Induction regulator for power flow control in an ac transmission network and a method of controlling such network

Abstract

A device for controlling the voltage and the phase angle of a polyphase electric transmission network including an induction regulator that is connected between the primary side and the secondary side of the transmission network. A gap is provided with a magnetic layer having a relative permeability that is controllable, wherein the magnitude (amplitude) of the secondary voltage vector is also adapted to be controlled by controlling the permeability of the magnetic layer. The magnetic layer may include a magnetic fluid or a solid material.

Description

FIELD OF THE INVENTION[0001]The present invention relates to an induction regulator for controlling the voltage and the phase angle of a polyphase electric transmission network, which induction regulator is connected between a primary side and a secondary side of the transmission network and comprises a stator with stator windings and stator poles and a partial rotatable rotor with rotor windings and rotor poles, and a gap between the respective stator pole and rotor pole.[0002]The invention also relates to a method of controlling voltage and phase angle of a polyphase transmission network.[0003]The invention further relates to use of a power-flow control device for a polyphase transmission network for high voltage.DESCRIPTION OF THE BACKGROUND ART[0004]The active power flow in an ac network is controlled by the equationP=U1U2Xsinδwhere U1 and U2 are the voltages at the transmitting and receiving ends, respectively, of the network. The line reactance is X and δ is the angle between ...

AI Technical Summary

Benefits of technology

"The present invention provides an induction regulator for controlling the voltage and phase angle of a polyphase electric transmission network. The regulator uses a power-flow control device to control the amplitude of the secondary voltage vector, which is independent of the control caused by a rotation of the rotor. The control function is achieved by changing the relative permeability of the magnetic layer by varying the temperature or pressure. The invention also provides a method for controlling voltage and phase angle, and the use of gadolinium as a material for the magnetic layer. The technical effects of the invention include improved voltage and phase angle control, improved stability, and reduced energy loss."

Problems solved by technology

If unforeseen events occur in a network, it will require that the generators be planned in a non-optimal way with regard to the production costs.

When influencing the active power flow by using a series capacitor, the reactance can only be reduced to a certain level and it is not possible to force the current irrespective of the state of the line since it is not possible in practice to overcompensate the line.

The disadvantages of existing UPFCs have primarily been associated with the difficulty of protecting the power electronics on the series-transformer side.

The control speed is low and considerable mechanical force is required to achieve the slow change of the output voltage.

An disadvantage of the induction regulator is that the voltage amplitude is changed when the angle δ is changed.

A device according to the first category is able to control the power flow within minimum and maximum ranges almost independently of the load states, whereas a control device according to the second category cannot always fulfil this requirement.

A drawback of the induction regulator is that the possibilities of control are limited to the voltage change that the secondary voltage vector achieves and this while changing the phase angle of the voltage.

This renders parallel connection of lines and apparatus difficult, since an angular rotation brings about a voltage change and hence a circulating reactive effect.

Images