JPH0446596A - Generator output controller - Google Patents

Abstract

PURPOSE:To widen operational range of generator by predicting rotor temperature based on reverse phase current and various state amounts and then controlling output, power factor, and the like of the generator based on allowable rotor temperature, generator output, external output command value, rotor field winding temperature, and the like. CONSTITUTION:A rotor temperature operating circuit 9 predicts temperature of a rotor 5 under steady state while a rotor temperature rise operating circuit 13 predicts rotor temperature rise due to reverse phase current and an output control circuit 14 predicts actual rotor temperature based on these predicted values and calculates a maximum generator output, within which rotor temperature does not exceed the allowable value, together with an allowable rotor temperature setter 15. Generator output is then set based on thus calculated generator output, an external generator output command value 16, and field winding temperature determined by a rotor field winding temperature operating circuit 18. According to the arrangement. generator output is automatically controlled so that the rotor temperature does not exceed the allowable value even if reverse phase current increases.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention (Industrial Application Field) The present invention relates to a generator output control device that measures a negative sequence current flowing through the generator to control the generator output.

(Prior art) In a turbine generator, when an anti-phase current flows through the generator, an electric torque with a frequency twice the rated frequency acts on the rotor, which becomes an excitation force that causes the shaft and blades of the turbine to move. There is a problem in that blade axis-coupled plate shear vibration occurs, which vibrates while influencing each other, which shortens the life of the blade.

Conventionally, a countermeasure to this problem has been to deviate the natural frequency of the turbine shaft and blades from twice the rated frequency, and various detuning countermeasures have been taken.

On the other hand, on the generator side, there remains the problem of negative sequence tolerance, and there is a limit to the magnitude of negative sequence current.

The negative sequence withstand capacity is limited by the amount of heat accumulated on the rotor surface due to short-term negative sequence current, and the other is limited by the rise in rotor surface temperature due to relatively long or continuous negative sequence current. There is a continuous capacity. However, in recent years, the capacity of a single unit in turbine generators has increased significantly, and this increase in capacity is largely due to cooling technology, and the heat capacity of the rotor has tended to decrease.

Currently, as a countermeasure when a reverse phase current flows during generator operation, an alarm or trip is issued by a reverse phase protection device inside the ship. 114). In addition, the standard value defines the negative sequence current that is allowed when the generator is at its rated output.

(Problem to be Solved by the Invention) However, in the case of a reverse-phase protection device that trips the generator when the reverse-sequence current flowing during generator operation exceeds a set value, the operating range of the generator is determined by the standard value. There was a problem that the driving range was restricted.

The purpose of the present invention is to predict and calculate the rotor temperature from the negative sequence current and various state quantities, and calculate the generator output based on the allowable rotor temperature, generator output, external output command value, rotor field winding temperature, etc. An object of the present invention is to provide a generator output control device that can expand the operating range of the generator by controlling the power factor and the like.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention includes negative sequence current calculation means that receives the output current of the generator and calculates the negative sequence current flowing to the generator from this current. , a rotor temperature rise value calculating means for calculating a predicted temperature rise value due to the negative sequence current of the rotor of the generator from the negative sequence current obtained by the negative sequence current calculating means, and incorporating various state quantities of the generator. A rotor temperature calculation means for calculating a predicted value of the rotor temperature of the generator in a steady state from these state quantities, and a predicted value of the rotor temperature in a steady state obtained by the rotor temperature calculation means and the rotor temperature increase. The actual temperature of the rotor is predicted based on the predicted temperature rise value due to the negative sequence current obtained by the value calculation means, and this predicted value is compared with the allowable temperature value to determine the generator output so that the rotor temperature does not exceed the allowable value. The present invention is configured to include output control means for determining the generator output and controlling the generator output from the relationship between the generator output and the field winding temperature of the rotor at that time.

(Function) The effective value of the generator's continuous negative sequence withstand capability is the temperature of the generator's rotor in its steady state plus the temperature rise due to negative sequence current, which is equal to the temperature allowed by the material of the rotor. If the rotor temperature in a steady state can be lowered, the negative sequence withstand capability of a generator can be increased accordingly. The rotor temperature in a steady state is determined by the relationship between generator loss and cooling capacity, and if the cooling capacity is constant, it can be achieved by reducing generator loss.

Therefore, in the generator output control device configured as described above, the rotor temperature is predicted and calculated from the negative sequence current and various state quantities, the generator output that does not exceed the rotor's allowable temperature is determined, and the By controlling the generator output, power factor, etc. in relation to the machine output and the temperature of the rotor field winding, it is possible to increase the negative phase withstand capacity. In other words, by controlling the generator output, power factor, etc. according to the magnitude of the negative sequence current, it is possible to operate the generator beyond the negative sequence current allowable value, which is the standard value (EC-114), and the power generation It is possible to perform outlet control that expands the operating range of the machine.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the configuration of a generator output control device according to the present invention. In FIG. 1, reference numeral 1 denotes a power transmission system, to which the output end of a generator 4 driven by a turbine is connected via a main transformer 3 and a breaker 2. In FIG. Further, the neutral points of the output windings of each of the three phases of the generator 4 are connected to a neutral point grounding device 6. 7 is a voltage transformer for detecting the output voltage of the generator 4, and 10 is a current transformer for detecting the output current. In addition, 8 is an input circuit that takes in the output voltage of the generator M4''4 detected by the instrument transformer 7 and the output current of the generator 4 detected by the current transformer UO, and 9 is taken in by this input circuit 8. A rotor temperature calculation circuit calculates a predicted value of the rotor temperature in a steady state based on the output voltage and output current detection signals of the generator 4. Furthermore, 11 is a rotor temperature calculation circuit that calculates the predicted value of the rotor temperature in a steady state based on the output voltage and output current detection signals of the generator 4. input circuit, 1
2 is a negative sequence current calculation circuit that calculates a negative sequence current based on the output current of the generator 4 taken into this input circuit 11; This is a rotor temperature rise value calculation circuit that predicts and calculates a child temperature rise value. Further, 18 is a rotor field winding temperature calculation circuit into which the temperature detection signal of the rotor field winding 5 of the generator 4 detected by the temperature detector 17 is inputted, and calculates the rotor field winding temperature; 15 is a rotor allowable temperature setting device for setting the allowable temperature of the rotor.

On the other hand, the output control circuit receives the output signals of the rotor temperature calculation circuit 9, the rotor temperature rise value calculation circuit 13, the rotor allowable temperature setting device 15, and the rotor field winding temperature calculation circuit 18, respectively. The output control circuit 14 calculates the generator output at which the rotor temperature does not exceed the allowable value based on the relationship with the rotor allowable temperature, and calculates the generator output at that time and the generator output command value 16 from the outside if there is one. The generator output is set based on the relationship between the command value and the field winding temperature determined by the rotor field winding temperature calculation circuit 18, and the generator output is controlled via the output circuit 19.

Next, the operation of the generator output control device configured as described above will be described with reference to the flowchart shown in FIG. Assuming that the generator 4 is in operation, the output voltage of the generator 4 at that time is detected by the instrument transformer 7, and the output current is detected by the current transformer 10, and these are the inputs of various legal quantities. It is input to the rotor temperature calculation circuit 9 through the circuit 8. This rotor temperature calculation circuit 9 calculates a predicted temperature value of the rotor 5 in a steady state, and inputs it to the output control circuit 14. On the other hand, the detection signal of the output current of the generator 4 is transmitted from the current transformer IO through the current input circuit 11 to the negative phase current calculation circuit 1.
2, the negative sequence current flowing through the generator 4 is determined and provided to the rotor temperature rise value calculation circuit 13. The rotor temperature rise value calculation circuit 13 calculates a predicted rotor temperature rise value due to the negative sequence current, and inputs the predicted rotor temperature rise value to the output control circuit 14.

In this output control circuit 14, when the predicted value of the rotor temperature in the steady state and the predicted rotor temperature rise value are taken in in step S1 of the flow shown in FIG. 2, the actual predicted rotor temperature is calculated in step S2. At the same time, in step S4, the generator maximum output at which the rotor temperature does not exceed the permissible value is calculated based on the relationship with the rotor permissible temperature set value taken in from the rotor permissible temperature setting device 15 in step S3. and,
In step S5, the generator output A at that time, the command value B if there is a generator output command value 16 from the outside, and the field winding temperature calculated by the rotor field winding temperature calculation circuit 18. Based on the relationship with C, a comparison is made to determine whether the output is to be increased, the current level maintained, or within the output range, and the generator output is set in step S6.

By setting the generator output in this way, the generator output will be automatically controlled so that the temperature of the generator rotor does not exceed the allowable value even when the negative sequence current increases. It is possible to perform control over an expanded operating range.

In the above embodiment, the output voltage and output current of the generator are supplied to the rotor temperature calculation circuit 8 in a steady state through the input circuit 8 for inputting various parameters. As shown, an input section 8A that takes in the output voltage and output current of the generator, and an input section 8B that takes in the refrigerant flow rate, refrigerant temperature, and refrigerant pressure of the generator are provided.

By taking into account the refrigerant condition in addition to the generator output conditions through 8B, it is possible to calculate changes in the generator rotor temperature when the refrigerant conditions change, allowing for more precise generator output control. becomes possible.

In addition, the present invention can be implemented with various modifications without changing the gist thereof.

[Effects of the Invention] As described above, according to the present invention, the rotor temperature is predicted and calculated from the negative sequence current and various state quantities, and the allowable rotor temperature, generator output, rotor field winding temperature, etc. Since the generator output, power factor, etc. are controlled based on the following relationships, it is possible to provide a generator output control device that can perform control over a wider operating range of the generator.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing one embodiment of a generator output control device according to the present invention, FIG. 2 is a flowchart for explaining the operation of the same embodiment, and FIG. 3 is a diagram showing an embodiment of a generator output control device according to the present invention. It is a block diagram of the various legal quantity input circuit and the rotor predicted temperature calculation circuit part in the Example. 4... Generator, 5... Rotor field winding, 7-0. −=Instrument transformer, 8... Various input circuits, 9... Rotor temperature calculation circuit, 10... Current transformer, 11 Current input circuit, 12... Negative sequence current calculation circuit, 13
...Rotor temperature rise value calculation circuit, 14...
... Output control circuit, 15 ... Rotor permissible temperature setting device, 16 ... External output command value, 17 ...
...Rotor field winding temperature detector, 18...Rotor field winding temperature calculation circuit, 19...Output circuit.

Claims (1)

[Claims] Negative sequence current calculation means that takes in the output current of the generator and calculates a negative sequence current flowing through the generator from this current, and a negative sequence current of the rotor of the generator from the negative sequence current calculated by the negative sequence current calculation means. a rotor temperature rise value calculation means for calculating a predicted temperature rise value according to the method; and a rotor temperature calculation means for taking various state quantities of the generator and calculating a predicted value of the rotor temperature of the generator in a steady state from the various state quantities. , the actual temperature of the rotor is predicted based on the predicted steady-state rotor temperature value obtained by the rotor temperature calculation means and the predicted temperature rise value due to the negative sequence current obtained by the rotor temperature rise value calculation means. Then, compare this predicted value with the allowable temperature value to determine the generator output that does not cause the rotor temperature to exceed the allowable value. 1. An output control device for a generator, comprising an output control means for controlling output.