The power direction and impedance test module of relay protection tester is mainly used to test the protection related to "direction" in power system, such as power direction protection, negative sequence power direction, zero sequence power direction, phase-to-phase power direction, reverse power square, phase-to-phase impedance and grounding impedance, and test their action boundary, maximum sensitive angle, voltage Current action value, action time, action impedance, etc.

　　The following describes each test unit of this test module by taking "power direction protection" as an example:

　　That is, various test items including power direction protection can also be tested for phase to phase and grounding impedance

　　The software introduces the "sudden variable startup" option, which can meet the test requirements of protection requiring sudden variable startup

　　Two diagrams are adopted to make the test process no longer mysterious and abstract

　　During boundary test, it can automatically draw two action boundaries, automatically calculate the maximum sensitivity angle and draw the maximum sensitivity line

　　Test item, test object name

　　The types of protection devices that can be selected are "power direction protection", "negative sequence power protection", "negative sequence power direction", "zero sequence power", "zero sequence power direction", "phase to phase power direction", "reverse power protection", "phase to phase impedance" and "grounding impedance".

　　Sudden variable start

　　When sudden variable startup is selected, the state quantity before fault is output first, and then the voltage and electric flow set in the test are output every time during the test. In order to meet the needs of some protections for sudden variable startup, the "time before fault" needs to be set. If sudden variable startup is not selected, the "time before fault" is invalid (automatically 0), During the test, the voltage and electric flow set by the test are directly output each time and change continuously.

　　Taking "measuring voltage" as an example, the meaning of sudden variable can be represented in the right figure. After clicking the "start test" button, the tester outputs the normal voltage first and maintains it until the end of "voltage before fault";; Then output "fault voltage 1" (fault voltage set on the interface) and maintain it until the end of "maximum fault time"; After the test, the relay protection tester stops output briefly (when the "test interruption time" is not 0).

　　After that, the relay protection tester outputs normal voltage again and maintains it until the end of "voltage before fault"; Then output "fault voltage 2" (the voltage after the variable changes by one step) and maintain it until the end of "maximum fault time"; After the test, the tester stops the output briefly (when the "test interruption time" is not 0). This cycle outputs. In this way, the output of relay protection tester always changes from normal voltage 100V to fault voltage.

　　Measuring boundary

　　The relay protection tester automatically tests the two action boundaries of directional protection and automatically calculates the maximum sensitive angle. In the display mode of "display action angle vector diagram", two boundary lines and maximum sensitive lines can be observed intuitively from the diagram on the right side of the main interface.

　　Test parameters

　　Select a voltage and a current output, the included angle (U, I) changes within a given range, and test the left and right action boundaries.

　　Considering that the protection generally adopts 90 ° wiring mode, the line voltage and the phase current of the third phase are generally taken during the test, such as voltage UAB and current IC. Sometimes one phase voltage and one phase current can be selected for the test, but generally the line current is not selected. Note that the value of the selected voltage and current can be set, but the voltage value of each phase not selected is equal to the rated voltage, the angle remains symmetrical, and the current of each phase not selected is 0.

　　set up φ When searching the range of (U, I), first understand the setting value of the "maximum sensitive angle" of the protection device, and ensure that the set search range can cover the actual two action boundaries of the protection, that is, the search start value and search end value should be set outside the action area, and the relay protection tester searches from the "non action area" to the "action area".

　　The protection does not act at the beginning of the search. When the angle changes to a certain value, the protection acts, that is, it is considered to find an action boundary, draw a line in the figure, and then immediately change the search direction to search for another boundary angle (Note: at this time, the starting angle output by the tester is the set "search end value"). When the second action boundary is searched, the software scribes again. After calculating the maximum sensitive line, the software will automatically mark the maximum sensitive line in the figure.