Subway power supply system

Abstract

The utility model provides a subway power supply system, and belongs to the technical field of power supply. According to the subway power supply system, the input end of a first voltage regulation and control module is connected with a first power supply, the output end of the first voltage regulation and control module is connected with the first power supply ends of a relay K1 and a relay K3, and the second power supply ends of the relay K1 and the relay K3 are grounded; the input end of the second voltage regulation and control module is connected with a second power supply, the output end of the second voltage regulation and control module is connected with the first power supply end of a relay K2, the second power supply end of the relay K2 is connected with the first end of a relay K3, and the second end of the relay K3 is grounded; the first end of the relay K1 is connected with a first power supply, the first end of the relay K2 is connected with a second power supply, and the second end of the relay K1 and the second end of the relay K2 are used for being connected into a traction substation. Normal running of the train can be guaranteed.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of power supply, in particular to a metro power supply system. BACKGROUND

[0002] In the urban traffic framework, the metro becomes the core force to alleviate urban congestion and improve commuting efficiency due to its large capacity and high efficiency. Stable power supply is undoubtedly the cornerstone of the normal operation of the metro system.

[0003] At present, many metro power supply systems are single power supply mode. Once the power supply fails, the entire power supply network will be paralyzed, which seriously affects the operation of the metro. Even if some use double power supply, the switching mechanism is old. When the main power supply has common problems such as three-phase imbalance and open phase, it cannot quickly respond and complete power switching, resulting in a long power supply interruption time and unable to guarantee the normal running of the train. CONTENT OF THE UTILITY MODEL

[0004] The present disclosure provides a metro power supply system to ensure the normal running of the train.

[0005] The present disclosure provides a metro power supply system, comprising: a first voltage regulation module, a second voltage regulation module, a relay K1, a relay K2 and a relay K3;

[0006] The input end of the first voltage regulation module is connected to a first power supply, and the output end of the first voltage regulation module is connected to the first power supply end of the relay K1 and the relay K3, respectively. The second power supply end of the relay K1 and the relay K3 is grounded.

[0007] The input end of the second voltage regulation module is connected to a second power supply, and the output end of the second voltage regulation module is connected to the first power supply end of the relay K2. The second power supply end of the relay K2 is connected to the first end of the relay K3, and the second end of the relay K3 is grounded.

[0008] The first end of the relay K1 is connected to the first power supply, and the second end of the relay K1 is used to access the traction substation. The first end of the relay K2 is connected to the second power supply, and the second end of the relay K2 is used to access the traction substation.

[0009] The first power supply and the second power supply are both provided with a main substation.

[0010] In an exemplary embodiment of the present disclosure, the first voltage regulation module and the second voltage regulation module have the same structure, and the first voltage regulation module comprises: a first sampling unit, a second sampling unit, a third sampling unit, an addition unit, a comparison unit and a control unit.

[0011] The first power supply and the second power supply are both three-phase alternating current;

[0012] The first sampling unit, the second sampling unit and the third sampling unit are respectively used for collecting A-phase electricity, B-phase electricity and C-phase electricity;

[0013] The output ends of the first sampling unit, the second sampling unit and the third sampling unit are connected with the input end of the adding unit, the output end of the adding unit is connected with the input end of the comparison unit, the output end of the comparison unit is connected with the input end of the control unit, and the output end of the control unit is used as the output end of the first voltage regulation module.

[0014] In an exemplary embodiment of the present disclosure, the first sampling unit comprises a transformer T1, a resistor R1, a capacitor C1, a diode D1, an operational amplifier U4 and a resistor R3.

[0015] The first input end of the transformer T1 is connected with A-phase electricity of the first power supply, the second input end of the transformer T1 is connected with the zero line of the first power supply, the first output end of the transformer T1 is connected with the first end of the resistor R1, the second end of the resistor R1 is connected with the anode of the diode D1, the capacitor C1 is connected with the resistor R1 in parallel, the cathode of the diode D1 is connected with the non-inverting input end of the operational amplifier U4, the inverting input end of the operational amplifier U4 is connected with a reference voltage, the output end of the operational amplifier U4 is connected with the inverting input end of the operational amplifier U4 through the resistor R3, and the output end of the operational amplifier U4 is connected with the input end of the adding unit.

[0016] The circuit structures of the first sampling unit, the second sampling unit and the third sampling unit are the same.

[0017] In an exemplary embodiment of the present disclosure, the first sampling unit further comprises a rheostat RP1, a resistor R2, a voltage stabilizer U5 and a capacitor C5.

[0018] The first end of the rheostat RP1 is connected with the cathode of the diode D1, the second end of the rheostat RP1 is grounded through the resistor R2, the sliding end of the rheostat RP1 is connected with the input end of the voltage stabilizer U5, the grounding end of the voltage stabilizer U5 is grounded, the output end of the voltage stabilizer U5 is grounded through the capacitor C5, and the output end of the voltage stabilizer U5 is connected with the inverting input end of the operational amplifier U4.

[0019] In an exemplary embodiment of the present disclosure, the adding unit comprises a resistor R14, an operational amplifier U10 and a resistor R13.

[0020] The inverting input end of the operational amplifier U10 is connected to the output end of the operational amplifier U4, the non-inverting input end of the operational amplifier U10 is grounded through the resistor R13, the output end of the operational amplifier U10 is connected to the non-inverting input end of the operational amplifier U10 through the resistor R14, and the output end of the operational amplifier U10 is connected to the input end of the comparison unit.

[0021] In an exemplary embodiment of the present disclosure, the comparison unit comprises an operational amplifier U11 and an operational amplifier U12.

[0022] The inverting input end of the operational amplifier U11 is connected to a Vref1 reference voltage, the non-inverting input end of the operational amplifier U11 is connected to the output end of the operational amplifier U10, the non-inverting input end of the operational amplifier U11 is connected to the non-inverting input end of the operational amplifier U12, the inverting input end of the operational amplifier U12 is connected to a Vref2 reference voltage, the output end of the operational amplifier U11 is connected to the output end of the operational amplifier U12, and the output end of the operational amplifier U11 is connected to the input end of the control unit.

[0023] In an exemplary embodiment of the present disclosure, the control unit comprises a transistor Q1 and a resistor R15.

[0024] The base of the transistor Q1 is connected to the output end of the operational amplifier U11, the collector of the transistor Q1 is connected to a VDD power supply through the resistor R15, and the emitter of the transistor Q1 serves as the output end of the control unit.

[0025] The subway power supply system provided by the embodiment of the present disclosure has the beneficial effects that the double power supply and the matched voltage regulation and relay module build a high-reliability power supply system. The first voltage regulation module and the second voltage regulation module monitor the state of the power supply in real time and can quickly detect abnormalities. Under normal conditions, the first power supply is preferentially powered to ensure stable daily operation. Once the first power supply fails, such as three-phase imbalance or open phase, the voltage regulation module immediately responds to change the state of the relay and automatically switch to the second power supply to ensure uninterrupted power supply of the traction substation and thus ensure normal train operation. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 is a structural schematic diagram of a subway power supply system provided by an embodiment of the present disclosure;

[0028] Figure 2 is a structural schematic diagram of a metro power supply system provided by another embodiment of the present disclosure.

[0029] Figure 3 is a circuit diagram of a first voltage regulation module provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0030] In order for those skilled in the art to better understand the present scheme, the technical solutions in the embodiments of the present scheme will be clearly described below in conjunction with the accompanying drawings in the embodiments of the present scheme. Obviously, the described embodiments are part of the embodiments of the present scheme, rather than all the embodiments. Based on the embodiments in the present scheme, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present scheme.

[0031] The terms "include", and other any variations thereof, in the specification and claims of the present scheme and the above-mentioned accompanying drawings, refer to "include but not limited to", and are intended to cover non-exclusive inclusion, and are not limited to the examples listed in the text. In addition, the terms "first" and "second" and the like are used to distinguish different objects, rather than to describe a specific order.

[0032] The implementation of the present disclosure is described in detail below in conjunction with specific accompanying drawings:

[0033] Figure 1 is a structural schematic diagram of a metro power supply system provided by an embodiment of the present disclosure. Referring to Figure 1 The metro power supply system comprises a first voltage regulation module, a second voltage regulation module, a relay K1, a relay K2 and a relay K3. The input end of the first voltage regulation module is connected to a first power supply, the output end of the first voltage regulation module is connected to the first power supply end of the relay K1 and the relay K3 respectively, and the second power supply end of the relay K1 and the relay K3 is grounded. The input end of the second voltage regulation module is connected to a second power supply, the output end of the second voltage regulation module is connected to the first power supply end of the relay K2, the second power supply end of the relay K2 is connected to the first end of the relay K3, and the second end of the relay K3 is grounded. The first end of the relay K1 is connected to the first power supply, and the second end of the relay K1 is used to access a traction substation. The first end of the relay K2 is connected to the second power supply, and the second end of the relay K2 is used to access the traction substation. Both the first power supply and the second power supply are arranged in a main substation.

[0034] In the present embodiment, the main substation can reduce the alternating high voltage (110kV) of the external power supply to 35kV alternating current, and then transmit it to the traction substation. The traction substation further reduces and rectifies the 35kV alternating current power supply to a 750V or 1500V direct current power supply for train traction.

[0035] In the embodiment, the main substation includes two power supply sources, i.e., a first power supply source and a second power supply source. When the first power supply source and the second power supply source are in normal operation, the first power supply source is preferentially used to supply power, and the first power supply source is sent to the traction substation. When the first power supply source fails, the second power supply source can be automatically switched to, so as to ensure normal operation of the train.

[0036] In the embodiment, the action contact of the relay K1 is in a normally open state, the contact of the relay K1 is attracted after the relay K1 is powered on, the action contact of the relay K2 is in a normally open state, the contact of the relay K2 is attracted after the relay K2 is powered on, and the action contact of the relay K3 is in a normally closed state, the contact of the relay K3 is disconnected after the relay K3 is powered on.

[0037] The first voltage regulation module and the second voltage regulation module are respectively used to detect voltages of the first power supply source and the second power supply source, and convert the detected voltage signals into corresponding control signals to control the relays K1, K2 and K3.

[0038] When the first voltage regulation module detects that the first power supply source is in normal operation, the detected voltage signal is converted into a corresponding control signal to power on the relay K1. Since the action contact of the relay K1 is in a normally open state, the contact of the relay K1 is attracted after being powered on. The first power supply source can pass through the attracted K1 contact from the first end to the second end, and then access the traction substation to provide 35kV alternating current for the traction substation.

[0039] When the first power supply source is in normal power supply, the second voltage regulation module also detects the voltage of the second power supply source, but will not output the control signal to power on the relay K2. Since the action contact of the relay K2 is in a normally open state, the relay K2 is in a disconnected state at this time, and the second power supply source cannot access the traction substation through the K2. The control signal output by the first voltage regulation module powers on the relay K3, and since the action contact of the relay K3 is in a normally closed state, the contact of the relay K3 is disconnected after being powered on. In the normal power supply condition, the disconnected state of the K3 has no effect on the path of the first power supply source to the traction substation through the K1.

[0040] When the first power supply source fails, such as serious three-phase imbalance or phase failure of three-phase alternating current, the first voltage regulation module can detect these abnormal conditions. And the detected abnormal voltage signal is converted into a corresponding control signal, which changes the states of the relays K1 and K3.

[0041] The control signal output by the first voltage regulation module de-energizes relay K1. Since K1's operating contact is normally open, its contact opens after de-energization, cutting off the connection between the first power supply and the traction substation, preventing the first power supply from supplying power to the traction substation. Similarly, because the first voltage regulation module detects a fault, it stops outputting the control signal to energize K3, causing relay K3 to de-energize. Its normally closed contact returns to the closed state, providing a path for the second power supply to connect to the traction substation. The second voltage regulation module detects that the second power supply is working normally and converts the detected voltage signal into a control signal to energize relay K2. Since relay K2's operating contact is normally open, its contact closes after energization. The second power supply flows from its first end to its second end through the closed K2 contact, and then connects to the traction substation through the closed K3 contact, achieving automatic switching from the first power supply to the second power supply.

[0042] After receiving 35kV AC power from the second power supply, the traction substation further steps down and rectifies it into 750V or 1500V DC power to ensure the normal operation of the train.

[0043] As can be seen from the above, the dual power supply and its associated voltage regulation and relay modules in this embodiment construct a highly reliable power supply system. The first and second voltage regulation modules monitor the power supply status in real time and can quickly detect abnormalities. Under normal operating conditions, the first power supply takes priority to ensure stable daily operation. Once the first power supply fails, such as due to three-phase imbalance or phase loss, the voltage regulation module immediately reacts, changes the relay status, and automatically switches to the second power supply to ensure uninterrupted power supply to the traction substation, thereby ensuring normal train operation.

[0044] like Figure 2 As shown, in one embodiment of this disclosure, the first voltage regulation module and the second voltage regulation module have the same structure. The first voltage regulation module includes: a first sampling unit, a second sampling unit, a third sampling unit, an adder unit, a comparator unit, and a control unit; both the first power supply and the second power supply are three-phase AC power; the first sampling unit, the second sampling unit, and the third sampling unit are used to collect A-phase power, B-phase power, and C-phase power, respectively; the output terminals of the first sampling unit, the second sampling unit, and the third sampling unit are all connected to the input terminal of the adder unit, the output terminal of the adder unit is connected to the input terminal of the comparator unit, the output terminal of the comparator unit is connected to the input terminal of the control unit, and the output terminal of the control unit serves as the output terminal of the first voltage regulation module.

[0045] In this embodiment, the first power supply is a three-phase AC power supply, including phase A, phase B, and phase C. The first sampling unit, second sampling unit, and third sampling unit in the first voltage regulation module sample phase A, phase B, and phase C in real time to obtain the voltage value of each phase.

[0046] The first sampling unit, the second sampling unit and the third sampling unit transmit the collected phase voltage values to the adding unit. In the case that the first power supply is normal, the three-phase power is in a balanced state, and according to the characteristics of the three-phase power, the sum of the sampled voltages of the three-phase power is 0. The adding unit adds the voltage values input by the three sampling units, and the result is 0, which is output to the comparison unit.

[0047] After receiving the voltage value (0) output by the adding unit, the comparison unit compares it with the pre-set threshold value. Since the output is 0 under normal circumstances, it does not exceed the set threshold value, so the control unit will not output the control signal for switching the power supply. At this time, the power supply system maintains the state that the first power supply normally supplies power to the traction substation. When the first power supply has three-phase imbalance or open-phase, the voltage values of phase A, phase B and phase C collected by the first sampling unit, the second sampling unit and the third sampling unit will change. The adding unit adds these changed voltage values, and the result is no longer 0. The adding unit outputs the non-zero voltage value to the comparison unit, and the comparison unit compares the voltage value with the pre-set threshold value. If the voltage output by the adding unit exceeds the set threshold value, it means that the three-phase power has a more serious abnormal situation. After detecting that the voltage exceeds the set threshold value, the comparison unit transmits the signal to the control unit. After receiving the signal, the control unit outputs the corresponding control signal. This control signal changes the state of the relays K1, K2 and K3, and realizes the switching from the first power supply to the second power supply, so as to ensure the stable operation of the subway power supply system.

[0048] The first voltage regulation module can monitor the power supply state of the first power supply in real time through a series of operations such as sampling of three-phase power, addition of voltage values, comparison with threshold value and output of control signal, and timely switching of power supply when an abnormality occurs. The second voltage regulation module has the same structure as the first voltage regulation module, and its working principle is similar, which is used to monitor the state of the second power supply.

[0049] As Figure 3As shown, in one embodiment of this disclosure, the first sampling unit includes: a transformer T1, a resistor R1, a capacitor C1, a diode D1, an operational amplifier U4, and a resistor R3; the first input terminal of the transformer T1 is connected to phase A of the first power supply, the second input terminal of the transformer T1 is connected to the neutral line of the first power supply, the first output terminal of the transformer T1 is connected to the first terminal of the resistor R1, the second terminal of the resistor R1 is connected to the anode of the diode D1, the capacitor C1 is connected in parallel with the resistor R1, the cathode of the diode D1 is connected to the non-inverting input terminal of the operational amplifier U4, the inverting input terminal of the operational amplifier U4 is connected to the reference voltage, the output terminal of the operational amplifier U4 is connected to the inverting input terminal of the operational amplifier U4 through the resistor R3, and the output terminal of the operational amplifier U4 is connected to the input terminal of the adder unit; the circuit structures of the first sampling unit, the second sampling unit, and the third sampling unit are the same.

[0050] In this implementation, the first sampling unit is mainly used to convert the A-phase AC power of the first power supply into a suitable DC signal and output it to the addition unit. The second and third sampling units operate on the same principle.

[0051] Taking the first sampling unit as an example: During operation, transformer T1 acts as a step-down transformer, reducing the relatively high phase A AC voltage to a suitable level for subsequent circuit processing. The stepped-down AC voltage enters a resistor-capacitor (RC) step-down circuit composed of resistor R1 and capacitor C1. Capacitor C1 is connected in parallel with resistor R1. This circuit not only further reduces the voltage, but capacitor C1 also filters the AC voltage, reducing fluctuations and noise. Next, the signal passes through a rectifier circuit composed of diode D1. Utilizing the unidirectional conductivity of the diode, the alternating positive and negative AC voltage is converted into a pulsating DC voltage with only a positive half-cycle. Capacitor C2 forms a filter circuit to convert the pulsating DC voltage into a DC voltage signal. Then, the DC voltage signal is input to the non-inverting input of operational amplifier U4, and its inverting input is connected to a reference voltage. The output of operational amplifier U4 is connected to the inverting input through resistor R3 to form negative feedback, stabilizing the amplification factor. Operational amplifier U4 compares and amplifies the input signal with the reference voltage, outputting a stable DC voltage signal. Finally, this signal is sent to the adder unit for subsequent three-phase electrical state determination.

[0052] like Figure 3 As shown, in one embodiment of this disclosure, the first sampling unit further includes: a variable resistor RP1, a resistor R2, a voltage regulator U5, and a capacitor C5; the first end of the variable resistor RP1 is connected to the cathode of the diode D1, the second end of the variable resistor RP1 is grounded through the resistor R2, the sliding end of the variable resistor RP1 is connected to the input end of the voltage regulator U5, the grounding end of the voltage regulator U5 is grounded, the output end of the voltage regulator U5 is grounded through the capacitor C5, and the output end of the voltage regulator U5 is connected to the inverting input end of the operational amplifier U4.

[0053] In this implementation, the variable resistor RP1, resistor R2, voltage regulator U5, and capacitor C5 constitute a voltage regulator circuit. The pulsating DC voltage output from the cathode of diode D1 is connected to the first terminal of variable resistor RP1. By adjusting the position of the sliding contact, variable resistor RP1 can perform preliminary voltage division regulation on the input voltage, thereby outputting a voltage value that meets the required range.

[0054] The voltage, after initial adjustment by the rheostat RP1, can be transmitted to the input terminal of the voltage regulator U5 through its sliding contact. The voltage regulator U5 eliminates fluctuations and interference in the input voltage, converting the unstable input voltage into a stable DC output voltage. Capacitor C5 acts as a filter. It further smooths the output voltage, reducing ripple and noise, resulting in a cleaner and more stable output voltage.

[0055] After processing, the resulting stable DC voltage is sent to the inverting input of operational amplifier U4 as its reference voltage. In this way, operational amplifier U4 can accurately compare and amplify the sampled signal input to the non-inverting input based on this stable reference voltage, thereby ensuring the accuracy and reliability of the output signal from the first sampling unit.

[0056] like Figure 3 As shown, in one embodiment of this disclosure, the adder unit includes: resistor R14, operational amplifier U10, and resistor R13; the inverting input terminal of operational amplifier U10 is connected to the output terminal of operational amplifier U4, the non-inverting input terminal of operational amplifier U10 is grounded through resistor R13, the output terminal of operational amplifier U10 is connected to the inverting input terminal of operational amplifier U10 through resistor R14, and the output terminal of operational amplifier U10 is connected to the input terminal of the comparator unit.

[0057] In this implementation, the voltages output by the first, second, and third sampling units are applied to the inverting input of operational amplifier U10. Resistor R14, operational amplifier U10, and resistor R13 form an adder circuit, and the output of operational amplifier U4 is only the output of the first sampling unit. The voltages output by the first, second, and third sampling units are added together. When the first power supply is functioning normally, the three phases are balanced, and the voltages output by the three sampling units cancel each other out after addition, resulting in a zero output voltage for operational amplifier U10. However, when the first power supply is malfunctioning, resulting in three-phase imbalance or a missing phase, the voltages output by the three sampling units no longer maintain balance, and the result of the addition is not zero, meaning the voltage output by operational amplifier U10 is not zero. The output signal of operational amplifier U10 is then sent to a comparator unit for further determination of the power supply status and control of power switching.

[0058] like Figure 3As shown, in one embodiment of this disclosure, the comparison unit includes: operational amplifier U11 and operational amplifier U12; the inverting input terminal of operational amplifier U11 is connected to the reference voltage Vref1, the non-inverting input terminal of operational amplifier U11 is connected to the output terminal of operational amplifier U10, the non-inverting input terminal of operational amplifier U11 is connected to the non-inverting input terminal of operational amplifier U12, the inverting input terminal of operational amplifier U12 is connected to the reference voltage Vref2, the output terminal of operational amplifier U11 is connected to the output terminal of operational amplifier U12, and the output terminal of operational amplifier U11 is connected to the input terminal of the control unit.

[0059] In this implementation, the voltage signal output by operational amplifier U10 in the adder unit is simultaneously connected to the non-inverting inputs of operational amplifiers U11 and U12. The inverting input of operational amplifier U11 is connected to Vref1, and the inverting input of operational amplifier U12 is connected to Vref2, with Vref1 < Vref2.

[0060] When the output voltage of op-amp U10 is higher than Vref2, op-amps U11 and U12 output high levels, indicating that the first power supply exceeds the upper limit of allowable power. When the output voltage is lower than Vref1, op-amps U11 and U12 output low levels, indicating that it is lower than the lower limit of allowable power. If it is between Vref1 and Vref2, the power supply is normal. The output signals of op-amps U11 and U12 are connected and transmitted to the control unit to provide a basis for power switching.

[0061] like Figure 3 As shown, in one embodiment of this disclosure, the control unit includes: a transistor Q1 and a resistor R15; the base of the transistor Q1 is connected to the output terminal of the operational amplifier U11, the collector of the transistor Q1 is connected to the VDD power supply through the resistor R15, and the emitter of the transistor Q1 serves as the output terminal of the control unit.

[0062] In this embodiment, the output of operational amplifier U11 in the comparator unit is connected to the base of transistor Q1. When the comparator unit determines that the first power supply exceeds the upper limit or falls below the lower limit, operational amplifier U11 outputs a corresponding level signal. If operational amplifier U11 outputs a high level, the base of transistor Q1 receives sufficient bias voltage and conducts. At this time, the VDD power supply outputs a signal from its emitter through resistor R15 and the conducting transistor Q1. This signal can be used as a control signal to change the states of relays K1, K2, and K3, thereby achieving power switching. If operational amplifier U11 outputs a low level, transistor Q1 is cut off, there is no signal output from the emitter, and the power supply state remains unchanged.

[0063] The control unit provides an efficient and reliable execution link for power supply system fault detection and handling, which greatly improves the stability and reliability of subway power supply and effectively ensures the safe operation of the subway.

[0064] The above examples are only used to illustrate the technical solutions of the present disclosure, rather than limit them; although the present disclosure has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A metro power supply system, characterized by, The utility model relates to a kind of voltage regulation module, including: First voltage regulation module, second voltage regulation module, relay K1, relay K2 and relay K3; The input end of the first voltage regulation module is connected to a first power supply, and the output end of the first voltage regulation module is connected to the first power supply end of the relay K1 and the relay K3 respectively, and the second power supply end of the relay K1 and the relay K3 is grounded. The input end of the second voltage regulation module is connected to a second power supply, and the output end of the second voltage regulation module is connected to the first power supply end of the relay K2, and the second power supply end of the relay K2 is connected to the first end of the relay K3, and the second end of the relay K3 is grounded. The first end of the relay K1 is connected to a first power supply, and the second end of the relay K1 is used to access a traction substation, and the first end of the relay K2 is connected to a second power supply, and the second end of the relay K2 is used to access a traction substation. The first power supply and the second power supply are both provided with a main substation.

2. A metro power supply system as claimed in claim 1, characterized in that The first voltage regulation module and the second voltage regulation module have the same structure, and the first voltage regulation module comprises a first sampling unit, a second sampling unit, a third sampling unit, an addition unit, a comparison unit and a control unit. The first power supply and the second power supply are both three-phase alternating current. The first sampling unit, the second sampling unit and the third sampling unit are respectively used to collect A-phase power, B-phase power and C-phase power. The output ends of the first sampling unit, the second sampling unit and the third sampling unit are connected to the input end of the addition unit, the output end of the addition unit is connected to the input end of the comparison unit, the output end of the comparison unit is connected to the input end of the control unit, and the output end of the control unit serves as the output end of the first voltage regulation module.

3. A metro power supply system as claimed in claim 2, characterized in that The first sampling unit comprises a transformer T1, a resistor R1, a capacitor C1, a diode D1, an operational amplifier U4 and a resistor R3. The first input end of the transformer T1 is connected to the A-phase power of the first power supply, the second input end of the transformer T1 is connected to the zero line of the first power supply, the first output end of the transformer T1 is connected to the first end of the resistor R1, the second end of the resistor R1 is connected to the anode of the diode D1, the capacitor C1 is connected to the resistor R1 in parallel, the cathode of the diode D1 is connected to the non-inverting input end of the operational amplifier U4, the inverting input end of the operational amplifier U4 is connected to a reference voltage, the output end of the operational amplifier U4 is connected to the inverting input end of the operational amplifier U4 through the resistor R3, and the output end of the operational amplifier U4 is connected to the input end of the addition unit. The circuit structure of the first sampling unit, the second sampling unit and the third sampling unit is the same.

4. A metro power supply system as claimed in claim 3, characterized in that The first sampling unit further comprises a rheostat RP1, a resistor R2, a voltage stabilizer U5 and a capacitor C5. The first end of the rheostat RP1 is connected to the cathode of the diode D1, the second end of the rheostat RP1 is grounded through the resistor R2, the sliding end of the rheostat RP1 is connected to the input end of the voltage stabilizer U5, the ground end of the voltage stabilizer U5 is grounded, the output end of the voltage stabilizer U5 is grounded through the capacitor C5, and the output end of the voltage stabilizer U5 is connected to the inverting input end of the operational amplifier U4.

5. A metro power supply system as claimed in claim 3, characterized in that The addition unit comprises a resistor R14, an operational amplifier U10 and a resistor R13. The inverting input end of the operational amplifier U10 is connected to the output end of the operational amplifier U4, the non-inverting input end of the operational amplifier U10 is grounded through the resistor R13, the output end of the operational amplifier U10 is connected to the inverting input end of the operational amplifier U10 through the resistor R14, and the output end of the operational amplifier U10 is connected to the input end of the comparison unit.

6. A metro power supply system as claimed in claim 5, characterized in that The comparison unit comprises an operational amplifier U11 and an operational amplifier U12. The inverting input end of the operational amplifier U11 is connected to a Vref1 reference voltage, the non-inverting input end of the operational amplifier U11 is connected to the output end of the operational amplifier U10, the non-inverting input end of the operational amplifier U11 is connected to the non-inverting input end of the operational amplifier U12, the inverting input end of the operational amplifier U12 is connected to a Vref2 reference voltage, the output end of the operational amplifier U11 is connected to the output end of the operational amplifier U12, and the output end of the operational amplifier U11 is connected to the input end of the control unit.

7. A metro power supply system as claimed in claim 6, characterized in that The control unit comprises a transistor Q1 and a resistor R15. The base of the transistor Q1 is connected to the output end of the operational amplifier U11, the collector of the transistor Q1 is connected to a VDD power supply through the resistor R15, and the emitter of the transistor Q1 serves as the output end of the control unit.

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