Stability control method and system for photovoltaic storage and charging station system

Abstract

The present invention provides a stability control method and system for a photovoltaic (PV)-storage-charging station system. The PV-storage-charging station system includes a station-level controller, a photovoltaic inverter, an energy storage converter, and a charging pile. A control method is applied to the station-level controller and includes: obtaining, in real time, the system grid-connected point voltage, the photovoltaic inverter grid-connected point voltage, and the charging pile grid-connected point voltage; determining whether the system grid-connected point voltage exceeds a first limited range to obtain a first determination result; if the first determination result is yes, generating a voltage adjustment instruction based on a preset system grid-connected point reference voltage, the system grid-connected point voltage, the photovoltaic inverter grid-connected point voltage, and the charging pile grid-connected point voltage; and transmitting the voltage adjustment instruction to the energy storage converter to adjust the system voltage. By real-time monitoring of voltage data at the system grid-connected point, the photovoltaic inverter grid-connected point, and the charging pile grid-connected point, the system grid-connected point voltage can be adjusted in real time, thereby suppressing voltage fluctuations during operation of the PV-storage-charging station system.

Description

Technical Field

[0001] The present invention relates to the field of new energy technologies, and in particular to a stability control method and system for a photovoltaic storage and charging station system. Background Art

[0002] The photovoltaic storage and charging station system is a system composed of many devices such as photovoltaics, energy storage and charging piles. The stable and reliable operation of the system requires fast and effective scheduling and control of each device, so a stability control method is very necessary.

[0003] Existing photovoltaic storage and charging station systems mainly perform output power scheduling and control based on demand response, making it difficult to suppress voltage fluctuations and achieve rapid and stable control during system operation. Summary of the Invention

[0004] The embodiments of the present invention provide a stability control method and system for a photovoltaic storage and charging station system, aiming to solve the problem in existing technical methods that it is difficult to achieve voltage fluctuation suppression and stability control during system operation.

[0005] In a first aspect, an embodiment of the present invention provides a stability control method for a photovoltaic storage and charging station system, wherein the photovoltaic storage and charging station system includes a station-level controller, a photovoltaic inverter, an energy storage converter and a charging pile, wherein the photovoltaic inverter, the energy storage converter and the charging pile are all connected to an AC bus, and the AC bus is connected to a public power grid. The station-level controller is communicatively connected to the photovoltaic inverter, the energy storage converter and the charging pile; the control method is applied to the station-level controller, and the control method includes: obtaining the system grid-connected point voltage, the photovoltaic inverter grid-connected point voltage and the charging pile grid-connected point voltage in real time; judging whether the system grid-connected point voltage exceeds a first limited range to obtain a first judgment result; if the first judgment result is yes, generating a voltage adjustment instruction based on a preset system grid-connected point reference voltage, the system grid-connected point voltage, the photovoltaic inverter grid-connected point voltage and the charging pile grid-connected point voltage; and sending the voltage adjustment instruction to the energy storage converter to adjust the system voltage.

[0006] In the second aspect, an embodiment of the present invention provides a photovoltaic storage and charging station system, including a station-level controller, a photovoltaic inverter, an energy storage converter and a charging pile. The stability control method of the photovoltaic storage and charging station system as described in the first aspect is applied to the station-level controller; the photovoltaic inverter, the energy storage converter and the charging pile are all connected to the AC bus, and the AC bus is connected to the public power grid; the station-level controller is connected to the photovoltaic inverter, the energy storage converter and the charging pile through a communication bus; the station-level controller is connected to the connection switch through DIO communication, and the connection switch includes the connection switch between the photovoltaic inverter, the energy storage converter and the charging pile and the AC bus; the station-level controller is connected to the system grid connection point, the photovoltaic inverter grid connection point and the charging pile grid connection point through AD communication.

[0007] An embodiment of the present invention provides a stability control method and system for a photovoltaic storage and charging station system, wherein the photovoltaic storage and charging station system includes a station-level controller, a photovoltaic inverter, an energy storage converter and a charging pile, wherein the photovoltaic inverter, the energy storage converter and the charging pile are all connected to an AC bus, and the AC bus is connected to a public power grid, and the station-level controller is communicatively connected to the photovoltaic inverter, the energy storage converter and the charging pile; the control method is applied to the station-level controller, and the control method includes: obtaining the system grid-connected point voltage, the photovoltaic inverter grid-connected point voltage and the charging pile grid-connected point voltage in real time; judging whether the system grid-connected point voltage exceeds a first limited range to obtain a first judgment result; if the first judgment result is yes, generating a voltage adjustment instruction based on a preset system grid-connected point reference voltage, the system grid-connected point voltage, the photovoltaic inverter grid-connected point voltage and the charging pile grid-connected point voltage; and sending the voltage adjustment instruction to the energy storage converter to adjust the system voltage. The embodiments of the present invention can detect the voltage data of the system grid connection point, the photovoltaic inverter grid connection point, and the charging pile grid connection point in real time, thereby adjusting the voltage of the system grid connection point in real time to stabilize it within a preset range, thereby achieving the purpose of stable operation of the system. It can also achieve voltage fluctuation suppression and stable control during the operation of the photovoltaic storage and charging station system, solving the problem that the existing photovoltaic storage and charging station system can only be controlled according to power demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0009] Figure 1A flow chart of a stability control method for a solar-storage-charging station system provided by an embodiment of the present invention;

[0010] Figure 2 A schematic diagram of the architecture of a solar-storage-charging station system provided in an embodiment of the present invention;

[0011] Figure 3 Another flow chart of the stability control method of the solar-storage-charging station system provided by an embodiment of the present invention;

[0012] Figure 4 Another flow chart of the stability control method of the solar-storage-charging station system provided by an embodiment of the present invention;

[0013] Figure 5 A schematic block diagram of a station-level controller provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0014] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0015] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0016] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0017] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0018] It should also be noted that, unless otherwise clearly specified and limited, terms such as "installed", "connected", "connected", "fixed", and "set" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intervening elements. The terms "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", "third", etc. may explicitly or implicitly include one or more of such features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0019] See also Figure 1 and Figure 2 An embodiment of the present invention provides a stability control method for a photovoltaic storage and charging station system, wherein the photovoltaic storage and charging station system includes a station-level controller, a photovoltaic inverter, an energy storage converter, and a charging pile. The photovoltaic inverter, the energy storage converter, and the charging pile are all connected to an AC bus, and the AC bus is connected to a public power grid. The station-level controller is communicatively connected to the photovoltaic inverter, the energy storage converter, and the charging pile; the control method is applied to the station-level controller.

[0020] In this embodiment, the solar-storage-charging station system may also include photovoltaic modules. A photovoltaic inverter converts the DC power generated by the photovoltaic modules into AC power for use by a load or fed into the public grid. The load may be an AC charging station. The energy storage converter performs bidirectional power conversion, for example, converting AC power from the public grid or photovoltaic inverter into DC power for storage in a battery, or converting DC power from a battery into AC power for use by a load or the public grid. Charging stations, which provide power to electric vehicles and serve as loads in the system, may include both AC and DC charging stations. The station-level controller, serving as the system's core controller, controls the photovoltaic inverter, energy storage converter, and charging stations within the system. It communicates directly with these devices via a communication bus, eliminating the need for intermediary devices in the communication loop. Compared to existing solar-storage-charging station systems, which rely on a communication management unit to collect real-time information from system devices and then communicate with the controller, the solar-storage-charging station system of this embodiment offers short communication latency, fast response times, and high control accuracy.

[0021] Wherein, the control method includes steps S1 to S4.

[0022] S1. Real-time acquisition of the system grid connection point voltage, the photovoltaic inverter grid connection point voltage, and the charging pile grid connection point voltage.

[0023] In this embodiment, the system grid connection point is the connection point between the AC busbar and the public grid, the PV inverter grid connection point is the connection point between the PV inverter grid connection point and the AC busbar, and the charging pile grid connection point is the connection point between the charging pile and the AC busbar. The station-level controller collects real-time voltage signals from the system grid connection point, the PV inverter grid connection point, and the charging pile grid connection point through analog-to-digital (A / D) communication, thereby obtaining real-time voltage information from the system grid connection point, the PV inverter grid connection point, and the charging pile grid connection point.

[0024] S2. Determine whether the voltage at the system grid connection point exceeds a first limited range, and obtain a first determination result.

[0025] In this embodiment, the first limit range is the range within which the system grid connection point voltage is allowed to fluctuate with respect to its reference voltage. For example, if its reference voltage is X, the first limit range may be 0.9X~1.1X. Exceeding the first limit range means being less than 0.9X or greater than 1.1X.

[0026] S3. If the first judgment result is yes, generate a voltage adjustment instruction based on the preset system grid connection point reference voltage, the system grid connection point voltage, the photovoltaic inverter grid connection point voltage and the charging pile grid connection point voltage.

[0027] S4. Send the voltage adjustment instruction to the energy storage converter to adjust the system voltage.

[0028] The sending period of the voltage regulation instruction is 10 ms, that is, the control period of the control method is 10 ms, and the response speed is fast.

[0029] If the first judgment result is no, step S9 is executed.

[0030] In this embodiment, taking the preset system grid-connection point reference voltage as X and the first limited range as 0.9X to 1.1X as an example, a first judgment result of yes indicates that the system grid-connection point voltage collected by the station-level controller is less than 0.9X or greater than 1.1X. If the first judgment result is yes, the station-level controller generates a voltage adjustment instruction based on the preset system grid-connection point reference voltage X, the real-time collected system grid-connection point voltage, the photovoltaic inverter grid-connection point voltage, and the charging pile grid-connection point voltage, and sends the voltage adjustment instruction to the energy storage inverter to adjust the system voltage. The station-level controller is connected to the photovoltaic inverter, energy storage inverter, and charging pile via a communication bus, allowing it to directly send voltage adjustment instructions to the energy storage inverter. Of course, as needed, the station-level controller can also send corresponding operating instructions to the photovoltaic inverter and charging pile.

[0031] In a specific embodiment, a PI controller is provided in the station-level controller; if the first judgment result is yes, a voltage regulation instruction is generated based on a preset system grid connection point reference voltage, the system grid connection point voltage, the photovoltaic inverter grid connection point voltage, and the charging pile grid connection point voltage, including:

[0032] A feedforward compensation calculation is performed on the system grid-connected point reference voltage, the system grid-connected point voltage, the photovoltaic inverter grid-connected point voltage, and the charging pile grid-connected point voltage to obtain a first calculation result; the first calculation result = upcc'-upcc-upv-uchar; wherein upcc' is the system grid-connected point reference voltage, upcc is the system grid-connected point voltage, upv is the photovoltaic inverter grid-connected point voltage, and uchar is the charging pile grid-connected point voltage; the first calculation result is input into the PI controller, and a voltage adjustment instruction is output based on the result of the PI calculation; the result of the PI calculation = Kp1*(upcc'-upcc-upv-uchar)+Ki1*(upcc'-upcc-upv-uchar), wherein Kp1 and Ki1 are PI parameters.

[0033] In this embodiment, the station-level controller has a built-in PI controller. If the system grid-connected point voltage exceeds a first limited range, the station-level controller can generate a voltage adjustment instruction based on the PI controller to control the energy storage converter to adjust its output, thereby adjusting the real-time voltage at the system grid-connected point. If the real-time collected system grid-connected point voltage is greater than the upper limit of the first limited range (e.g., 1.1X in the above embodiment), the value of the first calculation result (upcc'-upcc-upv-uchar) is negative, thereby controlling the energy storage converter to reduce its output voltage. If the real-time collected system grid-connected point voltage is less than the lower limit of the first limited range (e.g., 0.9X in the above embodiment), the value of the first calculation result (upcc'-upcc-upv-uchar) is positive, thereby controlling the energy storage converter to increase its output voltage.

[0034] Among them, Kp1 and Ki1 are positive numbers and can be adjusted according to the system. Specifically, when setting the PI parameters, the initial parameters can be set based on empirical values, for example, Kp1 = 0.5 and Ki1 = 0.1. Then, the system grid connection point voltage after adjustment is collected, and the time it takes to recover to within the first limited range is measured as the recovery time. If the recovery time is too long, that is, greater than a preset value, Kp1 or Ki1 is increased. If the system grid connection point voltage collected for the first time is less than the lower limit of the first limited range, and then after the voltage adjustment instruction is controlled, the collected system grid connection point voltage is greater than the upper limit of the first limited range, Kp1 or Ki1 is reduced. Similarly, if the system grid connection point voltage collected for the first time is greater than the upper limit of the first limited range, and then after the voltage adjustment instruction is controlled, the collected system grid connection point voltage is less than the lower limit of the first limited range, Kp1 or Ki1 is also reduced. In this way, Kp1 and Ki1 are adjusted to appropriate values.

[0035] In summary, the embodiments of the present invention can perform voltage stability control by real-time monitoring of voltage data at the system's grid connection point, the photovoltaic inverter's grid connection point, and the charging pile's grid connection point. This allows for real-time adjustment of the system's grid connection point voltage, stabilizing it within a preset range and achieving stable system operation. Specifically, the embodiments of the present invention can suppress voltage fluctuations and achieve rapid and stable control during the operation of a photovoltaic storage and charging station system, resolving the problem that existing photovoltaic storage and charging station systems can only be controlled based on power demand.

[0036] See also Figure 3 In a further embodiment, after S1, the real-time acquisition of the system grid connection point voltage, the photovoltaic inverter grid connection point voltage, and the charging pile grid connection point voltage, the control method further includes steps S5 to S8:

[0037] S5. Based on the system grid connection point voltage, the photovoltaic inverter grid connection point voltage, the charging pile grid connection point voltage and a preset calculation rule library, obtain the system grid connection point frequency, the photovoltaic inverter grid connection point frequency and the charging pile grid connection point frequency.

[0038] In this embodiment, the system grid connection point frequency, the PV inverter grid connection point frequency, and the charging pile grid connection point frequency are all AC voltage frequencies. The preset calculation rule library can be set with reference to three-phase phase-locked loop control theory, thereby achieving the real-time system grid connection point frequency, PV inverter grid connection point frequency, and charging pile grid connection point frequency based on the system grid connection point voltage, PV inverter grid connection point voltage, and charging pile grid connection point voltage collected by the station-level controller.

[0039] S6. Determine whether the system grid connection point frequency exceeds a second limited range, and obtain a second determination result.

[0040] In this embodiment, the second limited range is the range within which the system grid connection point frequency is allowed to fluctuate based on its reference frequency. For example, if its reference voltage is Y, the second limited range may be 0.9Y~1.1Y. Exceeding the second limited range means being less than 0.9Y or greater than 1.1Y.

[0041] S7. If the second judgment result is yes, generate a frequency adjustment instruction based on the preset system grid connection point reference frequency, the system grid connection point frequency, the photovoltaic inverter grid connection point frequency and the charging pile grid connection point frequency.

[0042] S8. Send the frequency adjustment instruction to the energy storage converter to adjust the system output frequency.

[0043] If the second judgment result is no, step S9 is executed.

[0044] In this embodiment, taking the preset system grid connection reference frequency Y and the first limited range of 0.9Y to 1.1Y as an example, the second judgment result is yes, which means that the system grid connection frequency calculated by the station-level controller based on the system grid connection voltage is less than 0.9Y or greater than 1.1Y. If the second judgment result is yes, the station-level controller generates a frequency adjustment instruction based on the preset system grid connection reference frequency Y, the real-time calculated system grid connection frequency, the photovoltaic inverter grid connection frequency, and the charging pile grid connection frequency, and sends the frequency adjustment instruction to the energy storage converter to adjust the system frequency.

[0045] In a specific embodiment, a PI controller is provided in the station-level controller; if the second judgment result is yes, generating a frequency adjustment instruction based on a preset system grid connection point reference frequency, the system grid connection point frequency, the photovoltaic inverter grid connection point frequency, and the charging pile grid connection point frequency includes:

[0046] A feedforward compensation calculation is performed on the system grid-connected point reference frequency and the system grid-connected point frequency, the photovoltaic inverter grid-connected point frequency, and the charging pile grid-connected point frequency to obtain a second calculation result; the second calculation result = Fpcc'-Fpcc-Fpv-Fchar; wherein, Fpcc' is the system grid-connected point reference frequency, Fpcc is the system grid-connected point frequency, Fpv is the photovoltaic inverter grid-connected point frequency, and Fchar is the charging pile grid-connected point frequency; the second calculation result is input into the PI controller, and a frequency adjustment instruction is output based on the result of the PI calculation; the result of the PI calculation = Kp2*(Fpcc'-Fpcc-Fpv-Fchar)+Ki2*(Fpcc'-Fpcc-Fpv-Fchar), wherein Kp2 and Ki2 are PI parameters.

[0047] In this embodiment, if the system grid connection point frequency exceeds the second limited range, the station-level controller can generate a frequency adjustment instruction based on the PI controller to control the energy storage converter to perform output adjustment, thereby adjusting the real-time frequency of the system grid connection point. If the real-time collected system grid connection point frequency is greater than the upper limit of the second limited range (e.g., 1.1Y in the above embodiment), the value of the second calculation result (Fpcc'-Fpcc-Fpv-Fchar) is negative, thereby controlling the energy storage converter to reduce its output frequency. If the real-time collected system grid connection point frequency is less than the lower limit of the second limited range (e.g., 0.9Y in the above embodiment), the value of the first calculation result (Fpcc'-Fpcc-Fpv-Fchar) is positive, thereby controlling the energy storage converter to increase its output frequency.

[0048] Among them, Kp2 and Ki2 are positive numbers and can be adjusted according to the system. The specific adjustment method can refer to the adjustment method for Kp1 and Ki1 in the above embodiment, which will not be repeated here.

[0049] In summary, the embodiments of the present invention can not only suppress voltage fluctuations and quickly and stably control the operation of the photovoltaic storage and charging station system, but also suppress and quickly control frequency fluctuations during system operation, thereby solving the problem that the existing photovoltaic storage and charging station system can only be controlled according to power demand, thereby ensuring the stable operation of the photovoltaic storage and charging station system.

[0050] See also Figure 4 In a further embodiment, in the photovoltaic storage and charging station system, the photovoltaic inverter, the energy storage converter and the charging pile are all provided in plurality, for example Figure 2The photovoltaic inverters 1...N, energy storage converters 1...N, and charging piles 1...N are shown; after S8, sending the frequency adjustment instruction to the energy storage converter to adjust the system output frequency, the control method further includes steps S9 to S11.

[0051] S9. Obtain the port voltage and port frequency of any of the energy storage converters.

[0052] In this embodiment, step S9 may also be performed after step S4. The port voltage and port frequency of the energy storage converter can be understood as the voltage and frequency of the connection port between any energy storage converter and the AC bus. The station-level controller can acquire the real-time port voltage of the energy storage converter by collecting the port voltage signal of the energy storage converter through AD communication, and can also obtain the real-time port frequency of the energy storage converter based on the port voltage and a preset calculation rule library. The setting of the calculation rule library can refer to the setting method of the calculation rule library in the embodiment description corresponding to step S5.

[0053] like Figure 2 As shown, the station-level controller is connected to the connection switch through DIO (Digital Input / Output) communication. The connection switch includes the connection switch between the photovoltaic inverter, the energy storage converter, and the charging pile and the AC bus. This allows the station-level controller to control the connection or disconnection of the energy storage converter and the AC bus. As needed, the station-level controller can also control the connection or disconnection of the photovoltaic inverter and the charging pile and the AC bus.

[0054] It can be understood that the station-level controller can also control the connection or disconnection between devices in the solar storage and charging station system, such as the connection or disconnection between the photovoltaic inverter and the load device, the connection or disconnection between the energy storage converter and the load device, etc.

[0055] S10: Determine whether the port voltage exceeds a third limited range to obtain a third determination result, and determine whether the port frequency exceeds a fourth limited range to obtain a fourth determination result.

[0056] S11. If the third judgment result and / or the fourth judgment result is yes, send a disconnection instruction to the corresponding energy storage converter to disconnect the corresponding energy storage converter.

[0057] In this embodiment, the third limit range is the range within which the port voltage of the energy storage converter is allowed to fluctuate relative to its standard voltage, and the fourth limit range is the range within which the port frequency of the energy storage converter is allowed to fluctuate relative to its standard frequency. If the real-time port voltage of the energy storage converter exceeds the third limit range or the real-time port frequency of the energy storage converter exceeds the fourth limit range, the station-level controller sends a disconnect instruction to the energy storage converter, disconnecting it from the AC bus, thereby disconnecting it from the grid. This prevents the unstable energy storage converter from affecting the stable operation of the system.

[0058] Thus, in this embodiment, in addition to adjusting the voltage and frequency of the system grid connection point in real time to suppress voltage and frequency fluctuations and ensure stable operation of the system, the port voltage and frequency of the energy storage inverter can be detected in real time to control the connection and disconnection of the energy storage inverter and the AC bus, further ensuring stable operation of the system.

[0059] In a further embodiment, before S10, determining whether the port voltage exceeds a third limited range to obtain a third determination result, and determining whether the port frequency exceeds a fourth limited range to obtain a fourth determination result, the control method includes:

[0060] Obtain the grid short-circuit ratio and the load rate of the photovoltaic storage and charging station system in real time;

[0061] Dynamically adjusting a third limited range based on the grid short-circuit ratio and the load rate;

[0062] The third limited range includes an undervoltage threshold and an overvoltage threshold, the undervoltage threshold is lower than a standard voltage threshold of the energy storage converter, and the overvoltage threshold is higher than the standard voltage threshold of the energy storage converter.

[0063] In this embodiment, the dynamic adjustment period can be set to 50ms or 100ms. The station-level controller can calculate the grid short-circuit ratio using Formula 1.

[0064] Formula 1: SCR = S grid / S PCS ;

[0065] Among them, SCR represents the grid short circuit ratio, S grid Indicates the current short-circuit capacity of the public power grid, S PCS Indicates the rated capacity of the energy storage converter, so as to judge whether the public grid is a strong grid or a weak grid in real time through the grid short-circuit ratio.

[0066] The station-level controller can calculate the load rate using Formula 2.

[0067] Formula 2: Load = (P load / P rated)·100%;

[0068] Among them, Load represents the load rate, P load Indicates the current load power of the system, P rated Indicates the rated capacity of the system.

[0069] In this way, the station-level controller can dynamically adjust the undervoltage threshold and overvoltage threshold in the third limited range by obtaining the real-time grid short-circuit ratio and the load rate of the photovoltaic storage and charging station system. On the one hand, it can avoid short-term voltage fluctuations in a weak grid and triggering the protection mechanism, that is, disconnecting the energy storage converter from the AC bus in the above embodiment; on the other hand, it can avoid voltage collapse caused by high load rates and frequent disconnection of the energy storage converter.

[0070] Specifically, the dynamically adjusting the third limited range based on the grid short-circuit ratio includes:

[0071] Determining whether the grid short-circuit ratio is greater than a first preset value or less than a second preset value;

[0072] If the grid short-circuit ratio is greater than a first preset value, increasing the undervoltage threshold and decreasing the overvoltage threshold;

[0073] If the grid short-circuit ratio is less than a second preset value, the undervoltage threshold is lowered and the overvoltage threshold is increased.

[0074] In this embodiment, the first preset value may be 10, and the second preset value may be 3. The initial undervoltage threshold of the third limited range may be set to 0.9Z, and the initial overvoltage threshold may be set to 1.1Z, where Z represents the standard voltage threshold of the energy storage converter. If the current grid short circuit ratio (SCR) is greater than 10, the public grid is determined to be a strong grid. The undervoltage threshold may be adjusted from 0.9Z to 0.92Z, and the overvoltage threshold may be adjusted to 1.08Z, thereby increasing the control sensitivity, i.e., the protection sensitivity, of the energy storage converter.

[0075] If the current grid short-circuit ratio SCR is less than 3, the public grid is judged to be a weak grid, and the undervoltage threshold is adjusted to 0.88Z and the overvoltage threshold is adjusted to 1.12Z, thereby relaxing the third limit range to avoid short-term voltage fluctuations and miscontrol.

[0076] Specifically, the dynamically adjusting the third limited range based on the grid short-circuit ratio and the load rate further includes:

[0077] determining whether the load rate is greater than a third preset value or less than a fourth preset value;

[0078] If the load rate is greater than a third preset value, lowering the undervoltage threshold and raising the overvoltage threshold;

[0079] If the load rate is less than a fourth preset value, the undervoltage threshold is increased and the overvoltage threshold is decreased.

[0080] In this embodiment, the third preset value can be set to 80%, and the fourth preset value can be set to 30%. If the current load rate is greater than 80%, the overvoltage threshold is adjusted to 1.12Z to prevent the energy storage converter from frequent disconnection from the grid; the undervoltage threshold is adjusted to 0.88Z to prevent voltage collapse.

[0081] If the current load rate is less than 30%, the overvoltage threshold will be adjusted back to 1.08Z and the undervoltage threshold will be adjusted to 0.92Z.

[0082] Specifically, Formula 3 and Formula 4 may be preset in the station-level controller to dynamically adjust the third limited range based on the grid short-circuit ratio and the load rate.

[0083] Formula 3: V high =V normol ·(1+α·1 / SCR+β·Load).

[0084] Formula 4: V low =V normol ·(1-γ·1 / SCR-δ·Load).

[0085] Among them, V high Indicates the overvoltage threshold of the third limited range, V low Indicates the undervoltage threshold of the third limited range, V normol This represents the standard voltage threshold of the energy storage converter. α, β, γ, and δ are empirical coefficients and are all positive. SCR is the current grid short-circuit ratio, and Load represents the current load rate of the solar-storage-charging station system.

[0086] In this way, in addition to achieving the suppression and rapid and stable control of voltage and frequency fluctuations during the operation of the photovoltaic storage and charging station system, the embodiments of the present invention can also dynamically adjust the voltage protection range of the energy storage inverter to avoid short-term voltage fluctuations that cause the energy storage inverter to frequently disconnect from the grid, thereby ensuring the stable operation of the system.

[0087] In a further embodiment, S11, if the third judgment result and / or the fourth judgment result is yes, sending a disconnection instruction to the corresponding energy storage inverter to cut off the corresponding energy storage inverter, including: judging whether the time for maintaining the third judgment result and / or the fourth judgment result as yes exceeds a fifth preset value; if the time for maintaining the third judgment result and / or the fourth judgment result as yes exceeds the fifth preset value, sending a disconnection instruction to the corresponding energy storage inverter to cut off the corresponding energy storage inverter.

[0088] In this embodiment, after detecting that the port voltage of the energy storage converter exceeds the third limit range and / or the port frequency exceeds the fourth limit range, the energy storage converter is not immediately disconnected. Instead, it continues to be monitored to determine whether the time of exceeding the limit exceeds the fifth preset value. For example, the fifth preset value may be 50ms. When the time of exceeding the limit exceeds 50ms, a disconnection instruction is sent to the corresponding energy storage converter to disconnect the corresponding energy storage converter, thereby realizing anti-shake protection and further avoiding frequent switching of the energy storage converter to ensure stable operation of the system.

[0089] Please refer again Figure 2 An embodiment of the present invention further provides a photovoltaic storage and charging station system, comprising a station-level controller, a photovoltaic inverter, an energy storage converter, and a charging pile. The stability control method of the photovoltaic storage and charging station system disclosed in the above embodiment is applied to the station-level controller; the photovoltaic inverter, the energy storage converter, and the charging pile are all connected to the AC bus, and the AC bus is connected to the public power grid; the station-level controller is connected to the photovoltaic inverter, the energy storage converter, and the charging pile through a communication bus; the station-level controller is connected to the connection switch through DIO communication, and the connection switch includes the connection switch between the photovoltaic inverter, the energy storage converter, and the charging pile and the AC bus; the station-level controller is connected to the system grid connection point, the photovoltaic inverter grid connection point, and the charging pile grid connection point through AD communication.

[0090] Among them, the photovoltaic inverter, energy storage converter and charging pile can be set to multiple, such as Figure 2 The photovoltaic inverters 1...N, energy storage converters 1...N, and charging piles 1...N are shown.

[0091] See also Figure 5 , an embodiment of the present invention further provides a station-level controller, Figure 5 It is a schematic block diagram of a station-level controller provided by an embodiment of the present invention.

[0092] See Figure 5 The station-level controller 500 includes a processor 502 , a memory, and a network interface 505 connected via a communication bus 501 , wherein the memory may include a storage medium 503 and an internal memory 504 .

[0093] The storage medium 503 can store an operating system 5031 and a computer program 5032. When the computer program 5032 is executed, the processor 502 can execute the stability control method of the solar-storage-charging station system described above. The storage medium 503 can be a volatile storage medium or a non-volatile storage medium.

[0094] The processor 502 is used to provide computing and control capabilities to support the operation of the entire station-level controller 500.

[0095] The internal memory 504 provides an environment for the operation of the computer program 5032 in the storage medium 503. When the computer program 5032 is executed by the processor 502, the processor 502 can execute the stability control method of the photovoltaic storage and charging station system.

[0096] The network interface 505 is used for network communication, such as providing data information transmission. Those skilled in the art will understand that Figure 5 The structure shown in the figure is merely a block diagram of a portion of the structure related to the solution of the present invention, and does not constitute a limitation on the station-level controller 500 to which the solution of the present invention is applied. The specific station-level controller 500 may include more or fewer components than those shown in the figure, or combine certain components, or have a different component arrangement.

[0097] The processor 502 is configured to run a computer program 5032 stored in a memory to implement corresponding functions in the stability control method of the solar-storage-charging station system.

[0098] Those skilled in the art will understand that Figure 5 The embodiment of the computer device shown in the figure does not constitute a limitation on the specific composition of the computer device. In other embodiments, the computer device may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently. For example, in some embodiments, the computer device may only include a memory and a processor. In such an embodiment, the structure and function of the memory and processor are the same as those in the figure. Figure 5 The embodiments shown are consistent and will not be described again here.

[0099] It should be understood that in the embodiment of the present invention, the processor 502 may be a central processing unit (CPU), and the processor 502 may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0100] In another embodiment of the present invention, a computer-readable storage medium is provided. The computer-readable storage medium may be volatile or non-volatile. The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps included in the stability control method for the aforementioned solar-storage-charging station system.

[0101] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described equipment, devices and units can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0102] In the several embodiments provided by the present invention, it should be understood that the disclosed devices, apparatuses and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, or units with the same function may be combined into one unit. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interfaces, devices or units, or may be an electrical, mechanical or other form of connection.

[0103] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected according to actual needs to achieve the objectives of the embodiments of the present invention.

[0104] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0105] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a computer-readable storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned computer-readable storage medium includes various media that can store program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a magnetic disk, or an optical disk.

[0106] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A stability control method for a solar-storage-charging station system, characterized in that: The photovoltaic storage and charging station system includes a station-level controller, a photovoltaic inverter, an energy storage converter, and a charging pile. The photovoltaic inverter, the energy storage converter, and the charging pile are all connected to an AC bus, which is connected to a public power grid. The station-level controller is in communication with the photovoltaic inverter, the energy storage converter, and the charging pile. The control method is applied to the station-level controller, wherein the station-level controller is provided with a PI controller, and the control method includes: Real-time acquisition of system grid connection point voltage, photovoltaic inverter grid connection point voltage, and charging pile grid connection point voltage; Determining whether the system grid connection point voltage exceeds a first limited range, and obtaining a first determination result; If the first judgment result is yes, generating a voltage adjustment instruction based on a preset system grid connection point reference voltage, the system grid connection point voltage, the photovoltaic inverter grid connection point voltage, and the charging pile grid connection point voltage; Sending the voltage adjustment instruction to the energy storage converter to adjust the system voltage; If the first judgment result is yes, generating a voltage adjustment instruction based on a preset system grid connection point reference voltage, the system grid connection point voltage, the photovoltaic inverter grid connection point voltage, and the charging pile grid connection point voltage includes: Performing a feedforward compensation calculation on the system grid connection point reference voltage, the system grid connection point voltage, the photovoltaic inverter grid connection point voltage, and the charging pile grid connection point voltage to obtain a first calculation result; The first calculation result = upcc'-upcc-upv-uchar; wherein upcc' is the system grid connection point reference voltage, upcc is the system grid connection point voltage, upv is the photovoltaic inverter grid connection point voltage, and uchar is the charging pile grid connection point voltage; inputting the first calculation result into the PI controller, and outputting a voltage regulation instruction based on the result of the PI calculation; The result of the PI calculation=Kp1*(upcc'-upcc-upv-uchar)+Ki1*(upcc'-upcc-upv-uchar), where Kp1 and Ki1 are PI parameters.

2. The stability control method of the solar-storage-charging station system according to claim 1, characterized in that: After obtaining the system grid connection point voltage, the photovoltaic inverter grid connection point voltage, and the charging pile grid connection point voltage in real time, the control method further includes: Based on the system grid connection point voltage, the photovoltaic inverter grid connection point voltage, and the charging pile grid connection point voltage and a preset calculation rule library, the system grid connection point frequency, the photovoltaic inverter grid connection point frequency, and the charging pile grid connection point frequency are obtained; Determining whether the system grid connection point frequency exceeds a second limited range, and obtaining a second determination result; If the second judgment result is yes, generating a frequency adjustment instruction based on a preset system grid connection point reference frequency, the system grid connection point frequency, the photovoltaic inverter grid connection point frequency, and the charging pile grid connection point frequency; The frequency adjustment instruction is sent to the energy storage converter to adjust the system output frequency.

3. The stability control method of the solar-storage-charging station system according to claim 2, characterized in that: The station-level controller is provided with a PI controller; if the second judgment result is yes, generating a frequency adjustment instruction based on a preset system grid connection point reference frequency, the system grid connection point frequency, the photovoltaic inverter grid connection point frequency, and the charging pile grid connection point frequency, including: Performing a feedforward compensation calculation on the system grid connection point reference frequency, the system grid connection point frequency, the photovoltaic inverter grid connection point frequency, and the charging pile grid connection point frequency to obtain a second calculation result; The second calculation result = Fpcc'-Fpcc-Fpv-Fchar; wherein Fpcc' is the system grid connection point reference frequency, Fpcc is the system grid connection point frequency, Fpv is the photovoltaic inverter grid connection point frequency, and Fchar is the charging pile grid connection point frequency; inputting the second calculation result into the PI controller, and outputting a frequency adjustment instruction based on the result of the PI calculation; The result of the PI calculation=Kp2*(Fpcc'-Fpcc-Fpv-Fchar)+Ki2*(Fpcc'-Fpcc-Fpv-Fchar), where Kp2 and Ki2 are PI parameters.

4. The stability control method of the solar storage and charging station system according to claim 2, characterized in that: In the photovoltaic storage and charging station system, the photovoltaic inverter, the energy storage converter, and the charging pile are all provided in plurality; after the frequency adjustment instruction is sent to the energy storage converter to adjust the system output frequency, the control method further includes: Obtaining the port voltage and port frequency of any of the energy storage converters; Determining whether the port voltage exceeds a third limited range to obtain a third determination result, and determining whether the port frequency exceeds a fourth limited range to obtain a fourth determination result; If the third judgment result and / or the fourth judgment result is yes, a disconnection instruction is sent to the corresponding energy storage converter to disconnect the corresponding energy storage converter.

5. The stability control method of the solar-storage-charging station system according to claim 4, characterized in that: Before determining whether the port voltage exceeds a third limited range to obtain a third determination result and determining whether the port frequency exceeds a fourth limited range to obtain a fourth determination result, the control method includes: Obtain the grid short-circuit ratio and the load rate of the photovoltaic storage and charging station system in real time; Dynamically adjusting a third limited range based on the grid short-circuit ratio and the load rate; The third limited range includes an undervoltage threshold and an overvoltage threshold, the undervoltage threshold is lower than a standard voltage threshold of the energy storage converter, and the overvoltage threshold is higher than the standard voltage threshold of the energy storage converter.

6. The stability control method of the solar-storage-charging station system according to claim 5, characterized in that: The dynamically adjusting the third limited range based on the grid short-circuit ratio includes: Determining whether the grid short-circuit ratio is greater than a first preset value or less than a second preset value; If the grid short-circuit ratio is greater than a first preset value, increasing the undervoltage threshold and decreasing the overvoltage threshold; If the grid short-circuit ratio is less than a second preset value, the undervoltage threshold is lowered and the overvoltage threshold is increased.

7. The stability control method of the solar-storage-charging station system according to claim 5, characterized in that: The dynamically adjusting the third limited range based on the grid short-circuit ratio and the load rate further includes: determining whether the load rate is greater than a third preset value or less than a fourth preset value; If the load rate is greater than a third preset value, lowering the undervoltage threshold and raising the overvoltage threshold; If the load rate is less than a fourth preset value, the undervoltage threshold is increased and the overvoltage threshold is decreased.

8. The stability control method of the solar-storage-charging station system according to claim 4, characterized in that: If the third judgment result and / or the fourth judgment result is yes, sending a disconnection instruction to the corresponding energy storage converter to disconnect the corresponding energy storage converter includes: determining whether a time for which the third judgment result and / or the fourth judgment result is maintained as yes exceeds a fifth preset value; If the time for which the third judgment result and / or the fourth judgment result is maintained as yes exceeds a fifth preset value, a disconnection instruction is sent to the corresponding energy storage converter to cut off the corresponding energy storage converter.

9. A photovoltaic storage and charging station system, comprising a station-level controller, a photovoltaic inverter, an energy storage converter and a charging pile, characterized in that: The stability control method of the photovoltaic storage and charging station system according to any one of claims 1 to 8 is applied to the station-level controller; the photovoltaic inverter, the energy storage converter and the charging pile are all connected to the AC bus, and the AC bus is connected to the public power grid; the station-level controller is connected to the photovoltaic inverter, the energy storage converter and the charging pile through a communication bus; the station-level controller is connected to the connection switch through DIO communication, and the connection switch includes the connection switch between the photovoltaic inverter, the energy storage converter and the charging pile and the AC bus; the station-level controller is connected to the system grid connection point, the photovoltaic inverter grid connection point and the charging pile grid connection point through AD communication.

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