Flexible alternating current/direct current electronic transformer checking device based on mixed sampling

[0020] The present invention will be further described below in conjunction with the accompanying drawings of the specification.

[0021] The hybrid sampling-based flexible AC/DC electronic transformer calibration device of the present invention adopts an embedded real-time operating system, so that the entire system has strong real-time performance, and a large current required for testing is generated by a primary up-current circuit. Test the accuracy of AC and DC electronic transformers in UPFC at different ratio points, relying on standard transformers as a reference for high-precision analog data acquisition, high-precision and low-temperature coefficient non-inductive sampling resistors to achieve precise I/V conversion, and secondary output A small voltage signal can reflect the true amount of current applied at a time, greatly reducing the accuracy requirements for the primary side signal source, reducing the difficulty and facilitating system implementation, such as figure 1 Shown, including primary up-current circuit, high-precision DC AD acquisition circuit, standard transformer, I/U converter, high-precision AC AD acquisition circuit, main control CPU module, digital acquisition module and host computer, unified power flow controller The internal electronic transformer body to be calibrated is connected in series with the input end of the standard transformer and the primary up-current circuit through the optical fiber. The output end of the standard transformer is connected to the input end of the high-precision AC AD acquisition circuit through the I/U converter The output terminal of the primary up-current circuit is connected with the input terminal of the high-precision DC AD acquisition circuit. The output terminals of the high-precision AC AD acquisition circuit and the high-precision DC AD acquisition circuit are respectively connected to the sampling input terminal of the main control CPU module. Connect, the input terminal of the digital acquisition module is connected with the merging unit in the unified power flow controller, the output terminal of the digital acquisition module is connected with the digital input terminal of the main control CPU module, and the main control CPU module also sends a synchronization signal to High-precision AC AD acquisition circuit, digital acquisition module, synchronization signal is responsible for marking a unified time reference for AC analog acquisition, serial data acquisition, and Ethernet data acquisition modules to ensure the time domain synchronization accuracy of all digital processes in the entire system. The CPU module controls the data communication with the host computer. The host computer completes the processing of all signals. Through the perfect AC and DC component extraction algorithm, it calculates the DC effective value, fundamental effective value, phase angle, and harmonic of the standard source and the tested object. The effective value and phase of the wave are analyzed, and the accuracy parameters such as DC accuracy, AC accuracy, and harmonic characteristics required for the calibration test are analyzed. Through time-domain time-scale debounce processing and comparative analysis, the delay of the measured object is obtained Time characteristic parameters such as time, digital discrete, and step rise time.

[0022] The input end of the digital quantity acquisition module is connected with the merging unit in the unified power flow controller through a serial data bus and an Ethernet data bus, and the digital quantity acquisition module is equipped with an FPGA chip.

[0023] The main control CPU module adopts a CPU containing a high-precision constant temperature crystal oscillator, the model is MPC8247 PowerPC processor, its stability and operation speed are reliably guaranteed, and the constant temperature crystal oscillator model is JKOC36A-50MhZ, and the accuracy level is 0.001PPM. Ensure that the time domain of the data source is stable.

[0024] The I/U converter is provided with a Karma chip-type non-inductive resistor to realize I/U conversion.

[0025] The high-precision DC AD acquisition circuit uses an 18-bit AD7690 chip for high-speed acquisition of DC analog data, the high-precision AC AD acquisition circuit uses a 24-bit ADS1271 chip for high-speed acquisition of AC analog data, and a 24-bit high-precision A/D The conversion chip improves the AC sampling accuracy of the entire system, and the 18-bit successive approximation A/D conversion chip improves the DC sampling accuracy of the entire system and improves the sampling accuracy.

[0026] The invention collects the AC current analog signal and DC voltage signal of the standard transformer as the sampling reference of the whole system, and obtains the AC and DC sampling accuracy of the electronic transformer body in the unified power flow controller (UPFC) system through testing. The test obtains the sampling delay of the entire electronic transformer system, and obtains the DC transient characteristic index through the DC step response capability test, thereby obtaining the overall parameter index of the electronic transformer in the unified power flow controller (UPFC) system.

[0027] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the industry should understand that the present invention is not limited by the foregoing embodiments. The foregoing embodiments and descriptions only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have Various changes and improvements, these changes and improvements fall within the scope of the claimed invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.