The South China University of Technology

Xiaohua Li

Shanshan Yin

Jiewen Li

Hao Li

Dui Liu

The present invention discloses a calculation method for a converter valve state and a valve current based on temporal features of a valve side current, the process is follows: collecting three-phase AC currents, DC currents on a valve side of a converter of a DC transmission system, and trigger pulses of converter valves; establishing a node current equation of the AC currents and valve currents; when detecting a rising edge of a trigger pulse of a converter valve, latching the number of the converter valve; according to the trigger pulses of the converter valves, and amplitude characteristics of the AC currents and characteristics of AC variations, to perform a conducting state and a blocking state judgment of valve states, and obtaining valve states; judging whether each phase has a bypass state; through summing the valve bypass states of the three phases to judge a number of bypass phases; supplementing bypass loop voltage equation; calculating the converter valve currents; when the calculated value of the valve currents is negative, the valve state is corrected to blocking state according to a one-way conductivity of the converter valves, otherwise do not correct; repeating the above steps again to calculate the valve current.

Method for solving for converter valve states and valve currents based on valve-side current timing characteristics

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.

Growing community of inventors

Guangzhou, China

Xiaohua Li