DISTURBANCE REDUCTION AT THE EXCITATION CIRCUIT OF A SYNCHRONOUS MACHINE BY LIMITING THE RATE OF RISE OF THE DIRECT-AXIS STATOR CURRENT
Publication Date: 2016-Jun-20
The IP.com Prior Art Database
The invention proposes a technique to reduce disturbances at excitation circuit of synchronous machines. The technique reduces the disturbances by limiting stator current dynamics without influencing torque dynamics. The technique reduces the torque dynamics of the drive. A machine controller calculates a load and a magnetizing current reference.
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DISTURBANCE REDUCTION AT THE EXCITATION CIRCUIT OF A SYNCHRONOUS MACHINE BY LIMITING THE RATE OF RISE OF THE DIRECT-
AXIS STATOR CURRENT
The present invention generally relates to a synchronous machine and more particularly to a technique for reducing disturbances at excitation circuit of the synchronous machines.
In general, for synchronous machines, any dynamic of stator current induces an additional voltage in rotor circuit. For high current dynamics, disturbance is so high that rotor current is not controlled as maximum voltage of the rotor converter is too low.
Converters controlling rotor current of a synchronous machine usually handles only one current direction. Negative rotor current is not required for operation of synchronous machines. Since rotor converter is not able to handle negative current, the drive trips and the rotor circuit is required to be protected against over voltage by surge arresters. Otherwise, the rotor converter gets damaged. The problem often occurs with machines with high transformation ratio between stator and rotor. As a result, high voltage is induced in the rotor. Applications that require very high torque and current dynamics are for instance rolling mills. Fast torque reduction at the end of a slab provides above described problems. Also, trip of the drive provides severe problems.
A conventional technique provides reduction of torque dynamics of the control loop. However, the conventional technique provides negative effects on quality of customer process.
Therefore there is a need in the art for a technique to reduce disturbances of synchronous machines.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 depicts technique to reduce disturbances at excitation circuit of synchronous machines.
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The invention proposes a technique to reduce disturbances...