Fault Detection Technology Of The Dry-type Air-core Reactor Based On The Frequency Characteristics Of The Impedance Variation

Dry-type hollow reactors have the functions of compensating for reactive power,suppressing power frequency overvoltage,limiting short-circuit current,and filtering.They are widely used in power grids.There are many parallel branches of dry-type air-core reactors,and inter-turn short-circuits and number-of-turn deviation faults are prone to occur during the manufacturing process;and during transportation,mechanical damage and other reasons may also cause inter-turn short-circuit faults,so Both faults need to be detected before the reactor leaves the factory and is put into operation on site.Existing DC resistance measurement and detection methods have low detection sensitivity for these two types of faults,and the power frequency detection method is greatly affected by the power frequency interference at the detection site,making it difficult to effectively detect reactor faults.In order to solve the above problems,this article has carried out related research work.In this paper,the circuit models of normal reactors,turn-to-turn short-circuit reactors,and turns deviation reactors are established.The calculation methods of equivalent resistance and equivalent inductance of normal reactors and fault reactors are given,and Matlab calculation programs are written.Taking a BKDK-20000 / 35dry-type hollow parallel reactor and a CKDGKL-2.5 / 10-1 dry-type hollow series reactor as examples,the relative changes in the equivalent inductance and equivalent resistance of the fault reactor Numerical calculations are performed with the frequency and change of the fault location.The principle of power frequency induction on the tested reactor is analyzed,and the calculation method of power frequency induction is given.A 35 k V dry-type hollow parallel reactor is used as an example to numerically calculate the magnitude of power frequency induction on the tested reactor.Based on this,a detection method for measuring the relative change in equivalent resistance at different frequencies to determine the dry-type hollow reactor fault is proposed.The corresponding detection circuit is designed,and the principle of eliminating power frequency induction by using the harmonic analysis method is analyzed.The high-power test power supply in the detection circuit is designed and verified by simulation.Finally,a test platform was built to verify the test method.The research results show that: when a dry-type hollow reactor has a short-toturn short circuit or a number of turns deviation fault,its equivalent resistance increases and its equivalent inductance decreases,and the relative changes of both increase first as the frequency increases.Later,it tends to be saturated,and the change of the equivalent resistance is much larger than that of the equivalent inductance.The proposed method is used to measure the relative change in the equivalent resistance of the faulty reactor.In the absence of power frequency induction,the measurement results and experimental measurements of the power analyzer are consistent with the theoretical calculations,which proves that the designed detection method is accurate.Correctness.The experimental measurement results after the presence of power frequency induction are almost the same as when there is no power frequency induction,which proves that the anti-power frequency induction method described in this paper has a good ability to resist power frequency interference.The detection method and circuit proposed in this paper can effectively detect the inter-turn short-circuit and turn-number deviation faults of dry-type hollow reactors.