JPH0136360B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an excitation device for a superconducting synchronous machine having a superconducting field winding, and particularly to an excitation device for a superconducting synchronous machine having a superconducting field winding. , voltage and reactive power can be automatically controlled.

In general, a superconducting synchronous machine, in which the field winding of the synchronous machine is in a superconducting state, can significantly reduce the size and power loss of the equipment compared to a normal synchronous machine, and therefore can be used as a single machine. It is now possible to manufacture a synchronous machine with a large capacity, and it is also possible to significantly increase the output voltage of the synchronous machine, so by adopting this type of superconducting synchronous machine, the design of the plant system can be significantly streamlined compared to the past. There are various advantages such as:

Furthermore, in this type of superconducting synchronous machine, unlike a normal synchronous machine, the leading phase power can be made almost equal to the rated KVA. In other words, in a normal synchronous machine, it is difficult to obtain a phase leading power close to the rated KVA because it is constrained by stability or by coil end heat, but in this type of superconducting synchronous machine, is not subject to such restrictions due to its structure. Therefore, this kind of superconducting synchronous machine is
Even when used as a phase modifier, it has various advantages, such as being significantly more advantageous than conventional ones, and also being able to be used as a generator.

However, when a superconducting synchronous machine is connected to a power system and used for any of the above-mentioned purposes, various fluctuation factors in the power system, namely, various fluctuations in active power, reactive power, voltage, etc. Alternatively, it is necessary to perform responsive excitation that can immediately respond to the occurrence of an accident in the power system.

On the other hand, in a superconducting synchronous machine, if the rate of change of the magnetic field of the field winding in the superconducting state exceeds a predetermined limit value, the superconducting state will be destroyed and stable operation cannot be continued. moreover,
Since the field winding has only inductance and its resistance is almost zero, the time constant of the excitation circuit is extremely large. However, there is a problem in that it is extremely difficult to apply to this type of superconducting synchronous machine.

The purpose of the present invention is to solve the above-mentioned conventional problems, and when a superconducting synchronous machine is connected to a power system and used, the excitation state can be changed in immediate response to fluctuations in various factors in the power system. An object of the present invention is to provide an excitation device for a superconducting synchronous machine that can quickly respond without destroying the superconducting state of a field winding.

That is, the excitation device of the present invention supplies an excitation current to a synchronous machine having a superconducting field winding via a thyristor converter, and also supplies a DC side that the thyristor converter can take in each of the converter region and the inverter region. The voltage or control angle is determined according to the permissible rate of change of the excitation current, and the operation mode can be set at these determined DC side voltage or control angle, or it can be applied in parallel to the thyristor converter itself or the excitation winding. The thyristor converter is controlled by selecting one of the bypass operation modes using the bypass gate circuit according to the voltage of the synchronous machine or the output signal of the regulator for reactive power. It is something to do.

The present invention will be described in detail below with reference to the drawings.

First, an example of the configuration of an excitation device for a superconducting synchronous machine according to the present invention is shown in FIG. In the illustrated configuration,
SY is a superconducting synchronous machine, and DS is its synchronous machine SY
PT and CT are the voltage transformer and current transformer respectively coupled to the connection line between the synchronous machine SY and the power system DS. In addition, A is the superconducting field winding of the synchronous machine SY, and B
is an AC/DC converter consisting of a three-phase bridge circuit configured by combining six thyristors TH, and C is a three-phase bridge circuit configured by combining six thyristors TH.
The bypass gate circuit is composed of transistors connected in parallel to the phase bridge circuit B, and the excitation current to the field winding A is adjusted by the three-phase bridge circuit B and the bypass gate circuit C. Sh is a field current detector that detects the field current. moreover,
D is a gate angle determining device that sets the gate angle of the thyristor TH constituting the three-phase bridge AC/DC conversion circuit B, and E is a voltage transformer PT and a current transformer.
This is a regulator that automatically controls the voltage or reactive power of the synchronous machine SY based on the voltage and _current from the CT. This is the α and β calculation unit to be set.

Therefore, when the gate angle of each thyristor TH constituting the three-phase bridge circuit B that supplies exciting current to the field winding A of the superconducting synchronous machine is α, the applied voltage across the field winding is +E〓, If the voltage applied across the field winding when the gate angle is β is −E〓,
The gate angles α and β are set so that the magnitudes of the applied voltages E〓 and E〓 are determined in accordance with the allowable field current change rate, and the gate angles α and β are determined according to the magnitude of the field current I _f . When changing the allowable field current rate of change, the values of the gate angles α and β of the thyristor described above are changed depending on the field current _If . If you set the thyristor gate angle in this way,
It is possible to excite a superconducting synchronous machine with excellent responsiveness to fluctuations in various factors in the power system without causing destruction of the superconducting state of the field winding.

In addition, when making a constant excitation current flow stably through the field winding, the gate angle of the thyristor should be set to the gate angle γ corresponding to the fully closed position (for example, a firing delay angle of 120° or more), and the gate angle should be set to 3. A shunt gate circuit C made up of a transistor connected in parallel to the phase bridge circuit B is turned on, and this shunt gate circuit C forms a circulation path for the field current, thereby placing the thyristor converter in a no-current state. This prevents the thyristor converter from drawing reactive power from the AC power supply during stable operation.

The operation of the excitation device of the present invention shown in FIG. 1, which performs immediate excitation of a superconducting synchronous machine by switching and setting the thyristor gate angle as described above, is as follows.

The output voltage and current of the superconducting synchronous machine SY are supplied to the voltage and reactive power regulator E via the voltage transformer PT and current transformer CT, and in this regulator E, the field is adjusted based on these voltage and current values. It is determined whether the magnetic current I _f should be increased, decreased, or maintained as it is. The output signal of regulator E is a three-position operation signal, and α,
Either β or γ is selected. When the field current If should be _increased , the thyristor gate angle is set to a gate angle α corresponding to the converter region.
By setting this thyristor gate angle α, the aforementioned voltage +E〓 is applied to both ends of the field winding A as shown in Fig. 2A, and in response to the application of this voltage +E〓, the field current I _f increases at the rate of change shown in Figure 2B.

In addition, when the field current I _f should be maintained at the current level, the thyristor gate angle is selected to be the gate angle γ corresponding to the fully closed position, and at the same time, the bypass gate circuit C is turned on to circulate the thyristor gate. to maintain a constant field current.

Furthermore, when the field current I _f is to be reduced, the thyristor gate angle is selected to be a gate angle β corresponding to the inverter region, and by selecting this gate angle β, the above-mentioned voltage − E〓
is applied as shown in the upper part of FIG. 2, and in response to the application of the voltage -E, the field _current If decreases at a rate of change as shown in the lower part of FIG.

Note that the permissible value of the rate of change of the field current I _f in the synchronous machine SY tends to change depending on the magnitude of the field current I _f itself, and if necessary, it can be adjusted to suit this tendency. , as shown in Fig. 1, the detection output signal regarding the magnitude of the field current I _f obtained from the field current detector Sh is supplied to the α, β calculation unit F, and the gate calculated by the calculation unit F is The values of angles α and β are supplied to the gate angle determination device D, and the gate angles α and β are determined by the commands of the voltage and reactive power regulator E.
Generally, when the field current I _f is large, it is necessary to set the gate angle so as to suppress the rate of change of the field current.
The contents of the calculation in the calculation unit F must be adapted to the characteristics of the synchronous machine to be controlled.

In addition, in the above explanation, superconducting synchronous machine
The thyristor gate angle for changing the field current in accordance with the deviation value of the voltage and reactive power in SY was set at three positions α, β, and γ.
Furthermore, if n is a value n>1, the gate angle is in the range of α to α/n for the converter region, the gate angle is in the range of β to β/n for the inverter region, and γ. It is also possible to increase the number of gate angle positions to be set so that the field current If can be controlled _even more smoothly when the deviation values of voltage and reactive power are small.

The control in the γ position of the thyristor converter B is such that the control angle of the thyristor belonging to one half of the thyristor bridge is set to the minimum possible control delay angle (e.g. near zero degrees), and the control angle of the thyristor belonging to the other bridge half is set to the minimum possible control delay angle (near zero degrees, for example). can be replaced with control that sets the maximum possible control delay angle (a value as close as possible to 180° within the commutable range), and in this case, the field current does not substantially pass through the AC side of the thyristor converter. A special bypass gate circuit C as shown in FIG. 1 is no longer necessary, since the bypass occurs via two series-connected thyristors in each case in the thyristor converter.

As is clear from the above description, according to the present invention, when a superconducting synchronous machine is connected to a power system and used, the superconducting synchronous machine can immediately respond to fluctuations in various factors in the power system. The excitation state of the field winding can be changed, and the field current can be quickly changed without destroying the superconducting state of the field winding.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a configuration example of the excitation device of the present invention, and FIGS. 2A and 2B are characteristic curve diagrams showing the change characteristics of the field winding applied voltage and field current, respectively, in the same excitation device. be. SY...Synchronous machine, DS...Power system, TH...Thyristor, A...Field winding, B...3-phase bridge circuit, C...Shunt gate circuit, D...Gate angle determination device, E ...Voltage, reactive power regulator, F...
α, β calculator, PT...voltage transformer, CT...current transformer.

Claims (1)

[Scope of Claims] 1. An excitation device for a superconducting synchronous machine having a superconducting field winding, comprising means for detecting the output voltage and output current of the synchronous machine; Voltage and reactive power adjustment means for instructing field current; a thyristor converter for supplying field current to the synchronous machine; The connected bypass gate circuit and the DC side voltage or control angle that the thyristor converter can take in each of the converter region and the inverter region are determined in advance in accordance with the permissible rate of change of the field current, and these determinations are The thyristor converter is operated by selecting either an operation mode at the DC side voltage or control angle, or a bypass operation mode using the bypass gate circuit, depending on the voltage and the output signal from the reactive power adjustment means. 1. An excitation device for a superconducting synchronous machine, comprising a control means for controlling the machine. 2. The excitation device according to claim 1, wherein the DC side voltage or control angle that the thyristor converter can take in each of the converter region and the inverter region is variably set according to the value of the field current. An excitation device for a superconducting synchronous machine characterized by: