Sub-square matrix alternating current side coupling optical storage system

Abstract

The invention relates to the technical field of photovoltaic power generation, in particular to a sub-matrix alternating current side coupling optical storage system. The energy storage system is dispersedly arranged in a photovoltaic power generation area, and the energy storage system and the inverter share one transformer for combined operation. And an energy storage system charging power supply is taken from a photovoltaic sub-matrix side power supply. According to the distributed energy storage system, the active light abandoning electric quantity of the high-capacity-ratio photovoltaic power generation system can be fully utilized, the active light abandoning electric quantity is used for energy storage charging while the optimal kilowatt-hour cost of the photovoltaic power generation system is guaranteed, and the energy storage charging cost is reduced; the power conversion link between the photovoltaic power generation system and the energy storage system is reduced, and the overall system efficiency is high; due to the distributed installation mode, the influence on the system is minimum when a single energy storage device breaks down; a photovoltaic system can be built in the early stage, an energy storage system is added in the later stage, and smooth upgrading is achieved; the control precision is high.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and in particular to a sub-array AC side coupled photo-storage system. Background Art

[0002] The traditional centralized solar storage system is centrally arranged in the photovoltaic power station booster station. The energy storage equipment is equipped with a booster transformer, which is directly connected to the low-voltage side of the booster station after being boosted to 10kV or 35kV. The charging power of the energy storage system is taken from the power supply on the booster station side.

[0003] Centrally arranged photovoltaic storage system The energy storage system is mainly composed of a battery system, a storage converter (PCS), a booster transformer, a battery management system, and an energy management system. The energy storage system is connected to the booster station side, and the power absorbed is the photovoltaic grid-connected power. There is no need for joint control and operation between the centralized energy storage system and the photovoltaic system, and the power source is mainly the grid-side power restriction. The centralized energy storage system is connected to the booster station side. The energy storage system and the photovoltaic power generation system are two independent systems. There is no joint control and operation. The energy storage system draws power from the power restriction on the booster station side, which has nothing to do with the photovoltaic capacity. The energy storage capacity is configured according to the historical grid-side power restriction data of the operating power station, and there is no requirement for photovoltaic capacity configuration.

[0004] At present, centralized access requires separate configuration of step-up transformers and other power distribution equipment, which results in large line losses and high investment. The energy storage absorbs the same amount of photovoltaic grid-connected electricity and has poor control accuracy. Summary of the invention

[0005] In view of the above problems, the present invention provides a sub-array AC-side coupled photovoltaic storage system, which is used to solve the problems that centralized access requires separate configuration of power distribution equipment such as step-up transformers, large line losses, high investment, the energy storage absorption power is photovoltaic grid-connected power, and the control accuracy is poor.

[0006] A sub-array AC side coupled optical storage system, comprising:

[0007] Energy storage systems and photovoltaic systems;

[0008] The photovoltaic system is used for photovoltaic power generation, and the energy storage system is used to absorb the photovoltaic power that is actively abandoned;

[0009] The energy storage system is distributed in the photovoltaic power generation area and operates together with the inverter using a common transformer. The charging power of the energy storage system is taken from the photovoltaic array side power supply.

[0010] The energy storage system includes: battery system, energy storage converter PCS, isolation transformer or distribution cabinet, battery management system BMS and energy management system;

[0011] Photovoltaic system includes: photovoltaic panels and inverters;

[0012] The energy storage system and photovoltaic system are connected in parallel to the low-voltage side of the photovoltaic array booster box.

[0013] Furthermore, the inverter includes: a string inverter, a centralized inverter and / or a distributed inverter.

[0014] Furthermore, when the inverter is a string inverter and the energy storage system uses an isolation transformer,

[0015] Each photovoltaic module is connected to the low-voltage side of the photovoltaic array booster box through an independent string inverter;

[0016] Several battery clusters of the battery system are connected to the energy storage converter PCS, and the energy storage converter PCS is connected to the low-voltage side of the photovoltaic array booster box through an isolation transformer.

[0017] Furthermore, when the inverter is a string inverter and the energy storage system uses a distribution cabinet,

[0018] Each photovoltaic module is connected to the low-voltage side of the photovoltaic array booster box through an independent string inverter;

[0019] Several battery clusters of the battery system are connected to the DC distribution cabinet, which is connected to the AC distribution cabinet through the energy storage converter PCS, and the AC distribution cabinet is connected to the low-voltage side of the photovoltaic array booster box.

[0020] Furthermore, when the inverter is a centralized inverter or a distributed inverter, and the energy storage system uses an isolation transformer,

[0021] Each photovoltaic module is connected to a centralized inverter or distributed inverter through an independent DC combiner box, and the centralized inverter or distributed inverter is connected to the low-voltage side of the photovoltaic array booster box;

[0022] Several battery clusters of the battery system are connected to the energy storage converter PCS, and the energy storage converter PCS is connected to the low-voltage side of the photovoltaic array booster box through an isolation transformer.

[0023] Furthermore, when the inverter is a string inverter,

[0024] The string inverter is connected to an AC low-voltage switch cabinet via a power line carrier, and the AC low-voltage switch cabinet is connected to a PLC power carrier module of a data acquisition device;

[0025] The battery management system BMS, DC side energy storage meter and AC side energy storage meter of the energy storage system are connected to the on-site monitoring equipment of the energy management system, and the on-site monitoring equipment of the energy management system is connected to the data acquisition device;

[0026] The data acquisition device is connected to the station control host through the optical fiber ring network switch at the interval layer of the photovoltaic power station monitoring system to realize the control communication of the photovoltaic storage system.

[0027] Furthermore, when the inverter is a centralized inverter or a distributed inverter,

[0028] The centralized inverter and / or distributed inverter, as well as the DC combiner box, are connected to the PLC power carrier module of the data acquisition device via RS485;

[0029] The battery management system BMS, DC side energy storage meter and AC side energy storage meter of the energy storage system are connected to the on-site monitoring equipment of the energy management system, and the on-site monitoring equipment of the energy management system is connected to the data acquisition device;

[0030] The data acquisition device is connected to the station control host through the optical fiber ring network switch at the interval layer of the photovoltaic power station monitoring system to realize the control communication of the photovoltaic storage system.

[0031] The present invention has at least the following beneficial effects:

[0032] The energy storage system of the present invention is dispersedly arranged in the photovoltaic power generation area, and operates jointly with the inverter by sharing a transformer. The charging power of the energy storage system is taken from the power supply on the photovoltaic sub-array side. The distributed arrangement of the energy storage system can make full use of the actively abandoned photovoltaic power of the high-capacity ratio photovoltaic power generation system. While ensuring the optimal cost per kilowatt-hour of the photovoltaic power generation system, the actively abandoned photovoltaic power is used for energy storage charging, thereby reducing the cost of energy storage charging; fully utilize the inverter equipment, boosting equipment and cables in the photovoltaic power generation system, with high equipment utilization, less equipment investment and less land occupation; reduce the power conversion link between the photovoltaic power generation system and the energy storage system, and the overall system efficiency is high; the distributed installation method minimizes the impact on the system when a single energy storage device fails; the photovoltaic system can be built in the early stage, and the energy storage system can be added in the later stage to achieve smooth upgrades; the control accuracy is high.

[0033] 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

[0034] 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.

[0035] Figure 1The first wiring diagram of the photovoltaic storage system for the distributed arrangement of string inverters;

[0036] Figure 2 The second wiring diagram of the photovoltaic storage system for the distributed arrangement of string inverters;

[0037] Figure 3 Schematic diagram of the wiring of the photovoltaic storage system for the centralized / distributed inverters;

[0038] Figure 4 Schematic diagram of the communication of the photovoltaic storage system with distributed arrangement of string inverters;

[0039] Figure 5 Schematic diagram of communication for centralized / distributed inverters and distributed photovoltaic storage systems;

[0040] Figure 6 A wiring diagram for the centralized arrangement of the photovoltaic storage system;

[0041] Figure 7 Schematic diagram of centralized optical storage system communication. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] In the prior art, the energy storage system is centrally arranged in the booster station of the photovoltaic power station. The energy storage equipment is equipped with a booster transformer, which is directly connected to the low-voltage side of the booster station after being boosted to 10kV or 35kV. The charging power of the energy storage system is taken from the power supply on the booster station side. Centralized access requires separate configuration of power distribution equipment such as booster transformers, which has large line losses and high investment. The energy storage absorbs the same amount of photovoltaic grid-connected electricity, and the control accuracy is poor.

[0044] To this end, the present invention proposes a sub-array AC side coupled optical storage system, comprising:

[0045] Energy storage systems and photovoltaic systems;

[0046] The photovoltaic system is used for photovoltaic power generation, and the energy storage system is used to absorb the photovoltaic power that is actively abandoned;

[0047] The energy storage system is distributed in the photovoltaic power generation area and operates together with the inverter using a common transformer. The charging power of the energy storage system is taken from the photovoltaic array side power supply.

[0048] The energy storage system includes: battery system, energy storage converter PCS, isolation transformer or distribution cabinet, battery management system BMS and energy management system;

[0049] Photovoltaic system includes: photovoltaic panels and inverters;

[0050] The energy storage system and photovoltaic system are connected in parallel to the low-voltage side of the photovoltaic array booster box.

[0051] In one embodiment, the inverter includes: a string inverter, a centralized inverter and / or a distributed inverter.

[0052] In one embodiment, if Figure 1 As shown in the figure, when the inverter is a string inverter and the energy storage system uses an isolation transformer,

[0053] Each photovoltaic module is connected to the low-voltage side of the photovoltaic array booster box through an independent string inverter;

[0054] Several battery clusters of the battery system are connected to the energy storage converter PCS, and the energy storage converter PCS is connected to the low-voltage side of the photovoltaic array booster box through an isolation transformer.

[0055] In one embodiment, if Figure 2 As shown in the figure, when the inverter is a string inverter and the energy storage system uses a distribution cabinet,

[0056] Each photovoltaic module is connected to the low-voltage side of the photovoltaic array booster box through an independent string inverter;

[0057] Several battery clusters of the battery system are connected to the DC distribution cabinet, which is connected to the AC distribution cabinet through the energy storage converter PCS, and the AC distribution cabinet is connected to the low-voltage side of the photovoltaic array booster box.

[0058] In one embodiment, if Figure 3 As shown, when the inverter is a centralized inverter or a distributed inverter, and the energy storage system uses an isolation transformer,

[0059] Each photovoltaic module is connected to a centralized inverter or distributed inverter through an independent DC combiner box, and the centralized inverter or distributed inverter is connected to the low-voltage side of the photovoltaic array booster box;

[0060] Several battery clusters of the battery system are connected to the energy storage converter PCS, and the energy storage converter PCS is connected to the low-voltage side of the photovoltaic array booster box through an isolation transformer.

[0061] In one embodiment, if Figure 4 As shown, when the inverter is a string inverter,

[0062] The string inverter is connected to an AC low-voltage switch cabinet via a power line carrier, and the AC low-voltage switch cabinet is connected to a PLC power carrier module of a data acquisition device;

[0063] The battery management system BMS, DC side energy storage meter and AC side energy storage meter of the energy storage system are connected to the on-site monitoring equipment of the energy management system, and the on-site monitoring equipment of the energy management system is connected to the data acquisition device;

[0064] The data acquisition device is connected to the station control host through the optical fiber ring network switch at the interval layer of the photovoltaic power station monitoring system to realize the control communication of the photovoltaic storage system.

[0065] In one embodiment, if Figure 5 As shown, when the inverter is a centralized inverter or a distributed inverter,

[0066] The centralized inverter and / or distributed inverter, as well as the DC combiner box, are connected to the PLC power carrier module of the data acquisition device via RS485;

[0067] The battery management system BMS, DC side energy storage meter and AC side energy storage meter of the energy storage system are connected to the on-site monitoring equipment of the energy management system, and the on-site monitoring equipment of the energy management system is connected to the data acquisition device;

[0068] The data acquisition device is connected to the station control host through the optical fiber ring network switch at the interval layer of the photovoltaic power station monitoring system to realize the control communication of the photovoltaic storage system.

[0069] In order to enable those skilled in the art to better understand the present invention, the principle of the present invention is described as follows in conjunction with the accompanying drawings:

[0070] The traditional centralized energy storage system is centrally arranged in the photovoltaic power station booster station. The energy storage equipment is equipped with a booster transformer, which is directly connected to the low-voltage side of the booster station after being boosted to 10kV or 35kV. The charging power of the energy storage system is taken from the power supply on the booster station side.

[0071] like Figure 6 As shown in the figure, the centralized energy storage system is mainly composed of a battery system, a storage converter (PCS), a step-up transformer, a battery management system, and an energy management system. The energy storage system is connected to the step-up station side, and the power absorbed is the photovoltaic grid-connected power. There is no need for joint control operation between the centralized energy storage system and the photovoltaic system, and the power source is mainly the grid-side power restriction.

[0072] like Figure 7 As shown, the energy storage system is centrally arranged and connected to the substation side. The energy storage system and the photovoltaic power generation system are two independent systems. There is no joint control operation. The energy storage system draws electricity from the power limit on the substation side and has nothing to do with the photovoltaic capacity. The energy storage capacity is configured according to the historical grid-side power limit data of the operating power station, and there is no requirement for photovoltaic capacity configuration.

[0073] The energy storage system of the present invention is dispersedly arranged in the photovoltaic power generation area and operates in conjunction with the string inverter using a common transformer. The charging power of the energy storage system is taken from the power supply on the photovoltaic array side.

[0074] The photovoltaic storage system is mainly composed of photovoltaic modules, string inverters / central inverters / distributed inverters, battery systems, energy storage converters (PCS), isolation transformers or DC / DC+AC and DC distribution cabinets, and battery management systems and energy management systems. The distributed energy storage system and photovoltaic modules + inverters are connected in parallel to the low-voltage side of the photovoltaic array booster box, and the power absorbed is the photovoltaic active abandoned power.

[0075] The control of a distributed photovoltaic storage system is relatively complex, and requires the integration of photovoltaic monitoring systems, energy storage monitoring systems, energy management systems, optical power prediction systems, AGC / AVC systems, etc., and the formulation of control strategies in accordance with the photovoltaic storage joint operation mode. A photovoltaic sub-array communication control unit is configured in the distributed photovoltaic storage power generation system. Each unit receives the control instructions of the photovoltaic power station-level EMS, directly controls the inverter output and energy storage charging and discharging, and can realize both conventional AGC / AVC control and fast power / voltage control, while greatly reducing the requirements for station-level EMS configuration. The station-level EMS function will focus on the management of thermal runaway of battery cells, SOC balancing management of energy storage systems, power prediction and energy storage model operation, system peak-shaving, frequency regulation and voltage regulation control, and optimization of joint operation control strategies.

[0076] The distributed energy storage system of the present invention is based on controlling and regulating the power of a single photovoltaic power generation system, so the capacity of a single energy storage system is small and the number is large. The photovoltaic and energy storage configuration capacity is as follows:

[0077] (1) When determining the photovoltaic capacity and capacity ratio, energy storage is configured according to the limited power generation of the photovoltaic system on the low-voltage side of the box transformer. The capacity of the energy storage system is determined on the principle of absorbing as much photovoltaic power as possible (while considering power balance, that is, the power of the over-allocated photovoltaic part should be less than or equal to the power of the energy storage system). The power of the energy storage system is calculated based on the energy storage capacity and the charge and discharge rate;

[0078] (2) When determining the power and capacity of the energy storage system (i.e. determining the power and capacity of a single PV sub-array energy storage system according to local energy storage configuration policy requirements), the configuration capacity and capacity ratio of the PV system are determined by comparing the amount of power that the energy storage system needs to absorb with the amount of power that is actively abandoned under different capacity ratios of the PV system (while taking power balance into account).

[0079] The energy storage system of the present invention is dispersedly arranged in the photovoltaic power generation area and operates jointly with the inverter by sharing a transformer. The charging power supply of the energy storage system is taken from the power supply on the photovoltaic sub-array side. The energy storage system makes full use of the actively abandoned photovoltaic power of the high-capacity ratio photovoltaic power generation system, and makes full use of the AC equipment and cables in the photovoltaic power generation system, reduces the power conversion link, and the overall system efficiency is high. The control of the photovoltaic storage system is relatively complex, and it is necessary to integrate the photovoltaic monitoring system, energy storage monitoring system, energy management system, optical power prediction system, AGC / AVC system, etc., and formulate a control strategy according to the photovoltaic storage joint operation mode. The photovoltaic power generation system and the energy storage system are jointly controlled, and the configuration needs to consider the coordination of the photovoltaic storage system.

[0080] The energy storage system of the present invention makes full use of the actively abandoned photovoltaic power of the high capacity ratio photovoltaic power generation system. The energy storage system makes full use of the AC equipment and cables in the photovoltaic power generation system. The power conversion link between the photovoltaic power generation system and the energy storage system is reduced, the line loss and investment are reduced, and the overall system efficiency is higher. The impact of the energy storage device failure on the system is small, and the secondary hazards of electricity and heat generated by the failure are reduced. The control accuracy is high, and each unit accepts the control instructions of the power station-level EMS, directly controls the inverter output and energy storage charging and discharging, and can realize both conventional AGC / AVC control and fast power / voltage control, reducing the configuration requirements of the station-level EMS.

[0081] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sub-array AC-side coupled optical storage system, It is characterized in that include: Energy storage systems and photovoltaic systems; The energy storage system includes: battery system, energy storage converter PCS, isolation transformer or distribution cabinet, battery management system BMS and energy management system; The photovoltaic system includes: photovoltaic panels and inverters; The energy storage system and photovoltaic system are connected in parallel to the low-voltage side of the photovoltaic array booster box; The photovoltaic system is used for photovoltaic power generation, and the energy storage system is used to absorb the photovoltaic power that is actively abandoned; The energy storage system is dispersedly arranged in the photovoltaic power generation area and operates jointly with the inverter using a common transformer; the charging power of the energy storage system is taken from the power supply on the photovoltaic sub-array side.

2. The sub-array AC-side coupled optical storage system according to claim 1, It is characterized in that Inverters include: string inverters, centralized inverters and / or distributed inverters.

3. The sub-array AC-side coupled optical storage system according to claim 1, It is characterized in that When the inverter is a string inverter and the energy storage system uses an isolation transformer, Each photovoltaic module is connected to the low-voltage side of the photovoltaic array booster box through an independent string inverter; Several battery clusters of the battery system are connected to the energy storage converter PCS, and the energy storage converter PCS is connected to the low-voltage side of the photovoltaic array booster box through an isolation transformer.

4. The sub-array AC-side coupled optical storage system according to claim 1, It is characterized in that When the inverter is a string inverter and the energy storage system uses a distribution cabinet, Each photovoltaic module is connected to the low-voltage side of the photovoltaic array booster box through an independent string inverter; Several battery clusters of the battery system are connected to the DC distribution cabinet, which is connected to the AC distribution cabinet through the energy storage converter PCS, and the AC distribution cabinet is connected to the low-voltage side of the photovoltaic array booster box.

5. The sub-array AC-side coupled optical storage system according to claim 1, It is characterized in that When the inverter is a centralized inverter or a distributed inverter, and the energy storage system uses an isolation transformer, Each photovoltaic module is connected to a centralized inverter or distributed inverter through an independent DC combiner box, and the centralized inverter or distributed inverter is connected to the low-voltage side of the photovoltaic array booster box; Several battery clusters of the battery system are connected to the energy storage converter PCS, and the energy storage converter PCS is connected to the low-voltage side of the photovoltaic array booster box through an isolation transformer.

6. The sub-array AC-side coupled optical storage system according to claim 1, It is characterized in that When the inverter is a string inverter, The string inverter is connected to an AC low-voltage switch cabinet via a power line carrier, and the AC low-voltage switch cabinet is connected to a PLC power carrier module of a data acquisition device; The battery management system BMS, DC side energy storage meter and AC side energy storage meter of the energy storage system are connected to the on-site monitoring equipment of the energy management system, and the on-site monitoring equipment of the energy management system is connected to the data acquisition device; The data acquisition device is connected to the station control host through the optical fiber ring network switch at the interval layer of the photovoltaic power station monitoring system to realize the control communication of the photovoltaic storage system.

7. The sub-array AC-side coupled optical storage system according to claim 1, It is characterized in that When the inverter is a centralized inverter or a distributed inverter, The centralized inverter and / or distributed inverter, as well as the DC combiner box, are connected to the PLC power carrier module of the data acquisition device via RS485; The battery management system BMS, DC side energy storage meter and AC side energy storage meter of the energy storage system are connected to the on-site monitoring equipment of the energy management system, and the on-site monitoring equipment of the energy management system is connected to the data acquisition device; The data acquisition device is connected to the station control host through the optical fiber ring network switch at the interval layer of the photovoltaic power station monitoring system to realize the control communication of the photovoltaic storage system.

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