Photovoltaic and energy-storage integrated power conversion topology based on DC bus collection

Abstract

The present invention relates to a photovoltaic-storage integrated power conversion topology based on DC bus collection, including a photovoltaic DC / DC module, an energy storage system, a DC bus, a photovoltaic storage inverter and a coordination controller, wherein the photovoltaic DC / DC module, the energy storage system and the photovoltaic storage inverter are all connected to the DC bus; the photovoltaic DC / DC module, the energy storage system and the photovoltaic storage inverter are all communicatively connected to the coordination controller; the photovoltaic DC / DC module has a maximum power point tracking function, which detects the power generation voltage of the photovoltaic string in real time and tracks the highest voltage and current value; the photovoltaic storage inverter has multiple maximum power trackers for the photovoltaic string to access, and multiple energy storage systems to access. Compared with the traditional photovoltaic storage AC coupling method, the present invention has higher photovoltaic storage system conversion efficiency and faster system response time. At the same time, the high system integration can also reduce the project construction period and construction difficulty.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic storage, and in particular relates to a photovoltaic storage integrated power conversion topology structure based on direct current bus collection. Background Art

[0002] The topological structure of traditional photovoltaic power stations with energy storage can be roughly divided into two types. The first is a distributed energy storage arrangement, in which the energy storage is distributed near the transformer and connected to the low-voltage side of the step-up transformer to achieve low-voltage photovoltaic and AC coupling. The second is centralized shared energy storage, in which tens of megawatts or hundreds of megawatts of energy storage are concentrated in one place, collected and stepped up, and then connected to the medium-voltage power grid to achieve medium-voltage photovoltaic and AC coupling.

[0003] In the AC coupling mode of distributed energy storage, the energy storage equipment and the photovoltaic power generation equipment are independent of each other. The joint operation of photovoltaic storage requires the configuration of an energy storage monitoring system, a new energy power generation monitoring system, an energy management system and an independent communication system. The electrical interface, control interface and communication interface of the two sets of equipment need to be configured with transformers, protocol converters and cables. The coordinated control execution cycle of the two sets of equipment is long, the response speed is slow, and the control accuracy is poor. In addition, the photovoltaic AC / DC capacity ratio under the optimal cost per kilowatt-hour cannot absorb the actively abandoned photovoltaic power, and the overall economic efficiency is poor.

[0004] In the centralized shared energy storage mode, the coupling between the energy storage system and photovoltaics is not strong. It can only use the photovoltaic wind and solar power abandoned in the case of insufficient transmission sections and weak system peak-shaving capacity as charging capacity, and cannot substantially solve the problem of unstable and uncontrollable photovoltaic output itself. Summary of the invention

[0005] The purpose of the present invention is to provide a photovoltaic-storage integrated power conversion topology structure based on DC bus collection in order to solve the above problems.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0007] A photovoltaic-storage integrated power conversion topology structure based on DC bus collection, comprising a photovoltaic DC / DC module, an energy storage system, a DC bus, a photovoltaic-storage converter and a coordination controller, wherein the photovoltaic DC / DC module, the energy storage system and the photovoltaic-storage converter are all connected to the DC bus; the photovoltaic DC / DC module, the energy storage system and the photovoltaic-storage converter are all connected to the coordination controller in communication;

[0008] The photovoltaic DC / DC module has a maximum power point tracking function, which detects the power generation voltage of the photovoltaic string in real time and tracks the maximum voltage and current value;

[0009] The photovoltaic storage inverter has multiple maximum power trackers for access to the photovoltaic strings and multiple energy storage systems.

[0010] As a further optimization solution of the present invention, it also includes a photovoltaic string, and the photovoltaic string is connected to the photovoltaic DC / DC module.

[0011] As a further optimization scheme of the present invention, it also includes a mutual inductor, through which the photovoltaic storage converter is connected to the power grid, and the mutual inductor is communicatively connected to the coordination controller.

[0012] As a further optimization solution of the present invention, it also includes an AGC / AVC system, and the AGC / AVC system is communicatively connected with the coordination controller.

[0013] As a further optimization solution of the present invention, it also includes a primary frequency modulation system, and the primary frequency modulation system is communicatively connected with the coordination controller.

[0014] As a further optimization solution of the present invention, it also includes a cluster control system, which is communicatively connected with the coordination controller.

[0015] The beneficial effects of the present invention are:

[0016] Compared with the traditional photovoltaic storage AC coupling method, the present invention has higher photovoltaic storage system conversion efficiency and faster system response time. At the same time, the high system integration can also reduce the project construction period and construction difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the present invention. DETAILED DESCRIPTION

[0018] The present application is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0019] like Figure 1 As shown, a photovoltaic-storage integrated power conversion topology based on DC bus collection includes photovoltaic strings, photovoltaic DC / DC modules, DC bus, photovoltaic-storage converters, mutual inductors, coordination controllers, energy storage systems, AGC / AVC systems, primary frequency modulation systems and cluster control systems;

[0020] The photovoltaic storage inverter integrates the functions of the original photovoltaic inverter and energy storage inverter, and at the same time cancels the isolation transformer on the AC side of the energy storage inverter. Several photovoltaic strings are connected to the DC bus through photovoltaic DC / DC modules with MPPT function. The energy storage system no longer goes through the energy storage DC / DC module and can be directly connected to the photovoltaic storage DC bus.

[0021] Photovoltaic DC / DC module: The photovoltaic DC / DC module has the maximum power point tracking (MPPT) function, which detects the power generation voltage of the solar panel in real time and tracks the maximum voltage and current values. The photovoltaic system is always maintained in MPPT mode, and the frequency and voltage regulation power are all provided by the energy storage system.

[0022] Photovoltaic storage inverter: Traditional photovoltaic inverters have the maximum power point tracking (MPPT) function, which can only realize DC / AC (inversion function) conversion, and cannot realize bidirectional conversion of electric energy, and cannot support the access of energy storage systems; traditional energy storage inverters can realize bidirectional conversion of electric energy between AC and DC, but do not have the maximum power point tracking (MPPT) function, and cannot support the access of photovoltaic strings. Integrating traditional photovoltaic inverters and energy storage inverters into photovoltaic storage inverters, it has multiple MPPTs (maximum power trackers) for the access of photovoltaic strings, and can also be used for the access of multiple energy storage systems, and can support 1000~1500Vdc voltage levels, and can support the access of various types of components such as 182 components and 210 components.

[0023] Each photovoltaic DC / DC module communicates with the coordination controller to realize the collection, transmission and control protection of photovoltaic system data by the coordination controller; the photovoltaic storage inverter communicates with the coordination controller to realize the output control of the photovoltaic storage inverter; the coordination controller communicates with the energy storage system and the mutual inductor to realize the information collection of the energy storage system and the current and voltage collection on the AC side; the coordination controller determines whether the energy storage system is chargeable / dischargeable according to the energy storage charge state, and realizes the charging and discharging control of the energy storage system by controlling the photovoltaic DC / DC modules and the photovoltaic storage inverter; the coordination controller communicates with the station-side AGC, AVC system, primary frequency regulation system, and cluster control system to realize the response to the station-side control target value, and realizes the synchronous response and balanced contribution of the power generation units in the station to maximize the regulation capacity of the entire station.

[0024] In the present invention, the photovoltaic storage inverter integrates the functions of the photovoltaic inverter and the energy storage inverter, and the equipment is highly integrated; the modular photovoltaic DC / DC equipment with MPPT function, when a single module fails, does not affect the normal operation of the other modules; due to the photovoltaic storage DC coupling topology structure, the photovoltaic capacity and the energy storage capacity can be configured according to different working conditions, and it is suitable for a variety of capacity ratios; the energy storage system is directly connected to the DC bus without passing through the DC / DC, and the charging and discharging of the energy storage system is controlled by the flow control method, which can reduce equipment investment, reduce investment costs, and improve response time; the coordination controller communicates with the photovoltaic DC / DC, the energy storage system, the photovoltaic storage inverter, the metering CT, etc., receives the station-side AGC, AVC system, the primary frequency modulation system, and the cluster control system communication, realizes the upload and download between the station end and the sub-array, realizes the optimization control inside the sub-array, and the control target value response between the power generation units and the whole station level.

[0025] The present invention eliminates the AC / DC system conversion link and realizes DC coupling of the photovoltaic storage system. It optimizes and improves the overall power generation efficiency of the system, equipment interface matching investment, collaborative control difficulty, control speed, etc., and provides key core equipment for realizing the "new energy + energy storage + local balance + inertia support" mode that actively supports the new power system.

[0026] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A photovoltaic-storage integrated power conversion topology based on DC bus collection, characterized in that: It includes a photovoltaic DC / DC module, an energy storage system, a DC bus, a photovoltaic storage converter and a coordination controller, wherein the photovoltaic DC / DC module, the energy storage system and the photovoltaic storage converter are all connected to the DC bus; the photovoltaic DC / DC module, the energy storage system and the photovoltaic storage converter are all connected to the coordination controller in communication; The photovoltaic DC / DC module has a maximum power point tracking function, which detects the power generation voltage of the photovoltaic string in real time and tracks the maximum voltage and current value; The photovoltaic storage inverter has multiple maximum power trackers for access to the photovoltaic strings and multiple energy storage systems.

2. According to claim 1, a photovoltaic-storage integrated power conversion topology structure based on DC bus collection is characterized in that: It also includes a photovoltaic string, which is connected to the photovoltaic DC / DC module.

3. According to claim 1, a photovoltaic-storage integrated power conversion topology structure based on DC bus collection is characterized in that: It also includes a mutual inductor, through which the photovoltaic storage converter is connected to the power grid, and the mutual inductor is communicatively connected to the coordination controller.

4. According to claim 1, a photovoltaic-storage integrated power conversion topology structure based on DC bus collection is characterized in that: It also includes an AGC / AVC system, which is communicatively connected with the coordination controller.

5. The photovoltaic-storage integrated power conversion topology structure based on DC bus collection according to claim 1 is characterized in that: It also includes a primary frequency modulation system, which is communicatively connected with the coordination controller.

6. The photovoltaic-storage integrated power conversion topology structure based on DC bus collection according to claim 1 is characterized in that: It also includes a cluster control system, which is communicatively connected with the coordination controller.

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