Large synchronous motor no-load characteristic idle speed test method

Abstract

The invention provides a large synchronous motor no-load characteristic idle speed test method, which comprises the following steps: preliminarily determining an adjustment interval of excitation current according to historical data, equally dividing the adjustment interval of the excitation current into N points, enabling each target excitation current to maintain a fixed time, inputting corresponding data into an excitation regulator and modifying relevant protection setting values of the unit; after the unit is started to the maximum allowable operating speed, quitting prime power input, modifying the excitation regulator to be in a current loop control mode, gradually increasing the magnet in an equal step length manner in the running-out process of the unit, and measuring and recording related electric quantity waveform in the whole test process; carrying out frequency conversion on the voltage waveform, and if the excitation current cannot rise to a specified value or the numberof measuring points cannot meet requirements, carrying out de-excitation on the unit, and carrying out re-measurement after modifying time step length or increasing magnetic step length; and after each electric quantity waveform finishes measuring and recording and meets requirements, further carrying out de-excitation and conversion on the measurement result, and finally, obtaining a no-load characteristic curve of a large synchronous motor. The method is especially suitable for the large synchronous motor with no prime motor dragging, and ensures correctness and effectiveness of an actually-measured no-load characteristic curve obtained after processing.

Description

technical field [0001] The invention relates to the technical field of field testing of large-scale motors, in particular to a method for testing the no-load characteristic idle speed of large-scale synchronous motors. Background technique [0002] The no-load characteristic curve is an important characteristic parameter of large synchronous motors (generators, condensers, motors), which can be used to calculate important parameters such as motor synchronous reactance and short circuit ratio, and can also be used to judge the magnetization performance of the motor core during transportation, failure or durability Whether unacceptable changes occur after operation. After the first manufacturing of large synchronous motors is completed, before they are shipped to the site for commissioning and connected to the grid, during overhaul or when necessary (such as overvoltage, overheating, etc.), it is necessary to measure the no-load characteristic curve to judge whether the qualit...

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Problems solved by technology

[0004] Aiming at the above-mentioned deficiencies in the prior art, the present invention provides a method for measuring the no-load characteristics of a large synchronous motor in an idle state, which does not need to disconnect the self-shunt excitation circuit at the machine end and modify it to a separate excitation method, which greatly simplifies the on-site At the same time, it solves the problem that the no-load characteristics cannot be measured because the rated speed cannot be maintained on site, and the demagnetization conversion and frequency conversion are also considered in the method to ensure the correctness and validity of the measured no-load characteristic curve after processing. It can be directly compared with the factory test data of the unit

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