Method for series voltage equalization of supporting insulators in high voltage flexible DC converter valves

Abstract

The invention discloses series voltage equalization method of support insulators of a high-voltage flexible direct-current converter valve. The method belongs to the field of electric field algorithms of the converter valve, and includes two steps of selecting a waterway clamp point, and calculating an optimization effect by circuit equivalence. A waterway and metal parts connected with an insulator string are mutually clamped, a phenomenon of uneven electric potential distribution caused by uneven stray capacitance distribution is directly and quickly ameliorated through characteristics that potential distribution of the waterway is even and a waterway resistance value is low than a capacitance reactance value, the principle is simple and easy to understand, structure features of the converter valve are utilized very well, an extra structure is not needed to be added, engineering requirements can be well satisfied, installation costs are small, and engineering implementation is convenient. In order to more conveniently calculate an optimization result, a circuit equivalence calculation method is used for calculation, and repeatedly modifying a clamp point position and finding the best optimization scheme are facilitated. Circuit parameter calculation is carried out through equivalent resistance and capacitance values, the calculation is simple, calculation time is short, and engineering costs and time can be greatly saved.

Description

technical field [0001] The invention belongs to the field of electric field algorithms of converter valves, in particular to a method for equalizing the series voltage of supporting insulators of high-voltage flexible DC converter valves. Background technique [0002] While the traditional UHV DC transmission is developing, the flexible DC transmission technology based on the voltage source converter is also developing continuously. From Nanhui, Zhoushan, Nan'ao, Xiamen to Luxi projects, the voltage level has been continuously increased from ±30kV to ±800kV. At the same time, the structure of the converter valve has also undergone great changes. The insulator plays an important role in support and insulation. The role has become the focus of attention. When the working voltage increases, the support of a single insulator can no longer meet the engineering requirements, and it has become an inevitable trend to form insulator strings composed of multiple insulators with simpl...

AI Technical Summary

Problems solved by technology

[0009] The water circuit before being clamped can be equivalent to a resistor R with a very large resistance, and C 1 、C 2 、C 3 The circuit equivalent relationship (such as figure 2 shown), after adding a clamping point connected to the metal part of the insulator on the water pipe, the circuit is equivalent (the circuit diagram is shown in image 3 shown) for R 1 is the resistance of the upper part of the clamping point of the waterway, R 2 is the resistance of the lower section of the clamp point of the waterway; the valve tower model is equivalent to two capacitors in series, two resistors in series, and then these two groups of components are connected in parallel; the potential of the waterway is linearly distributed under the current field, and the resistance value of the waterway is higher than the capacitance The reactance value is small, and the change of the clamping point can make and Closer, so that the voltage distribution is even, and then the waterway clamping can effectively improve the problem of uneven voltage distribution caused by stray capacitance; specifically, it includes two steps: the selection of the waterway clamping point and the calculation of the optimization effect, and the position of the clamping point is selected repeatedly. Optimum position of the clamping point; the optimization effect calculation currently generally adopts the finite element electric field calculation: first select the appropriate clamping point of the waterway, try to consider the position of the water pipe at a relatively short distance from the metal part of the insulator series connection, and repeatedly select and optimize the clamping point of the waterway , different clamping points correspond to different water resistance and different voltage distribution results

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