Delayed alarm protection method for alternating current (AC) variable-pitch motor

Abstract

The invention discloses a delayed alarm protection method for an alternating current (AC) variable-pitch motor. The method includes the following steps: step one, a given current loop is changed in a current loop control circuit, a maximum overload multiple, maximum overload time and delayed time of a delayed program are set; step two, when current starts to increase, an accumulated value of an accumulator starts to record time to accumulate, and when the current starts to decrease, the accumulated value starts to reduce and is reduced to zero; step three, when given current reaches the maximum overload multiple of rated current and the accumulated value reaches the maximum overload time, the current loop control circuit reduces the given current to the rated current; and step four, whether the given current keeps to be the rated current in the delayed time is judged, whether rotation speed of a direct current series excited motor is always less than a zero-speed threshold value is judged, if yes, output of a driver is cut off, and fault warning is alarmed, and if not, no action occurs. The delayed alarm protection method for the AC variable-pitch motor enhances production efficiency and safety performance.

Description

technical field [0001] The invention relates to the field of wind power generation, in particular to a delay alarm protection method for an AC variable pitch motor. Background technique [0002] At present, among the pitch systems used in wind farms, the DC pitch system occupies a large market. The pitch motors used are mainly series-excited DC motors. Since the DC pitch motors can directly supply power to the motors through the backup power supply, thus The reliability of the system is increased, but DC pitch motors are generally used in small wind power pitch systems. High-power DC pitch motors are not easy to install due to their large size and heavy weight, and they have commutators and motors. Brushes bring maintenance problems for subsequent commutators and brushes. Therefore, medium and large wind power pitch systems are dominated by AC pitch systems, and the pitch motors used are mainly asynchronous motors or permanent magnet synchronous motors. [0003] Compared wi...

AI Technical Summary

Problems solved by technology

[0002] At present, among the pitch systems used in wind farms, the DC pitch system occupies a large market. The pitch motors used are mainly series-excited DC motors. Since the DC pitch motors can directly supply power to the motors through the backup power supply, thus The reliability of the system is increased, but DC pitch motors are generally used in small wind power pitch systems. High-power DC pitch motors are not easy to install due to their large size and heavy weight, and they have commutators and motors. brushes, which brings maintenance problems for subsequent commutators and brushes, so medium and large wind power pitch systems are dominated by AC pitch systems, and the pitch motors used are mainly asynchronous motors or permanent magnet synchronous motors

[0003] Compared with the soft characteristics of series-excited DC motors, the characteristics of AC motors are relatively hard. When the external load torque increases, the speed does not change much, but the current will rise rapidly. If the current continues to maintain a large value output, that is, the external When the load is always relatively large, the motor will burn out if it works for a long time in this state