WO2003041263A1 - Switching power supply excitation system for synchronous generator - Google Patents

Abstract

The present invention adopts Superpower Switching Power Supply in stead of AC exciter, auxiliary exciter and SCR, so that the excitation current of the generator is independent of both the power network voltage and the generator terminal voltage. Consequently, the generator runs with high stability through providing an instaneous response to and sufficient damping of the output voltage fluctuation. Meanwhile, Remote Terminal Detection means is adopted to automatically stabilize the voltage at the far end of the power network. And semiconductor parts are adopted in stead of mechanical switch to compose an automatic collapsing magnet circuit. The excitation system as a whole has the advantages of being simple in structure, excellent in function, small in size, light in weight, cheap in cost and suitable for using in not only moderate and low power synchronous generator but also large capacity synchronous generator, such as at the stage of million KW.

Description

 TECHNICAL FIELD

 The present invention relates to generator technology, and in particular, to a separately excited static excitation system for a synchronous generator. Background technique

 The excitation system is an important part of the generator set. It includes control equipment and automatic devices that supply the generator's excitation current and its circuits. In the event of a power system failure or other transient state, the operating state of the generator set is largely related to the excitation system. Especially in recent years, the single-unit capacity and transmission distance have been increasing, and the excitation system has higher requirements. The excitation system has a greater impact on the stability of power operation and the reliability of the generator set itself. The excitation system should have an independent excitation power source, not affected by the external power grid, and should have high reliability to facilitate automatic control. The ceiling voltage of the excitation should be high and the rising speed should be fast. It can meet the stable operation of the generator set and power system. It is required that the structure and wiring of the device should be simple, which is convenient for arrangement and operation and maintenance.

 The following analyzes several situations to further illustrate the key role of the excitation system on the generator set: the speed of forced excitation and voltage rise: when the generator set voltage drops to a certain limit, the strong excitation circuit is started, and its role is to quickly Increase the potential of the generator set and speed up the voltage recovery process after a fault, prevent excessive increase of the power angle of the generator set when it is disturbed, and improve the working stability of the power system. Practice has proved that this is an extremely important measure to improve the working stability of the power system. In terms of improving the stability of the system, it is hoped that the higher the peak voltage after the strong excitation operation, the better, and the faster the excitation voltage rise speed, the better, but the improvement of these two items is limited by the structure and cost of the exciter. According to the technical standards of JB636-65 and JB863-66, the excitation ceiling voltage is 1.8-2.0 times, and the voltage rising speed is 1.3-2.0 times.

 Forced demagnetization due to voltage rise during hydro-generator load shedding: When hydro-generator load shedding, the water flow through the turbine is not interrupted, so its speed will increase a lot, and the output voltage of the generator will increase even more. many. In order to ensure the safe operation, the 7-wheel generator set should have the function of forced demagnetization to prevent over-voltage. When the voltage rises to a certain value, the forced demagnetization function works to make the excitation voltage rapidly decay and prevent endangering the safety of insulation.

 Deactivation of the generator set voltage must be demagnetized. The requirements for demagnetization are:

 1. Demagnetization time is as short as possible;

 2. The overvoltage of the rotor during demagnetization should not exceed the allowable value;

 3. The residual magnetization after demagnetization should not be sufficient to maintain a short-circuit arc.

In the separately excited semiconductor excitation circuit, the current and temperature of the rotor are inconvenient to measure, and a deactivation device cannot be added. The requirements for semiconductor components and their protection components are too high, and the control system is complicated. In the self-excited semiconductor excitation circuit, In the case of a three-phase short-circuit of a generator set, the generator set loses its excitation. When an asymmetric short-circuit occurs, the excitation voltage will change dramatically, which makes the excitation in a very unfavorable condition. The semiconductor element here is actually a thyristor. When it is used as a controllable rectifier, the current waveform is seriously distorted, causing harmonic pollution to the power grid, and greatly reducing the power factor.

 With the development of the power system, especially after the direct cooling of the generator set, the single-unit capacity rapidly increased, and the excitation capacity increased sharply. The excitation capacity of the 200,000-kilowatt turbo-generator set was 600 kW, and the excitation current at full load was close to 2000 amps. It's even bigger during strong encouragement. Under the high-speed rotation of the steam turbine, it is very difficult to manufacture such a large DC excitation motor due to the limitation of commutation rectification. Even for low-speed hydro-generator sets, DC-excited motors are difficult to meet the requirements for the peak excitation voltage and voltage rise speed due to high-voltage long-distance transmission. At present, the only way to solve this problem at home and abroad is to use semiconductor rectifier excitation. The method is: use thyristor rectification to provide the excitation current to the auxiliary exciter, and then the auxiliary exciter provides the excitation current to the AC exciter. Only provide the excitation current to the generator.

 Figure 1 is a separately excited static semiconductor excitation system. JL and JFL are AC exciter and auxiliary exciter, respectively. The excitation coils LJ and LIF are provided by thyristor three-phase full-wave rectifier circuits TSCR1, TSCR2 and TSCR3. JL passes The three-phase full-wave rectifier bridge TBR3 supplies an excitation current to the excitation winding L of the large-scale generator F. Because the exciter has a thyristor load, its output waveform changes variably, which makes the generator set unstable and the reactive power swing is large. Since the input power of the entire excitation system must be provided by the AC voltage, the generator cannot start power generation without AC voltage. Summary of the Invention

 The purpose of the present invention is to overcome the shortcomings of the above-mentioned various excitation circuits, and use an ultra-high-power DC converter to connect to a non-inverter uninterruptible power supply circuit form. The excitation current of the output voltage changes in the opposite direction and has nothing to do with the output voltage of the generator. This current can be rapidly increased, reduced and interrupted quickly according to the requirements of forced excitation, forced de-excitation and de-excitation, and can be automatically stabilized. Voltage magnitude at any remote ground.

 In order to achieve the above object, the present invention provides a synchronous generator switching power supply excitation system, which uses an ultra-high power DC converter SHC1 and SHC2 connected to form a non-inverter uninterruptible power supply circuit directly to the excitation winding of the synchronous generator F L01 provides excitation current with a voltage change range of 5-100%; replaces mechanical demagnetization with a thyristor deactivation circuit, and establishes several detection points at the far end of the power grid. The remote signal enters the remote signal control circuit through an automatic telecontrol system. .

The said excitation system constitutes a single-phase full-wave current circuit BR1 and BR2 without an inverter and an uninterruptible power supply. The full-wave current circuits TBR1 and TB 2 are replaced, and the switching power supplies SW1 and SW2 are replaced by ultra-high-power DC converters SHC1 and SHC2.

 In the excitation system, the thyristor deactivation circuit is composed of thyristors SCR02-SCR04, D01, R02, R03, and C03. After D01 and R02 are connected in series, they are connected in parallel with the excitation winding L01, and after being connected in parallel, they are connected in series with SCR02 and then connected in parallel. To the output terminal of SHC2, R03, SCR04, and SCR03 are also connected in parallel to the output terminal of SHC2 after connecting in series. The negative terminals of SCR02 and SCR03 are connected to the negative terminal of SHC2. One terminal of R03, the negative terminal of D01, and the other terminal of L01 are connected to the positive terminal of SHC2, and SCR04. The negative terminal is connected to the positive terminal of SCR03 and the positive terminal of C03, and the other end of L01 is connected to the positive terminal of SCR02 and the negative terminal of C03.

 In the excitation system, each remote detection signal is sent back in the form of a telemetry value through an automatic remote control system, and after being restored to an analog quantity, it enters a remote signal control circuit. The remote signal control circuit is composed of a detection circuit and a trigger circuit.

In the excitation system, the detection circuit is composed of n + 2 detection channels, the first channel is composed of a resistor R12 and a transistor D46 in series, R12 is connected to the emitter of the transistor Q3, and the negative electrode of D46 is connected to the output signal terminal VReg2 _{; the} rest n + The structure of 1 channel is the same; the first channel is composed of optocoupler OPT8, transistor Q18, timing circuit U7 and its surrounding components. The anode of OPT8's light-emitting tube is connected to the input signal terminal capacitor C007 positive electrode through resistor R114, and its cathode passes The potentiometer VR17 is connected to the C00 negative electrode, and the collector of the OPT8 triode is connected to + 17V, and its emitter is grounded through the resistor R113, and at the same time connected to the base of Q18; the collector of Q18 is connected to + 17V, and its shovel is grounded through the resistor R112. Resistors R116 and R117 are connected to U7-2 and U7-6 respectively. Resistor R115 and diode D41 are connected in series. R115 is connected to the emitter of Q18. The negative electrode of D41 is connected to the output signal terminal V eg2; U7-1 is grounded, U7-5 is grounded through capacitor C80 U7-4 and U7-8 are connected to + 5V, U7-2 and U7-6 are connected to ground through potentiometers VR19 and VR18 respectively, and the output of U7-3 is connected to the signal terminal AutoKillO; the input of the second channel is connected to the signal terminal Remotel and the output is connected to Signal end AutoKilll, its Flat and so on.

In the excitation system, the trigger circuit is composed of TTL circuits U13-U17, three driving circuits with the same structure, and switching power supply SW5-SW8; the pull-up resistors R163-R170 are connected to pins 1-6 and 11-12 of U13, and U13-1 Connect U15-5, U13-2 to AutoKillO, U13-3 to AutoKilll, and so on, U13-8 to U16-3, U16-4 to output signal SWOfi2, SWOffi to U3-7, and U13-8 to U16- l, U17-5, U17-2; U14-3 and U14-4 are connected, reset switch S4 and capacitor C87 are connected in parallel, one end is connected to U14-3, and the other end is grounded. U14-3, U14-5, U14-11 pass through Resistors Rl 60, R16K, R156 are connected to + 5V, U14-11 is also connected to U14-10 through capacitor C86, U14-6 is connected to U15-3; U15-1 is connected to + 5V through resistor R158, grounded through capacitor C39, and U15-4 is connected through resistor R157 is connected to + 5V, U15-6 is connected to U15-2, resistor R155 is connected to U17-1 and U17-4, and the other end is connected to + 5V; the anode of the optocoupler OPT13 is connected to the input signal terminal U17-3 through the resistor R146. The cathode is grounded through the potentiometer VR32, OPT13 The collector of the triode is connected to the positive electrode of SW5, and its emitter is connected to the output signal terminal G2 through the resistor R145, and is also connected to the base of the transistor Q23. The collectors of the transistors Q23 and Q24 are connected to the positive electrode of SW5. Their emitters are connected through the resistors R144 and R143. Connect the output signal G2, and the negative pole of SW5 is connected to K2; the other two channels have the same structure. The input signal of the second channel is connected to U17-6, the output signal is connected to G4, and the negative electrode of SW6 is connected to K4. The input signal of the third channel is connected to U15. -2, the output signal is connected to G3, and the negative pole of SW7 is connected to K3.

 The large-scale synchronous generator excitation system uses an ultra-high-power DC converter (application number: 01128301.7). SHC1 and SHC2 are connected to a non-inverter uninterruptible power supply (application number: 97241194.1) in the form of a circuit to generate an uninterrupted excitation current. The specific method is: The output terminal of SHC2 is connected to the field winding, and the input terminal is connected to the two DC inputs of the battery and the rectifier TBR2. The detection circuit reflects the change of the generator output voltage or the remote voltage. SHC2 adjusts the voltage according to this change and changes the entry. The current of the exciting winding makes the output voltage of the generator or the voltage at the far end of the grid tend to be stable. When the detection circuit senses the forced excitation signal, SHC2 outputs a ceiling voltage with a certain rising speed to the exciting winding according to the requirements, so that the generator enters the strong excitation. State, when the detection circuit senses the forced demagnetization signal, SHC2 outputs a negative top voltage with a certain falling speed to the field winding according to the requirements, so that the generator enters a forced demagnetization state. When the detection circuit senses the local or remote demagnetization signal, on the one hand, SHC2 is turned off, and on the other hand, SCR03 is turned on, so that the induced voltage on the field winding is quickly discharged through R02 for advanced demagnetization.

 An inverter-free uninterruptible power supply can provide a stable, uninterrupted DC voltage to the load. The voltage compensation method is used. The method is: superimpose a low and adjustable DC voltage (that is, the compensation voltage) on the fluctuating input voltage to form a stable output voltage, and the power of the compensation voltage only accounts for less than 10% of the output power. Obviously, the adjustment range of the output voltage of the non-inverter power supply is 90-100%, which is far from meeting the requirements of the adjustment range of the excitation voltage of 10-100%. Therefore, the output voltage of SHC2 is no longer superimposed on the input voltage and is directly output. To the excitation winding of the generator, its adjustment range can theoretically reach 100%

 Since the present invention eliminates the AC exciter, the auxiliary exciter and the thyristor rectifier circuit, it replaces an inverter-free uninterruptible power supply composed of a super-high-power DC converter, and because the switching power supply is inherent to the thyristor rectifier circuit, The advantages of the invention and the non-electrical characteristics of the uninterruptible power supply, the present invention has the following characteristics:

 1. The top voltage of forced excitation and the rising speed of the voltage can be made very large, which greatly improves the stability of the grid operation;

 2. Incorporate the generator output voltage into the closed-loop control of the power grid to make the generator run stably, adjust the output voltage fluctuations smoothly, respond quickly, and greatly improve the power supply quality of the power grid;

 3. The remote detection method is adopted, which can automatically adjust the voltage amplitude at any remote end of the power grid to further improve the power supply quality.

4. The switching power supply is stable and reliable, the remote detection circuit is fast and accurate, and the advanced demagnetization is crisp and sharp, which greatly improves The safety of power grid operation;

 5. Since the switching power supply can directly input DC, the excitation system of the generator is completely independent of the grid voltage and the output voltage of the generator;

 6. Since the Tongguan power supply is used to replace the large exciter, auxiliary exciter and thyristor rectifier circuit, the invention has a simple structure, excellent performance, small size, light weight, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

 Figure 1 is a circuit diagram of a separately excited semiconductor excitation system;

 FIG. 2 is a principle block diagram of the present invention;

 Figure 3 is a schematic diagram of thyristor demagnetization;

 Figure 4 is a schematic diagram of an inverter-free uninterruptible power supply circuit;

 Figure 5 is a three-phase rectifier circuit TBR1 and TBR2;

 Figure 6 is a circuit schematic diagram of the high-power DC converters HSW1 and HSW2;

⁷ is a detection circuit of a remote signal control circuit;

 Fig. 8 is a driving circuit of a remote signal control circuit. detailed description

 FIG. 2 is a principle block diagram of the present invention. The super-high-power DC converters SHC1 and SHC2 are connected into a transformer uninterruptible power supply circuit form, replacing the main exciter JL and auxiliary exciter JFL, and the controllable rectifier circuits TSCR1 and TSCR2 (please (Refer to FIG. 1), directly provide the excitation winding L01 of the synchronous generator F with an excitation current with a supply voltage ranging from 5 to 100%; replace the mechanical demagnetization with a thyristor deactivation circuit, and set up several detection points at the far end. The remote signal enters the remote signal control circuit through the automatic remote control system.

 Single-phase full-wave current circuits BR1 and BR2, which constitute an inverter-free uninterruptible power supply, are replaced by three-phase full-wave rectifier circuits TBR1 and TBR2 (refer to Figure 5), and switching power supplies SW1 and SW2 are replaced by super-high-power DC converters SHC1 and SHC2. Replace (see Figure 4).

 The de-excitation circuit in Figure 3 is composed of SCRs SCR02-SCR04, D01, R02, R03 and C03. After D01 and R02 are connected in series, they are connected in parallel with the field winding L01, after being connected in parallel, they are connected in series with SCR02, and then connected to the output terminal of SHC2. R03, SCR04, and SCR03 are also connected in parallel to the output of SHC2. The negative electrodes of SCR02 and SCR03 are connected to the negative electrode of SHC2. One end of R03, the negative electrode of D01, and one end of L01 are connected to the positive electrode of SHC2. The negative electrode of SCR04 and the positive electrode of SCR03. And the positive end of C03 is connected, the other end of L01 is connected to the positive end of SCR02 and the negative end of C03.

Each remote detection signal is sent back in the form of a telemetry value through an automated telecontrol system. After being restored to an analog quantity, Enter the remote signal control circuit. The remote signal control circuit is composed of a detection circuit and a trigger circuit, (refer to Figure 3) o

The detection circuit in Figure 7 consists of n + 2 detection channels. The first channel is composed of a resistor R12 and a transistor D46 connected in series, R12 is connected to the emitter of transistor Q3, and the negative electrode of D46 is connected to the output signal terminal VReg2 _{; the} remaining n + 1 channels The structure is the same: the first channel is composed of the photocoupler OFT8, the transistor Q18, the timing circuit U7 and its surrounding components. The anode of the OPT8 light-emitting tube is connected to the positive end of the input signal capacitor C00 through the resistor R114, and the cathode is passed through the potentiometer VR17. Connect to C00 negative pole, the collector of OPT8 triode part is connected to + 17V, its fiber pole is connected to ground via resistor R113, and the base of Q18 is connected at the same time; the collector of Q18 is connected to + 17V, and its emitter is connected to ground via resistor R112, through resistors R116, R117 is connected to U7-2 and U7-6, resistor R115 and diode D41 are connected in series, R115 is connected to the emitter of Q18, and the negative of D41 is connected to the output signal terminal VReg2 _; U7-1 is connected to the ground, U7-5 is connected to the ground through the capacitor C80, and U7-4 U7-8 is connected to + 5V, U7-2 and U7-6 are grounded through potentiometers VR19 and V18 respectively, and U7-3 output is connected to signal terminal AutoKillO; the input of the second channel is connected to signal terminal Remotel, and the output is connected to signal terminal AutoKilll , The remaining channels use this Push.

 The trigger circuit in Figure 8 consists of TTL circuits U13-U17, three drive circuits with the same structure, and switching power supplies SW5-SW8; resistors R163-R170 are connected to pins 1-6 and 11-12 of U13, and U13-1 is connected to U15-5 U13-2 to AutoKillO, U13-3 to AutoKilll, and so on, U13-8 to U16-3, U16-4 to output signal SWOffi, SWOfi2 to U3-7, U13-8 to U16-1, U17- 5. U17-2; U14-3 and U14-4 are connected, the reset switch S4 and capacitor C87 are connected in parallel, one end is connected to U14-3, and the other end is grounded. U14-3, U14-5, and U14-11 are connected through resistors R160 and R161, respectively. R156 is connected to + 5V, U14-11 is also connected to U14-10 through capacitor C86, υΐΦ6 is connected to U15-3; U15-1 is connected to U16-6 through resistor R158, grounded through capacitor C89, U15-4 is connected to + 5V through resistor R157, U15-6 is connected to U15-2, resistor R155 is connected to U17-1 and U17-4, and the other end is connected to + 5V; the anode of the optocoupler OPT13 light-emitting tube is connected to the input signal terminal U17-3 through the resistor R146, and the cathode is connected to the potentiometer VR32 The collector of the OPT13 transistor is connected to the positive electrode of SW5, and the emitter is connected to the output signal terminal G2 through the resistor R145, and is also connected to the base of the transistor Q23, and the transistors Q23 and Q24. The collector is connected to the positive pole of SW5, and their emitters are connected to the output signal G2 through resistors R144 and R143, and the negative pole of SW5 is connected to K2; the other two channels have the same structure. The input signal of the second channel is connected to U17-6, and the output signal is connected to G4. The negative electrode of SW6 is connected to K4; the third input signal is connected to U16-2, the output signal is connected to G3, and the negative electrode of SW7 is connected to K3.

The output of the ultra-high-power DC converter SHC2 is connected to the excitation winding L01 of the generator F, the input is connected to two DC inputs, one is the battery E01, the other is the rectifier filter TBR2, and the detection circuit of the SHC2 is connected to the generator output and remote detection signal. The detection circuit reflects the changes in the generator output voltage and the remote voltage. SHC2 adjusts the voltage according to this change to change the current entering the exciting winding L01, so that the generator output voltage or remote voltage When the detection circuit senses the forced excitation signal, SHC2 outputs a ceiling voltage with a certain rising speed to the excitation winding according to the requirements, so that the generator enters the strong excitation state. When the detection circuit senses the forced demagnetization signal, SHC2 According to the requirements, a negative peak voltage with a certain falling speed is output to the field winding, so that the generator enters a forced demagnetization state. The output terminal of the ultra-high-power DC converter SHC1 charges the battery pack E01, and the input terminal is connected to the rectifier filter TBR1. Its detection circuit is connected to the terminal voltage of the battery. SHC1 performs fast and floating charging on E01, so that it is always in the best state. Ensure that SHC2 has sufficient DC input power with or without AC voltage. Even if the generator has a three-phase short circuit or an asymmetric short circuit, the generator set will not lose its excitation and the excitation voltage will not change.

 The working process of the de-excitation circuit is as follows: When the excitation system is started, SCR04 and SCR02 are first turned on, so SHC2 injects the excitation current to L01 through SCR02. At the same time, SHC2 charges the capacitor C03 through R03 and SCR04. When the voltage across C03 is charged, When it is equal to the voltage on L01, the charging current is zero and SCR04 is automatically turned off. When the detection circuit senses the near-earth or far-field demagnetization signal, the SHC2 is turned off, the current is prohibited from entering L01, and the SCR03 is turned on at the same time, so that the positive voltage on C03 is added to the cathode of SCR02, so SCR02 is turned off, and the exciting winding L01 is turned off. Disconnected from SHC2. Because the current on the inductor cannot be abruptly changed, the current on L01 is quickly discharged through R02 and D01, leading to leading demagnetization. The size of R02 can be selected according to the specific requirements of demagnetization. The smaller the R02, the faster the discharge and the faster the demagnetization.

 The working process of the excitation system is as follows: When generator F has not yet generated power, B3 has no output, and only the battery E01 DC power supply. After the DC voltage is added, the switching power supply SW5-SW8 has a DC output. After power-on, a positive transition voltage is generated in U14-3. This positive transition voltage has no effect on U14, because pins 3 and 4 of the 74LS121 are pulsed. The falling edge works. This positive transition voltage causes U16C to output a negative transition voltage, which causes U15A to reset. The low level of U15-5 output causes U13-8 to output a high level. Because U17-1 and U17-4 are connected to + 5V through R155, U17-3 and U17-6 output a high level, and U16-2 outputs a low level. As a result, the driving circuits of G2 and G4 are turned on and the driving circuit of G3 is turned off. Therefore, SCR02 and SCR04 are turned on and SCR03 is turned off. It can be seen that an exciting current flows through the exciting winding L01, and F starts to generate electricity. During the generation of F, SHC2 detects the output voltage of F and automatically controls the excitation current injected into L01, so that the generation voltage tends to be stable. U17A and U17B are redundant gates to prevent the risk and competition of logic circuits, so that the triggering signals of the thyristors can arrive at the same time.

In the detection channel of the detection circuit, when the input terminal voltage rises, the voltage at its VReg2 output terminal also rises accordingly. The n + 2 output signals are ORed here. As a result, the That channel signal controls the excitation current injected into L01. Adjusting the potentiometer at the input end, such as the cathode potentiometer VR17 of the OPT8 LED in the second channel, can adjust the voltage output to VReg2. Channel 1 is an original detection channel of the uninterruptible uninterruptible power supply. Its detection input is the terminal voltage of the field winding L01. The detection input of channel 2 is the output voltage of the generator F. It is taken from both ends of the capacitor C00. The rest The n detection input signals are Remitel- emoten, detects the voltage values of the n remote ground power grids. Generally, the voltage output from channel 2 to VReg2 is adjusted slightly higher, so that the output voltage of generator F is used to directly control the excitation current injected into L01.

 When the output voltage of generator F rises, VReg2 becomes high, which makes the detection voltage entering SHC2 become rampant. Due to the feedback control, the output voltage of SHC2 decreases and the exciting current injected into L01 becomes smaller. The output of generator F The voltage is reduced, thereby automatically stabilizing the output voltage of F.

 Although the remaining n + 1 control signals output to VReg2 are adjusted lower, when the voltage at a remote end is suddenly too high due to an unexpected event, the voltage is sufficient to make this output to VReg2 higher than the second. Then the current channel rises to be the main character controlling the injection of the exciting current of L01. When the voltage of this channel returns to normal, the voltage output to VReg2 is lower than that of the second channel. This control method can ensure that the voltages at the n remote ends of the power grid are not too high.

 The timing circuit NE555 in the N + 1 detection channels closely monitors the level of the control signal from the emitter of the transistor. Once it exceeds the set range, its output signal AutoKill goes high, making the output level of U12-8 low. When SWOffi is high, the output voltage of SHC2 is turned off, U17-3 and U17-6 are changed at the same time, and SCR02 and SCR04 are turned off, that is, the exciting current injected into L01 is cut off. At the same time, U16-2 goes high, turning on SCR02 and starting the demagnetization process. Adjust the potentiometers connected to pins 2 and 6 of NE555, you can adjust the voltage range of automatic demagnetization. Switch S4 is a manual manual demagnetization in an emergency. When S4 is pressed, a negative transition signal is generated at U14-3. This signal causes U16-6 to output a high level. This high level causes U15 to flip and U15. The output of -5 changes from low to high, and the output of U13-8 changes to low, so that U17-3 and U17-6 output low, and U16-2 and U16-4 output high, and the demagnetization program is started. After the negative transition voltage generated on U14-3 passes U16C, it becomes a positive transition voltage. Since the reset terminal of 74LS74 is a negative pulse transition, the action of reset switch S4 does not affect the state of U15.

 Due to the good transient response characteristics of the switching regulator power supply, forced excitation and forced demagnetization are no longer a problem and can only be used for normal adjustment.

If the excitation power is calculated as three-thousandths of the output power of the generator set, the excitation power of the 1 million kilowatt-class synchronous generator set is 3000 kilowatts, and the excitation current at full load operation is close to 10,000 amps. The bridge circuit in SHC2 can use Germany's Siemens SKM500GA123D or Japan's Fuji MBI600PX-120, with a rated voltage of 1200 V and a rated current of 500A and 600A. Four connected bridge circuits can output 200KW, and 16 bridges are connected in parallel. Running, you can output 3000KW rated power. The high-frequency transformer uses H7C1 5KW magnetic cores, 40 magnetic cores are divided into four groups, each group is assembled into a high-frequency transformer, each transformer has 10 H7C1 5KW magnetic cores, and the turns ratio is 1: 1 after the winding is made, four The transformer is connected in series at the primary and the secondary. After three-phase full-wave rectification and filtering, the voltage is 600VDC, the output voltage is 300VDC, the duty cycle is about 0.6, and the output power is 200KW. It is just matched with one of the above-mentioned bridge circuits. The parallel point of the 16 bridge circuits is at the CC point in the figure, and the PWM control chip is shared. There are independent driving and inverter circuits, and the total output power can reach more than 3000KW. SHC1 is used to charge the battery E01. If calculated based on the output of 10000A, the charging current is 2000A. Because the charging voltage is the superposition of the rectified and filtered voltage and the output voltage of SHC1, its output power is: P = 3000X0.2X 0.1 = 60KW. Therefore, SHC1 only needs one of the above-mentioned bridge circuits. (For details, refer to the ultra-high-power DC converter: 01128301.7) . .

 In addition to the synchronous generator switching power supply excitation system applied to 1 million KW class generators, it can also be applied to the excitation of small and medium power synchronous generators. The advantages are obvious.

Claims

Rights request 1. A synchronous generator switching power supply excitation system, which is characterized in that: a high-power DC converter SHC1 and SHC2 are connected to form a non-inverter uninterruptible power supply circuit to directly supply voltage to the exciting winding L01 of the synchronous generator F The variation range is 5-100% of the excitation current; the mechanical demagnetization is replaced by a thyristor deactivation circuit, and several detection points are set up at the far end of the power grid. The remote signal enters the remote signal control circuit through the automatic remote control system.  2. The excitation system according to claim 1, characterized in that: the single-phase full-wave current circuits BR1 and BR2 constituting an inverter-free uninterruptible power supply are replaced by three-phase full-wave current circuits TBR1 and TBR2, and the switching power supplies SW1 and SW1 and SW2 is replaced by super high-power DC converters SHC1 and SHC2.  3. The excitation system according to claim 1, wherein the thyristor deactivation circuit is a thyristor SCR02- SCR04, DOl, R02, R03 and C03 are composed. D01 and R02 are connected in series with the field winding L01 in parallel, then connected in parallel with SCR02, and then connected to the output of SHC2. R03, SCR04, and SCR03 are also connected in parallel to SHC2 The output terminals of SCR02 and SCR03 are connected to the negative terminal of SHC2. One terminal of R03, the negative terminal of D01, and the positive terminal of L01 are connected to the positive terminal of SHC2. The negative terminal of SCR04 is connected to the positive terminal of SCR03 and the positive terminal of C03. The other terminal of L01 is connected to SCR02. Connect the positive terminal of C03 and the negative terminal of C03.  4. The excitation system according to claim 1, characterized in that: each remote detection signal is sent back in the form of a telemetry value through an automatic remote control system, and after being restored to an analog quantity, it enters a remote signal control circuit, and the remote signal The control circuit is composed of a detection circuit and a trigger circuit.  5. The excitation system according to claim 4, characterized in that the detection circuit is composed of n + 2 detection channels, the first channel is composed of a resistor R12 and a transistor D46 in series, R12 is connected to the wrong pole of the transistor Q3, and D46 The negative electrode is connected to the output signal terminal VReg2; the structure of the remaining n + 1 channels is the same; the first channel is composed of the optocoupler OPT8, the transistor Q18, the timing circuit U7, and its surrounding components. The anode of the OPT8 light-emitting tube is connected through the resistor R114. Input signal terminal capacitor C007 positive electrode, its cathode is connected to C00 negative electrode through potentiometer VR17, the collector of OPT8 triode part is connected to + 17V, its emitter is connected to ground via resistor R113, and the base of Q18 is connected at the same time; the collector of Q18 is connected to + 17V , Its emitter is grounded through resistor R112, and resistors R116 and R117 are connected to U7-2 and U7-6, resistor R115 and diode D41 are connected in series, R115 is connected to the emitter of Q18, and the negative electrode of D41 is connected to the output signal terminal VReg2; U7-1 Ground, U7-5 is connected to ground through capacitor C80, U7-4 and U7-8 are connected to + 5V, U7-2 and U7-6 are connected to ground through potentiometers VR19 and VR18 respectively, and U7-3 output is connected to signal terminal AutoKillO; second An input terminal connected to the signal path Remotel, an output signal terminal connected AutoKilll, so the rest of the channel. 6. The excitation system according to claim 4, characterized in that: the trigger circuit is composed of TTL circuits U13-U17, three driving circuits of the same structure, and switching power supplies SW5-SW8; the pull-up resistors R163-R170 are connected to U1-1- 6 With pins 11-12, U13-1 to U15-5, U13-2 to AutoKillO, U13-3 to Auto illl, and so on, U13-8 to U16-3, U16-4 to output signal SWOffi, and SWOffi to U3 -7, U13-8 is connected to U16-1, U17-5, U17-2 at the same time; U14-3 is connected to U14-4, reset switch S4 is connected in parallel with capacitor C87, one end is connected to U14-3, and the other end is grounded, U14-3 , U14-5, U14-11 are connected to + 5V through resistors R160, R161, and R156 respectively. Ul 4- 11 is also connected to U14-10 through capacitor C86, U14-6 to U15-3; U15-1 to + 5V through resistor R158. Connect to ground via capacitor C39, U15-4 to + 5V through resistor R157, U15-6 to U15-2, resistor R155 to U17-1 and U17-4, and the other end to + 5V; the anode of the optocoupler OPT13 light-emitting tube passes The resistor R146 is connected to the input signal terminal U17-3. Its cathode is grounded through the potentiometer VR32. The collector of the OPT13 transistor is connected to the positive electrode of SW5. Its emitter is connected to the output signal terminal G2 through the resistor R145. At the same time, it is connected to the base of transistor Q23 and transistor Q23. The collector of Q24 is connected to the positive electrode of SW5, their emitters are connected to the output signal G2 through resistors R144 and R143, and the negative electrode of SW5 is connected to K2; the other two channels have the same structure, and the second input signal is terminated to U17-6, and the output The signal is connected to G4, the negative of SW6 is connected to K4; the third input signal is connected to U15-2, the output signal is connected to G3, and the negative of SW7 is connected to K3. +