be configured, standard MODBUS protocol;

(7) All alarm signals are provided with relay contact output.

  5. Device hardware configuration

1. Power supply part: This device adopts high-frequency switching power supply, which has the characteristics of strong anti-interference ability and large allowable input voltage fluctuation range. The output voltage is DC+5V, ±12V;

2. The control center of the device adopts the latest ARM processor, which has the characteristics of strong control ability and safe and reliable operation. And there is a monitoring timer inside, which can relieve the crash caused by software failure at any time, which provides a guarantee for long-term safe and reliable operation;

3. The data memory adopts the latest F1ash memory chip, which has the advantages of large storage capacity and no data loss when power off;

4. Data acquisition part: its function is to convert analog quantity into digital quantity for computer processing;

5. Display part: used as a clock under normal conditions of the system, when the system fails, it can display related failure information;

6. Resonance elimination control: Control the resonance elimination circuit and start high-power resonance elimination components to quickly eliminate ferromagnetic resonances of various frequencies.

  6. How the device works

This device uses the ARM processor as the core component to cyclically detect the PT open delta voltage (ie zero sequence voltage). Under normal working conditions, the voltage is less than 30V, and the high-power harmonic elimination component SCR in the device is in a blocking state, which has no effect on the system. When the PT open delta voltage is greater than 30V, it indicates that the system is malfunctioning. The device starts to collect data on the open delta voltage. Through digital measurement, filtering, amplification and other digital signal processing technologies, the data is analyzed and calculated to determine the current fault state. If a certain frequency of ferromagnetic resonance occurs, the CPU immediately starts the resonance elimination circuit (to turn on the thyristor) so that the ferromagnetic resonance disappears quickly under strong damping. After the ferromagnetic resonance is eliminated, the CPU will make corresponding records and storage, and automatically alarm and display relevant resonance information (including occurrence time, frequency, amplitude, etc.). If it is over-voltage or single-phase grounding, after the CPU makes a diagnosis, the device will respectively display and alarm, and automatically record and store related fault information. Finally, the CPU returns to the initial state and continues to detect the open triangle voltage.

   7. Device software composition

This device adopts C language as the programming software, and the software is mainly composed of monitoring program, floating point operation library, diagnosis software, harmonic elimination, recording and other parts. The real-time monitoring program completes tasks such as voltage detection, sampling, diagnosis, elimination of resonance, clock, keyboard commands, and display. The simple block diagram is shown in Figure 1:

8. Device installation

This device is installed on the PK screen or in the terminal box, and each device can be connected to 1~4 sections of bus. The schematic diagram of the terminal wiring behind the device is shown in Figure 2:

(1) "1PT*" and "1PT" are respectively connected to the same-named and non-same-named ends of the open delta voltage of the first section of the bus, "2PT*" and "2PT". Respectively connect the same-named and non-same-named ends of the open triangle voltage of the second section of the bus, and so on;

(2) The "RS48 5" terminal is a communication terminal, which can be directly connected to the RS485 communication bus;

(3) The "power" terminal can be connected to AC power or DC power regardless of polarity. The voltage range is 80~250V;

(4) The "grounding alarm" terminal is connected to an external alarm signal, and this terminal is a normally open contact when there is no fault. Closed when the fault occurs, the delay is about 1 minute after the fault disappears, and the contact capacity is AC220V/5A;

(5) The "resonance alarm" terminal is connected to an external alarm signal, and this terminal is a normally open contact when there is no fault. Closed when a fault occurs, its contact capacity is AC 220V/5A.

9. Instructions for use

10. Device installation method