HYXQT microcomputer harmonic elimination device is an intelligent harmonic elimination device developed by our company in response to the serious accidents in which voltage transformers (PT) burn out or even explode due to ferromagnetic resonance that often occur in power departments and users. This device uses an ARM processor as the core processing element of the device. The device has the advantages of stable performance and strong anti-interference ability. Not only can it eliminate ferromagnetic resonance, but it can also provide alarm instructions for overvoltage and single-phase grounding.
(1) Working power supply: AC/DC80~250V, power consumption less than 15W;
(2) Ambient temperature: -45℃~+50℃;
(3) Environmental humidity: no more than 90%RH;
(4) Can eliminate resonant frequencies: 17Hz (1/3 frequency division), 25Hz (1/2 frequency division), 50Hz power frequency, 150HzZ (3 times frequency), 300Hz (6 times frequency).
(1) Applicable to various voltage levels, various resonant frequencies (1/3 frequency division, 1/2 frequency division, power frequency, 3 times frequency, 6 times) frequency and wide application range;
(2) No setting and debugging is required, it automatically enters the running state after starting up, and the amount of maintenance is small;
(3) Ferromagnetic resonance, overvoltage, and single-phase grounding can be distinguished;
(4) Automatically display and record single-phase grounding, ferromagnetic resonance occurrence time and related parameters (resonant frequency, amplitude);
(5) 100 fault information can be stored for recall and display, and data will not be lost for 100 years after power failure;
(6) Configurable RS485 communication interface, standard MODBUS protocol;
(7) All alarm signals are provided with relay contact output.
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 new ARM processor, which has the characteristics of strong control ability and safe and reliable operation. And there is an internal monitoring timer, which can eliminate the crash caused by software failure at any time, providing a guarantee for long-term safe and reliable operation;
3. The data memory uses the new F1ash memory chip, which has the advantages of large storage capacity and no loss of data when power is lost;
4. Data acquisition part: Its function is to convert analog quantities into digital quantities for computer processing;
5. Display part: It functions as a clock under normal conditions of the system. When the system fails, relevant fault information can be displayed;
6. Harmonic elimination control: Control the harmonic elimination circuit and activate high-power harmonic elimination components to quickly eliminate ferromagnetic resonance at various frequencies.
This device uses an ARM processor as the core component to perform cyclic detection of the PT opening triangle voltage (i.e. zero sequence voltage). Under normal operating conditions, the voltage is less than 30V, and the high-power harmonic elimination element thyristor in the device is in a blocking state and has no impact on the system. When the PT opening triangle voltage is greater than 30V, it indicates that the system is faulty. The device starts to collect data on the open triangle voltage. Through digital signal processing technologies such as digital measurement, filtering, and amplification, the data is then analyzed and calculated to determine the current fault status. If ferromagnetic resonance of a certain frequency occurs, the CPU immediately starts the detuning circuit (turning on the thyristor) so that the ferromagnetic resonance quickly disappears under strong damping. After the ferromagnetic resonance is eliminated, the CPU will record and store accordingly, and automatically alarm and display relevant resonance information (including occurrence time, frequency, amplitude, etc.). If it is overvoltage or single-phase grounding, after the CPU makes a diagnosis, the device will display and alarm respectively, and automatically record and store relevant fault information. The CPU returns to the initial state and continues to detect the open triangle voltage.
This device uses C language as programming software. The software is mainly composed of monitoring program, floating point operation library, diagnostic software, harmonic elimination, recording and other parts. The real-time monitoring program completes tasks such as voltage detection, sampling, diagnosis, harmonic elimination, clock, keyboard commands, and display. The simple block diagram is shown in Figure 1:
This device is installed on the PK panel or in the terminal box. Each device can be connected to 1 to 4 sections of busbar. The schematic diagram of terminal wiring at the rear of the device is shown in Figure 2:
(1) "1PT*" and "1PT" are respectively connected to the same-name terminal and non-name-name terminal of a busbar open triangle voltage, "2PT*" and "2PT". Connect the same-named terminal and the non-named-named terminal of the second busbar opening triangle voltage respectively, and so on;
(2) The "RS48 5" terminal is a communication terminal and can be directly connected to the RS485 communication bus;
(3) The "power" terminal can be connected to AC power supply or DC power supply regardless of polarity. The voltage range is: 80~250V;
(4) The "ground alarm" terminal is connected to an external alarm signal. This terminal is a normally open contact when there is no fault. It closes when a fault occurs and delays for about 1 minute after the fault disappears. Its contact capacity is AC220V/5A;
(5) The "resonance alarm" terminal is connected to an external alarm signal. This terminal is a normally open contact when there is no fault. It is closed when a fault occurs, and its contact capacity is AC 220V/5A.
