CN209860604U

CN209860604U - Energy storage system

Info

Publication number: CN209860604U
Application number: CN201920544556.5U
Authority: CN
Inventors: 吴昌垣; 谌守禄; 肖伟超; 程凌星; 熊建英
Original assignee: China Electric Construction Group Jiangxi Electric Power Construction Co Ltd
Current assignee: China Electric Construction Group Jiangxi Electric Power Construction Co Ltd
Priority date: 2019-04-22
Filing date: 2019-04-22
Publication date: 2019-12-27
Anticipated expiration: 2029-04-22

Abstract

The utility model relates to an energy storage system, include: the sampling module is connected with the current transformation module and used for acquiring a sampling signal; the control module is connected with the sampling module and used for sending a charging signal or a discharging signal according to the feedback and sampling signals; the current transformation module is connected with the control module and used for transforming the alternating current into the direct current according to the charging signal and then reducing the voltage, or transforming the direct current into the alternating current after boosting the voltage according to the discharging signal; the energy storage control module is connected with the current transformation module and is used for balancing and controlling the distribution of direct current; and the energy storage module is connected with the energy storage control module and is used for storing or providing direct current. The utility model amplifies the DC voltage of the iron-zinc flow battery, inverts the DC voltage into an AC voltage signal and then merges the AC voltage signal into the power grid; the control strategy can be reasonably selected according to different use scenes, the output of new energy power generation is smoothened to a great extent, the power supply quality of a power grid is improved, the safe and reliable operation of the system is guaranteed, and the economical efficiency and the safety of the operation of the power grid are improved.

Description

Energy storage system

Technical Field

The utility model belongs to the technical field of the energy storage, concretely relates to energy storage system.

Background

The energy storage technology is a key core technology of energy systems such as a distributed power generation technology, a micro-grid and a smart grid. Common energy storage technologies include pumped power stations, compressed air, super-magnetic, batteries, flow batteries, and the like. The redox flow battery is a novel high-capacity redox electrochemical energy storage device, is different from a conventional battery, has the characteristics that an active substance of the redox flow battery is not on an electrode, but is dissolved in an electrolyte and is a component of the electrolyte, the redox flow battery is high in capacity, wide in application field and long in cycle service life, and is a new energy product.

In a power grid, the energy storage technology of the zinc-iron flow battery has the characteristics of low cost, high safety, environmental friendliness and the like, and has a good application prospect. In order to stably connect the zinc-iron flow battery to a power grid, the stability of an output voltage signal and a current signal of the zinc-iron flow battery needs to be ensured, but the input and output voltage signals of the conventional zinc-iron flow battery are low, the current is high, and the conventional zinc-iron flow battery cannot be stably connected to the power grid, so that the power supply quality is reduced, and the economical efficiency and the safety of the operation of the power grid are poor.

SUMMERY OF THE UTILITY MODEL

In order to solve the technical defects and shortcomings existing in the prior art, the embodiment of the application provides an energy storage system. The to-be-solved technical problem of the utility model is realized through following technical scheme:

an embodiment of the utility model provides an energy storage system, include:

the sampling module is connected with the current transformation module and used for acquiring a sampling signal;

the control module is connected with the sampling module and used for sending a charging signal or a discharging signal according to feedback and the sampling signal;

the current transformation module is connected with the control module and used for converting alternating current into direct current according to the charging signal and then reducing the voltage, or converting the direct current into alternating current after boosting the voltage according to the discharging signal;

the energy storage control module is connected with the current transformation module and is used for balancing and controlling the distribution of direct current;

and the energy storage module is connected with the energy storage control module and is used for storing or providing direct current.

In an embodiment of the present invention, the sampling signal includes a current sampling signal and a voltage sampling signal.

In an embodiment of the present invention, the control module includes: the system comprises at least one EIA-485 communication interface, at least one RJ-45 Ethernet interface, at least one CAN interface, at least one optical fiber interface, at least one RS-232 printing interface and at least one RS-485 time pairing interface.

In an embodiment of the invention, the feedback comprises one or more of active power tracking, peak clipping and valley filling, plan curves, frequency modulation and voltage regulation, fluctuation leveling, power distribution and SOC adjustment.

In an embodiment of the present invention, the converter module includes:

the direct current filter circuit is connected with the energy storage control module and used for reducing direct current common mode interference;

the boosting circuit is connected with the direct current filter circuit and used for increasing direct current voltage;

the CL filter circuit is connected with the booster circuit and is used for filtering high-frequency components in direct current;

the conversion circuit is connected with the CL filter circuit and is used for converting alternating current into direct current and then reducing the voltage or converting the direct current into alternating current after boosting the voltage;

the LCL filter circuit is connected with the conversion circuit and is used for reducing high-frequency harmonic waves in alternating current;

and the alternating current filter circuit is connected with the LCL filter circuit and is used for inhibiting high-frequency interference in alternating current.

In an embodiment of the present invention, the converter module further includes: the multiple groups of bypass switches are connected between the direct current filter circuit and the energy storage control module; and, between said LCL filter circuit and said AC filter circuit; and an output terminal of the AC filter circuit.

In an embodiment of the present invention, the boost circuit is a non-isolated Buck circuit or an isolated Buck circuit.

In an embodiment of the present invention, the switching circuit is a three-phase full-bridge IGBT switching circuit.

In an embodiment of the present invention, the energy storage module is a zinc-iron flow battery.

As can be seen from the above, in the energy storage system provided in the embodiment of the application, the direct-current voltage of the zinc-iron redox flow battery is amplified by using the current transformation module, and then the amplified direct-current voltage is inverted into the alternating-current voltage and then is merged into the power grid; the control module can reasonably select a control strategy according to different use scenes, so that the output of new energy power generation is smoothed to a great extent, the power supply quality of a power grid is improved, the safe and reliable operation of the system is ensured, and the economical efficiency and the safety of the operation of the power grid are improved.

Other aspects and features of the present invention will become apparent from the following detailed description, which proceeds with reference to the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

Drawings

Fig. 1 is a schematic structural diagram of an energy storage system according to an embodiment of the present disclosure;

fig. 2 is a schematic diagram illustrating peak clipping and valley filling in an energy storage system according to an embodiment of the present disclosure;

fig. 3 is a schematic diagram of a programmed curve in an energy storage system according to an embodiment of the present disclosure;

fig. 4 is a schematic diagram of an auxiliary frequency modulation in an energy storage system according to an embodiment of the present disclosure;

fig. 5 is a schematic diagram of auxiliary voltage regulation in an energy storage system according to an embodiment of the present disclosure;

FIG. 6 is a schematic diagram of wave suppression in an energy storage system according to an embodiment of the present disclosure;

fig. 7 is a schematic diagram of power distribution during charging in an energy storage system according to an embodiment of the present disclosure;

fig. 8 is a schematic diagram of power distribution during discharging in an energy storage system according to an embodiment of the present disclosure;

fig. 9 is a schematic diagram of SOC adjustment in an energy storage system according to an embodiment of the present disclosure;

fig. 10 is a circuit diagram of a current transformer module in an energy storage system according to an embodiment of the present application.

Detailed Description

In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments of the present invention are described in detail below with reference to the accompanying drawings.

Referring to fig. 1, fig. 1 is a schematic structural diagram of an energy storage system according to an embodiment of the present disclosure.

The energy storage system that this embodiment provided includes:

the control module is connected with the sampling module and used for sending a charging signal or a discharging signal according to the feedback and sampling signals;

the current transformation module is connected with the control module and used for transforming the alternating current into the direct current according to the charging signal and then reducing the voltage, or transforming the direct current into the alternating current after boosting the voltage according to the discharging signal;

Specifically, the energy storage system provided by the embodiment of the application is applied to a power grid, and can convert surplus alternating current electric energy on the power grid at night or on weekdays into direct current electric energy and then store the direct current electric energy into the energy storage module in a voltage reduction mode, and feed back the direct current electric energy to the power grid to balance peak and valley of the power grid when the electric energy of the power grid is insufficient, and the control module can reasonably select a control strategy according to different use scenes, namely different feedbacks, so that the functions of charge/discharge management, smooth alternating current side load power, island operation and the like of the energy storage module are. Meanwhile, the energy storage system provided by the application is applied to a new energy power generation system with intermittence, such as wind energy, solar energy, tide and the like, so that the output of new energy power generation can be smoothed to a great extent, the power supply quality of a micro-grid is improved, a large-scale renewable energy system is safely and reliably merged into the power grid, and 'green electric energy conversion' is really embodied.

In one embodiment, the sampling signal includes a current sampling signal and a voltage sampling signal.

Specifically, the sampling module is connected with the converter module and the control module, and is used for acquiring a current sampling signal and a voltage sampling signal in the converter module and the power grid in real time and transmitting the sampling signals to the control module. The control module can be according to different use scenes, namely different feedbacks, including one or more in above-mentioned active power tracking, peak clipping and valley filling, plan the curve, frequency modulation and voltage regulation, stabilize fluctuation, power distribution and SOC adjustment, combine above-mentioned voltage sampling signal and current sampling signal, choose the control strategy rationally, send and charge the signal or discharge the signal to the conversion module, the conversion module can be according to discharge the signal and convert the alternating current electric energy into the direct current electric energy and then step down and store to the energy storage module, or according to charging the signal and convert the direct current electric energy into the alternating current electric energy after stepping up, carry to the electric wire netting through the transformer.

In one embodiment, the control module further comprises: the system comprises at least one EIA-485 communication interface, at least one RJ-45 Ethernet interface, at least one CAN interface, at least one optical fiber interface, at least one RS-232 printing interface and at least one RS-485 time pairing interface.

Specifically, the control module adopts a PCS-9567C standard 4U case framework with powerful measurement and control, communication and energy management functions, and is characterized in that: a UAPC hardware platform with high performance and high reliability, and a friendly man-machine interface; the optional plug-in with powerful functions can meet various requirements on site; the totally-enclosed chassis is strictly separated from strong current and weak current, the traditional backboard wiring mode is cancelled, and meanwhile, corresponding anti-interference measures are also adopted in software design, so that the anti-interference capability of the device is greatly improved, and the external electromagnetic radiation also meets the relevant standards; the flexible background communication mode is provided with communication interfaces (optionally with super-five types of wires or optical fibers) such as an RJ-45 Ethernet interface, an EIA-485 interface, a CAN interface and the like, is convenient for realizing various communication modes, and is convenient for communication access with a sampling module, a current transformation module, an energy storage control module and other auxiliary equipment; the application is suitable for the high altitude of less than 6000 meters; the device adopts an internal high-speed bus and intelligent I/O, has flexible hardware configuration, is universal, is easy to expand and is easy to maintain. The device has convenient field device testing functions including remote signaling test, outlet transmission test, remote signal testing and the like. A plurality of time setting modes can be selected: the time setting interface can support various GPS time setting modes, including IRIG-B, SNTP time setting modes and IEEE1588V2 high-precision network synchronous time setting modes; the complete event recording function can record 64 alarm reports, 64 fault recording waveforms, 1024 self-checking reports, 1024 displacement reports and 1024 latest remote control reports.

The specific electrical parameters are shown in the following table:

1) alternating current

2) Alternating voltage

3) AC/DC sampling

Input device	±15V	±600mA
			Allowing maximum input	-35V～35V	-2A～2A
Sampling accuracy	0.5％(7.5V)	0.5％(200mA)
			Input impedance	19.02kΩ	0.5Ω

4) Direct current sampling

Input device	0～5V	0～20mA
			Sampling accuracy	0.5％(5V)	0.5％(20mA)
Input impedance	20kΩ	235Ω

5) Device power supply

Using a standard	GB/T 8367-1987(idt IEC 60255-11：2008)
		Rated voltage	110Vdc，220Vdc，220VAC
Input range	88～264Vdc，88～264VAC
		Ripple wave	Less than or equal to 15 percent of rated voltage
Static power consumption	＜35W
		Power consumption during operation	＜40W

6) Switching value input

7) Switching value output

8) Mechanical structure

9) Environmental condition parameter

Using a standard	GB/T 14047-1993(idt IEC 60225-1：2009)
		Working temperature range	-20℃～+55℃
Storage temperature range	-40℃～+70℃
		Transport temperature range	-40℃～+70℃
Relative humidity	5% -95%, no condensation and no icing inside the equipment

10) Communication method and port

a) Communication method

Display device	Liquid crystal display device
		Standard communication mode	RS485, RJ45 Ethernet, CAN, LC optical fiber, RS232 printing, time synchronization

b) EIA-485 interface

c) Ethernet interface

d) CAN interface

Transmission rate	1Mbps
		Transmission standard	ISO11898
Transmission distance	Less than 40 m
		Communication protocol	CAN bus protocol
Wiring form	Shielded twisted pair

e) Optical fiber interface

Characteristics of	Glass optical fiber
		Terminal with a terminal body	SC
Optical cable type	Multiple modes
		Typical transmission distance	＜2km

f) Printing interface

g) Time setting interface

Transmission distance	＜500m
		Maximum load capacity	32

Time synchronization standard	Pulse per second, pulse per minute, IRIG-B
		Interface form	RS-485

PCS-9567C may implement the following functions when applied:

measurement and control functions:

1) the sampling input is provided with 6 paths of alternating voltage and 6 paths of alternating current (1A or 5A is optional);

2) the circuit has 6 paths of alternating current and direct current 3 paths of +/-15V voltage input and 3 paths of +/-600 mA current sampling input;

3) 12 direct current sampling inputs of 0-20mA or 0-5V (selectable by a jumper) are provided;

4) 25 paths of self-defined remote communication are provided;

5) the system is provided with 11 paths of remote control independent control opening/closing output nodes;

6) event and SOE records;

the communication function is as follows:

1) to the lower communication

a) Various protocols such as Modbus, DLT645, GOOSE, CAN and the like are supported;

b) support communication with PCS, BMS, electric meters and other auxiliary equipment;

c) the system is provided with 12 RJ-45 network ports (each network port can be replaced by an LC optical fiber interface according to requirements) to support ModbusTCP/GOOSE protocol;

d) the device is provided with 5 paths of EIA-485/RS-232 serial ports (which can be selected through jumper wires), and supports serial port protocols such as a serial port Modbus, a serial port DLT645 and the like;

e) the device is provided with 4 standard CAN interfaces and supports a standard CAN bus protocol.

2) To-last communication

a) Supports the protocols of IEC104, IEC61850, IEC103, Modbus and the like, supports network communication with EMS and a monitoring background,

b) the system is provided with 3 paths of R-J45 net ports;

c) the device is provided with 2 paths of EIA-485 communication interfaces;

d) the printer is provided with 1 path of RS232 printing interfaces;

e) the device is provided with 1 path of RS485 time setting interfaces;

f) a large-capacity database is adopted, at most 5 ten thousand points are supported, and related data can be checked in the liquid crystal.

g) Editing and synthesizing forwarding information.

Energy management function:

1) active power tracking

The energy storage module can quickly respond to the scheduling instruction and realize the function of auxiliary power regulation. The controller power tracking control can select to support a remote mode or a local mode through a constant value control word. The remote mode is that the controller controls the energy storage charging and discharging power according to an active instruction value sent by a master station end (SCADA monitoring system); the local control means controlling the energy storage charging and discharging power according to an active instruction value set by a fixed value in the controller. The coordination control device controls the active power output of the energy storage system by detecting the currently output active power and the received power instruction in real time, so that the scheduling instruction is responded quickly and accurately.

2) Peak clipping and valley filling

The energy storage module has excellent peak regulation performance due to the quick response characteristic, can be used as a power supply to release electric energy in the peak period of power utilization, and can be used as a load to absorb electric energy in the valley period of power utilization, so that the economical efficiency and the safety of power grid operation are improved.

As shown in FIG. 2, the controller peak clipping and valley filling control can selectively support the remote mode or the local mode through the constant value control word. The remote mode is that the controller controls the energy storage charging and discharging power according to the peak value and the valley value sent by a main station end (SCADA monitoring system); the local control means controlling the energy storage charging and discharging power according to the peak and valley values set by fixed values in the controller. When the output power is greater than the peak power, the energy storage system is charged to absorb the peak power; and when the output power is smaller than the valley power, the energy storage system discharges to fill the valley power.

3) Plan curve

The function of the plan curve is to control the output of the energy storage system to make the charging and discharging plan according to the preset plan curve. As shown in FIG. 3, the controller may select to support either the remote mode or the local mode by means of a constant value control word. The remote mode is that the controller controls the energy storage charging and discharging power according to the planned curve power value sent by a main station end (SCADA monitoring system); the local control means controlling the energy storage charging and discharging power according to the power value of a planned curve set by a fixed value in the controller.

4) Frequency and voltage modulation

The stored energy can assist the frequency modulation of the power grid, and the frequency modulation effect is improved by utilizing the quick response characteristic of the stored energy. Meanwhile, the energy storage system can also output reactive power, and the effect of auxiliary voltage regulation is achieved.

As shown in fig. 4, the frequency of the power grid depends on the balance relationship between the power generation active power and the load active power, and when the power generation active power is greater than the load active power, the system frequency rises; when the active power of the power generation is smaller than the active power of the load, the frequency of the system is reduced. The energy storage system assists in adjusting the generating active power through active-frequency (P-F) droop control, so that the generating active power and the load active power are balanced in real time, and the system frequency is stabilized. When the frequency of the system is reduced, the energy storage system discharges to increase active output; when the system frequency rises, the energy storage system charges to reduce the active output.

As shown in fig. 5, the voltage of the grid depends on the balance relationship between the generating reactive power and the load reactive power, and when the generating reactive power is greater than the load reactive power, the system voltage rises; and when the generating reactive power is less than the load reactive power, the system voltage is reduced. The energy storage system assists in adjusting the reactive power of power generation through reactive-voltage (Q-V) droop control, so that the reactive power of power generation and the reactive power of a load are balanced in real time, and the voltage of the system is stabilized. When the system voltage drops, the energy storage system sends out reactive power; when the system voltage rises, the energy storage system absorbs reactive power.

5) Smoothing wave motion

The photovoltaic power generation, the wind power generation and other new energy power generation have larger intermittence and fluctuation, and the performance of grid-connected power generation is seriously influenced. More and more researches utilize the energy storage capacity of the energy storage battery to stabilize the power fluctuation of new energy power generation through the charging and discharging of the battery.

As shown in fig. 6, the steady fluctuation control is divided into a first-order filtering control mode and a power fluctuation limiting control mode according to an algorithm, and can be set by a control word. The first-order filtering control strategy is to perform first-order low-pass filtering according to the output power of the power supply end, and eliminate the power component which changes rapidly and does not meet the fluctuation limit requirement by using the energy storage system, so that the rest is the smooth power component with small fluctuation. The power fluctuation limiting control strategy is to detect the output power of the power supply end in real time, count the fluctuation amount of the power supply end in a certain time period, and if the power fluctuation component exceeds the fluctuation limiting value set by the device, the energy storage system performs charging and discharging to inhibit the fluctuation amount. The device can be adjusted through a fixed value, so that the control target meets the power fluctuation limits of different time scales.

6) Power distribution and SOC adjustment

For the energy storage unit with large capacity, the charging and discharging characteristics of each battery pack are different, and the SOC values are also different. In order to ensure the balanced charging and discharging of each battery pack and prolong the service life of the battery, the coordination control device is provided with a power balanced distribution strategy and an SOC (System on chip) adjustment control strategy.

As shown in fig. 7 and 8, the present controller acquires the SOC state of each battery pack, and for each charging and discharging power, allocates the SOC state to each battery pack in proportion to the SOC of each battery pack. During charging, the battery pack with small SOC is charged preferentially, and the charging power is high; during discharge, the battery pack having a large SOC is discharged with priority, and the discharge power is large.

In order to enable each battery pack of the energy storage system to have a proper SOC value, each charging and discharging instruction can respond, as shown in fig. 9, SOC adjustment control is performed on the premise that the operation of other functional modules is not affected, and the SOC is controlled within a reasonable range by using a control strategy of slow charging and slow discharging.

Specifically, the sampling module monitors a current signal and a voltage signal in a converter module circuit in real time, acquires the voltage sampling signal and the current sampling signal and transmits the voltage sampling signal and the current sampling signal to the control module in time, the control module can track active power, load shifting, a planning curve, frequency modulation and voltage regulation, fluctuation stabilization, power distribution and one or more of SOC (system on chip) adjustment according to the specific use scene of the energy storage system, and sends a charging signal or a discharging signal to the converter module in combination with the voltage sampling signal and the current sampling signal, and the converter module converts alternating current electric energy into direct current electric energy according to the discharging signal and then stores the direct current electric energy into the energy storage module in a voltage reduction mode, or converts the direct current electric energy into alternating current electric energy according to the charging signal and then transmits the alternating current electric energy into a power grid through.

In one embodiment, the converter module comprises:

the LCL filter circuit is connected with the conversion circuit and used for reducing high-frequency harmonic waves in alternating current;

In a specific embodiment, the converter module further includes: the bypass switches are connected between the direct current filter circuit and the energy storage control module; and, between LCL filter circuit and AC filter circuit; and an output terminal of the AC filter circuit.

In a specific embodiment, the boost circuit is a non-isolated Buck circuit or an isolated Buck circuit.

In a specific embodiment, the converter circuit is a three-phase full-bridge IGBT converter circuit.

Specifically, as shown in fig. 10, the converter module employs a PCS energy storage converter, and a main circuit of the converter module includes a DC/AC conversion circuit and a three-way DC/DC boost (or buck) circuit. The DC/AC conversion circuit consists of a single three-phase full-bridge IGBT conversion circuit, the alternating current side is connected with a network or a transformer, and the direct current side is connected with the high-voltage side of the three-way DC/DC booster circuit. And the low-voltage side of the three DC/DC booster circuits is connected with the zinc-iron flow battery. An alternating current filter circuit, namely an alternating current EMI filter, is arranged on the alternating current side of the DC/AC conversion circuit and is used for inhibiting high-frequency interference in alternating current energy; and a direct current filter circuit, namely a direct current EMI filter, is arranged on the low-voltage side of each DC/DC booster circuit and is used for reducing direct current common mode interference generated by the zinc-iron flow battery. A CL filter circuit, namely a CL filter, is arranged on the high-voltage side of each DC/DC booster circuit, so that high frequency in direct current generated by each module can be filtered, and the stability of output current and voltage is reduced; the CL filter is also arranged on the direct current side of the DC/AC conversion circuit, so that the medium-high frequency direct current generated by the DC/AC conversion circuit can be filtered out when the zinc-iron redox flow battery is charged, and the service life of the zinc-iron redox flow battery is prolonged; each phase of the alternating current side of the DC/AC conversion circuit is connected with one LCL filter, and each group of LCL filters share one group of capacitor and one group of inductor, so that the high-frequency harmonic current of the alternating current side can be reduced, and meanwhile, the interference of unstable parameters of a power grid is reduced.

A voltage sampling circuit is arranged at the confluence of the low-voltage side and the low-voltage side of each DC/DC booster circuit; and a current sampling circuit is arranged at the confluence of the high-voltage side of each DC/DC booster circuit. A voltage and current sampling circuit is also arranged on the direct current side of the DC/AC conversion circuit; a voltage sampling circuit is arranged on the alternating current side of the DC/AC conversion circuit; meanwhile, a current circuit is provided in each IGBT circuit. The sampling circuit is used for realizing interconnection among the energy storage module, the energy storage control module and the control module so as to ensure the generation of the energy storage module and the stable operation of the current conversion module.

The converter module of the embodiment of the application adopts three 100kW DC/DC booster circuits to adapt to the characteristics of low voltage and high current of the high-capacity zinc-iron flow battery, and the product is convenient to upgrade. The low-voltage end of each DC/DC booster circuit can receive the output (or charge) of 138V-228V voltage, and the current of 2391A can be received through the three DC/DC booster circuits in parallel. Therefore, the current transformation of the zinc-iron flow battery with low voltage, high current and large capacity of energy storage is realized. The three DC/DC booster circuits boost the direct-current low voltage at the end of the energy storage battery to 650V direct-current high voltage, then the direct-current low voltage is converted into 315V three-phase alternating current through the DC/AC conversion circuit, and then the three-phase alternating current is converted into 315/400V isolation to realize power supply for a load or charging by commercial power.

The LCL filter on the alternating current side can greatly reduce high-frequency harmonic waves on the alternating current side, meanwhile, the influence of unstable factors of a power grid can be reduced, and the stability of equipment is improved. The alternating current side EMI filter can not only restrain the influence of high-frequency interference in a power grid on equipment, but also restrain the interference of the equipment on the power grid. The direct current side CL filter can filter high-frequency components in direct current, reduce ripples of output current and voltage, and prolong the service life of the energy storage battery. The direct current side EMI filter can reduce common mode interference of the direct current side and improve stability of equipment.

The sampling circuit in the embodiment of the application can be favorably interconnected with the control module and the current transformation module. The system can realize a steady-state control function, ensure the safe and reliable operation of the system, and simultaneously make corresponding control strategies according to different scenes. The power grid has the characteristics of quick response and excellent peak regulation performance, can be used as a power supply to release electric energy in the peak period of power utilization, and can be used as a load to absorb electric energy in the valley period of power utilization, so that the economical efficiency and the safety of power grid operation are improved.

The operation of the energy storage system will be described in detail below:

(1) charging process

And when the control module detects that redundant electric energy exists in the power grid, the energy storage system is switched to a charging mode. In the charging mode, the high-voltage side of the DC/DC booster circuit is an input end, and the low-voltage side of the DC/DC booster circuit is an output end. The electric energy output by the electric energy application system is subjected to voltage reduction through the DC/DC booster circuit, and then is subjected to alternating current-direct current conversion through the DC/AC conversion circuit and then is transmitted to the zinc-iron flow battery, so that the zinc-iron flow battery is charged.

In the process of charging the zinc-iron flow battery, an energy storage control module, namely a battery management unit, can perform heat management, electric quantity equalization and charging management according to the state condition of the zinc-iron flow battery managed by the energy storage control module; meanwhile, the DC/DC booster circuit adjusts the voltage of the low-voltage side according to the state condition of the zinc-iron flow battery in the energy storage module, so that the charging voltage of the zinc-iron flow battery is stable; and the transmission voltage and the transmission power of the energy storage system are ensured to be stable in cooperation with other DC/DC booster circuits in the energy storage system.

(2) Discharge process

When the control module detects that the zinc-iron redox flow battery is required to provide electric energy in the power grid and the energy storage system has the electric energy which can be discharged, the energy storage system is switched to a discharging mode. In the discharging mode, the low-voltage side of the DC/DC booster circuit is an input end, and the high-voltage side of the DC/DC booster circuit is an output end; the electric energy stored in the zinc-iron flow battery is transmitted to the DC/DC booster circuit, after being boosted by the DC/DC booster circuit, the DC/AC conversion circuit carries out DC-AC conversion and then transmits the converted electric energy to the power grid, and the discharging process of the zinc-iron flow battery is realized.

In the discharging process of the zinc-iron flow battery, an energy storage control module, namely a battery management unit, performs heat management, electric quantity equalization and discharge management on the battery pack according to the monitored state of the battery pack; meanwhile, the DC/DC booster circuit adjusts the voltage output by the high-voltage side according to the state of the zinc-iron flow battery in the energy storage module where the DC/DC booster circuit is located, and the higher the voltage of the high-voltage side of the DC/DC booster circuit is, the larger the output energy is; conversely, the smaller the voltage on the high-voltage side of the DC/DC boost circuit, the smaller the output energy. And ensuring the transmission voltage and transmission power of the energy storage system to be stable together with other DC/DC booster circuits in the energy storage system.

In a specific implementation mode, the current conversion module PCS has a reliable and comprehensive protection method in the operation process, once faults and abnormity are detected, the PCS stops working and sends out an alarm signal, and the protection is divided into hardware protection and software protection, wherein the hardware protection comprises IGBT over-temperature over-current protection and direct-current bus voltage protection. Software protection includes the following.

(1) And D, direct current over-voltage and under-voltage protection: the PCS allows the maximum input voltage of the direct current side to be 350V, and when the converter detects that the input voltage is higher than a limit value, the converter disconnects the energy storage device from the power grid within 0.2-1s and sends corresponding alarm information; when the PCS detects that the direct-current voltage is lower than the set undervoltage fixed value, the converter can be protected to shut down, and corresponding alarm information is sent out.

(2) And D, direct current overcurrent protection: the PCS can monitor the direct current side current in real time, when the current value exceeds a setting fixed value, the converter can disconnect the energy storage device from the power grid within 0.2-1s, and corresponding alarm information is sent out. The fixed value setting needs to be matched with the battery charging and discharging limiting current.

(3) And (3) direct current reverse connection protection: the PCS detects the direct-current incoming line voltage of the converter module in real time, and when the converter detects that the incoming line is in positive and negative reversal connection, the grid-connected contactor is automatically tripped off, and the direct-current circuit breaker is tripped. After the polarity is connected positively, the converter can work normally.

(4) AC over/under voltage protection: in the grid-connected operation process of the converter, the allowable deviation of the power grid voltage at the power grid interface is +/-10% of a rated value, when the power grid voltage exceeds a specified range, the converter stops working, and corresponding alarm information is displayed on a liquid crystal display screen of the control device.

(5) Cross-flow/under-frequency protection: and in the grid-connected operation process of the converter, the allowable range of the power grid frequency is 48.5Hz-51.5Hz, when the power grid frequency exceeds the specified range, the converter stops working, and corresponding alarm information is displayed on a liquid crystal display screen of the control device.

(6) And (3) alternating current overcurrent protection: in the grid-connected operation process of the converter, when a power grid is short-circuited, the converter can limit the alternating current output current to be within 120% of a rated value, and simultaneously disconnect the energy storage device from the power grid within 60s and send out corresponding alarm information.

In a particular embodiment, the energy storage module may be a zinc-iron flow battery.

Particularly, the zinc-iron flow battery has the characteristics of low electrolyte cost, high safety, environmental friendliness and the like, and has a good application prospect in large-scale flow batteries. At present, a typical energy storage inverter is mostly applied to a lithium battery, and therefore, it is very important to develop an energy storage converter compatible with a zinc-iron flow battery.

According to the energy storage system provided by the embodiment of the application, the direct-current voltage signal of the zinc-iron flow battery is amplified by using the current transformation module, and then the amplified direct-current voltage signal is inverted into an alternating-current voltage signal and is merged into a power grid; the control module reasonably selects the control strategy according to different use scenes, so that the output of new energy power generation can be smoothed to a great extent, the power supply quality of a power grid is improved, the safe and reliable operation of the system is ensured, and the economical efficiency and the safety of the operation of the power grid are improved.

The foregoing is a more detailed description of the present invention, taken in conjunction with the specific preferred embodiments thereof, and it is not intended that the invention be limited to the specific embodiments shown and described. To the utility model belongs to the technical field of ordinary technical personnel, do not deviate from the utility model discloses under the prerequisite of design, can also make a plurality of simple deductions or replacement, all should regard as belonging to the utility model discloses a protection scope.

Claims

1. An energy storage system, comprising:

2. The energy storage system of claim 1, wherein the sampled signals comprise current sampled signals and voltage sampled signals.

3. The energy storage system of claim 1, wherein the control module comprises: the system comprises at least one EIA-485 communication interface, at least one RJ-45 Ethernet interface, at least one CAN interface, at least one optical fiber interface, at least one RS-232 printing interface and at least one RS-485 time pairing interface.

4. The energy storage system of claim 1, wherein the feedback comprises one or more of active power tracking, peak clipping and valley filling, projected curves, frequency and voltage modulation, ripple settling, power splitting, and SOC adjustment.

5. The energy storage system of claim 1, wherein the converter module comprises:

6. The energy storage system of claim 5, wherein the converter module further comprises: the multiple groups of bypass switches are connected between the direct current filter circuit and the energy storage control module; and, between said LCL filter circuit and said AC filter circuit; and an output terminal of the AC filter circuit.

7. The energy storage system of claim 5, wherein the boost circuit is a non-isolated Buck circuit or an isolated Buck circuit.

8. The energy storage system of claim 5, wherein the converter circuit is a three-phase full bridge IGBT converter circuit.

9. The energy storage system of claim 1, wherein the energy storage module is a zinc-iron flow battery.