JPH0745868B2 - Operation control method of turbine generator - Google Patents

Description

Description: A. Field of Industrial Application The present invention relates to a method for controlling a turbine generator, and more particularly to a method for controlling the operation of a turbine generator that facilitates control of a governor section in the turbine generator.

B. Conventional Technology Generally, in an electric governor system for a turbine generator, a vector control system of an induction motor is used as a drive system of a servo system for moving a turbine guide valve.

That is, FIG. 3 shows a conventional operation control device for a water turbine generator. In FIG. 3, 1 is a commercial power source, 2 is an auxiliary power generator for power source, 3 is a backup DC power source, 4 is a forward exchange section, 5 Is a vector control unit having an inverter 6 and a control circuit 8. 11 is an electric motor emergency control unit, 12 is an induction motor, 13 is an actuator, 14 is a guide valve, 15 is a water turbine, 16
Is a main generator driven by the water turbine 15, and 17 is an automatic voltage adjusting circuit of the auxiliary generator 2.

In order to improve the reliability of the system, the power supply system is composed of three systems: a power supply auxiliary generator 2 directly connected to the turbine, a commercial power supply 1 in the power plant, and a DC power supply (battery) 3 installed in the power plant. Normally, the auxiliary generator 2 is operated by the on-site commercial power source 1, and the DC power source 3 is an emergency backup power source when a power failure occurs in both the commercial power source 1 and the auxiliary generator 2.

Normally, the AC power of the commercial power source 1 is converted into DC power by the forward conversion unit 4, and this DC power is input to the transistor inverter unit 6 of the vector control unit 5. The inverter unit 6 converts the DC power from the forward conversion unit 4 into AC power, drives and controls the induction motor by this AC power, and thereby controls the actuator. By controlling the actuator, the guide valve 14 and the water turbine are controlled, and finally the main generator 16 is controlled. Further, according to the launch, the output power of the auxiliary generator 2 is used instead of the commercial power source 1 to execute the above-mentioned operation.

C. Problems to be Solved by the Invention Generally, the induction motor is designed for AC200V (AC200V) system in order to downsize the body and improve efficiency, and the line voltage of the induction motor at rated speed and rated output. Requires about 200V.

By the way, the maximum output voltage V _ACMAX of the inverter 6 is expressed by the equation (1).

In the case of an ordinary auxiliary generator and a commercial power source, since Edc = 280V, the inverter 6 can output 200V. However, as a DC power supply, it is usually 10
Use an on-site DC power supply of about 0V. In this case, the rated rotation speed of the induction motor 12 was disabled from the formula (1), and performance and reliability were lacking. Further, for example, when a command of rated speed is input at 105V DC, the output voltage of the inverter 6 is saturated and vector control becomes impossible. Therefore, it is necessary to prepare a backup power supply exclusively for the governor system, which reduces the cost. It was also disadvantageous.

The present invention has been made in view of the above conventional problems, and an object thereof is to use a DC drive power supply when an AC drive power supply is abnormal, and to use a DC valve drive power supply according to the voltage value of the DC drive power supply. It is an object of the present invention to provide a low-cost, highly reliable, and high-performance operation control method for a turbine generator by controlling the opening / closing of the turbine.

D. Means for Solving the Problems In order to achieve the above object, the present invention controls the driving of an AC electric motor by switching between an AC driving power supply and a DC driving power supply, and a guide valve of a water turbine by the AC motor. In a driving device for a water turbine generator configured to open and close, a power failure of the AC drive power supply is detected, and a maximum value of a speed command of the AC motor is limited according to a voltage value of the DC drive power supply. .

E. Function According to the present invention, if the AC drive power source has a power failure, it is detected and switched to the DC drive power source. The guide valve of the water turbine is fully closed by limiting the maximum value of the speed command for vector control according to the voltage value of the DC drive power source.

F. Examples Hereinafter, the present invention will be described more specifically with reference to Examples shown in FIGS. 1 and 2.

FIG. 1 shows a control device of a water turbine generator for carrying out the present invention. Reference numeral 1 is a commercial power supply of AC210V, 2 is an auxiliary power generator for the power supply, and 3 is a backup DC power supply. Here, the output voltage of the auxiliary generator 2 is AC200V, and the DC power supply 3 is DC105V. Reference numeral 4 denotes a forward converter, which is composed of a rectifier 4a for converting the electric power of the commercial power supply 1 into DC power and a rectifier 4b for rectifying the AC output of the auxiliary power generator 2. A vector control unit 5 is composed of an inverter 6, a power failure detection circuit 7, a control circuit 8 and a speed command circuit 9. The control circuit 8 has DC / DC conversion circuits 8a and 8b. Reference numeral 10 denotes a speed control unit, which has DC / DC conversion circuits 10a and 10b.

In the operating device having the above configuration, the AC power from the commercial power source is rectified by the rectifier 4a of the forward conversion unit 4, and then the inverter 6, the DC / DC conversion circuit 8a of the control circuit 8 and the speed control unit 10 are provided.
Is supplied to the DC / DC conversion circuit 10a. The speed command signal from the speed control unit 10 is supplied to the control circuit 8 via the speed command circuit 9. The inverter 6 is vector-controlled by a control signal from the control circuit 8, and the induction motor 12 is drive-controlled by its AC output. The actuator 13 is operated by the mechanical output of the induction motor 12 to open / close the guide valve 14. The rotation of the water turbine is controlled by the opening / closing operation of the guide valve 14, and the main electric motor 16 is controlled accordingly. Auxiliary generator 2
The armature 2a is mechanically connected to the rotating shaft of the main generator 16, and the AC output voltage of the auxiliary generator 2 is determined by the rotation speed of the armature 2a and the field current flowing in the field winding 2b. However, the AC output voltage of the auxiliary generator 2 is applied to the inverter 6 after being rectified by the rectifier 4b of the forward conversion unit 4 by switching the switch 18b which is set to a predetermined value by the automatic voltage adjusting circuit 17, for example, 210V. The induction motor is driven and controlled by the AC output of the inverter 6, and the above-described control operation is performed.

When a power failure occurs in both the commercial power supply 1 and the auxiliary generator 2, the power failure detection circuit 7 operates and supplies an operation command signal to the speed command circuit 9. The speed command circuit 9 limits the speed command signal from the speed control command unit 10 in response to the operation command signal from the power failure detection circuit 7, whereby a signal is issued from the control circuit 8 and power from the inverter 6 to the induction motor 12 is output. Is supplied. As a result, the actuator 13 fully closes the guide valve 14 and stops the main generator 16. Under these conditions, the switches 18a and 18b of the electromagnetic switch (not shown) are switched to the DC power source 3 side, and the DC power source 3 supplies power to the induction motor 12 via the inverter 6.

FIG. 2 shows an operation example when both the commercial power supply 1 and the auxiliary generator 2 have a power failure.

As shown in FIG. 2 (A), Edc = 280V when any of the AC power supplies is used. When both AC power supply fails, Edc = 105V. Since the rotation speed of the induction motor 12 is almost proportional to the input voltage, the maximum output speed that can be output when the DC voltage is reduced can be obtained from the following equation.

[(DC voltage to operate) / (DC voltage at rating)] x [Rated speed] (2) In the case of CD105V operation, set the speed command value to the rated value as shown in Fig. 2 (B). By limiting the output to a certain level, the output voltage is prevented from being saturated as shown in FIG. 2 (C) and the rated torque is output. Therefore, as shown in FIGS. 2 (D) and (E), the servo stroke of the actuator 13 and the opening of the guide valve 14 can be controlled to normally execute the fully closing operation of the guide valve.

According to the above-described embodiment, different power supplies such as DC105V can be used by limiting the speed setting maximum value according to the voltage value of the backup DC power supply during a power failure of the 210V AC system (DC280V). . Therefore, the DC power supply normally installed in the power plant can be used for the guide valve fully closing operation in an emergency, and it is not necessary to prepare a backup power supply exclusively for the governor system.

G. Effect of the Invention According to the present invention, a power failure of the AC drive power supply system is detected, and while switching to the DC drive power supply system, the maximum value of the speed command of the electric motor is limited according to the voltage value of the DC drive power supply system. Since the guide valve of the water turbine is controlled by using the water turbine, it is possible to obtain a low cost, high performance and highly reliable operation method of the water turbine generator.

[Brief description of drawings]

FIG. 1 is a block connection diagram of an apparatus for carrying out an operation control method for a water turbine generator according to the present invention, FIG. 2 is an operation explanatory view of the apparatus shown in FIG. 1, and FIG. 3 is a conventional operation control method for a water turbine generator. It is a block connection diagram showing. 1 ... Commercial power supply, 2 ... Auxiliary generator, 3 ... Backup DC power supply, 5 ... Vector control unit, 8 ... Control circuit, 9 ... Power failure detection circuit, 10 ... Speed control unit, 12 ...... Induction motor, 13 ...... Actuator, 14 ...... Guide valve.

Claims (1)

[Claims] 1. A driving apparatus for a water turbine generator, wherein an AC electric motor is drive-controlled by switching between an AC driving power supply and a DC driving power supply, and a guide valve of a water turbine is opened and closed by the AC electric motor. A method for controlling the operation of a water turbine generator, which detects a power failure of a power source and limits a maximum value of a speed command of the AC motor according to a voltage value of the DC drive power source.