Voltage loss protection device for direct current power supply of transformer substation

Abstract

The invention discloses a voltage loss protection device for a direct-current power supply of a transformer substation. Comprising a first voltage monitoring unit, a first current monitoring unit, a second voltage monitoring unit, a second current monitoring unit, a main processor, a first voltage reduction unit, a second voltage reduction unit, a first direct-current power supply, a second direct-current power supply, a first charger, a first storage battery, a second charger and a second storage battery. According to the invention, a charger fault or a storage battery pack fault is distinguished through multi-point monitoring, corresponding voltage loss control strategies are established for different voltage loss, and the voltage reduction units are connected in parallel in two groups of DC power supplies. The two groups of independent direct-current power supplies adopt voltage reduction units, so that no-delay power supply can be realized when any group of batteries of the direct-current power supply system is in power loss or fault.

Description

Technical Field

[0001] The invention relates to the technical field of transformer substation protection, and in particular to a direct current power supply undervoltage protection device for a transformer substation. Background Art

[0002] The DC power supply system is the main working power supply of the substation, often called the power operating power supply. It provides uninterrupted working power supply for the relay protection equipment, switchgear, communication equipment, etc. in the substation.

[0003] Substations have extremely high requirements for the continuity and stability of the DC power supply system. Therefore, the power system usually has two sets of independent DC power supply systems to ensure the continuity and reliability of power supply. Each DC power supply system mainly includes components such as battery packs, chargers and feeder switches. When the charger fails or the AC power is cut off, the battery pack will be used as the working power output to provide power for relay protection equipment, switchgear, etc., thereby ensuring the reliability of the DC power supply.

[0004] However, because the DC power supply system needs to work reliably, for higher reliability, the two sets of DC power supply systems are completely isolated and work independently under normal conditions, and cannot be directly connected and used. When a DC power supply system in a substation loses voltage, manual operation is required to merge the two power supplies into one, which increases the complexity of operation and limits the flexibility of the system.

[0005] It can be seen that how to automatically convert a DC power supply system under a voltage loss fault has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0006] The invention provides a DC power supply undervoltage protection device for a transformer substation, which is used to automatically switch a dual DC power supply system under a undervoltage fault.

[0007] In order to solve the above technical problems, an embodiment of the present invention provides a substation DC power supply undervoltage protection device, comprising:

[0008] A first voltage monitoring unit, a first current monitoring unit, a second voltage monitoring unit, a second current monitoring unit, a main processor, a first step-down unit, a second step-down unit, a first DC power supply, a second DC power supply, a first charger, a first battery, a second charger, and a second battery.

[0009] The power supply line of the first DC power supply is provided with an input end of the first voltage monitoring unit and an input end of the first current monitoring unit, and the power supply line of the second DC power supply is provided with an input end of the second voltage monitoring unit and an input end of the second current monitoring unit.

[0010] An output terminal of the first voltage monitoring unit, an output terminal of the first current monitoring unit, an output terminal of the second voltage monitoring unit, and an output terminal of the second current monitoring unit are connected to an input terminal of the main processor.

[0011] The input end of the first step-down unit is connected to the first DC power supply, and the output end of the first step-down unit is connected to the second DC power supply; the input end of the second step-down unit is connected to the second DC power supply, and the output end of the second step-down unit is connected to the first DC power supply.

[0012] The output end of the first charger and the output end of the first battery are connected to the first DC power supply, and the output end of the second charger and the output end of the second battery are connected to the second DC power supply.

[0013] Furthermore, the first voltage monitoring unit includes a DC bus voltage transmitter, a positive-to-ground voltage transmitter, a negative-to-ground voltage transmitter, a battery pack voltage transmitter and a charger voltage transmitter.

[0014] Furthermore, the first current monitoring unit is used to monitor the output currents of the first DC power supply, the first charger, the first storage battery and the second step-down unit.

[0015] Furthermore, the second voltage monitoring unit includes a DC bus voltage transmitter, a positive-to-ground voltage transmitter, a negative-to-ground voltage transmitter, a battery pack voltage transmitter and a charger voltage transmitter.

[0016] Furthermore, the second current monitoring unit is used to monitor the output current of the second DC power supply, the second charger, the second storage battery and the first step-down unit.

[0017] Furthermore, the device also includes an alarm unit;

[0018] The input end of the alarm unit is connected to the output end of the main processor, and the alarm unit includes a buzzer speaker and an LED warning light.

[0019] Furthermore, the main processor is used to receive circuit operation data collected by the first voltage monitoring unit, the first current monitoring unit, the second voltage monitoring unit and the second current monitoring unit, analyze and process the circuit operation data, and determine whether voltage loss occurs based on the analysis results.

[0020] Furthermore, the device also includes a display;

[0021] The input end of the display is connected to the output end of the main processor, and the display is an industrial control screen for displaying the circuit operation data and the analysis results.

[0022] Furthermore, both the first buck unit and the second buck unit adopt a bidirectional DC / DC converter.

[0023] Further, the first step-down unit and the second DC power supply are connected via a first diode, an input end of the first diode is connected to an output end of the first step-down unit, and an output end of the first diode is connected to the second DC power supply;

[0024] The second step-down unit and the first DC power supply are connected via a second diode, an input end of the second diode is connected to an output end of the first step-down unit, and an output end of the second diode is connected to the first DC power supply.

[0025] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0026] (1) Multi-point monitoring is used to distinguish between charger failure and battery pack failure. Multi-point connection can be performed according to different fault conditions on site, and different voltage loss controls can be performed for any DC power loss in a complementary manner. DC power loss mainly includes battery failure, fuse blown, charger voltage loss, AC power failure voltage loss and other information. Corresponding voltage loss control strategies can be established for different voltage losses, and the accuracy of voltage loss compensation can be determined through data verification.

[0027] (2) A step-down unit is connected in parallel to realize two sets of DC power supplies. The two independent DC power supplies use a step-down unit so that when any battery in the DC power supply system loses power or fails, power can be supplied without delay. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A structural block diagram of a DC power supply undervoltage protection device for a substation provided by an embodiment of the present invention;

[0029] Figure 2 A connection diagram between any voltage monitoring unit and a circuit provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. 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.

[0031] In the description of this application, the terms "first", "second", "third", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", "third", etc. may explicitly or implicitly include one or more of the feature. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0032] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 a connection between the two elements. The terms "vertical", "horizontal", "left", "right", "upper", "lower" and similar expressions used herein are only for illustrative purposes, 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, and therefore cannot be understood as a limitation on the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0033] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0034] An embodiment of the present invention provides a DC power supply undervoltage protection device for a substation. For details, see Figure 1 , Figure 1 The structure block diagram of a DC power supply undervoltage protection device for a transformer substation in one embodiment of the present invention is shown, and the device includes:

[0035] A first voltage monitoring unit, a first current monitoring unit, a second voltage monitoring unit, a second current monitoring unit, a main processor, a first step-down unit, a second step-down unit, a first DC power supply, a second DC power supply, a first charger, a first battery, a second charger, and a second battery.

[0036] The power supply line of the first DC power supply is provided with an input end of a first voltage monitoring unit and an input end of a first current monitoring unit, and the power supply line of the second DC power supply is provided with an input end of a second voltage monitoring unit and an input end of a second current monitoring unit.

[0037] like Figure 2 As shown, Figure 2 The diagram shows the connection relationship between any voltage monitoring unit and the circuit provided by the embodiment of the present invention. The first voltage monitoring unit includes a DC bus voltage transmitter, a positive voltage to ground transmitter, a negative voltage to ground transmitter, a battery pack voltage transmitter and a charger voltage transmitter, which can measure the DC bus voltage, positive voltage to ground, negative voltage to ground, charger output voltage, battery pack voltage and other parameters of the first DC power supply of the substation in real time.

[0038] The second voltage monitoring unit includes a DC bus voltage transmitter, a positive-to-ground voltage transmitter, a negative-to-ground voltage transmitter, a battery pack voltage transmitter and a charger voltage transmitter, which can measure the DC bus voltage, positive-to-ground voltage, negative-to-ground voltage, charger output voltage, battery pack voltage and other parameters of the second DC power supply of the substation in real time.

[0039] Among them, the DC bus voltage transmitter measures the DC bus voltage in real time to ensure that the voltage value is within a reasonable range to avoid damage to the equipment caused by excessively high or low voltage; the positive ground voltage transmitter and the negative ground voltage transmitter measure the positive and negative ground voltages of the DC power supply to ensure that the ground voltage is within a safe range to prevent ground faults; the battery pack voltage transmitter measures the voltage of the battery pack in real time to ensure that the battery pack has sufficient power supply and is in a healthy state; the charger voltage transmitter measures the output voltage of the charger to ensure that the charging voltage meets the charging requirements of the battery pack.

[0040] The first current monitoring unit is used to monitor the output current of the first DC power supply, the first charger, the first storage battery and the second step-down unit.

[0041] The second current monitoring unit is used to monitor the output current of the second DC power supply, the second charger, the second storage battery and the first step-down unit.

[0042] The input end of the first step-down unit is connected to the first DC power supply, and the output end of the first step-down unit is connected to the second DC power supply; the input end of the second step-down unit is connected to the second DC power supply, and the output end of the second step-down unit is connected to the first DC power supply.

[0043] The output end of the first charger and the output end of the first battery are connected to the first DC power supply, and the output end of the second charger and the output end of the second battery are connected to the second DC power supply.

[0044] Among them, monitoring the output current of the first DC power supply and the second DC power supply can ensure that the current value is within a safe range and avoid damage to the equipment due to overcurrent; monitoring the output current of the first charger and the second charger can measure the output current of the charger to ensure that the charging current meets the charging requirements of the battery pack, ensure the normal charging process of the battery pack, and avoid charging problems caused by excessive or insufficient charging current; monitoring the output current of the first battery and the second battery can measure the output current of the battery pack to ensure that the current of the battery pack is stable during the discharge process, avoid damage to the battery pack due to overdischarge, help to timely discover abnormal discharge of the battery pack, and ensure the backup power supply of the power system. Monitoring the output current of the first step-down unit and the second step-down unit measures the output current of the step-down unit to ensure that the current after step-down meets the power supply requirements of the equipment and avoid equipment failures due to current mismatch.

[0045] An output terminal of the first voltage monitoring unit, an output terminal of the first current monitoring unit, an output terminal of the second voltage monitoring unit, and an output terminal of the second current monitoring unit are connected to an input terminal of the main processor.

[0046] The main processor receives the circuit operation data collected by the first voltage monitoring unit, the first current monitoring unit, the second voltage monitoring unit and the second current monitoring unit, and compares the calculation result with the original set value through calculation, and displays the collected circuit operation data and calculation analysis results on the display in real time. Specifically, the display of this embodiment uses an industrial control panel.

[0047] If the deviation between the calculated result and the preset result is greater than the fault tolerance deviation range, it is determined that the equipment has lost pressure, the equipment fault information is displayed on the display, and an alarm signal is sent to the alarm unit. After receiving the alarm signal, the alarm unit controls the LED warning light and the buzzer to send out an audible and visual alarm signal to alert the staff to the fault information.

[0048] The first step-down unit and the second step-down unit both adopt a bidirectional DC / DC converter for realizing bidirectional conversion of DC voltage between the first DC power supply side and the second DC power supply side.

[0049] The first step-down unit and the second DC power supply are connected via a first diode, an input end of the first diode is connected to an output end of the first step-down unit, and an output end of the first diode is connected to the second DC power supply.

[0050] The second step-down unit and the first DC power supply are connected via a second diode, an input end of the second diode is connected to an output end of the first step-down unit, and an output end of the second diode is connected to the first DC power supply.

[0051] Among them, the first diode and the second diode are unidirectionally conductive and will not cause a voltage difference on both sides. They are also used for protection and are clamping potentials. When the dual DC power supplies are working normally, the outputs of the first DC power supply and the second DC power supply are completely bidirectionally isolated from each other using the unidirectional conductive characteristics of the diodes until a voltage loss failure occurs in one of the DC power supplies. The normally working side provides power to the voltage-loss side through the corresponding step-down unit.

[0052] This embodiment takes the case where the first DC power supply loses power or voltage as an example. When the first DC power supply loses power completely, the second DC power supply serves as the input power supply, and its output is connected to the first DC power supply to provide power output for the electrical appliances on the first DC power supply side. When the first charger or the first battery fails, the first DC power supply on the first DC power supply side is still working, but the voltage on the first DC power supply side is lower than the normal range. When the voltage difference between the two sides is greater than 4V, the second DC power supply is output to the first DC power supply side through the DC / DC converter. Specifically, the second DC power supply is used to supply power to the first DC power supply side by taking power from the bus of the second DC power supply through the second step-down unit, reducing the voltage to a value 4V less than the actual voltage of the second DC power supply, and outputting it to the first DC power supply side.

[0053] The above is the device processing process when a voltage loss fault occurs on the first DC power supply side. Similarly, when a power loss or voltage loss occurs on the second DC power supply side, the first DC power supply supplies power to the electrical equipment on the second DC power supply side.

[0054] Preferably, the device further comprises a communication unit for receiving data collected, processed and analyzed by the main processor, as well as fault alarm information.

[0055] The substation DC power supply undervoltage protection device of the present invention utilizes multi-point monitoring to distinguish whether a charger failure or a battery group failure can be connected at multiple points according to different fault conditions on site, and different undervoltage controls can be performed for any section of DC power supply undervoltage conditions in a complementary manner. The DC power supply undervoltage mainly includes information such as battery failure, fuse blowing, charger undervoltage, AC power supply failure undervoltage, etc. Corresponding undervoltage control strategies can be established for different undervoltages, and the accuracy of undervoltage compensation can be determined through data verification. A step-down unit is used in parallel to realize two groups of DC power supplies. The two independent groups of DC power supplies use a step-down unit so that any group of batteries in the DC power supply system can be powered without delay when it loses power or fails.

[0056] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A DC power supply undervoltage protection device for a substation, characterized in that: include: A first voltage monitoring unit, a first current monitoring unit, a second voltage monitoring unit, a second current monitoring unit, a main processor, a first step-down unit, a second step-down unit, a first DC power supply, a second DC power supply, a first charger, a first storage battery, a second charger, and a second storage battery; The power supply line of the first DC power supply is provided with an input end of the first voltage monitoring unit and an input end of the first current monitoring unit, and the power supply line of the second DC power supply is provided with an input end of the second voltage monitoring unit and an input end of the second current monitoring unit; The output end of the first voltage monitoring unit, the output end of the first current monitoring unit, the output end of the second voltage monitoring unit and the output end of the second current monitoring unit are connected to the input end of the main processor; The input end of the first step-down unit is connected to the first DC power supply, and the output end of the first step-down unit is connected to the second DC power supply; the input end of the second step-down unit is connected to the second DC power supply, and the output end of the second step-down unit is connected to the first DC power supply; The output end of the first charger and the output end of the first battery are connected to the first DC power supply, and the output end of the second charger and the output end of the second battery are connected to the second DC power supply.

2. The substation DC power supply undervoltage protection device according to claim 1, characterized in that: The first voltage monitoring unit includes a DC bus voltage transmitter, a positive-to-ground voltage transmitter, a negative-to-ground voltage transmitter, a battery pack voltage transmitter and a charger voltage transmitter.

3. The substation DC power supply undervoltage protection device according to claim 1, characterized in that: The first current monitoring unit is used to monitor the output currents of the first DC power supply, the first charger, the first storage battery and the second step-down unit.

4. The substation DC power supply undervoltage protection device according to claim 1, characterized in that: The second voltage monitoring unit includes a DC bus voltage transmitter, a positive-to-ground voltage transmitter, a negative-to-ground voltage transmitter, a battery pack voltage transmitter and a charger voltage transmitter.

5. The substation DC power supply undervoltage protection device according to claim 1, characterized in that: The second current monitoring unit is used to monitor the output current of the second DC power supply, the second charger, the second storage battery and the first step-down unit.

6. The substation DC power supply undervoltage protection device according to claim 1, characterized in that: The device also includes an alarm unit; The input end of the alarm unit is connected to the output end of the main processor, and the alarm unit includes a buzzer speaker and an LED warning light.

7. The substation DC power supply undervoltage protection device according to claim 1, characterized in that: The main processor is used to receive circuit operation data collected by the first voltage monitoring unit, the first current monitoring unit, the second voltage monitoring unit and the second current monitoring unit, analyze and process the circuit operation data, and determine whether voltage loss occurs based on the analysis results.

8. The substation DC power supply undervoltage protection device according to claim 7, characterized in that: The device also includes a display; The input end of the display is connected to the output end of the main processor, and the display is an industrial control screen for displaying the circuit operation data and the analysis results.

9. The substation DC power supply undervoltage protection device according to claim 1, characterized in that: The first buck unit and the second buck unit both use a bidirectional DC / DC converter.

10. The substation DC power supply undervoltage protection device according to claim 9, characterized in that: The first step-down unit and the second DC power supply are connected via a first diode, an input end of the first diode is connected to an output end of the first step-down unit, and an output end of the first diode is connected to the second DC power supply; The second step-down unit and the first DC power supply are connected via a second diode, an input end of the second diode is connected to an output end of the first step-down unit, and an output end of the second diode is connected to the first DC power supply.

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