A switching module includes a determiner to open a first bidirectional switch and close a second bidirectional switch from a first time point over a testing period to determine that the first bidirectional switch has a short circuit failure when a differential absolute value of voltage values detected by voltmeters is equal to a preset voltage threshold value or less, and to open the first bidirectional switch and close the second bidirectional switch from a second time point after a period of n+½ times, where n is a positive integer, the set cycle from the first time point elapses, over a testing period to determine that the first bidirectional switch has a short circuit failure when a differential absolute value of the voltage values detected by the voltmeters is equal to the voltage threshold value or less.

The present invention discloses a bypass thyristor valve group inspection method and control apparatus for inspecting sub-modules in a bypass thyristor valve group, and in particular, including: dividing the bypass thyristor valve group into N sub-modules, where N is greater than or equal to 2, N is a natural number, and each sub-module is formed by connecting one or more thyristors in series; under the condition that the bypass thyristor valve group bears a normal forward voltage, sequentially triggering, by the bypass thyristor valve group control apparatus, the sub-modules according to a certain time period; detecting whether the sub-modules are capable of operating normally or not; and if not, sending an alarm signal. According to the bypass thyristor valve group inspection method and control apparatus, the problem of thyristor performance monitoring under the condition that the bypass thyristor valve group does not operate for a long time is effectively solved, and safety in operation of a protected voltage source current converter is guaranteed.

A thyristor valve test system based on cooperation of logic functions of software, wherein the test system comprises: a thyristor valve (5) to be tested, a VBE (3) and a tester (4), and the VBE (3) has a dedicated test mode, the tester (4) provides three steps for each test item. The thyristor valve (5) to be tested and the VBE (3) are connected by optical fibers (1), and the thyristor valve (5) to be tested and the tester (4) are connected by cables (2), and there is no connection between the VBE (3) and the tester (4).

A method for determining failure of a power element for use in an electronic device is provided. The electronic device includes a power element and a detection circuit. The method includes the steps of: obtaining a temperature-calculation model of the power element, and obtaining a parameterized temperature-calculation model of a power-element parameter and a parameterized temperature of the power element; detecting load information and the power-element parameter by the detection circuit; calculating a modeled temperature of the power element according to the load information and the temperature-calculation model, and calculating the parameterized temperature of the power element according to the power-element parameter and the parameterized temperature-calculation model; determining whether an error between the modeled temperature and the parameterized temperature exceeds a permitted range; and determining that the power element has failed in response to the error exceeding the permitted range.

A switching module includes a determiner to open a first bidirectional switch and close a second bidirectional switch from a first time point over a testing period to determine that the first bidirectional switch has a short circuit failure when a differential absolute value of voltage values detected by voltmeters is equal to a preset voltage threshold value or less, and to open the first bidirectional switch and close the second bidirectional switch from a second time point after a period of n+ times, where n is a positive integer, the set cycle from the first time point elapses, over a testing period to determine that the first bidirectional switch has a short circuit failure when a differential absolute value of the voltage values detected by the voltmeters is equal to the voltage threshold value or less.

A method for determining failure of a power element for use in an electronic device is provided. The electronic device includes a power element and a detection circuit. The method includes the steps of: obtaining a temperature-calculation model of the power element, and obtaining a parameterized temperature-calculation model of a power-element parameter and a parameterized temperature of the power element; detecting load information and the power-element parameter by the detection circuit; calculating a modeled temperature of the power element according to the load information and the temperature-calculation model, and calculating the parameterized temperature of the power element according to the power-element parameter and the parameterized temperature-calculation model; determining whether an error between the modeled temperature and the parameterized temperature exceeds a permitted range; and determining that the power element has failed in response to the error exceeding the permitted range.

A thyristor valve test system based on cooperation of logic functions of software, wherein the test system comprises: a thyristor valve (5) to be tested, a VBE (3) and a tester (4), and the VBE (3) has a dedicated test mode, the tester (4) provides three steps for each test item. The thyristor valve (5) to be tested and the VBE (3) are connected by optical fibers (1), and the thyristor valve (5) to be tested and the tester (4) are connected by cables (2), and there is no connection between the VBE (3) and the tester (4).

The present invention discloses a DC converter valve state detection method based on temporal features of converter terminal currents, including the following steps: collecting three-phase AC currents on a converter valve-side of a DC transmission system; defining a current when the currents of two commutating valves are equal as a base value, greater than the base value as a valve conducting current, and less than the base value as a valve blocking current; constructing a valve conducting state by a relative relationship among amplitudes of the three-phase AC currents, and calculating a time interval of each valve conducting state; comparing time intervals of 6 valve conducting states with a time interval of a valve conducting state in normal operation, and determining whether the 6 valve states are normal according to the result of comparison and locating all abnormal valves. The present invention can reliably detect valve states and locate abnormal valves through sequence detection. This method can be applied to actual fault phase judgment and commutation failure judgment, providing a good support for accurate judgment of DC control and protection.

A method for monitoring a protective device, which has a series circuit of a multiplicity of thyristors. The protective device has a series circuit of N>1 thyristors. The series circuit is connected in a parallel circuit with an electrical device to be protected. A snubber branch is connected in parallel with each thyristor. For the purpose of testing a firing capacity, n<N thyristors in a first thyristor group are fired when a positive voltage is present across the series circuit and a negative snubber current is flowing through the snubber branches of the thyristors in the first thyristor group.

A fault detector for an anti-parallel thyristor includes: a power supply unit configured to supply power to the first and second thyristors; a first current sensor configured to output a first current measurement value that flows through the first thyristor; a second current sensor configured to output a second current measurement value that flows through the second thyristor; and a detector which notifies a fault of a thyristor when the first and second current measurement values satisfy a set fault condition.