A high temperature protection method for cooling water entering the valve in the valve cooling system of the diverter valve

Abstract

An inner cold water entrance valve temperature high protection method for a valve cooling system of a converter valve. The method comprises: a valve cooling control protection system reading a direct current real-time value from a pole control apparatus, and reading inner cold water entrance valve real-time temperature values from three inner cold water entrance valve temperature sensors at the same time; if all the three temperature sensors break down, the valve cooling control protection system sending a tripping command to lock a direct-current power transmission system, or else, selecting a maximum temperature value as the inner cold water entrance valve real-time temperature value; calculating a real-time junction temperature of a converter valve thyristor according to the inner cold water entrance valve temperature and a direct current value; and comparing a junction temperature value of the thyristor with a junction temperature limit value, sending an alarm signal when the junction temperature of the thyristor reaches an alarm value, and sending the tripping command to lock the direct-current power transmission system when the junction temperature of the thyristor reaches the junction temperature limit value. The method has good coordination control performance and can be adapted to various voltage levels and direct-current power transmission system converter valves in various direct-current load conditions.

Description

technical field [0001] The invention relates to the field of cooling control of converter valves in electric power systems, in particular to a method for protecting the high temperature of cooling water entering a valve in a converter valve cooling system used in a high-voltage or ultra-high voltage direct current transmission system. Background technique [0002] At present, the converter valves for HV or UHV DC transmission are mainly composed of thyristors connected in series, and the working state of the thyristors, the core component, is closely dependent on the temperature of its chip (silicon), that is, the junction temperature. When the junction temperature rises, the dielectric capacity of silicon is weakened, and the fatigue resistance is reduced, which is mainly manifested as a decrease in withstand voltage capability, an increase in reverse recovery charge, and a decrease in service life. In short, the junction temperature of the thyristor not only affects the op...

AI Technical Summary

Problems solved by technology

When the DC transmission system operates under rated DC conditions, this protection method reduces the operating margin; when the DC transmission system operates above rated DC conditions (1.2 times overload operation), this protection method may There is a risk of causing the junction temperature of the thyristor to exceed the limit value of 90°C, damaging the thyristor or shortening the service life of the thyristor

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