Method for reducing influences imposed on user voltage sag by external grid single-phase grounding fault
A single-phase ground fault and voltage sag technology, applied in the direction of measuring electricity, measuring electrical variables, measuring devices, etc., can solve the problem of grid voltage sag that cannot be systematically solved, solve the problem of high cost, and reduce the impact of voltage sag. , the effect of less investment
Active Publication Date: 2015-07-01
SHANGHAI BAOSTEEL IND TECHNOLOGICAL SERVICE
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[0014] In summary, none of the above solutions to deal with voltage sags can systematically solve the problem of grid voltage sags, and can only be partially improved and the solution cost is generally high
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[0039] The method of the present invention to reduce the influence of the external network single-phase grounding fault on the user's voltage sag includes the following steps:
[0040] Step 1, such as figure 1 As shown, the equivalent power source 11 of the external grid 1 is connected to the incoming bus 21 of the internal grid 2 through the transmission line 12, the step-down transformer 22 is connected between the incoming bus 21 of the internal grid 2 and the distribution bus 23, and the step-up transformer 24 Connect between the distribution bus 23 of the internal grid 2 and the generator set 25, construct the zero-sequence impedance loop of the step-down transformer 22 and the step-up transformer 24 in the internal grid 2 and calculate the total zero-sequence impedance loop under the voltage of the distribution bus 23 Current and the partial current through step-down transformer 22 and step-up transformer 24 neutral point grounding resistors 26,27;
[0041] Step two, su...
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The invention discloses a method for reducing influences imposed on user voltage sag by an external grid single-phase grounding fault. According to the method disclosed by the invention, a zero-sequence impedance circuit of a step-down transformer and a step-up transformer in an internal power grid is established, total current of the zero-sequence impedance circuit at a distribution bus side and branch current flowing through a step-down transformer neutral-point grounding resistor and a step-up transformer neutral-point grounding resistor are calculated, and voltage deviation, which is caused by the branch current, of neutral points of the step-down transformer and the step-up transformer and a line voltage sag value, which is caused by the voltage deviation, of a distribution bus are calculated. An appropriate grounding resistor is configured through calculating distribution system voltage sag values corresponding to different transformer neutral-point grounding resistance values, thereby achieving requirements of users for the voltage sag percentage. The method achieves an objective of reducing the influences imposed on the user internal grid voltage sag by the external grid single-phase grounding fault to the maximum range by adopting simple, reliable and low-risk measures.
Description
technical field [0001] The invention relates to a method for reducing the influence of a single-phase grounding fault of an external network on user voltage sags. Background technique [0002] In the power supply system, affected by the short-circuit fault of the external network, the voltage sag of the high-voltage power supply and distribution system of the user grid will have a greater impact on the safe production of the user. The problem of voltage sag has attracted more and more attention, and has become an important hot issue of power quality. [0003] Voltage sag refers to the phenomenon that the amplitude of the voltage suddenly deviates from the normal working range at a certain moment, and returns to the normal state after a short period of time. At present, many technical literatures use the amplitude and duration of voltage sag as the characteristic quantity to describe the voltage sag, but there is no uniform standard for the definition range of the amplitude ...
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Inventor 沈国芳杨左勇陆志明成善武俞徐斌
Owner SHANGHAI BAOSTEEL IND TECHNOLOGICAL SERVICE