A backup power automatic throw-in tester

Abstract

The utility model belongs to the technical field of power system equipment, provide a spare power automatic throw-in tester, including power supply circuit, still including current power amplifier circuit, voltage power amplifier circuit, main control board, on -off value input output board and multiplex output circuit, the power supply circuit has four way power supply output, is used respectively for the power supply of current power amplifier circuit, voltage power amplifier circuit, main control board, on -off value input output board, the main control board still has the on -line communication interface through the serial port. The utility model through the circuit design of current power amplifier circuit, voltage power amplifier circuit and on -off value input output board's reasonable design, solved the existing equipment power amplifier gain and stability to be not good, the relay action in on -off value input output board has certain delay, cannot guarantee the problem of action consistency.

Description

Technical Field

[0001] This utility model belongs to the field of power system equipment technology, and in particular relates to a backup automatic transfer tester. Background Technology

[0002] Automatic transfer switch (ATS) testers are key automation devices in power systems, used to quickly and automatically switch loads to backup power sources when the main power supply fails, thus ensuring the continuity and reliability of power supply. An ATS tester is a device that includes a PT (Potential Transformer) simulator, a CT (Current Transformer) simulator, and a circuit breaker simulator. The ATS tester can simulate various main wiring configurations of a substation during operation through these key circuits, such as a typical one-and-a-half-unit wiring configuration in a 500kV substation. By switching the energized and de-energized states of each simulator, it provides detection signals and actuators to the tested object, thereby detecting and verifying whether the operating logic and blocking conditions of the tested object are consistent with expectations. Each independent energized or de-energized area in the test is called a bay, and the bay outlets are connected by circuit breakers.

[0003] The PT simulator is implemented using a voltage power amplifier circuit, the CT simulator using a current power amplifier circuit, and the circuit breaker simulator using a digital input / output board. As the technical requirements of power systems gradually increase, the circuit design of current automatic transfer switch (ATS) testers still has some problems: such as insufficient gain and stability of the voltage and current power amplifiers, and a certain delay in the operation of the relays in the digital input / output board, making it impossible to guarantee consistent operation. Utility Model Content

[0004] In view of the above problems, the purpose of this utility model is to provide a backup automatic transfer tester, which aims to solve the above-mentioned technical problems existing in the circuit design of the existing backup automatic transfer tester.

[0005] The present invention adopts the following technical solution:

[0006] The automatic transfer switch tester includes a power supply circuit for connecting to mains power, as well as a current amplifier circuit, a voltage amplifier circuit, a main control board, a digital input / output board, and a multiplexed output circuit. The power supply circuit has four power outputs, which are used to power the current amplifier circuit, the voltage amplifier circuit, the main control board, and the digital input / output board, respectively. The main control board is also connected to an online communication interface via a serial port.

[0007] The beneficial effects of this utility model are as follows: This utility model, through the reasonable design of the current power amplifier circuit, voltage power amplifier circuit, and switch input / output board circuit design, wherein the power supply circuit mainly uses a power transformer to supply power, avoiding high-frequency noise of high-power switching power supplies, the voltage power amplifier circuit adopts multi-stage amplification to effectively improve gain, the current power amplifier circuit adopts push-pull method and proportional-integral control to achieve the effect of fast tracking and elimination of steady-state error, and the switch input / output board adopts accelerated engagement method to reduce the action delay of relays and improve their action consistency. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the automatic switching tester provided by this utility model.

[0009] Figure 2 This is a circuit diagram of the voltage power amplifier circuit provided by this utility model.

[0010] Figure 3 This is a circuit diagram of the current amplifier circuit provided by this utility model.

[0011] Figure 4 This is a circuit diagram of the input circuit provided by this utility model.

[0012] Figure 5 This is a circuit diagram of the switching output circuit provided by this utility model. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this utility model patent clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the scope of the present utility model.

[0014] To illustrate the technical solution described in this utility model, specific embodiments are described below.

[0015] For ease of explanation, only the parts relevant to the embodiments of this utility model are shown.

[0016] Combination Figure 1 As shown, the automatic transfer switch tester includes a power supply circuit for connecting to mains power, as well as a current amplifier circuit, a voltage amplifier circuit, a main control board, a digital input / output board, and a multiplexed output circuit. The power supply circuit has four power outputs, which are used to power the current amplifier circuit, the voltage amplifier circuit, the main control board, and the digital input / output board, respectively. The main control board is also connected to an online communication interface via a serial port.

[0017] The power supply circuit primarily uses a power transformer to avoid interference from the high-frequency noise of high-power switching power supplies on the small signals of the main board and the output of downstream voltage and current amplifier circuits. This results in low voltage and current output interference, good stability, and high accuracy. The secondary winding of the power transformer has four outputs, which are connected to the current amplifier circuit, voltage amplifier circuit, main control board, and digital input / output board, respectively. Of the four outputs, except for the main control board, the other three use rectifier and filter circuits. Specifically, a bridge rectifier converts the input AC power into unidirectional pulsating DC power; then, a capacitor filter network is used to filter out the AC component in the pulsating DC power, making the output voltage smoother and more stable, providing a high-quality DC power supply for subsequent circuits. Several key circuits are described below.

[0018] (1) A specific structure of a voltage power amplifier circuit

[0019] like Figure 2 As shown, the voltage power amplifier circuit structure consists of four DC-coupled amplifier stages, where the first stage uses operational amplifiers, the second stage uses differential amplifiers, the third stage uses transistor amplifiers, and the fourth stage uses a hybrid transistor-MOS amplifier.

[0020] The first stage of amplification includes operational amplifier U1. The output terminal of operational amplifier U1 is connected to the negative terminal of the input terminal of U1 through capacitor C1 and resistor R12. The positive terminal of the input terminal of U1 is grounded.

[0021] The two-stage amplifier includes two identical transistors Q1 and Q2. The positive power supply is connected to the negative power supply through resistor R14 and transistor Q1, and simultaneously through resistor R15 and transistor Q2. The positive power supply is connected to the negative power supply through resistor R16. The base of transistor Q1 is connected to the output of operational amplifier U1. The output of the voltage amplifier circuit is connected to the base of transistor Q2 after voltage division through resistors R18 and R17. The collector of transistor Q1 serves as the output.

[0022] The three-stage amplifier includes transistor Q3. The positive power supply is connected to the negative power supply through resistor R19, transistor Q3, and resistor R10. The emitter of transistor Q3 serves as the output.

[0023] The four-stage amplifier includes transistors Q4 and Q6, and MOSFETs Q5 and Q7 connected in parallel with diodes. The positive power supply is connected to the output of the voltage amplifier circuit through transistor Q4, resistor R111, and in parallel through MOSFET Q5. There is a resistor R112 between the emitter of transistor Q4 and the gate of MOSFET Q5. The negative power supply is connected to the output of the voltage amplifier circuit through resistor R114, transistor Q6, and in parallel through resistor R115 and MOSFET Q7. There is a resistor R113 between the collector of transistor Q6 and the gate of MOSFET Q7.

[0024] The output of the voltage power amplifier circuit is also connected to the negative input terminal of the operational amplifier U1 through the feedback resistor R13.

[0025] The voltage amplifier circuit outputs a voltage analog interval energized within the normal operating range of the voltage transformer. For example, 0-120V is exactly 120% of the voltage of a 100V voltage transformer, which is the upper limit of the system voltage allowable. In practical applications, a multi-channel voltage amplifier circuit can be built in, and the output can be selected through a multiplexed output circuit.

[0026] This voltage amplifier circuit is a high-voltage, low-frequency power amplifier circuit with a push-pull structure. The upper half amplifies the positive half-cycle, and the lower half amplifies the negative half-cycle. Following the signal flow, the voltage amplifier circuit can be viewed as a four-stage DC-coupled amplifier, achieving high-gain amplification. In the circuit diagram, the voltage outer loop negative feedback precisely controls the accuracy and dynamic response of the output voltage. The two-stage differential amplifier circuit (built with high-voltage transistors) performs level shifting to ensure correct signal transmission; the circuit's output uses voltage division as its negative feedback. The third-stage amplifier amplifies the signal power, improving the output drive capability. The fourth-stage amplifier is a follower stage combining BJTs (bipolar junction transistors) and MOSFETs, achieving low-impedance output and enhancing load capacity.

[0027] (2) A specific structure of a current power amplifier circuit

[0028] like Figure 3 As shown, the current amplifier circuit includes a preamplifier circuit, a high-power push-pull circuit, and a current negative feedback loop.

[0029] The preamplifier circuit includes operational amplifier U2. The output terminal of operational amplifier U2 is connected to the negative terminal of input terminal U2 through capacitor C2 and resistor R22. The positive terminal of input terminal U2 is grounded.

[0030] The high-power push-pull circuit includes transistors Q8-Q11. The positive power supply passes through resistor R24, transistor Q8, and resistor R26, and simultaneously through transistor Q9 and resistor R27, then through resistor R212 to the output terminal of the high-power push-pull circuit. There is a resistor R25 between the collector of transistor Q8 and the base of transistor Q9. The negative power supply passes through resistor R211, transistor Q10, and resistor R28, and simultaneously through transistor Q11 and resistor R29 to the output terminal of the high-power push-pull circuit. There is a resistor R210 between the collector of transistor Q10 and the base of transistor Q11.

[0031] The current negative feedback loop includes operational amplifier U3 and resistor R23. The positive and negative input terminals of operational amplifier U3 are connected to the two ends of resistor R212, respectively, and the output terminal of operational amplifier U3 is connected to the negative input terminal of operational amplifier U2 through resistor R23.

[0032] The CT simulator uses a current amplifier circuit to replace the output of the current transformer (CT) in a power system, simulating the working load of a live bus during the test. The rated secondary current of the CT is 1A or 5A, and the output range of the amplifier (0-6A) can simulate light and heavy load conditions of the power grid. In the power-off state, there is no voltage and no current in the corresponding bay.

[0033] This circuit is a precision current power amplifier circuit with negative feedback control, combining a pre-amplifier and a high-power push-pull amplifier structure to achieve high-precision, high-current power output. The current negative feedback loop samples the output current IOUT, compares it with the input signal to form negative feedback, ensuring the accuracy and stability of the output current, achieving fast tracking and eliminating steady-state error. The final high-power push-pull amplification stage is implemented using high-power transistors. The current output of the current amplifier circuit is sent to a multiplexed output circuit for output selection.

[0034] (3) A specific structure of a digital input / output board

[0035] The digital input / output board includes a digital input circuit and a digital output circuit.

[0036] like Figure 4 As shown, the input circuit includes an internal power supply, an input terminal, and an input detection circuit. The input detection circuit includes an optocoupler U4. The input terminal of the optocoupler U4 is connected to the main board I / O port of the main control board. The output terminal of the optocoupler U4 is connected in parallel with a resistor R3. One end of the resistor R3 is connected to the input terminal through a diode D2, and the other end is connected to the input terminal through the resistor R4 and the internal power supply. The input terminal forms an output.

[0037] like Figure 5 As shown, the switching output circuit includes a relay instantaneous impulse power supply, a control circuit, and a power supply for maintaining operation. The instantaneous impulse power supply is connected in series with a resistor R9 and a diode D1, followed by a capacitor C3 in parallel. A switch is also shown in the diagram. The control circuit includes transistors Q12 and Q13, diodes D3 and D4, a resistor R10, and a relay RL2. The positive terminal of the power supply is maintained through resistor R10, transistors Q13 and Q12 to the negative terminal. Simultaneously, the positive terminal of the power supply is maintained through diode D3, the parallel diode D4, and the relay RL2, connected to the collector of transistor Q12. Furthermore, the two ends of capacitor C3 are connected to the parallel diode D4, one end of relay RL2, and the emitter of transistor Q12.

[0038] In practical applications, relays are used to simulate the status feedback of power system circuit breakers, and the operating logic is specified by software as either positive or negative logic. Positive logic means that when the relay is closed, the circuit breaker is in the closed position, and when it is open, the circuit breaker is in the tripped position. Conversely, the opposite is true. Each simulated circuit breaker consists of two output signals, two input signals (connected to trip and close signals respectively), and status indicator lights.

[0039] The input circuit is isolated by an optocoupler. The optocoupler excitation shares the internal power supply of the device. The optocoupler receives command signals from the motherboard I / O port and connects the internal power supply to the input terminal.

[0040] The instantaneous surge power supply is 20% higher than the relay's rated operating voltage. When the relay trips, energy is stored in capacitor C3 for backup. The operating power supply remains closed, with the voltage between the release voltage and the rated voltage, typically the rated voltage.

[0041] The operation of the digital output circuit is as follows: When the CR signal (base of Q13) is low, the switch of the acceleration power supply can be periodically (e.g., 1kHz) closed, allowing the high-voltage capacitor C3 to be fully charged and ready for use. Due to the isolation effect of the diode, the operating power supply remains unaffected. When CR is high, the relay coil conducts through the Darlington transistors (Q12, Q13), and the high-voltage power supply forms a drive circuit through the coil, causing the relay to quickly engage. Simultaneously with the relay engaging, due to the latching effect of CR, the charging switch of the acceleration capacitor C3 is quickly turned off, preventing the coil from being subjected to prolonged high-voltage surges. When the voltage of the acceleration capacitor drops to maintain the voltage, the relay coil is powered by the closed maintenance power supply, ensuring safe operation.

[0042] This accelerated engagement operation reduces the relay's operating delay and improves its operational consistency. In this operating mode, the voltage across the accelerating capacitor switches between the sustaining voltage and the accelerating voltage. The transient surge power supply can also directly replenish the capacitor with high voltage without pulse charging. Since the capacitor has no additional discharge path, its stored energy can be maintained for a long time after the transient surge power supply is disconnected; only the capacitor's self-attenuation needs to be replenished at appropriate times.

[0043] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A self-starting tester, characterized in that: The system includes a power supply circuit for connecting to mains power, a current amplifier circuit, a voltage amplifier circuit, a main control board, a digital input / output board, and a multiplexed output circuit. The power supply circuit has four power outputs, which are used to power the current amplifier circuit, the voltage amplifier circuit, the main control board, and the digital input / output board, respectively. The main control board is also connected to an online communication interface via a serial port. The voltage amplifier circuit is composed of a four-stage DC-coupled amplifier, where the first stage uses an operational amplifier, the second stage uses a differential amplifier, the third stage uses a transistor amplifier, and the fourth stage uses a hybrid transistor-MOSFET amplifier. The first stage of amplification includes operational amplifier U1. The output terminal of operational amplifier U1 is connected to the negative terminal of the input terminal of U1 through capacitor C1 and resistor R12. The positive terminal of the input terminal of U1 is grounded. The two-stage amplifier includes two identical transistors Q1 and Q2. The positive power supply is connected to the negative power supply through resistor R14 and transistor Q1, and simultaneously through resistor R15 and transistor Q2. The positive power supply is connected to the negative power supply through resistor R16. The base of transistor Q1 is connected to the output of operational amplifier U1. The output of the voltage amplifier circuit is connected to the base of transistor Q2 after voltage division through resistors R18 and R17. The collector of transistor Q1 serves as the output. The three-stage amplifier includes transistor Q3. The positive power supply is connected to the negative power supply through resistor R19, transistor Q3, and resistor R10. The emitter of transistor Q3 serves as the output. The four-stage amplifier includes transistors Q4 and Q6, and MOSFETs Q5 and Q7 connected in parallel with diodes. The positive power supply is connected to the output of the voltage amplifier circuit through transistor Q4, resistor R111, and in parallel through MOSFET Q5. There is a resistor R112 between the emitter of transistor Q4 and the gate of MOSFET Q5. The negative power supply is connected to the output of the voltage amplifier circuit through resistor R114, transistor Q6, and in parallel through resistor R115 and MOSFET Q7. There is a resistor R113 between the collector of transistor Q6 and the gate of MOSFET Q7. The output of the voltage power amplifier circuit is also connected to the negative input terminal of the operational amplifier U1 through the feedback resistor R13.

2. The automatic switching tester as described in claim 1, characterized in that: The current amplifier circuit includes a preamplifier circuit, a high-power push-pull circuit, and a current negative feedback loop. The preamplifier circuit includes operational amplifier U2. The output terminal of operational amplifier U2 is connected to the negative terminal of input terminal U2 through capacitor C2 and resistor R22. The positive terminal of input terminal U2 is grounded. The high-power push-pull circuit includes transistors Q8-Q11. The positive power supply passes through resistor R24, transistor Q8, and resistor R26, and simultaneously through transistor Q9 and resistor R27, then through resistor R212 to the output terminal of the high-power push-pull circuit. There is a resistor R25 between the collector of transistor Q8 and the base of transistor Q9. The negative power supply passes through resistor R211, transistor Q10, and resistor R28, and simultaneously through transistor Q11 and resistor R29 to the output terminal of the high-power push-pull circuit. There is a resistor R210 between the collector of transistor Q10 and the base of transistor Q11. The current negative feedback loop includes operational amplifier U3 and resistor R23. The positive and negative input terminals of operational amplifier U3 are connected to the two ends of resistor R212, respectively, and the output terminal of operational amplifier U3 is connected to the negative input terminal of operational amplifier U2 through resistor R23.

3. The automatic switching tester as described in claim 2, characterized in that: The digital input / output board includes a digital input circuit and a digital output circuit.

4. The automatic switching tester as described in claim 3, characterized in that: The input circuit includes an internal power supply, an input terminal, and an input detection circuit. The input detection circuit includes an optocoupler U4. The input terminal of the optocoupler U4 is connected to the main board I / O port of the main control board. The output terminal of the optocoupler U4 is connected in parallel with a resistor R3. One end of the resistor R3 is connected to the input terminal through a diode D2, and the other end is connected to the input terminal through a resistor R4 and the internal power supply. The input terminal forms an output.

5. The automatic switching tester as described in claim 4, characterized in that: The switching output circuit includes a relay instantaneous impulse power supply, a control circuit, and a power supply for maintaining operation. The instantaneous impulse power supply is connected in series with a resistor R9 and a diode D1, followed by a capacitor C3 in parallel. The control circuit includes transistors Q12 and Q13, diodes D3 and D4, a resistor R10, and a relay RL2. The positive terminal of the power supply is maintained through resistor R10, transistors Q13 and Q12 to the negative terminal. Simultaneously, the positive terminal of the power supply is maintained through diode D3, the parallel diode D4, and the relay RL2, connected to the collector of transistor Q12. The two ends of capacitor C3 are connected to the parallel diode D4, one end of the relay RL2, and the emitter of transistor Q12.

Images