Photovoltaic energy storage overvoltage protection control method

Abstract

The invention relates to a photovoltaic energy storage overvoltage protection control method, which is based on a photovoltaic energy storage overvoltage protection circuit, and the photovoltaic energy storage overvoltage protection circuit comprises one or more MPPT (maximum power point tracking) circuits with cascade structures. The MPPT circuit comprises a first controllable switch device used for controlling connection or disconnection of an MPPT access path according to a first control signal, and a second controllable switch device used for controlling connection or disconnection of the MPPT circuit according to a second control signal. The third controllable switching device is used for being switched on or switched off according to the third control signal; and the inductive element is connected in series in an MPPT (Maximum Power Point Tracking) circuit. Controlling the first controllable switch device to be switched on, keeping the second controllable switch device and the third controllable switch device to be switched off, and judging a fault if current is detected on the inductive element; and after the fault is judged, the third controllable switching device is controlled to be switched on, and the first controllable switching device is controlled to be switched off, so that fault current is eliminated, over-high MPPT voltage is effectively handled, the whole circuit system is protected, and a fault circuit is identified for corresponding processing.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic energy storage systems, and in particular to a photovoltaic energy storage overvoltage protection control method. Background Art

[0002] Photovoltaic energy storage is a power generation system that combines a solar photovoltaic power generation system with an energy storage device. It is mainly composed of photovoltaic equipment and energy storage equipment. Photovoltaic equipment converts sunlight energy into electrical energy through the photovoltaic effect of semiconductor materials, while energy storage equipment is used to store electrical energy so that it can be released when there is insufficient light or when it is needed.

[0003] In the current photovoltaic energy storage system, photovoltaic equipment has multiple outputs based on MPPT (maximum power point tracking), and the directly connected energy storage equipment, namely the energy storage battery, constitutes the bus on the DC side. Since the energy storage battery is directly connected to the bus, the bus voltage is limited by the battery voltage and cannot float, which will cause the MPPT voltage to be higher or lower than the bus voltage. Therefore, the MPPT circuit must use cascade buck-Boost. When the MPPT voltage is high, such as 1300V, but the maximum bus voltage is limited to 1100V, the excessively high voltage will cause the bus voltage to rise rapidly and damage the device under certain conditions. For example, when the energy storage battery is disconnected and the switching device is short-circuited, the photovoltaic PV output will quickly fill the bus electrolytic capacitor and cause it to burst due to overvoltage. Summary of the invention

[0004] It can be seen that in order to solve the problem that the MPPT voltage in the existing MPPT circuit is too high, causing the bus voltage to rise rapidly and damage the device, the embodiment of the present invention provides a photovoltaic energy storage overvoltage protection circuit and a control method thereof.

[0005] An embodiment of the present invention provides a photovoltaic energy storage overvoltage protection circuit, including one or more MPPT circuits in a cascade structure;

[0006] Wherein, the MPPT circuit comprises:

[0007] A first controllable switch device, used to control the on or off of the MPPT access path according to a first control signal;

[0008] A second controllable switch device, used to control the on or off of the MPPT circuit according to a second control signal;

[0009] A third controllable switch device, used to be turned on or off according to a third control signal;

[0010] The inductive element is connected in series in the MPPT circuit.

[0011] The photovoltaic energy storage overvoltage protection circuit of the embodiment of the present invention includes one or more MPPT circuits of cascade structure. Among them, the MPPT circuit includes: a first controllable switch device, used to control the conduction or shutoff of the MPPT access path according to the first control signal; a second controllable switch device, used to control the conduction or shutoff of the MPPT circuit according to the second control signal; a third controllable switch device, used to turn on or off according to the third control signal; an inductive element, which is connected in series in the MPPT circuit. Through the conduction or shutoff of each switch device, a control basis for coping with overvoltage is provided, and the MPPT circuit with overvoltage fault can be identified through the switch device and current detection, which is convenient for protection processing.

[0012] As one of the optional embodiments, the first controllable switch device is a relay.

[0013] As one of the optional embodiments, the second controllable switch device and the third controllable switch device are semiconductor switch devices.

[0014] As one of the optional embodiments, the second controllable switch device and the third controllable switch device are switch tubes.

[0015] As an optional embodiment, the inductive element is an inductor.

[0016] As one of the optional embodiments, the MPPT circuit further includes:

[0017] a first capacitor connected in parallel with the MPPT access path;

[0018] The first capacitor, the MPPT access path and the first controllable switch device may form a single loop.

[0019] As one of the optional embodiments, the MPPT circuit further includes:

[0020] a second capacitor connected in parallel with the energy storage battery;

[0021] The second capacitor and the energy storage battery may form a single loop.

[0022] As one of the optional embodiments, the MPPT circuit further includes:

[0023] a first diode connected in parallel with the energy storage battery;

[0024] The first diode, the inductive element and the third controllable switch device may form a single loop.

[0025] As one of the optional embodiments, the MPPT circuit further includes:

[0026] A second diode connected in series in the MPPT circuit;

[0027] Wherein, the anode of the second diode is connected to the inductive element, and the cathode is connected to the energy storage battery.

[0028] The embodiment of the present invention further provides a photovoltaic energy storage overvoltage protection control method, which is applied to the photovoltaic energy storage overvoltage protection circuit of the above disclosed embodiment, comprising the steps of:

[0029] Controlling the first controllable switch device to be turned on, keeping the second controllable switch device and the third controllable switch device turned off, and determining a fault if a current is detected on the inductive element;

[0030] After determining a fault, the third controllable switch device is controlled to be turned on and the first controllable switch device is controlled to be turned off to eliminate the fault current.

[0031] The photovoltaic energy storage overvoltage protection control method of the embodiment of the present invention is based on the photovoltaic energy storage overvoltage protection circuit, controls the first controllable switch device to be turned on, keeps the second controllable switch device and the third controllable switch device turned off, and if current is detected on the inductive element, determines that a fault has occurred; after determining that the fault has occurred, controls the third controllable switch device to be turned on and controls the first controllable switch device to be turned off to eliminate the fault current, effectively deal with the excessive MPPT voltage, protect the overall circuit system, and identify the faulty circuit for corresponding processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of a photovoltaic energy storage overvoltage protection circuit module according to a disclosed embodiment;

[0033] Figure 2 A schematic diagram of a photovoltaic energy storage overvoltage protection circuit according to a preferred embodiment;

[0034] Figure 3 The present invention is a flow chart of a photovoltaic energy storage overvoltage protection control method according to a disclosed embodiment. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0036] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0037] In order to keep the following description of the embodiments of the present disclosure clear and concise, the present disclosure omits detailed descriptions of some known functions and known components.

[0038] An embodiment of the present disclosure provides a photovoltaic energy storage overvoltage protection circuit.

[0039] Figure 1 FIG. 1 is a schematic diagram of a photovoltaic energy storage overvoltage protection circuit module according to a disclosed embodiment. Figure 1 As shown, a photovoltaic energy storage overvoltage protection circuit of a disclosed embodiment includes one or more MPPT circuits of cascade structure;

[0040] Wherein, the MPPT circuit comprises:

[0041] A first controllable switch device 100, used to control the on or off of the MPPT access path according to a first control signal;

[0042] A second controllable switch device 101, used to control the on or off of the MPPT circuit according to a second control signal;

[0043] A third controllable switch device 102, configured to be turned on or off according to a third control signal;

[0044] The inductive element 103 is connected in series in the MPPT circuit.

[0045] like Figure 1 As shown, the overall design idea of ​​the MPPT circuit is to connect in parallel with the energy storage battery Vbus and form a DC bus at the connection. Multiple MPPT circuits are cascaded, and each MPPT circuit is independent.

[0046] like Figure 1As shown, in each MPPT circuit, the first controllable switch device 100 controls the on or off of the MPPT access path. When it is on, the MPPT (MPPT+ / MPPT-) is connected, and when it is off, the MPPT (MPPT+ / MPPT-) is isolated.

[0047] like Figure 1 As shown, assuming that the first controllable switch device 100 is turned on, the MPPT (MPPT+ / MPPT-) is connected, the MPPT circuit forms a path, and establishes an electrical connection with the energy storage battery. The second controllable switch device 101 is connected in series in the path of the MPPT circuit. When the second controllable switch device 101 is turned on, the path condition of the MPPT circuit is formed, and when it is turned off, the MPPT circuit is turned off.

[0048] As one of the optional embodiments, in the same MPPT circuit, one or two first controllable switch devices 100 may be included. When two first controllable switch devices 100 are included, each first controllable switch device 100 controls the access of a corresponding MPPT (MPPT+ / MPPT+-).

[0049] like Figure 1 As shown, assuming that the first controllable switch device 100 is turned on and the second controllable switch device 101 is turned on, the MPPT circuit forms a path. At this time, if the third controllable switch device 102 is turned on, since it is connected in parallel with the energy storage battery, an independent sub-loop with the energy storage battery is formed, and interacts with the MPPT circuit.

[0050] like Figure 1 As shown, the inductive element 103 is connected in series in the MPPT circuit. When the MPPT circuit is turned on to form a loop, the inductive element 103 forms a current based on the voltage. The current has visualization or detection conditions, for example, it can be detected by an external detection tool.

[0051] As a preferred embodiment, Figure 1 As shown, the inductive element 103 is connected in series between the second controllable switch device 101 and the third controllable switch device 102 .

[0052] The device selection of the first controllable switch device 100, the second controllable switch device 101 and the third controllable switch device 102 is determined according to the application requirements of the MPPT circuit. The device selection can be electronic switch devices, semiconductor switches, relays, etc.

[0053] As a preferred embodiment, Figure 2 FIG. 1 is a schematic diagram of a photovoltaic energy storage overvoltage protection circuit according to a preferred embodiment. Figure 2 As shown, the first controllable switch device 100 is a relay (K1 . . . Kn). The second controllable switch device 101 and the third controllable switch device 102 are semiconductor switch devices.

[0054] Preferably, the second controllable switch device 101 and the third controllable switch device 102 are switch tubes. External switch tube driving signals are used as the second control signal and the third control signal to control the two to be turned on or off. Figure 2 As shown, the second controllable switch device 101 is T11 ... Tn1, and the third controllable switch device 102 is T12 ... Tn2.

[0055] Wherein, the inductive element 103 is an inductive element or a resistive element. Preferably, as Figure 2 As shown, the inductive element 103 is an inductor (L1 . . . Ln).

[0056] As one of the preferred embodiments, Figure 2 As shown, the MPPT circuit also includes:

[0057] A first capacitor C1 connected in parallel with the MPPT access path;

[0058] The first capacitor C1, the MPPT access path and the first controllable switch device 100 may form a single loop.

[0059] As one of the preferred embodiments, Figure 2 As shown, the MPPT circuit also includes:

[0060] A second capacitor C2 connected in parallel with the energy storage battery;

[0061] The second capacitor C2 and the energy storage battery can form a single loop.

[0062] As one of the preferred embodiments, Figure 2 As shown, the MPPT circuit also includes:

[0063] A first diode D1 connected in parallel with the energy storage battery;

[0064] The first diode D1 , the inductive element 103 and the third controllable switch device 102 may form a single loop.

[0065] The anode of the first diode D1 is used to connect to the ground terminal or the negative voltage terminal.

[0066] As one of the preferred embodiments, Figure 2 As shown, the MPPT circuit also includes:

[0067] A second diode D2 connected in series in the MPPT circuit;

[0068] The anode of the second diode D2 is connected to the inductive element 103 , and the cathode is connected to the energy storage battery.

[0069] The photovoltaic energy storage overvoltage protection circuit of any embodiment of the present disclosure includes one or more MPPT circuits of cascade structure. The MPPT circuit includes: a first controllable switch device 100, used to control the conduction or shutoff of the MPPT access path according to a first control signal; a second controllable switch device 101, used to control the conduction or shutoff of the MPPT circuit according to a second control signal; a third controllable switch device 102, used to conduct or shutoff according to a third control signal; an inductive element 103, connected in series in the MPPT circuit. By turning on or off each switch device, a control basis for coping with overvoltage is provided, and the MPPT circuit with overvoltage fault can be identified through switch devices and current detection, which is convenient for protection processing.

[0070] Based on the photovoltaic energy storage overvoltage protection circuit, the embodiment of the present disclosure also provides a control method of the photovoltaic energy storage overvoltage protection circuit.

[0071] Figure 3 FIG. 1 is a flow chart of a photovoltaic energy storage overvoltage protection control method according to a disclosed embodiment. Figure 3 As shown, a photovoltaic energy storage overvoltage protection control method of a disclosed embodiment includes steps S10 and S11:

[0072] S10, controlling the first controllable switch device to be turned on, keeping the second controllable switch device and the third controllable switch device turned off, and determining that a fault occurs if a current is detected on the inductive element;

[0073] S11, after determining a fault, controlling the third controllable switch device to be turned on and controlling the first controllable switch device to be turned off to eliminate the fault current.

[0074] by Figure 2 Based on the preferred embodiment, when it is detected that the bus voltage is too large (for example, >1000V), turn off the switch tube Tn1 drive, turn on the switch tube Tn2 drive and keep the switch tube Tn2 normally on. Detect the current of each inductor Ln, and judge that the current is greater than the set current value of the i-th MPPT circuit. Disconnect the first controllable switch device Ki of the i-th MPPT circuit. When the current of the i-th circuit is close to 0 and the current of other MPPT circuits is also 0, identify and report the fault of the i-th MPPT circuit and block all switches. Subsequently, restart the overall circuit after the fault of the i-th MPPT circuit is resolved.

[0075] The photovoltaic energy storage overvoltage protection control method of the embodiment of the present invention is based on the photovoltaic energy storage overvoltage protection circuit, controls the first controllable switch device to be turned on, keeps the second controllable switch device and the third controllable switch device turned off, and if current is detected on the inductive element, determines that a fault has occurred; after determining that the fault has occurred, controls the third controllable switch device to be turned on and controls the first controllable switch device to be turned off to eliminate the fault current, effectively deal with the excessive MPPT voltage, protect the overall circuit system, and identify the faulty circuit for corresponding processing.

[0076] There are a few points to note about this disclosure:

[0077] (1) The drawings of the embodiments of the present disclosure only relate to the structures related to the embodiments of the present disclosure, and other structures may refer to the general design.

[0078] (2) For the sake of clarity, the thickness and size of layers or structures are exaggerated in the drawings used to describe the embodiments of the present invention. It is understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "under" another element, the element may be "directly" "on" or "under" the other element, or there may be intervening elements.

[0079] (3) In the absence of conflict, the embodiments of the present disclosure and the features in the embodiments may be combined with each other to obtain new embodiments. The above are only specific implementation methods of the present disclosure, but the protection scope of the present disclosure is not limited thereto. The protection scope of the present disclosure shall be based on the protection scope of the claims.

[0080] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0081] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A photovoltaic energy storage overvoltage protection control method, characterized in that: Applied to a photovoltaic energy storage overvoltage protection circuit, the photovoltaic energy storage overvoltage protection circuit includes one or more cascaded MPPT circuits; Wherein, the MPPT circuit comprises: A first controllable switch device, used to control the on or off of the MPPT access path according to a first control signal; A second controllable switch device, used to control the on or off of the MPPT circuit according to a second control signal; A third controllable switch device, used to be turned on or off according to a third control signal; An inductive element, connected in series in the MPPT circuit; Includes steps: Controlling the first controllable switch device to be turned on, keeping the second controllable switch device and the third controllable switch device turned off, and determining a fault if a current is detected on the inductive element; After determining a fault, the third controllable switch device is controlled to be turned on and the first controllable switch device is controlled to be turned off to eliminate the fault current.

2. The photovoltaic energy storage overvoltage protection control method according to claim 1 is characterized in that: The first controllable switch device is a relay, a load switch or a circuit breaker.

3. The photovoltaic energy storage overvoltage protection control method according to claim 1 is characterized in that: The second controllable switch device and the third controllable switch device are semiconductor switch devices.

4. The photovoltaic energy storage overvoltage protection control method according to claim 1 is characterized in that: The second controllable switch device and the third controllable switch device are switch tubes.

5. The photovoltaic energy storage overvoltage protection control method according to claim 1 is characterized in that: The inductive element is an inductor.

6. The photovoltaic energy storage overvoltage protection control method according to claim 1 is characterized in that: The MPPT circuit further includes: a first capacitor connected in parallel with the MPPT access path; The first capacitor, the MPPT access path and the first controllable switch device may form a single loop.

7. The photovoltaic energy storage overvoltage protection circuit according to claim 1, characterized in that: The MPPT circuit further includes: a second capacitor connected in parallel with the energy storage battery; The second capacitor and the energy storage battery may form a single loop.

8. The photovoltaic energy storage overvoltage protection control method according to claim 1 is characterized in that: The MPPT circuit further includes: a first diode connected in parallel with the energy storage battery; The first diode, the inductive element and the third controllable switch device may form a single loop.

9. The photovoltaic energy storage overvoltage protection control method according to claim 1, characterized in that: The MPPT circuit further includes: A second diode connected in series in the MPPT circuit; Wherein, the anode of the second diode is connected to the inductive element, and the cathode is connected to the energy storage battery.

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