摘要:
Disclosed is a method for providing warning about a failure in a converter valve. The method comprises: within a predetermined time range, recording time information of status indication signals fed back by thyristor control units (TCU) of a converter valve, performing statistics and comparison of the pieces of time information using a bias statistics method, marking a thyristor level whose bias exceeds a preset value, and determining a probability of failure in the thyristor according to the marking result. Also disclosed is a system for providing warning about a failure in a converter valve. The system comprises a register array used to store bias data of thyristor levels of a converter valve and a high-speed processor used to process, using a bias statistics method, status indication signals fed back by TCUs. The solution of the present invention can identify a thyristor level with a relatively high probability of failure, achieve early warning, and provide a reference for device replacement, thereby reducing a probability of outage of a direct current system due to a failure of a thyristor level, and providing references for device performance optimization and circuit design optimization of a converter valve.
摘要:
The invention discloses a high voltage/ultrahigh voltage direct current transmission inverter side frequency control implementing method, comprising the following steps: transmitting a deviation between the inverter side power grid frequency and rated frequency to the inverter side frequency controller, wherein the frequency controller regulates and outputs a modulation quantity by adopting self-adaptive parameters according to different operation conditions; when the interstation communication is normal, the modulation quantity output of the inverter side frequency controller causes the rectifier side and the inverter side to form a new power/current order through the interstation communication, thus realizing the inverter side frequency control by changing the size of the transmission power; when the interstation communication is abnormal, converting the inverter side to current control from voltage control and converting the rectifier side to voltage control from current control; superposing the modulation quantity output of the inverter side frequency controller to the power/current order of the inverter side, changing the size of the transmission power to realizing the inverter side frequency control. The method realizes the fast efficient regulation function on the inverter side frequency, and effectively solves the problem of the inverter side frequency control for the interstation communication failure.
摘要:
Disclosed in the present invention is a hybrid back-to-back direct current transmission system. The system comprises an LCC converter and a VSC converter in a back-to-back connection, and a first changeover switch, a second changeover switch, a third changeover switch and a fourth changeover switch. The first changeover switch is connected to a first alternating current system and the LCC converter; the second changeover switch is connected to the first alternating current system and the VSC converter; the third changeover switch is connected to a second alternating current system and the VSC converter; and the fourth changeover switch is connected to the second alternating current system and the LCC converter. In forward power delivery, the first changeover switch and the third changeover switch are closed; and in reverse power delivery, the second changeover switch and the fourth changeover switch are closed. Thereby, it is ensured that the VSC converter always performs inversion operation in any power direction, so as to avoid the problem of potential commutation failure for the LCC converter when being in inversion operation. Also provided is a fast power flow reversal control method of the hybrid back-to-back direct current transmission system.
摘要:
A method and apparatus for controlling a hybrid direct-current (DC) transmission system. The method comprises: adjusting the total number of inserted sub-modules of a modular multi-level converter and the polarity of an output level of the inserted sub-modules in real time, according to a DC voltage of a rectifier station at other end; or adjusting the total number of inserted sub-modules of a modular multi-level converter and the polarity of an output level of the inserted sub-modules in real time, according to the magnitude of a DC current or DC power; or adjusting the total number of inserted sub-modules of a modular multi-level converter and the polarity of an output level of the inserted sub-modules in real time, according to both the magnitude of the DC current and the DC voltage of the rectifier station at the other end. The method can effectively control the DC voltage and the direct current of a hybrid DC transmission system, avoiding the power transmitting breakdown.
摘要:
Provided are a commutation control method and a commutation control apparatus. The method includes: detecting whether transient disturbance in a DC transmission system satisfies a disturbance criterion condition (101); when the transient disturbance satisfies the disturbance criterion condition, determining a maximum trigger delay angle used in a commutation operation performed by a current converter on an inverter side of the DC transmission system, the determined maximum trigger delay angle being smaller than a maximum trigger delay angle used before the transient disturbance (102); and controlling the current converter on the inverter side of the DC transmission system to perform the commutation operation based on the determined maximum trigger delay angle (103). By means of the method and the apparatus, a corresponding maximum trigger delay angle can be determined according to the degree of transient disturbance in a DC transmission system, thereby ensuring the commutation margin and avoiding a commutation failure when large transient disturbance occurs.
摘要:
Disclosed in the present invention is a voltage and current control method for a direct-current transmission system. The method comprises: calculating a DC voltage reference value of a voltage source converter of a DC voltage control end, on the basis whether a direct-current voltage end of a direct-current pole of a direct-current transmission system substantially controls a direct-current voltage; using 1/2 of the calculated direct-current voltage reference value of the voltage source converter as a bridge arm voltage direct-current bias, calculating a difference between the direct-current voltage reference value of the voltage source converter and a measured direct-current voltage value, and inputting the difference into a direct-current voltage control outer loop of the voltage source converter to perform closed-loop control, so as to control the direct-current voltage or the direct current of the direct-current pole. Correspondingly, also provided is a voltage and current control device for the direct-current transmission system. By the means of the present invention, the direct-current voltage and the direct current of the direct-current transmission system provided with the voltage source converter can be effectively controlled.