Direct current insulation monitoring method and device

Abstract

The invention relates to a direct current insulation monitoring method which comprises sampling resistors, large-resistance resistors, small-resistance resistors and switching tubes. The large-resistance resistors, the small-resistance resistors and the sampling resistors are connected in series between an anode and the ground and between a cathode and the ground respectively, and the two small-resistance resistors are connected in parallel with the switching tubes respectively. Insulation resistance values of the anode and the cathode can be obtained by making and breaking the two switching tubes respectively, measuring voltage values across the sampling resistors and making calculation on the measured values. The method has the advantages that with the adoption of the low-voltage switching tubes, quick making and breaking can be achieved, the measurement speed is high, the cost is lower, and the influence of a ground capacitor in a system is small, so that the robustness and measurement precision are high. The invention further provides a direct current insulation monitoring device.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation DC systems, in particular to a DC insulation monitoring method and device. Background technique [0002] At present, with the extensive application of DC systems in industry, civil, energy and other fields, its safety has also begun to receive attention, because DC systems cannot be equipped with fast leakage protection devices like AC systems. Especially if electric vehicle charging piles and photovoltaic panels are installed outdoors, there are various possibilities such as impact, rain, water or moisture in the equipment, and cable damage, all of which can easily lead to insulation degradation. When leakage occurs in these DC systems, it is easy to cause casualties, so it is particularly important to equip DC systems with insulation monitoring devices. [0003] However, there are various problems in the traditional DC insulation monitoring method: the balanced bridge meth...

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Problems solved by technology

[0003] However, there are various problems in the traditional DC insulation monitoring method: the balanced bridge method cannot accurately detect the insulation resistance value to the ground when the insulation of the two poles drops; the high voltage injection method and the unbalanced bridge method are affected by the internal grounding capacitance of the system The impact is large, and the insulation resistance value to the ground cannot be quickly measured, and the measurement will also be inaccurate, and a high-voltage switch tube is required, and the cost is high

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