Non-energy-storage dynamic voltage restorer and system

Abstract

The utility model discloses a dynamic voltage restorer without energy storage, which is used for compensating the voltage of a subway escalator and comprises an energy taking unit, an inverter circuit, a detection and control circuit and a bypass unit, one end of the energy taking unit is connected to the subway direct-current traction network, the other end is connected to the inverter circuit, and the energy taking unit is used for obtaining direct current from the subway direct-current traction network; the inverter circuit is connected to two ends of the bypass unit; the detection and control circuit is used for detecting power supply voltage and load voltage of the escalator and generating modulation waves, and the detection and control circuit is connected to the inverter circuit; the bypass unit is arranged between a subway escalator power supply and a subway escalator load, the bypass unit is a switch, when voltage sag of a power supply network is detected, the switch is switched off, and the inverter circuit supplies power. The energy-storage-free dynamic voltage restorer disclosed by the utility model has the advantages of high response speed, high cost effectiveness and compact volume.

Description

Technical Field

[0001] The utility model relates to the technical field of urban rail transit, in particular to a non-energy storage dynamic voltage restorer and a system. Background Art

[0002] With the acceleration of urbanization, subways, as an important part of urban public transportation, have a direct impact on the public's travel experience and the city's operating efficiency due to their safety and reliability. In the subway system, escalators are key facilities for transporting passengers, and they have extremely high requirements for voltage stability. However, during the operation of the power grid, voltage sags may occur due to various factors (such as power grid failures, load mutations, etc.). Such voltage sags often cause sensitive equipment such as escalators to operate unstably or even stop suddenly, causing inconvenience to passengers and, in serious cases, may cause safety accidents.

[0003] Existing voltage sag solutions, such as using uninterruptible power supplies (UPS) or static voltage restorers (SVR), can provide voltage support to a certain extent, but existing technologies usually have problems such as slow response speed, bulky size, and high cost. Especially in subway stations, where space is limited and there are strict requirements on equipment size and cost, the applicability of existing solutions is limited.

[0004] Therefore, it is urgent to invent a dynamic voltage restorer to solve the problems of slow response speed, bulky size and low cost-effectiveness of the existing voltage recovery devices for subway escalators. Summary of the invention

[0005] In view of this, an embodiment of the utility model provides a dynamic voltage restorer and system without energy storage, which at least partially solve the problems existing in the prior art.

[0006] Other features and advantages of the present invention will become apparent from the following detailed description or may be learned in part from the practice of the present invention.

[0007] In order to achieve the above purpose, the embodiment of the utility model provides the following technical solutions:

[0008] According to a first aspect of an embodiment of the utility model, a non-storage dynamic voltage restorer is provided, which is used to compensate for the voltage of a subway escalator. The non-storage dynamic voltage restorer includes: an energy taking unit, an inverter circuit, a detection and control circuit, and a bypass unit;

[0009] One end of the energy acquisition unit is connected to the subway DC traction network, and the other end is connected to the inverter circuit, and the energy acquisition unit is used to obtain DC power from the subway DC traction network;

[0010] The inverter circuit is connected to both ends of the bypass unit;

[0011] The detection and control circuit is used to detect the escalator power supply voltage and the escalator load voltage and generate a modulation wave, and the detection and control circuit is connected to the inverter circuit;

[0012] The bypass unit is arranged between the subway escalator power supply and the subway escalator load. The bypass unit is a switch. When a temporary drop in the power supply network voltage is detected, the switch is disconnected and the inverter circuit supplies power.

[0013] Furthermore, the energy acquisition unit includes: a power diode D, a circuit breaker Q, a pre-charging circuit and a DC support capacitor C1;

[0014] One end of the pre-charging circuit is connected to the subway DC traction network, and the other end is connected to the power diode D;

[0015] The circuit breaker Q is connected in parallel with the pre-charging circuit;

[0016] The DC support capacitor C1 is arranged between the positive and negative electrodes of the output terminal of the energy acquisition unit.

[0017] Furthermore, the pre-charging circuit is composed of a contactor K and a pre-charging resistor R connected in series, and the pre-charging circuit is used to prevent impact current.

[0018] Further, the detection and control circuit includes a voltage detection circuit and a control circuit;

[0019] The voltage detection circuit is used to detect the power supply voltage and the load voltage of the subway escalator, and send the generated compensation voltage reference value to the control circuit;

[0020] The control circuit is used to generate a PWM modulation wave according to the compensation voltage reference value;

[0021] The non-energy storage dynamic voltage restorer adopts PWM modulation technology.

[0022] Furthermore, the inverter circuit includes at least one single-phase full-bridge circuit; and each of the single-phase full-bridge circuits is connected in parallel.

[0023] Furthermore, the single-phase full-bridge circuit includes a DC side capacitor C2, a first bridge arm and a second bridge arm;

[0024] The DC side capacitor C2, the first bridge arm and the second bridge arm are sequentially connected in parallel with the output end of the energy acquisition unit;

[0025] The midpoint of the first bridge arm and the midpoint of the second bridge arm serve as output ports of the single-phase full-bridge circuit.

[0026] Furthermore, the first bridge arm includes a first switch tube Q1 and a second switch tube Q2;

[0027] The emitter of the first switch tube Q1 is connected to the collector of the second switch tube Q2 to form a first bridge arm;

[0028] The second bridge arm includes a third switch tube Q3 and a fourth switch tube Q4;

[0029] The emitter of the third switch tube Q3 is connected to the collector of the fourth switch tube Q4 to form a second bridge arm;

[0030] The switch tube adopts an insulated gate bipolar transistor IGBT or a metal oxide semiconductor field effect transistor MOSFET.

[0031] Furthermore, the inverter circuit further includes an inverter low-pass filter, which is formed by a filter inductor La and a filter capacitor Ca connected in series, and the filter capacitor Ca is connected in parallel with the bypass unit.

[0032] Furthermore, the inverter circuit includes three single-phase full-bridge circuits, which are connected in parallel, and each single-phase full-bridge circuit is respectively connected to each phase of the three-phase main circuit of the subway escalator.

[0033] According to a second aspect of an embodiment of the utility model, a subway escalator voltage recovery system is provided, the system comprising a subway escalator power supply and a subway escalator load, and also comprising a dynamic voltage restorer without energy storage as described in any of the above items.

[0034] The utility model has the following advantages:

[0035] The utility model discloses a non-storage dynamic voltage restorer for subway escalators, which obtains active energy from a DC traction network through an energy acquisition unit, without the need for a separate energy storage element, thereby meeting voltage compensation requirements and reducing maintenance difficulty and cost, thereby effectively improving the economy of the voltage restorer. The utility model provides a non-storage dynamic voltage restorer that can quickly compensate for the voltage sag of subway escalators, effectively preventing subway escalators from generating safety hazards due to voltage sags, and has the advantages of fast response speed, high cost-effectiveness, and compact size. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the implementation of the utility model or the technical solution in the prior art, the following is a brief introduction to the drawings required for the implementation or the prior art description. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0037] Figure 1A schematic diagram of the structure of a dynamic voltage restorer without energy storage provided by an embodiment of the utility model;

[0038] Figure 2 A wiring diagram of an energy taking unit provided in an embodiment of the utility model;

[0039] Figure 3 One of the wiring diagrams of the non-storage dynamic voltage restorer provided in the embodiment of the utility model;

[0040] Figure 4 The second wiring diagram of the dynamic voltage restorer without energy storage provided by the embodiment of the utility model;

[0041] Figure 5 A schematic structural diagram of a subway escalator voltage recovery system provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0043] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0045] In the description of the present utility model, it should be noted that the nouns indicating orientation or positional relationships appearing in the content of this specification are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships in which the utility model product is usually placed when in use. They are only for the convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as a limitation on the present utility model.

[0046] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] refer to Figure 1 The embodiment of the utility model provides a dynamic voltage restorer without energy storage, which is used to compensate the voltage of subway escalators. The dynamic voltage restorer without energy storage includes: an energy taking unit, an inverter circuit, a detection and control circuit and a bypass unit.

[0048] One end of the energy acquisition unit is connected to the subway DC traction network, and the other end is connected to the inverter circuit. The energy acquisition unit is used to obtain DC power from the subway DC traction network for use by the subsequent inverter circuit. The output voltage is U dc , generally 750V.

[0049] Specifically, refer to Figure 2 The energy acquisition unit includes: a power diode D, a circuit breaker Q, a pre-charging circuit and a DC support capacitor C1. One end of the pre-charging circuit is connected to the subway DC traction network, and the other end is connected to the power diode D; the circuit breaker Q is connected in parallel with the pre-charging circuit; the DC support capacitor C1 is arranged between the positive and negative poles of the output end of the energy acquisition unit.

[0050] Furthermore, the pre-charging circuit is composed of a contactor K and a pre-charging resistor R connected in series. The pre-charging circuit is used to prevent impact current. The power diode D is used to ensure that energy can only be transferred from the DC traction network to the dynamic voltage restorer without energy storage.

[0051] The utility model directly obtains direct current from the subway direct current traction network through the energy acquisition unit, does not require a separate energy storage device, effectively improves economic cost-effectiveness, and effectively reduces the size of the dynamic voltage restorer.

[0052] The inverter circuit is connected to both ends of the bypass unit.

[0053] Specifically, refer to Figure 3 The above-mentioned inverter circuit includes at least one single-phase full-bridge circuit, and each single-phase full-bridge circuit is connected in parallel.

[0054] Furthermore, the above-mentioned single-phase full-bridge circuit includes a DC side capacitor C2, a first bridge arm and a second bridge arm; the DC side capacitor C2, the first bridge arm and the second bridge arm are connected in parallel with the output end of the energy acquisition unit in sequence, and the midpoint of the first bridge arm and the midpoint of the second bridge arm serve as output ports of the single-phase full-bridge circuit.

[0055] Furthermore, the first bridge arm includes a first switch tube Q1 and a second switch tube Q2, the emitter of the first switch tube Q1 is connected to the collector of the second switch tube Q2, forming the first bridge arm; the second bridge arm includes a third switch tube Q3 and a fourth switch tube Q4, the emitter of the third switch tube Q3 is connected to the collector of the fourth switch tube Q4, forming the second bridge arm; wherein the switch tube adopts an insulated gate bipolar transistor IGBT or a metal oxide semiconductor field effect transistor MOSFET. The energy acquisition unit inputs direct current into the DC side capacitor C2, one end of the DC side capacitor C2 is connected to the collector of the first switch tube Q1 and the collector of the third switch tube Q3, and the other end of the DC side capacitor C2 is connected to the emitter of the second switch tube Q2 and the emitter of the fourth switch tube Q4.

[0056] In addition, since the output of the single-phase full-bridge circuit is a series of rectangular waves, it includes not only the 50Hz power frequency voltage component, but also high-frequency harmonics of the same switching frequency and its multiples. In order to obtain the 50Hz power frequency voltage, the inverter circuit also includes an inverter low-pass filter. The inverter low-pass filter adopts an LC second-order filter, which is composed of a filter inductor La and a filter capacitor Ca connected in series. The filter capacitor Ca is connected in parallel with the bypass unit. The output port of the single-phase full-bridge circuit is connected to the inverter low-pass filter, that is, the midpoint of the first bridge arm and the second bridge arm is connected to the inverter low-pass filter. The output of the inverter low-pass filter is connected to the main circuit of the subway escalator, that is, the filter capacitor Ca is connected in series to the main circuit of the subway escalator.

[0057] The cutoff frequency of the above-mentioned inverter low-pass filter must be much higher than the power frequency, and the voltage drop on the filter inductor La must be less than the rated voltage of the load. Therefore, the cutoff frequency in this embodiment is 10 times the power frequency, that is, the cutoff frequency is 500Hz, and the voltage drop of the inductor is 20% of the rated voltage of the escalator load.

[0058] The independent single-phase full-bridge type non-energy storage dynamic voltage restorer has a clear structure and adopts PWM modulation, which is easy to implement in engineering.

[0059] The detection and control circuit is used for detecting the escalator power supply voltage and the escalator load voltage and generating a modulation wave, and the detection and control circuit is connected to the inverter circuit.

[0060] Specifically, the detection and control circuit includes a voltage detection circuit and a control circuit; the voltage detection circuit is respectively connected to the subway escalator power supply and the subway escalator load through a data acquisition module, detects the subway escalator power supply voltage and the subway escalator load voltage, and sends the generated compensation voltage reference value to the control circuit; the control circuit is used to generate a drive pulse according to the received compensation voltage reference value and input it to the inverter circuit to control the dynamic voltage restorer without energy storage.

[0061] The bypass unit is arranged between the subway escalator power supply and the subway escalator load of the subway escalator main circuit, and the bypass unit is a switch SCR (thyristor); when the subway escalator is powered normally, the subway escalator power supply current flows to the escalator load through the bypass unit, and the bypass unit bypasses the other parts of the dynamic voltage restorer without energy storage; when the voltage detection circuit detects a temporary voltage drop in the escalator power supply network, the bypass unit is disconnected and the inverter circuit starts to supply power to ensure the stability of the subway escalator voltage.

[0062] Preferably, reference Figure 4 , corresponding to the above-disclosed non-energy storage dynamic voltage restorer, the embodiment of the utility model further discloses a non-energy storage dynamic voltage restorer whose inverter circuit includes three single-phase full-bridge circuits. The three single-phase full-bridge circuits have the same structure, namely, A-phase full-bridge circuit, B-phase full-bridge circuit and C-phase full-bridge circuit. The three-phase voltage is independently compensated. There is no common connection point between the three phases except the input parallel connection. The output of each phase compensation voltage is +Udc and -Udc. Each single-phase full-bridge circuit is connected to the bypass unit on each phase of the three-phase main circuit of the subway escalator through an inverter low-pass filter. Each phase main circuit of the above-mentioned three-phase main circuit of the subway escalator includes a subway escalator power supply and a subway escalator load.

[0063] Corresponding to the above-disclosed non-energy storage dynamic voltage restorer, the utility model embodiment discloses a subway escalator voltage recovery system, referring to Figure 5 The above system includes a subway escalator power supply and a subway escalator load, and also includes a dynamic voltage restorer without energy storage as described in any of the above items.

[0064] The embodiment of the utility model provides a non-energy storage dynamic voltage restorer for compensating the voltage of a subway escalator. The non-energy storage dynamic voltage restorer includes: an energy acquisition unit, an inverter circuit, a detection and control circuit, and a bypass unit; one end of the energy acquisition unit is connected to the subway DC traction network, and the other end is connected to the inverter circuit, and the energy acquisition unit is used to obtain DC power from the subway DC traction network; the inverter circuit is connected to both ends of the bypass unit; the detection and control circuit is used to detect the escalator power supply voltage and the escalator load voltage and generate a modulation wave, and the detection and control circuit is connected to the inverter circuit; the bypass unit is arranged between the subway escalator power supply and the subway escalator load, and the bypass unit is a switch. When a temporary drop in the power supply network voltage is detected, the switch is disconnected and the inverter circuit supplies power. The non-energy storage dynamic voltage restorer disclosed by the utility model has the advantages of fast response speed, high cost-effectiveness and compact size.

[0065] The above-listed embodiments show and describe the basic principles and main features of the utility model, but the utility model is not limited to the above-mentioned embodiments. Any modifications, equivalent changes and modifications made to the utility model by those skilled in the art without making any creative work should fall within the scope of protection of the technical solution of the utility model.

Claims

1. A dynamic voltage restorer without energy storage, characterized in that: Used to compensate for the voltage of subway escalators, the non-energy storage dynamic voltage restorer includes: an energy taking unit, an inverter circuit, a detection and control circuit, and a bypass unit; One end of the energy acquisition unit is connected to the subway DC traction network, and the other end is connected to the inverter circuit, and the energy acquisition unit is used to obtain DC power from the subway DC traction network; The inverter circuit is connected to both ends of the bypass unit; The detection and control circuit is used to detect the escalator power supply voltage and the escalator load voltage and generate a modulation wave, and the detection and control circuit is connected to the inverter circuit; The bypass unit is arranged between the subway escalator power supply and the subway escalator load. The bypass unit is a switch. When a temporary drop in the power supply network voltage is detected, the switch is disconnected and the inverter circuit supplies power.

2. The non-storage dynamic voltage restorer according to claim 1, characterized in that: The energy acquisition unit includes: a power diode D, a circuit breaker Q, a pre-charging circuit and a DC support capacitor C1; One end of the pre-charging circuit is connected to the subway DC traction network, and the other end is connected to the power diode D; The circuit breaker Q is connected in parallel with the pre-charging circuit; The DC support capacitor C1 is arranged between the positive and negative electrodes of the output terminal of the energy acquisition unit.

3. The non-storage dynamic voltage restorer according to claim 2, characterized in that: The pre-charging circuit is composed of a contactor K and a pre-charging resistor R connected in series, and the pre-charging circuit is used to prevent impact current.

4. The non-storage dynamic voltage restorer according to claim 1, characterized in that: The detection and control circuit includes a voltage detection circuit and a control circuit; The voltage detection circuit is used to detect the power supply voltage and the load voltage of the subway escalator, and send the generated compensation voltage reference value to the control circuit; The control circuit is used to generate a PWM modulation wave according to the compensation voltage reference value; The non-energy storage dynamic voltage restorer adopts PWM modulation technology.

5. The non-storage dynamic voltage restorer according to claim 1, characterized in that: The inverter circuit includes at least one single-phase full-bridge circuit; each of the single-phase full-bridge circuits is connected in parallel.

6. The non-storage dynamic voltage restorer according to claim 5, characterized in that: The single-phase full-bridge circuit comprises a DC side capacitor C2, a first bridge arm and a second bridge arm; The DC side capacitor C2, the first bridge arm and the second bridge arm are sequentially connected in parallel with the output end of the energy acquisition unit; The midpoint of the first bridge arm and the midpoint of the second bridge arm serve as output ports of the single-phase full-bridge circuit.

7. The non-storage dynamic voltage restorer according to claim 6, characterized in that: The first bridge arm includes a first switch tube Q1 and a second switch tube Q2; The emitter of the first switch tube Q1 is connected to the collector of the second switch tube Q2 to form a first bridge arm; The second bridge arm includes a third switch tube Q3 and a fourth switch tube Q4; The emitter of the third switch tube Q3 is connected to the collector of the fourth switch tube Q4 to form a second bridge arm; The switch tube adopts an insulated gate bipolar transistor IGBT or a metal oxide semiconductor field effect transistor MOSFET.

8. The non-storage dynamic voltage restorer according to claim 1, characterized in that: The inverter circuit further includes an inverter low-pass filter, which is formed by a filter inductor La and a filter capacitor Ca connected in series, and the filter capacitor Ca is connected in parallel with the bypass unit.

9. The dynamic voltage restorer without energy storage according to any one of claims 5 to 7, characterized in that: The inverter circuit includes three single-phase full-bridge circuits, which are connected in parallel, and each single-phase full-bridge circuit is respectively connected to each phase of the three-phase main circuit of the subway escalator.

10. A subway escalator voltage recovery system, characterized in that: The system includes a subway escalator power supply and a subway escalator load, and also includes the dynamic voltage restorer without energy storage as described in any one of claims 1-9.

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