Communication control circuit and method for string type optical storage power generation system

Abstract

The invention belongs to the technical field of photovoltaic power generation, and particularly relates to a string type optical storage power generation system communication control circuit and method. The circuit comprises a photovoltaic module, an energy storage battery and a superior scheduling module, wherein the photovoltaic module is connected with a string type inverter; the circuit further comprises a GOOSE network switch, and the GOOSE network switch is downwards connected with the energy storage battery and the string type inverter respectively. According to the invention, the coordination controller, the GOOSE network switch and the MMS network switch are added in a conventional optical storage power generation system of a string inverter AC coupling mode, a communication control system is reconstructed, the coordination controller directly controls the string inverter data acquisition devices (EMS) and PCS, the response is fast, the precision is high, and the coordination controller can output power in real time according to photovoltaic power, so that the power generation efficiency is improved. And the output threshold of the optical storage system is flexibly adjusted.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic power generation, and in particular relates to a communication control circuit and method for a string-type photovoltaic storage power generation system. Background Art

[0002] At present, the control method of the photovoltaic power generation system configured with the AC coupling mode of the string inverter is relatively simple, and the communication control is collected and controlled by the battery management system (Battery Management System, BMS), the energy management system (Energy Management Unit, EMU), and the data acquisition device (Energy Management System, EMS).

[0003] ① When transmitting upward: First, the BMS collects all battery information and transmits it to the EMU. The EMU collects BMS information, power conversion system (PCS) information, energy storage meter information and other information and uploads them to the EMS. The EMS collects EMU information, string inverter information, box transformer low-voltage side information and other information for upward transmission.

[0004] ② When controlling downward: First, the dispatcher sends the information to the EMS. The EMS sends instructions to the EMU by comparing the power size. The EMU controls the charging and discharging of the energy storage battery. The EMS also controls the inverter to control the photovoltaic output.

[0005] Long response time: When EMS directly collects information from each photovoltaic power generation unit in the site, the huge amount of data will place higher requirements on the EMS hardware performance and software control capabilities. Since a control system needs to control dozens or even hundreds of photovoltaic inverters and PCSs to run simultaneously, from data collection (including protocol conversion), logical judgment, command issuance to on-site response, the overall closed-loop operation time will be as long as tens of seconds, which cannot give full play to the advantages of rapid energy storage regulation.

[0006] Poor control accuracy: Since the information of photovoltaic and energy storage is collected separately, and then the inverter output and energy storage charging and discharging are controlled separately, the time for uploading and adjusting the response of the two parts of photovoltaic and energy storage is different. From the perspective of the overall output of the photovoltaic and energy storage power generation unit, the coordination consistency of photovoltaic power generation and energy storage charging and discharging is poor, resulting in large fluctuations in the output of the photovoltaic and energy storage power generation unit.

[0007] Single control mode: The existing AGC / AVC system at the station control layer can only use the rated capacity of the transformer of each photovoltaic power generation unit as the maximum control power of the power generation unit's grid connection point, and the output threshold remains unchanged. It is not possible to dynamically adjust the daily maximum output threshold of the grid connection point according to the actual weather, resulting in low energy storage utilization in cloudy weather and energy storage not working in rainy weather. At the same time, the output threshold issued by the existing AGC / AVC only considers photovoltaic output and does not consider the role of energy storage, making the utilization rate of energy storage lower in actual operation. Summary of the invention

[0008] In view of the above problems, the present invention provides a communication control circuit for a string photovoltaic storage power generation system, the circuit comprising a photovoltaic module, an energy storage battery and an upper-level scheduling module, the photovoltaic module being connected to a string inverter; the circuit further comprising:

[0009] A GOOSE network switch, wherein the GOOSE network switch is respectively connected to the energy storage battery and the string inverter;

[0010] A coordination controller, wherein the coordination controller is connected to the GOOSE network switch at the bottom, connected to the upper-level dispatching module via an optical fiber at the top, and connected to the low-voltage side circuit of the box-type transformer via a cable;

[0011] The MMS network switch is connected to the string inverter and the energy storage battery respectively at the bottom, and is connected to the upper scheduling module via optical fiber at the top.

[0012] Preferably, the circuit further comprises an energy storage converter, wherein the energy storage converter is connected to the energy storage battery at the bottom and connected to the GOOSE network switch at the top.

[0013] Preferably, the circuit further comprises an energy management system, and the energy management system is connected to the MMS network switch.

[0014] Preferably, the circuit further comprises an energy storage watt-hour meter and a transformer signal non-electric quantity measurement module, and the energy storage watt-hour meter and the transformer signal non-electric quantity measurement module are connected to the energy management system.

[0015] Preferably, the energy storage watt-hour meter includes a DC energy storage watt-hour meter and an AC energy storage watt-hour meter.

[0016] Preferably, the coordination controller includes a calculation module, an output module, an input module and a control module.

[0017] The present invention also proposes a communication control method for a string photovoltaic storage power generation system, the control method comprising:

[0018] The GOOSE network switch stores the data of the energy storage battery and string inverter into the GOOSE network;

[0019] The MMS network switch obtains data from the energy storage battery and string inverter, and uploads the data to the upper-level dispatch module;

[0020] The coordination controller obtains the required data from the GOOSE network, collects the current of the low-voltage side circuit of the box-type transformer, and uploads it to the upper-level dispatching module.

[0021] Preferably, the GOOSE network switch stores the data of the energy storage battery in the GOOSE network, including:

[0022] The energy storage battery data is uploaded to the energy storage converter;

[0023] The GOOSE network switch stores the data of the energy storage battery in the energy storage inverter into the GOOSE network.

[0024] Preferably, the MMS network switch obtains data from the energy storage watt-hour meter and the transformer signal non-electric quantity measurement module through the energy management system, and uploads the data to the upper-level scheduling module.

[0025] Preferably, the energy storage watt-hour meter includes a DC energy storage watt-hour meter and an AC energy storage watt-hour meter.

[0026] The present invention has the following beneficial effects:

[0027] The present invention adds a coordination controller, a GOOSE network switch and an MMS network switch to the photovoltaic storage power generation system in the AC coupling mode of the traditional string inverter, and rebuilds the communication control system. The coordination controller directly controls the string inverter data acquisition device (EMS) and PCS, with fast response and high accuracy. In addition, the coordination controller can flexibly adjust the output threshold of the photovoltaic storage system according to the real-time photovoltaic output.

[0028] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 creative work.

[0030] Figure 1A primary diagram of a photovoltaic power generation system configured with a string inverter in an AC coupling mode according to an embodiment of the present invention is shown;

[0031] Figure 2 A communication block diagram of a photovoltaic power generation system configured with a string inverter in an AC coupling mode according to an embodiment of the present invention is shown;

[0032] Figure 3 A control diagram of a photovoltaic power generation system configured with a string inverter in AC coupling mode in an embodiment of the present invention is shown;

[0033] Figure 4 A schematic diagram of a coordination controller module in an embodiment of the present invention is shown;

[0034] Figure 5 A diagram showing a communication control method for a string photovoltaic power generation system in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0035] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as being limited to the examples set forth herein; on the contrary, these embodiments are provided so that the present disclosure will be more comprehensive and complete, and the concepts of the example embodiments are fully conveyed to those skilled in the art. The described features, structures, or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced while omitting one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known technical solutions are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0036] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware units or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0037] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the steps. For example, some steps may be decomposed, while some steps may be combined or partially combined, so the actual execution order may change according to the actual situation.

[0038] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example.

[0039] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or sub-modules is not necessarily limited to those steps or sub-modules explicitly listed, but may include other steps or sub-modules not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0040] The present invention adds a coordination controller, a GOOSE network switch and an MMS network switch to the photovoltaic storage power generation system in the AC coupling mode of the traditional string inverter, and rebuilds the communication control system. The coordination controller directly controls the string inverter data acquisition device (EMS) and PCS, with fast response and high accuracy. In addition, the coordination controller can flexibly adjust the output threshold of the photovoltaic storage system according to the real-time photovoltaic output.

[0041] like Figure 1 As shown, the present invention includes an AC-coupled photovoltaic storage system of PCS, in which both the photovoltaic and energy storage systems are connected to the AC bus on the low-voltage side of the box-type transformer. After receiving instructions from the coordination controller, the photovoltaic inverter controls the output of the photovoltaic system, and after receiving instructions from the coordination controller, the PCS controls the charging and discharging of the energy storage system.

[0042] like Figure 2 As shown, the present invention proposes a communication control circuit for a string photovoltaic storage power generation system, the circuit comprising a photovoltaic module, an energy storage battery and an upper-level scheduling module, the photovoltaic module is connected to a string inverter; the circuit also includes:

[0043] A GOOSE network switch, wherein the GOOSE network switch is respectively connected to the energy storage battery and the string inverter;

[0044] A coordination controller, wherein the coordination controller is connected to the GOOSE network switch at the bottom, connected to the upper-level dispatching module via an optical fiber at the top, and connected to the low-voltage side circuit of the box-type transformer via a cable;

[0045] The MMS network switch is connected to the string inverter and the energy storage battery respectively at the bottom, and is connected to the upper scheduling module via optical fiber at the top.

[0046] The circuit also includes an energy storage converter, which is connected to an energy storage battery at the bottom and to a GOOSE network switch at the top.

[0047] The circuit also includes an energy management system, and the energy management system is connected to the MMS network switch.

[0048] The circuit also includes an energy storage watt-hour meter and a transformer signal non-electric quantity measurement module, and the energy storage watt-hour meter and the transformer signal non-electric quantity measurement module are connected to the energy management system.

[0049] Specifically, in Figure 2 In the GOOSE network switch, the GOOSE network switch is connected to the PCS and inverter data acquisition device (EMS) through the network port (RJ45) at the bottom, and the protocol is IEC 61850-GOOSE; it is connected to the coordination controller through the network port at the top, and the protocol is IEC61850-GOOSE. The MMS network switch is connected to the inverter data acquisition device (EMS), BMS, and EMU through the network port (RJ45) at the bottom, and the protocol is IEC61850-MMS; it is connected to the optical fiber terminal box through the optical port at the top, and the protocol is IEC61850-MMS.

[0050] The energy management system (EMU) is connected to the photovoltaic DC / DC, energy storage meter, non-electricity signal, etc. through the RS485 serial port; it is connected to the MMS network switch through the network port.

[0051] The coordination controller is connected to the GOOSE network switch and the current information on the low-voltage side of the box-type transformer downward, and is connected to the optical fiber distribution frame through the optical port upward. The protocol is IEC 61850.

[0052] BMS monitors the energy storage battery information and uploads it to PCS and MMS network through the network port.

[0053] The GOOSE network collects information from the PCS and inverter data acquisition device (EMS) and uploads it to the coordination controller; the MMS network switch collects BMS information and EMU information and uploads it to the upper-level dispatcher; the coordination controller uses a cable to directly collect the low-voltage side current information of the box-type transformer from the mutual inductor; the BMS collects battery information, and the EMU collects information such as the electricity meter.

[0054] like Figure 3 As shown, the control system controls:

[0055] (1) The coordination controller is connected to systems A, B, and C at the substation control layer respectively above, receives control instructions from each system, realizes steady-state (AGC / AVC control) and transient (primary frequency regulation control) operations. The communication interfaces are independent of each other and support IEC 61850. Below, it directly collects data acquisition devices of inverters inside the photovoltaic and energy storage power generation unit, energy storage converters, etc., and supports IEC 61850.

[0056] (2) The coordination controller directly collects analog quantities of voltage and current on the low-voltage side of the step-up transformer.

[0057] (3) The coordination controller accesses the action signals (dry contacts) of the step-up transformer measurement and control device (including protection function).

[0058] (4) The coordination controller controls the inverter (realized through the data acquisition device), the energy storage converter, and can also control the opening and closing of the circuit breaker on the low-voltage side of the step-up transformer and the circuit breaker of the energy storage device.

[0059] (5) The coordination controller collects internal information of the photovoltaic and energy storage power generation unit in real time. It can either receive control instructions from various systems at the substation control layer, coordinate photovoltaic power generation and energy storage charging and discharging according to remote control instructions, and realize functions such as photovoltaic and energy storage combined power generation (steady-state operation), peak shaving (steady-state operation), and primary frequency regulation (transient operation); or compare the collected photovoltaic output value with the rated capacity of the step-up transformer, automatically and dynamically set the power threshold for daily output control locally, and use this threshold as an instruction to realize photovoltaic and energy storage combined power generation (steady-state operation).

[0060] As Figure 4 shown, the coordination controller is a controller that includes an operation module, a control module, an input module, and an output module.

[0061] Operation logic:

[0062] ① The coordination controller receives the dispatching instruction P1, compares P1 with 1.1 times the rated power of the box transformer, calculates the minimum value of the two as Pmax (here to ensure that Pmax does not exceed 1.1 times the rated power of the box transformer), then collects the power P of the photovoltaic inverter. Then, the coordination controller compares P with Pmax. When P = Pmax, the energy storage system neither charges nor discharges. When P > Pmax, the coordination controller controls the PCS to start charging. When P < Pmax, the coordination controller controls the PCS to start discharging; after the energy storage system acts, the coordination controller collects the power P_box on the low-voltage side of the box transformer as a feedback value, compares P_box with Pmax, and then uses the coordination controller for correction again to make P_box = Pmax.

[0063] Or ② The coordination controller does not accept the dispatching instruction, compares the power P at the photovoltaic inverter collected with 1.1 times the rated power of the box transformer, takes the smaller value as Pmax, and the rest of the calculation logic remains unchanged.

[0064] The control module requires that the coordination controller can directly control the photovoltaic inverter or its data collector, photovoltaic DC / DC, PCS, etc., can control multiple PCSs to run in parallel, and evenly distribute the power of multiple PCSs according to the SOC value of each battery pack, and balance the SOC value of each battery pack. The communication interfaces are independent and can accept and quickly execute various superior dispatches. According to the real-time collection of photovoltaic output, the dynamic photovoltaic storage power generation unit output control threshold can be automatically set on-site according to different weather conditions to avoid the problem of low storage utilization in cloudy weather and inability to put storage into operation in cloudy weather.

[0065] The input and output modules are required to have various interface types such as multiple network ports, optical ports, serial ports, etc., and the protocols must support unified protocols such as IEC 61850, IEC604, Modbus, etc.

[0066] like Figure 5 As shown, the present invention also proposes a communication control method for a string photovoltaic storage power generation system, the control method comprising the following steps:

[0067] S1 GOOSE network switch stores the data of energy storage batteries and string inverters into the GOOSE network;

[0068] The S2 MMS network switch obtains the data of the energy storage battery and string inverter, and uploads the data to the upper-level dispatch module;

[0069] The S3 coordination controller obtains the required data from the GOOSE network, collects the current of the low-voltage side circuit of the box-type transformer, and uploads it to the upper-level dispatching module.

[0070] Specifically, the S1 GOOSE network switch stores the energy storage battery data in the GOOSE network, including:

[0071] The energy storage battery data is uploaded to the energy storage converter;

[0072] The GOOSE network switch stores the data of the energy storage battery in the energy storage inverter into the GOOSE network.

[0073] The control method further comprises:

[0074] S4 The MMS network switch obtains data from the energy storage watt-hour meter and the transformer signal non-electricity measurement module through the energy management system, and uploads it to the upper-level scheduling module.

[0075] Those skilled in the art should understand that although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible to modify the technical solutions described in the aforementioned embodiments, or to make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A communication control circuit for a string photovoltaic power generation system. It is characterized in that The circuit includes a photovoltaic module, an energy storage battery and an upper-level scheduling module, and the photovoltaic module is connected to a string inverter; the circuit also includes: A GOOSE network switch, wherein the GOOSE network switch is respectively connected to the energy storage battery and the string inverter; A coordination controller, wherein the coordination controller is connected to the GOOSE network switch at the bottom, connected to the upper-level dispatching module via an optical fiber at the top, and connected to the low-voltage side circuit of the box-type transformer via a cable; The MMS network switch is connected to the string inverter and the energy storage battery respectively at the bottom, and is connected to the upper scheduling module via optical fiber at the top.

2. The communication control circuit of the string photovoltaic power generation system according to claim 1, It is characterized in that The circuit also includes an energy storage converter, which is connected to an energy storage battery at the bottom and to a GOOSE network switch at the top.

3. The communication control circuit of the string photovoltaic power generation system according to claim 1, It is characterized in that The circuit also includes an energy management system, and the energy management system is connected to the MMS network switch.

4. The communication control circuit of the string photovoltaic power generation system according to claim 3, It is characterized in that The circuit also includes an energy storage watt-hour meter and a transformer signal non-electric quantity measurement module, and the energy storage watt-hour meter and the transformer signal non-electric quantity measurement module are connected to the energy management system.

5. The communication control circuit of the string photovoltaic power generation system according to claim 4, It is characterized in that The energy storage watt-hour meter includes a DC energy storage watt-hour meter and an AC energy storage watt-hour meter.

6. The communication control circuit of the string photovoltaic power generation system according to claim 1, It is characterized in that The coordination controller includes a calculation module, an output module, an input module and a control module.

7. A control method for a communication control circuit of a string photovoltaic power generation system according to any one of claims 1 to 6, It is characterized in that The control method comprises: The GOOSE network switch stores the data of the energy storage battery and string inverter into the GOOSE network; The MMS network switch obtains data from the energy storage battery and string inverter, and uploads the data to the upper-level dispatch module; The coordination controller obtains the required data from the GOOSE network, collects the current of the low-voltage side circuit of the box-type transformer, and uploads it to the upper-level dispatching module.

8. The control method according to claim 7, It is characterized in that The GOOSE network switch stores the data of the energy storage battery in the GOOSE network, including: The energy storage battery data is uploaded to the energy storage converter; The GOOSE network switch stores the data of the energy storage battery in the energy storage inverter into the GOOSE network.

9. The control method according to claim 7, It is characterized in that The control method further comprises: The MMS network switch obtains data from the energy storage watt-hour meter and the transformer signal non-electricity measurement module through the energy management system, and uploads the data to the upper-level scheduling module.

10. The control method according to claim 7, It is characterized in that The energy storage watt-hour meter includes a DC energy storage watt-hour meter and an AC energy storage watt-hour meter.

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