53results about How to "Improve operational safety and stability" patented technology

The invention discloses an AC / DC decoupling control method of a modular multi-level converter. The method comprises the steps as follows: DC control is added to current inner loop control and comprises positive DC control and negative DC control, so that an output of AC control, an output of positive DC control and an output of negative DC control are taken as main components of output voltage reference values of various phase bridge arms of an MMC; and control on the main components of the output voltage reference values of various phase bridge arms of the MMC can be achieved by controlling the reference values and the outputs of the AC control, the positive DC control and the negative DC control, thereby preventing the converter from being locked due to overcurrent of the bridge arms in a DC failure. The invention further discloses an application of the method in the flexible DC power transmission system. According to the method disclosed by the invention, the condition that AC and DC are maintained within a safety range can be ensured, so that DC fault ride-through of the overhead flexible DC power transmission system is achieved.

The invention provides a secondary air online measuring method for a turbulent burner, and the secondary air online measuring method is used for measuring the air speed in a secondary air duct of theturbulent burner. The measuring method comprises the following steps of selecting three measuring radiuses in the secondary air duct, wherein three circumferences taking the central point of the secondary air duct as the center of a circle by the three measuring radiuses, and the three circumferences are successively an inside circumference, a middle circumference and an outside circumference; anddividing the radial cross section of the secondary air duct into four annular regions by the three circumferences, wherein the radiuses of the three circumferences are successively r1, r2 and r3. Themethod provided by the invention can measure the blast capacities of secondary air hoses truly and effectively, provides a good basis for optimizing air distribution, optimizes the air distribution mode, reduces the electric consumption of a fan, reduces the station service power consumption rate, and improves the economical efficiency of a boiler.

The invention provides a turbulent burner secondary air on-line measuring system. The turbulent burner secondary air on-line measuring system comprises three sets of primary measuring elements which are radially distributed in three circumferences of radial sections of secondary air ducts. The three circumferences use the center points of the secondary air ducts as a center of a circle, and the three circumferences are sequentially the inner circumference, the middle circumference and the outer circumference. The radiuses of the three circumferences are sequentially r1, r2 and r3, and the radiuses are in units of meters. The radius of a first inner wall is rh, and the unit is meter; the radius of a second inner wall is re, and the unit is meter; and r1 is greater than rh, and r3 is less than re. The turbulent burner secondary air on-line measuring system truly and effectively measures the air volume of the secondary air ducts, provides a good foundation for optimizing air distribution,optimizes the air distribution mode to save power consumption of a fan, reduces the power consumption rate of a plant, and improves the economy of a boiler.

The invention provides a rotor structure of a permanent magnet motor, which can balance the axial temperature distribution of the permanent magnets, including a rotor core, a plurality of permanent magnets and eddy current rings; a plurality of permanent magnets and eddy current rings are embedded in the rotor core; The iron core extends axially and is arranged around the axis of the rotor iron core. The section of each permanent magnet is V-shaped; the outer surface of each permanent magnet is fitted with an eddy current ring, and the eddy current ring is located in the axial middle of the permanent magnet. The rotor structure provided by the present invention reduces the eddy current loss where the permanent magnet is wrapped by the eddy current ring by putting the eddy current ring on the axial center of the permanent magnet, thereby balancing the axial temperature distribution of the permanent magnet and reducing thermal stress. Problems with permanent magnet motor failure caused by balance. At the same time, the eddy current ring can reduce the maximum temperature of the permanent magnet, avoid the problem of partial demagnetization of the permanent magnet caused by local high temperature, and improve the safety and stability of the permanent magnet motor.

The invention discloses a safety control method and system for suppressing continuous commutation failure of a DC system, including a DC safety and stability control master station, a rectification and commutation control subsystem, and an inverter side state detection subsystem. Based on the commutation failure mechanism, through The number of commutation failures in the DC system and the commutation bus voltage on the inverter side are detected, and the DC power is rapidly reduced, thereby realizing the suppression of continuous DC commutation failures. The present invention can still reduce the risk of continuous commutation failure in the weak AC state of the receiving end power grid, can effectively prevent the continuous commutation failure of the DC system, and improve the safety and stability of the AC-DC hybrid system.

The invention discloses a power transmission line grounding distance protection III segment protection method. The method is characterized in that grounding fault phase voltage, grounding fault phase current, grounding fault phase negative sequence current, and zero sequence current of a power transmission line protection installation part can be measured; a grounding arc voltage phase can be calculated by using the phase of the grounding fault phase negative sequence current, and a grounding arc voltage amplitude of a power transmission line grounding fault point can be calculated, and a voltage amplitude variable quantity corresponding to a power transmission line grounding fault front / rear grounding fault point can be calculated, and then the grounding distance protection III segment protection criterion can be formed by using the voltage amplitude variable quantity corresponding the grounding fault point and the power transmission line rated phase voltage amplitude. The power transmission line grounding distance protection III segment protection criterion can be formed by using the grounding arc voltage amplitude characteristic of the power transmission line grounding fault point, and in principle, the influence of the additional impedance caused by the transition resistance on the grounding distance protection III segment protection motion performance can be eliminated, and then the capability of tolerating the strong transition resistance and the strong load current influence can be provided, and therefore the power transmission line grounding distance protection III segment protection correct motion can be guaranteed, the power grid flow big transfer caused by the back-up distance protection motion can be effectively prevented, and the safety and stability of the operation of the power grid can be enhanced.