Excitation adjusting circuit

Abstract

The utility model provides an excitation adjusting circuit, comprising a power unit used for converting an alternating current into a direct current and controlling an output voltage; the control unit is used for executing a control algorithm and generating a control signal; the signal interface unit is used for realizing electrical isolation and signal conditioning; the protection unit is used for monitoring the running state of the system and triggering a protection action under an abnormal condition; wherein the control unit is electrically connected with the power unit, the signal interface unit and the protection unit.

Description

[Technical Field]

[0001] This utility model relates to the field of power system control technology, specifically to an excitation regulation circuit for a generator excitation system. [Background Technology]

[0002] The generator excitation system is one of the key devices ensuring the normal operation of the generator. Its main function is to provide DC excitation current to the generator rotor and control the generator terminal voltage and reactive power output. Existing excitation regulation devices typically include power conversion units, control units, and protection units, but they have the following problems: signal transmission between the power unit and the control unit is susceptible to electromagnetic interference, affecting the stability and reliability of the system. The system integration is low, with functional modules scattered, which is not conducive to equipment miniaturization and maintenance. [Utility Model Content]

[0003] In view of this, this application provides an excitation regulation circuit that solves the problems of signal transmission being susceptible to interference, insufficient control accuracy, single protection function, and low system integration in the existing excitation regulation devices.

[0004] This application provides an excitation regulation circuit, including:

[0005] The power unit is used to convert AC power to DC power and control the output voltage;

[0006] The control unit is used to execute control algorithms and generate control signals;

[0007] The signal interface unit is used to implement electrical isolation and signal conditioning; and

[0008] The protection unit is used to monitor the system's operating status and trigger protection actions in abnormal situations;

[0009] The control unit is electrically connected to the power unit, the signal interface unit, and the protection unit.

[0010] The power unit includes: a rectifier bridge for converting alternating current to direct current; a thyristor for controlling the output voltage; a current transformer for measuring current; and a voltage transformer for measuring voltage; wherein the output terminal of the rectifier bridge is connected to the input terminal of the thyristor, the output terminal of the thyristor is connected to the excitation winding via the current transformer, and the voltage transformer is connected in parallel to the output terminal of the thyristor.

[0011] The control unit includes: a microprocessor for executing control algorithms; an analog-to-digital converter for converting analog signals into digital signals; a digital-to-analog converter for converting digital signals into analog signals; and a memory for storing programs and data; wherein the microprocessor is connected to the analog-to-digital converter, the digital-to-analog converter, and the memory via a data bus.

[0012] The input terminal of the analog-to-digital converter is connected to the voltage transformer and current transformer of the power unit to receive voltage and current signals; the output terminal of the digital-to-analog converter is connected to the thyristor of the power unit to output control signals.

[0013] The signal interface unit includes: an opto-isolator for electrical isolation; and a signal conditioning circuit for signal amplification and filtering; wherein the opto-isolator is connected between the control unit and the external device, and the signal conditioning circuit is used to process signals entering and exiting the opto-isolator.

[0014] The protection unit includes: an overvoltage protection circuit; an overcurrent protection circuit; and a loss-of-magnetism protection circuit; wherein the overvoltage protection circuit, the overcurrent protection circuit, and the loss-of-magnetism protection circuit are connected in parallel at the output terminal of the power unit and send protection signals to the control unit.

[0015] The excitation regulation circuit further includes: a power supply circuit for providing operating power to the control unit, the signal interface unit, and the protection unit; a communication interface for enabling data exchange with external devices; a human-machine interface for displaying the system operating status and receiving operation commands; a cooling system for dissipating the heat generated by the power unit; and a housing for housing and protecting the various units of the excitation regulation circuit.

[0016] The communication interface includes an RS485 interface and an Ethernet interface; the human-machine interface includes an LCD screen and buttons; the cooling system includes a radiator and a fan.

[0017] The excitation regulation circuit further includes: a demagnetizing switch for controlling the on / off state of the excitation magnetic field; a generator terminal voltage detection circuit for monitoring the generator terminal voltage; a system voltage detection circuit for monitoring the system voltage; a manual control circuit for enabling central control manual and local manual operation; and a status indication circuit for indicating the system's operating status and fault information; wherein the demagnetizing switch, the generator terminal voltage detection circuit, the system voltage detection circuit, the manual control circuit, and the status indication circuit are all electrically connected to the control unit.

[0018] The status indication circuit includes: rectifier fault indicator, demagnetizing switch status indicator, excitation fault indicator, demagnetization indicator, PSS activation indicator, forced excitation indicator, leading phase indicator, air stop indicator, and PT disconnection indicator; wherein, the on / off state of the indicator lights is controlled by the control unit according to the system operating status.

[0019] This application has the following technical effects:

[0020] 1. Electrical isolation and signal conditioning are achieved through the signal interface unit, which effectively improves the system's anti-interference capability and signal transmission quality.

[0021] 2. The use of a high-performance microprocessor and a precise digital-to-analog converter improves the real-time performance and accuracy of the control algorithm, enabling it to better adapt to rapidly changing power grid conditions.

[0022] 3. Multiple protection circuits are set up, including overvoltage, overcurrent and loss of magnetism protection, which comprehensively improves the safety and reliability of the system.

[0023] 4. The highly integrated design integrates all functional modules into one circuit, achieving miniaturization and ease of maintenance of the device.

[0024] 5. Equipped with multiple communication interfaces and human-machine interaction interfaces, facilitating remote monitoring and on-site operation of the system.

[0025] 6. The addition of a demagnetizing switch, voltage detection circuit, and manual control circuit further enhances the system's flexibility and controllability.

[0026] 7. A status indicator circuit is used to intuitively display the system's operating status and fault information, facilitating rapid diagnosis and troubleshooting. [Attached Image Description]

[0027] Figure 1a The overall structural block diagram of the excitation regulation circuit provided in the embodiment of this utility model;

[0028] Figure 1b A schematic diagram of the excitation regulation circuit provided in an embodiment of this utility model;

[0029] Figure 1c A schematic diagram of the excitation regulation circuit provided for an embodiment of this utility model;

[0030] Figure 1d An external structural diagram of the excitation regulation circuit provided in an embodiment of this utility model;

[0031] Figure 2 A schematic diagram of the circuit structure of the power unit provided in an embodiment of this utility model;

[0032] Figure 3This is a block diagram of the internal structure of the control unit provided in an embodiment of the present utility model;

[0033] Figure 4 A schematic diagram of the circuit structure of the signal interface unit provided in an embodiment of this utility model;

[0034] Figure 5 A schematic diagram of the circuit structure of the protection unit provided in an embodiment of this utility model;

[0035] Figure 6 A connection diagram of the status indication circuit provided in an embodiment of this utility model.

Detailed Implementation Methods

[0036] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and is not to be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0037] It should be understood that the steps described in the method embodiments of this utility model may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of this utility model is not limited in this respect.

[0038] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to". The term "connection" can refer to a direct connection or an indirect connection via intermediate components (elements). The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Definitions of other terms will be given in the following description.

[0039] It should be noted that the concepts of "first" and "second" mentioned in this utility model are only used to distinguish between devices, modules or units, and are not used to limit these devices, modules or units to necessarily be different devices, modules or units, nor are they used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0040] Example 1

[0041] The specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0042] Figure 1a This is a block diagram of the excitation regulation circuit. (Example) Figure 1aAs shown, the excitation regulation circuit provided by this utility model includes a power unit, a control unit, a signal interface unit, and a protection unit. These units work together to complete the control and protection functions of the generator excitation system.

[0043] like Figure 1a As shown, the circuit includes: a power unit for converting AC power to DC power and controlling the output voltage; a control unit for executing control algorithms and generating control signals; a signal interface unit for achieving electrical isolation and signal conditioning; and a protection unit for monitoring the system operating status and triggering protection actions in abnormal situations; wherein the control unit is electrically connected to the power unit, the signal interface unit, and the protection unit.

[0044] Figure 1b This is a schematic diagram of the excitation regulation circuit, mainly involving the control and monitoring of the excitation system. The components and their connections are shown below:

[0045] Power supply section: including control bus (+WC, -WCL), AC power supply (QA1), etc.

[0046] Voltage monitoring section: The generator terminal PT is used to monitor the generator terminal voltage, including U-phase voltage, V-phase voltage, etc.

[0047] Switches and protection components (i.e. protection units): circuit breakers (QF), demagnetizing switches (KM2), and related protection devices such as fuses (FU).

[0048] Control section (i.e., control unit): includes various buttons and switches, such as SB33, SB22, SB55, etc., used to control different operations.

[0049] Signal output section (i.e., signal interface unit): such as signal output (COM2), used to output various status signals. The working principle is roughly as follows: the terminal voltage is monitored by the terminal PT, and the control bus provides power to the system. AC power supplies the system with AC power; signals such as the disappearance of DC power (735) and AC power (733) are monitored and fed back accordingly. The demagnetizing switch controls the on / off state of the excitation magnetic field, and the circuit breaker position nodes (61, 62) monitor the status of the circuit breaker. Various buttons and switches are used to implement different control operations such as central control manual and local manual, including central control magnetization, central control magnetization demagnetization, start-up, and fan stop. Simultaneously, the system also monitors and protects against rectifier faults (737), excitation faults, loss of magnetization, and forced excitation, and provides feedback through signal output. The specific working principle requires detailed analysis based on the actual circuit connections and system requirements.

[0050] The definitions, functions, or roles of each parameter are described below:

[0051] +WCL, -WCL: Control bus, providing control power to the system.

[0052] KM2: Field deactivation switch, used to control the on / off state of the excitation magnetic field to protect the generator and excitation system.

[0053] Closing bus: Provides power during closing operation.

[0054] Circuit: Indicates the connection path of a circuit.

[0055] Terminal PT: Voltage transformer, used to measure the voltage at the terminal, including U-phase voltage, V-phase voltage, etc., to provide voltage monitoring data for the system.

[0056] COM2: Signal output port, used to output various status signals of the system.

[0057] +WC: Another part of the control bus.

[0058] QA1: AC power input point, providing AC power to the system.

[0059] 60FU, SB5, FU602: Fuses and manual switches used to protect circuits and control the switching on and off of circuits.

[0060] U-phase voltage: The U-phase voltage value measured by the PT at the generator terminal.

[0061] 733: Signal indication of AC power loss.

[0062] 735: Signal indication of DC power loss.

[0063] Automatic and separately excited: The operating modes of the excitation system. In automatic mode, the system automatically adjusts the excitation. In separately excited mode, the excitation is provided by an external power source.

[0064] Machine-end CT: Current transformer, used to measure the current at the machine end.

[0065] System PT: Used to measure the voltage of the system.

[0066] 737: Signal indication of rectifier failure.

[0067] Demagnetizing switch position: Indicates the open / closed state of the demagnetizing switch.

[0068] Central control manual, protection interlock, and machine-side manual: These are indications of the control mode, indicating whether the operation is performed via central control manual, protection interlock, or machine-side manual.

[0069] 24VG(vss): 24V DC power supply.

[0070] Local magnetization, local magnetization, central magnetization, and central magnetization are used to adjust the increase or decrease of excitation.

[0071] U-phase current, V-phase current, and W-phase current: Measured values ​​of the terminal current for each phase.

[0072] U-phase voltage, V-phase voltage, and W-phase voltage: Measured values ​​of each phase of the terminal voltage.

[0073] 747, 757, 745, 753, 755, 749, 743, 739, 751, 741: These are signals or parameters related to various condition monitoring.

[0074] Loss of excitation, phase advance, air stoppage, manual / A-type, PSS activation, excitation fault, forced excitation, rotor overvoltage, PT disconnection, manual / B-type: These are the various status indicators of the system. When these statuses occur, the corresponding indicator lights or signals will provide a prompt.

[0075] Fan: A device used for cooling or ventilation.

[0076] 771, 772, 773, 774: Parameters or indications related to control and signals.

[0077] KTL START: Power-on control signal.

[0078] TJL: Air stop control signal.

[0079] 776: This is a signal or parameter related to power-on.

[0080] 777: This is a signal or parameter related to ventilation shutdown.

[0081] 779 and 780 are parameters related to other controls or monitoring.

[0082] Circuit breaker position node: Used to monitor the position status of the circuit breaker.

[0083] Air outage (fault): Indication of air outage fault.

[0084] Leading phase: Indicates the status of the generator operating in the leading phase.

[0085] ULGYO and JX0 are parameters or signals related to system operation.

[0086] ODM, AT672, HR4, and FUSE1 are components or signals related to circuit protection or control.

[0087] Rectifier fault indicator, demagnetizing switch on indicator, demagnetizing switch off indicator, excitation fault indicator: Indicators used to visually display the corresponding faults or statuses.

[0088] Manual P line, demagnetization, SCO, PTDX0: These are signals related to control or protection.

[0089] RST starts machine A and resets machine B; RST starts machine B and resets machine A: This is used to control the switching of the working states of machine A and machine B.

[0090] Constant current, 485 communication, and serial port to the backend server: functions related to current control and communication of the excitation system.

[0091] PSS testing and PSS activation: Operations or states related to the Power System Stabilizer (PSS). In general, these parameters and components work together to control, monitor, and protect the generator excitation system, ensuring stable system operation.

[0092] Figure 1c This is the schematic diagram of the excitation regulation circuit. Figure 1c In this context, the definitions of parameters and symbols are as follows:

[0093] TAu: refers to a current transformer or current transformer.

[0094] QF: Indicates circuit breaker, used to disconnect the circuit.

[0095] G: refers to generators or other related equipment.

[0096] L602, L601, etc.: are inductive components.

[0097] RM: Resistor.

[0098] QDM: is a circuit breaker or switch.

[0099] TV: stands for voltage transformer.

[0100] X5, X6, etc.: These are terminal blocks or connectors.

[0101] +WC1 and -WC1 are the connection points for the positive and negative DC power supplies.

[0102] DC220V: Indicates a DC voltage of 220 volts.

[0103] AC380V: Indicates an AC voltage of 380 volts.

[0104] VA-11: This refers to a voltmeter or other measuring device.

[0105] TM: Transformer.

[0106] QA2, QAI, etc.: These are identifiers for circuit breakers or switches.

[0107] ILI, 1IL1, etc.: are current indicators or sensors.

[0108] SCR1, SCR2, SCR3, etc.: are silicon controlled rectifier (SCR) devices.

[0109] KM1, KM3, etc.: These are contactors.

[0110] FU1(P1)-FU3(P3): These are fuses.

[0111] KH1: This refers to a thermal relay or other protective device.

[0112] R1, R2, R3, R4, R5, etc.: represent resistors.

[0113] C11, C12, C14, C15, C16, etc.: These represent capacitors.

[0114] VD1, VD2, VD3, etc.: These represent diodes.

[0115] +24Y, VSS, etc.: These are power supply related markings.

[0116] The connections between the components are as follows:

[0117] TAu is connected to QF.

[0118] L602 is connected to components such as RM, QDM, and L601.

[0119] The connections between X5, X6 and surrounding components are not detailed.

[0120] +WC1 is connected to DC220V, -WCI, etc.

[0121] TM is connected to 609, +WC, QA2, etc.

[0122] X1 is connected to 012, 731, 11, 12, etc., and X4 is connected to QIM, BU, QDM, X2, etc.

[0123] The dual microcomputer control unit is connected to L604, X3, etc., and L604 is connected to X3, 4-20mA, X1, etc.

[0124] L603 has connections with 50w, OK, +24Y, VSS, GP2, 1HW2, HWI, etc.

[0125] 2pT3 is connected to TR1, 513 is connected to KM1, QDM, etc., and KM1 is connected to QDM, 6T3, -CL1, +ICL1, R1, ILI, etc.

[0126] 2T11 is connected to R2, 2, VD1, etc., and VD1 is connected to +24Y, YSS, etc.

[0127] 1IL1 is connected to BC, RS1, ~20mA, etc.

[0128] ILI is connected to A2N, R12, C12, K2, G2, SCR1, C11, AIN, K1, R11, etc. For example, A2N is connected to R12, C12, K2, G2, SCR1, etc.

[0129] SCR1 is connected to C11, AIN, K1, R11, etc., and R11 is connected to 5, 2, FU9, RV3, etc.

[0130] A2N is connected to K2, R16, R14, C14, C16, G2, SCR2, C15, R15, R13, etc. For example, K2 is connected to R16, R14, C14, C16, G2, SCR2, etc.

[0131] SCR2 is connected to C15, R15, R13, etc., and R13 is connected to RV4, RV5, SA2, QA3, etc.

[0132] QA3 is connected to 2122, K5, 5453, KM3, 14, KM3, etc. For example, K5 is connected to 5453, KM3, 14, KM3, etc.

[0133] DA1 is connected to SCR3, 34, 6, TR2, JA2, KM31L, L3L25L3, etc. For example, SCR3 is connected to 34, 6, TR2, JA2, KM31L, etc.

[0134] The connection relationship between components 12, 15, and 16 and their surrounding components is not clear.

[0135] 2TI|4T26T3 is connected to 2468, ①657, etc.

[0136] FU1(P1)

[0137] The connections of FU3(P3), KH1 and other components are not detailed.

[0138] The connection relationship between M and other components is not mentioned.

[0139] The connections between components R3, R4, VD2, SCR4, B, VD3, R5, C, D, E, and their surrounding components are not explicitly described in the document.

[0140] Figure 1d This is a schematic diagram of the external structure of excitation circuit-related products. In this diagram, the left side is the front view, the middle side is the internal front view, and the right side is the rear view. Specifically...

[0141] Component parameter definitions:

[0142] Excitation screen: Used to display the excitation current.

[0143] SLHL: Electrical equipment or components.

[0144] R2: is a resistor used to limit current or divide voltage.

[0145] PV1, PY2, PA1, SCR1, SCR4: These are components related to power control or regulation, such as voltmeters, ammeters, wattmeters, and thyristors.

[0146] FU1: Fuse, used to protect circuits from damage caused by overload or short circuit.

[0147] SB2 and TR5 are components such as switches or transformers.

[0148] Adjustment unit: Used to adjust excitation current or other parameters.

[0149] PWL-4C and PIL-4C are model numbers for regulators or controllers.

[0150] MCB, MCB6: Miniature circuit breakers used to protect branches of a circuit.

[0151] QDM and QK refer to circuit breakers or switches.

[0152] RV3, RV4, RV5, and VD1 are components such as rheostats and diodes.

[0153] Grounding busbar: Used for grounding to ensure electrical safety.

[0154] The excitation system generates an excitation current, which is regulated and controlled by a regulating unit. Instruments such as PV1, PY2, and PA1 are used to monitor power parameters, while components such as SCR1 and SCR4 are used to control the on / off state or magnitude of the excitation current.

[0155] The FU1 fuse protects the circuit by melting when the current exceeds the rated value to prevent damage to the circuit.

[0156] MCB and MCB6 miniature circuit breakers are used to protect branches of a circuit by disconnecting it when an overload or short circuit occurs in that branch.

[0157] Switching devices such as QDM and QK are used to control the on / off state of circuits.

[0158] RV3, RV4, RV5 and other rheostats are used to adjust the resistance value in the circuit, and VD1 diode is used for rectification or protection circuit.

[0159] A grounding busbar is used to conduct electrical charges in a circuit to the ground to ensure electrical safety.

[0160] The power unit is used to convert alternating current (AC) to direct current (DC) and control the output voltage. For example... Figure 2As shown, the power unit includes a rectifier bridge, thyristors, a current transformer, and a voltage transformer. The rectifier bridge converts the input AC to DC, and its output is connected to the input of the thyristors. The thyristors control the output voltage, and their output is connected to the excitation winding via the current transformer. The voltage transformer is connected in parallel to the output of the thyristors to measure the output voltage. This design allows the power unit to precisely control the excitation current while providing accurate voltage and current feedback signals.

[0161] Specifically, the power unit is the core component of the excitation regulation circuit, responsible for converting alternating current into controllable direct current and providing the required current to the generator's excitation winding. This application analyzes each of its components and their functions in its embodiments:

[0162] 1. Rectifier bridge:

[0163] A rectifier bridge typically consists of multiple power diodes or thyristors, employing a full-bridge rectifier circuit. Its main function is to convert the input alternating current (AC) into pulsating direct current (DC). The input terminals of the rectifier bridge are connected to an AC power source (usually the auxiliary winding of a generator or plant power), while the output terminals provide unsmoothed DC power.

[0164] 2. Thyristor:

[0165] The thyristor (also known as a silicon controlled rectifier, SCR) is connected to the output of the rectifier bridge. Its main function is to control the output voltage. By adjusting the thyristor's firing angle, the conduction time can be changed, thereby controlling the average voltage output to the excitation winding. This characteristic of the thyristor allows the power unit to quickly and accurately regulate the excitation current.

[0166] 3. Current transformer:

[0167] A current transformer is installed between the output terminal of the thyristor and the excitation winding. Its main function is to measure the current flowing to the excitation winding. The current transformer proportionally converts large currents into smaller currents, facilitating subsequent measurement and control circuitry. This current feedback signal is crucial for achieving precise current control and overcurrent protection.

[0168] 4. Voltage transformer:

[0169] A voltage transformer is connected in parallel to the output of the thyristor to measure the output voltage. It proportionally converts the high voltage to a low voltage for easy use in control circuits. This voltage feedback signal is used for voltage regulation and overvoltage protection.

[0170] 1. Alternating current is first converted into pulsating direct current by a rectifier bridge.

[0171] 2. The thyristor receives a trigger signal from the control unit and adjusts the output voltage by changing the conduction angle.

[0172] 3. The regulated DC power passes through a current transformer and is then supplied to the generator's excitation winding.

[0173] 4. The current transformer measures the current flowing to the excitation winding in real time and feeds the measurement results back to the control unit.

[0174] 5. The voltage transformer simultaneously measures the output voltage and feeds the measurement results back to the control unit.

[0175] 6. Based on these feedback signals and combined with the preset control algorithm, the control unit calculates new control quantities and continues to adjust the firing angle of the thyristor to form a closed-loop control system.

[0176] Advantages of this structural design:

[0177] 1. Precise control: By controlling the phase of the thyristor, the output voltage can be finely adjusted, thereby precisely controlling the excitation current.

[0178] 2. Fast response: Thyristors have a fast switching speed and can quickly respond to control signals, adapting to rapid changes in power grid conditions.

[0179] 3. Reliable feedback: Current transformers and voltage transformers provide accurate current and voltage feedback signals, providing a reliable basis for closed-loop control.

[0180] 4. High efficiency: Compared to using high-power resistors for voltage regulation, this structure has a higher energy conversion efficiency.

[0181] 5. Protection capability: By monitoring current and voltage, rapid overcurrent and overvoltage protection can be achieved.

[0182] The control unit is the core of the entire excitation regulation circuit, used to execute the control algorithm and generate control signals. For example... Figure 3 As shown, the control unit includes a microprocessor, an analog-to-digital converter (ADC), a digital-to-analog converter (DAC), and a memory. The microprocessor is connected to the ADC, DAC, and memory via a data bus. The input terminals of the ADC are connected to the voltage and current transformers of the power unit to receive voltage and current signals; the output terminals of the DAC are connected to the thyristors of the power unit to output control signals. This design enables rapid conversion between analog and digital signals, ensuring efficient execution of the control algorithm and precise control.

[0183] The signal interface unit is used to achieve electrical isolation and signal conditioning, improving the system's anti-interference capability. For example... Figure 4As shown, the signal interface unit includes an opto-isolator and a signal conditioning circuit. The opto-isolator connects the control unit and external devices to achieve electrical isolation; the signal conditioning circuit processes the signals entering and exiting the opto-isolator, including signal amplification and filtering. This design effectively reduces the impact of electromagnetic interference on the system and improves the quality and reliability of signal transmission.

[0184] Specifically, the signal interface unit plays a crucial role in the excitation regulation circuit, mainly consisting of two key components: an opto-isolator and a signal conditioning circuit.

[0185] a) Opto-isolator:

[0186] An opto-isolator is a device that achieves electrical isolation using the principle of photoelectric coupling. It typically consists of a light-emitting diode (LED) and a photosensitive element (such as a phototransistor or photodiode).

[0187] The input electrical signal drives the LED to light up.

[0188] The photosensitive element receives optical signals and converts them back into electrical signals.

[0189] Since signal transmission is accomplished through light, the input and output terminals are electrically completely isolated.

[0190] advantage:

[0191] Effectively blocks common-mode interference and ground loop interference.

[0192] Improve the system's anti-interference capability and electrical safety.

[0193] It allows signal transmission between circuits of different voltage levels.

[0194] b) Signal conditioning circuit:

[0195] The signal conditioning circuit is mainly responsible for processing the signals entering and exiting the opto-isolator, including the following functions:

[0196] Signal amplification: Using operational amplifiers and other devices to amplify weak signals to a suitable amplitude.

[0197] Filtering: Using low-pass filters, band-pass filters, etc., to remove high-frequency noise and interference from signals.

[0198] Level conversion: Converting signals of different voltage levels into the standard levels required by the system.

[0199] Linearization: For nonlinear sensors, signal linearization processing is performed.

[0200] Workflow:

[0201] 1. External signals first undergo preliminary processing (such as amplification and filtering) through signal conditioning circuitry.

[0202] 2. The processed signal is electrically isolated by an opto-isolator.

[0203] 3. The isolated signal undergoes further processing (such as level conversion) through the signal conditioning circuit before being transmitted to the control unit.

[0204] Advantages of this design:

[0205] Improve the signal-to-noise ratio and enhance the useful signal.

[0206] Eliminate electromagnetic interference and improve the system's anti-interference capability.

[0207] Protect the control unit from damage caused by high voltage or surge.

[0208] Improve the accuracy and reliability of signal transmission.

[0209] The protection unit is used to monitor the system's operating status and trigger protective actions in abnormal situations. For example... Figure 5 As shown, the protection unit includes overvoltage protection circuit, overcurrent protection circuit, and loss-of-magnetism protection circuit. These protection circuits are connected in parallel at the output of the power unit and send protection signals to the control unit. When an abnormal situation is detected, the protection unit can respond quickly, triggering the corresponding protection action to ensure the safe operation of the system.

[0210] Specifically, the protection unit is a key guarantee for the safe operation of the excitation system, and mainly includes overvoltage protection circuit, overcurrent protection circuit and loss of excitation protection circuit.

[0211] a) Overvoltage protection circuit:

[0212] Function: Prevents excitation voltage from exceeding safety limits and protects generator winding insulation.

[0213] The output voltage of the power unit is continuously monitored. When the voltage exceeds a preset threshold, a protection action is triggered.

[0214] Protection actions may include reducing the thyristor's firing angle and triggering the demagnetizing switch.

[0215] b) Overcurrent protection circuit:

[0216] Function: Prevents excessive excitation current and protects the power unit and generator windings.

[0217] The excitation current is monitored by a current transformer. When the current exceeds the safety limit, the protection system is triggered.

[0218] Protection actions may include limiting the firing angle of the thyristor, triggering the circuit breaker, etc.

[0219] c) Loss of excitation protection circuit:

[0220] Function: To prevent the generator from losing excitation, which could lead to loss of synchronism or other serious consequences.

[0221] Monitor the excitation current and generator terminal voltage. When an abnormal decrease or disappearance of the excitation current is detected, the protection system is triggered.

[0222] Protection actions may include triggering an alarm, activating the backup excitation system, or tripping the generator unit.

[0223] Workflow:

[0224] 1. Each protection circuit is connected in parallel to the output terminal of the power unit to continuously monitor the system's operating status.

[0225] 2. When an abnormal situation is detected, the protection circuit immediately generates a protection signal.

[0226] 3. The protection signal is sent to the control unit.

[0227] 4. The control unit executes the corresponding protection strategy based on the received protection signal.

[0228] 5. At the same time, the control unit may activate the status indicator circuit to display fault information.

[0229] Advantages of this design:

[0230] Multiple protections: Through the coordinated operation of multiple protection circuits, the system safety is fully protected.

[0231] Rapid response: Direct monitoring of key parameters enables rapid response in the early stages of a fault.

[0232] Flexible control: Protection signals are sent to the control unit, allowing for more complex protection strategies.

[0233] High reliability: Basic protection functions are implemented using hardware circuitry, ensuring that basic protection is still provided even if the control unit fails.

[0234] Through the coordinated operation of the signal interface unit and the protection unit, the excitation regulation circuit can effectively cope with various abnormal situations while ensuring signal transmission quality, greatly improving the reliability and safety of the system.

[0235] To further improve the functionality and reliability of the system, the excitation regulation circuit of this invention also includes the following components:

[0236] 1. Power supply circuit: Provides a stable power supply for the control unit, signal interface unit and protection unit to ensure the normal operation of each unit.

[0237] 2. Communication Interfaces: Includes RS485 and Ethernet interfaces for data exchange with external devices. This diverse communication interface design enhances system compatibility and scalability, facilitating data interaction with different types of monitoring systems.

[0238] 3. Human-Machine Interface: Includes an LCD screen and buttons, used to display system operating status and receive operation commands. This intuitive interaction method allows operators to easily monitor system status and make necessary operational adjustments.

[0239] 4. Cooling System: Includes a radiator and fan to dissipate heat generated by the power units. Effective heat dissipation design ensures stable system operation under high load conditions.

[0240] 5. Housing: Used to house and protect the various units of the excitation regulation circuit, improving the overall system integrity and anti-interference capability.

[0241] In addition, the excitation regulation circuit of this utility model also includes the following functional modules, which further improve the flexibility and controllability of the system:

[0242] 1. Demagnetizing switch: Used to control the on / off state of the excitation magnetic field, playing a key role when it is necessary to quickly cut off the excitation current.

[0243] 2. Generator terminal voltage detection circuit: Used to monitor the generator terminal voltage and provide accurate feedback signals for voltage regulation.

[0244] 3. System voltage detection circuit: used to monitor the system voltage and ensure the coordination between the excitation system and the grid voltage.

[0245] 4. Manual control circuit: used to realize central control manual and local manual operation, improving the system's flexibility and emergency operation capability.

[0246] 5. Status indication circuit: such as Figure 6 As shown, the system includes multiple indicator lights to indicate its operating status and fault information. These indicators include a rectifier fault indicator, a demagnetizing switch status indicator, an excitation fault indicator, a demagnetizing indicator, a PSS activation indicator, a forced excitation indicator, a leading phase indicator, a fan stop indicator, and a PT disconnection indicator. The on / off state of these indicator lights is controlled by the control unit based on the system's operating status, providing operators with intuitive system status information.

[0247] Specifically, of course, I will explain in detail how these functional modules work and their importance.

[0248] 1. Demagnetizing switch:

[0249] A demagnetizing switch is a device that quickly disconnects the excitation current. It typically consists of power semiconductor devices (such as high-power transistors or IGBTs) and control circuitry.

[0250] During normal operation, the demagnetizing switch is in the conducting state, allowing the excitation current to flow.

[0251] When it is necessary to quickly cut off the excitation current (such as in the event of a serious fault or emergency shutdown), the control signal causes the demagnetizing switch to open rapidly.

[0252] Meanwhile, the demagnetizing switch usually short-circuits the excitation winding or connects a discharge resistor to accelerate the decay of the magnetic field.

[0253] In an emergency, the excitation current can be quickly cut off to prevent generator overvoltage or loss of synchronism.

[0254] Accelerate magnetic field decay and shorten generator downtime.

[0255] Improve system security and reliability.

[0256] 2. Terminal voltage detection circuit:

[0257] This circuit typically consists of a voltage transformer (PT) and a signal conditioning circuit.

[0258] The voltage transformer converts the high voltage at the generator terminals into a low voltage signal proportionally.

[0259] The signal conditioning circuit filters, amplifies, and digitizes the signal.

[0260] The processed signal is sent to the control unit for voltage regulation calculations.

[0261] Providing accurate generator terminal voltage feedback is the foundation of closed-loop voltage control. It is used to detect voltage anomalies, such as overvoltage or undervoltage conditions.

[0262] It helps to synchronize the generator with the power grid.

[0263] 3. System voltage detection circuit:

[0264] Similar to a generator terminal voltage detection circuit, but it monitors the grid-side voltage. The grid voltage is acquired through a voltage transformer.

[0265] The signal is conditioned and then sent to the control unit.

[0266] The control unit compares the system voltage and the generator terminal voltage and adjusts the excitation current to ensure that the generator output voltage matches the grid voltage.

[0267] Used to implement automatic voltage regulation (AVR) function.

[0268] Assist in detecting power grid anomalies, such as voltage fluctuations or faults.

[0269] 4. Manual control circuit:

[0270] It includes two operation modes: central control manual and machine-side manual.

[0271] Central control manual: Send commands to the control unit via the remote console.

[0272] Manual operation at the machine site: Excitation parameters can be adjusted directly through the on-site control panel.

[0273] Manual control signals typically have higher priority than automatic control signals.

[0274] It offers flexible operating methods to adapt to different operational needs.

[0275] Provide backup control measures when the automatic control system fails.

[0276] It facilitates system debugging, testing, and manual intervention under special operating conditions.

[0277] 5. Status indication circuit:

[0278] It consists of multiple indicator lights and drive circuits, and is connected to the control unit.

[0279] The control unit controls the illumination of each indicator light based on the system status and fault information. Each indicator light represents a specific system status or fault type.

[0280] Specific indicator light functions:

[0281] Rectifier fault indicator: Indicates a fault in the rectifier section of the power unit. Field deactivation switch status indicator: Shows the on / off status of the field deactivation switch. Excitation fault indicator: Indicates a general fault in the excitation system.

[0282] Loss of excitation indicator light: indicates that the generator has lost excitation.

[0283] PSS Engagement Indicator: Indicates whether the Power System Stabilizer (PSS) is engaged.

[0284] Strong excitation indicator light: indicates that the system is in a strong excitation state.

[0285] Leading phase indicator light: Indicates that the generator is in leading phase operation mode.

[0286] Stop air indicator light: Indicates that the generator cooling system has stopped operating.

[0287] PT disconnection indicator light: indicates that there is a disconnection fault in the voltage transformer circuit.

[0288] Provides intuitive system operating status and fault information.

[0289] It helps operators quickly identify system anomalies.

[0290] It facilitates fault diagnosis and system maintenance.

[0291] The integrated application of these functional modules greatly improves the reliability, flexibility, and operability of the excitation regulation circuit. Together, they constitute a comprehensive monitoring and protection system, ensuring the safe and stable operation of the generator under various operating conditions. Through these modules, operators can fully grasp the system status and respond promptly to various abnormal situations, thereby improving the overall operating efficiency and safety of the power generation system.

[0292] In practical applications, the excitation regulation circuit of this invention operates as follows:

[0293] 1. The power unit receives AC power and converts it to DC power through a rectifier bridge.

[0294] 2. The control unit receives voltage and current feedback signals from the power unit via an analog-to-digital converter.

[0295] 3. The microprocessor executes a preset control algorithm and calculates the required control quantity based on the feedback signal and system setpoint.

[0296] 4. The control unit sends control signals to the thyristors of the power unit through a digital-to-analog converter to regulate the output voltage.

[0297] 5. The signal interface unit processes external input signals and internal output signals in real time to ensure signal isolation and conditioning.

[0298] 6. The protection unit continuously monitors the system's operating status and immediately triggers protection actions when an anomaly is detected.

[0299] 7. The status indicator circuit displays the system's operating status and fault information in real time.

[0300] 8. Operators can monitor the system status through the human-machine interface and perform manual control when necessary.

[0301] 9. The communication interface enables data exchange with external monitoring systems, facilitating remote monitoring and management.

[0302] Through the above design and operation process, the excitation regulation circuit of this utility model achieves high-precision voltage control, comprehensive system protection, flexible operation mode and user-friendly human-machine interaction, which significantly improves the reliability, stability and controllability of the generator excitation system.

[0303] These are some exemplary embodiments of the utility model. However, those skilled in the art will understand that changes can be made to these exemplary embodiments without departing from the principles or spirit of the present utility model, the scope of which is defined by the claims and their equivalents.

Claims

1. An excitation regulation circuit, characterized in that... ,include: The power unit is used to convert AC power to DC power and control the output voltage; The control unit is used to execute control algorithms and generate control signals. The signal interface unit is used to achieve electrical isolation and signal conditioning; as well as The protection unit is used to monitor the system's operating status and trigger protection actions in abnormal situations. The control unit is electrically connected to the power unit, the signal interface unit, and the protection unit.

2. The excitation regulation circuit according to claim 1, characterized in that... The power unit includes: A rectifier bridge is used to convert alternating current (AC) to direct current (DC). Thyristors are used to control output voltage. Current transformers are used to measure current; and Voltage transformers are used to measure voltage. The output terminal of the rectifier bridge is connected to the input terminal of the thyristor, the output terminal of the thyristor is connected to the excitation winding via the current transformer, and the voltage transformer is connected in parallel to the output terminal of the thyristor.

3. The excitation regulation circuit according to claim 1, characterized in that... The control unit includes: Microprocessors are used to execute control algorithms; An analog-to-digital converter (ADC) is used to convert analog signals into digital signals. A digital-to-analog converter (DAC) is used to convert digital signals into analog signals; and Memory, used to store programs and data; The microprocessor is connected to the analog-to-digital converter, the digital-to-analog converter, and the memory via a data bus.

4. The excitation regulation circuit according to claim 3, characterized in that... The input terminal of the analog-to-digital converter is connected to the voltage transformer and current transformer of the power unit to receive voltage and current signals; the output terminal of the digital-to-analog converter is connected to the thyristor of the power unit to output control signals.

5. The excitation regulation circuit according to claim 1, characterized in that... The signal interface unit includes: Opto-isolators are used to achieve electrical isolation; and Signal conditioning circuitry, used for signal amplification and filtering; The opto-isolator is connected between the control unit and the external device, and the signal conditioning circuit is used to process the signals entering and exiting the opto-isolator.

6. The excitation regulation circuit according to claim 1, characterized in that... The protection unit includes: Overvoltage protection circuit; Overcurrent protection circuit; as well as Loss of excitation protection circuit; The overvoltage protection circuit, the overcurrent protection circuit, and the loss-of-magnetism protection circuit are connected in parallel at the output terminal of the power unit and send the protection signal to the control unit.

7. The excitation regulation circuit according to claim 1, characterized in that... Also includes: A power supply circuit is used to provide operating power to the control unit, the signal interface unit, and the protection unit. A communication interface is used to exchange data with external devices. The human-computer interaction interface is used to display the system's operating status and receive operation commands; A cooling system is used to dissipate the heat generated by the power unit; as well as The housing is used to house and protect the various units of the excitation regulation circuit.

8. The excitation regulation circuit according to claim 7, characterized in that... The communication interface includes an RS485 interface and an Ethernet interface; the human-machine interface includes an LCD screen and buttons; the cooling system includes a radiator and a fan.

9. The excitation regulation circuit according to claim 1, characterized in that... It also includes: A demagnetizing switch is used to control the on / off state of the excitation magnetic field. Generator terminal voltage detection circuit, used to monitor generator terminal voltage; System voltage detection circuit, used to monitor system voltage; Manual control circuitry is used to enable both central control manual and local manual operation; and Status indicator circuit, used to indicate the operating status and fault information of the system; The demagnetizing switch, the terminal voltage detection circuit, the system voltage detection circuit, the manual control circuit, and the status indication circuit are all electrically connected to the control unit.

10. The excitation regulation circuit according to claim 9, characterized in that... The status indication circuit includes: Rectifier fault indicator, demagnetizing switch status indicator, excitation fault indicator, demagnetization indicator, PSS activation indicator, forced excitation indicator, leading phase indicator, air stop indicator, and PT disconnection indicator; The on / off state of the indicator light is controlled by the control unit according to the system operating status.

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