CN216390529U

CN216390529U - Inverter parallel system and grid-connected power generation system

Info

Publication number: CN216390529U
Application number: CN202122874059.1U
Authority: CN
Inventors: 方伟; 杨远钢
Original assignee: Suzhou Huichuan Control Technology Co Ltd
Current assignee: Suzhou Huichuan Control Technology Co Ltd
Priority date: 2021-11-22
Filing date: 2021-11-22
Publication date: 2022-04-26
Anticipated expiration: 2031-11-22

Abstract

The utility model discloses an inverter parallel system and a grid-connected power generation system, wherein the grid-connected power generation system comprises a master controller, and the inverter parallel system comprises: the communication bus is used for being connected with the master controller; the communication ends of the N inverters are connected with the master controller through a communication bus, and the N inverters are used for working according to a control signal output by the master controller so as to realize grid connection/grid disconnection; wherein N is more than or equal to 2.

Description

Inverter parallel system and grid-connected power generation system

Technical Field

The utility model relates to the technical field of grid-connected power generation, in particular to an inverter parallel system and a grid-connected power generation system.

Background

With the development of the photovoltaic industry, user demands and gradually increased and flexible system capacity, capacity adjustment of the system in a module mode occurs, a grid-connected power generation system generally adopts a master controller to centrally control each inverter to work, and in a plurality of inverters, communication connection is generally performed between the inverters in a hand-in-hand mode, as long as one inverter in a hand-in-hand link has a problem and stops working, other inverters below cannot communicate and cannot be connected to the grid, great troubles are brought to maintenance, and the whole system is forced to be closed, so that the reliability is very low. In addition, due to the physical connection of the hand pulling device, when the number of inverters is large, the communication wire is long, interference is generated on the communication quality, and the communication has time delay.

SUMMERY OF THE UTILITY MODEL

The utility model mainly aims to provide an inverter parallel system and a grid-connected power generation system, aiming at improving the reliability and the communication quality of the inverter system.

In order to achieve the above object, the present invention provides an inverter parallel system, which is applied to a grid-connected power generation system, wherein the grid-connected power generation system includes a master controller, and the inverter parallel system includes:

the communication bus is used for being connected with the master controller;

the communication ends of the N inverters are connected with the master controller through the communication bus, and the N inverters work according to a control signal output by the master controller to realize grid connection/grid disconnection; wherein N is more than or equal to 2.

Optionally, one of the N inverters is a master, and the remaining N-1 inverters are slaves; the host is used for receiving the control signal output by the master controller through the communication bus, carrying out grid connection/grid disconnection according to the control signal, and communicating with each slave machine through the communication bus so as to control the slave machines to work.

Optionally, when the master machine fails, the remaining N-1 slave machines serving as slave machines are switched to the master machine according to a control signal received from the master controller, and communicate with each slave machine through the communication bus to control the N-2 slave machines to operate.

Optionally, the N inverters are hosts, and each host is configured to receive a control signal output by the master controller through the communication bus, and perform grid connection/grid disconnection according to the control signal.

Optionally, the inverter parallel system further includes three-channel adapters, the number of the three-channel adapters corresponds to the number of the inverters, two terminals of each three-channel adapter are sequentially connected in series to the communication bus, and a third terminal of each three-channel adapter is connected to a communication end of one inverter.

Optionally, the dc sides of the N inverters are arranged in parallel, and the ac sides of the N inverters are arranged in parallel.

Optionally, each of the inverters comprises:

the input end of the inverter circuit is connected with a power generation system through a direct current bus, and the output end of the inverter circuit is connected to a power grid AC through an alternating current bus;

and the controller is connected with the controlled end of the inverter circuit, receives the control signal output by the master controller through the communication bus, controls the inverter circuit to work, converts direct current accessed from the direct current bus into alternating current and outputs the alternating current to the power grid AC through the alternating current bus.

Optionally, the communication bus is a CAN communication bus, or the communication bus is a 485 communication bus.

The utility model relates to a grid-connected power generation system which comprises a master controller and an inverter parallel system as described above;

the inverter parallel system comprises N inverters, and communication ends of the N inverters are connected with the master controller through the communication bus.

Optionally, the grid-connected power generation system further includes:

the photovoltaic array comprises N photovoltaic sub-arrays, and each photovoltaic sub-array is connected with the direct current side of one inverter through a direct current bus.

The inverter parallel system is provided with the communication bus and is in communication connection with the master controller, so that the communication ends of the N inverters are connected with the master controller through the communication bus, and the N inverters work according to the control signal output by the master controller to realize grid connection/off-grid. The utility model can realize the communication among the parallel connection of a plurality of inverters of the inverter system, when one inverter in the middle breaks down, the inverter is removed, the communication of other inverters is not influenced, and the grid-connected power generation can still be realized, in addition, the communication of each inverter is hung on the bus, the problem of long communication lines is solved, and the communication quality is ensured.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

Fig. 1 is a schematic circuit structure diagram of an embodiment of an inverter parallel system applied to a grid-connected power generation system according to the present invention;

FIG. 2 is a schematic diagram of the inverter of FIG. 1 in conjunction with an embodiment of the system;

fig. 3 is a schematic diagram of the inverter of fig. 1 in conjunction with an embodiment of the present invention.

The reference numbers illustrate:

reference numerals	Name (R)	Reference numerals	Name (R)
				100	Inverter with a voltage regulator	400	Photovoltaic array
200	Master controller	CN1	Communication bus
				300	Three-channel adapter

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.

In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

The term "and/or" herein is merely an association describing an associated object, meaning that three relationships may exist, e.g., a and/or B, may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

The utility model provides an inverter parallel system, which is applied to a grid-connected power generation system.

Referring to fig. 1, in an embodiment of the present invention, the inverter parallel system includes:

a communication bus CNL1 for connecting with the master controller 200;

the communication ends of the N inverters 100 are connected with the master controller 200 through the communication bus CNL1, and the N inverters 100 are used for working according to a control signal output by the master controller 200 to realize grid connection/grid disconnection; wherein N is more than or equal to 2.

In this embodiment, the communication bus CNL1 is a CAN communication bus CNL1, or the communication bus CNL1 is a 485 communication bus CNL1, and each inverter is connected to the communication bus CNL1, that is, each inverter may be in communication connection with the master controller 200 through the communication bus CNL1, and the inverters may also be in communication connection with each other through the communication bus CNL1 to perform signal interaction. Each inverter can be directly controlled by the master controller 200 or controlled by other inverters, and communication lines from the communication bus CNL1 to each inverter are short, so that signal damage can be reduced, a signal transmission path can be shortened, and the signal transmission speed can be increased, so that the communication quality between the master controller 200 and the inverters and between the inverters is good. The inverter can be a photovoltaic inverter and also can be a wind energy inverter, and the inverter is also called a power supply regulator and can be classified according to purposes and waveform modulation modes: the inverter can be divided into an independent power supply and a grid-connected power supply according to the application of the inverter in a grid-connected power generation system; the inverter for the grid-connected system may be further classified into a square wave inverter, a step wave inverter, a sine wave inverter, and a combined inverter according to a waveform modulation method, and the inverter for the grid-connected system may be further classified into a transformer-type inverter and a transformer-free inverter according to the presence or absence of a transformer, and the type of the inverter may not be particularly limited. The inverter is used as a photovoltaic inverter to explain the embodiments of the present invention. Further, in this embodiment, the inverter may be an MPPT (Maximum Power Point Tracking) inverter, and the MPPT inverter can monitor the generated voltage of the photovoltaic array 400 in real time and track the Maximum voltage current Value (VI), so that the Power generation system transmits electric energy to the grid AC by the current output at the Maximum Power, and the natural solar energy, wind energy, hydraulic energy, and the like are used for generating Power and transmitting electric energy, thereby avoiding environmental pollution. The number of the inverters can be 2 or more than 2, for example, 4, 6, 8, etc., the alternating current sides of the inverters can be directly connected in parallel, and other devices, such as switches, etc., can be arranged to be connected in parallel.

The inverter may obtain the number of photovoltaic modules or panels of the photovoltaic array 400, the number of photovoltaic modules or panels of the photovoltaic array 400 that are actively operating, the generation time, the total amount of power generation, the voltage or current, the amount of power generation of each photovoltaic module or panel of the photovoltaic array 400 that is actively operating, and so on. The inverter can send the parameter information of the photovoltaic array 400 to the master controller 200 through the communication bus CNL1, and the master controller 200 can issue a control instruction, that is, a control signal, to the inverter according to the data information sent by the photovoltaic inverter, so as to control the inverter to invert the dc voltage output by the photovoltaic array 400 into an ac voltage. The pv array 400 transmits electric energy to the corresponding pv inverter for inversion power generation, and thus the control signals may include a grid-connected control signal and a grid-disconnected control signal. According to the grid-connected control signal, the inverters can be controlled to be connected to the grid, and also part of the inverters can be controlled to be connected to the grid, that is, the photovoltaic inverter system can be controlled to be connected with all the photovoltaic arrays 400 or part of the photovoltaic arrays 400, so that the corresponding number of the photovoltaic arrays 400 output electric energy to the inverters, and the inverters convert direct-current power generated by the photovoltaic arrays 400 or direct-current power released by batteries into alternating-current power required by loads.

According to the utility model, the communication bus CNL1 is arranged and is in communication connection with the master controller 200, so that the communication ends of the N inverters 100 are connected with the master controller 200 through the communication bus CNL1, and the N inverters 100 work according to the control signals output by the master controller 200, thereby realizing grid connection/grid disconnection. The utility model can realize the communication among the parallel connection of a plurality of inverters of the inverter system, when one inverter in the middle breaks down, the inverter is removed, the communication of other inverters is not influenced, and the grid-connected power generation can still be realized, in addition, the communication of each inverter is hung on the bus, the problem of long communication lines is solved, and the communication quality is ensured.

Referring to fig. 2, in an embodiment, one of the N inverters 100 is a master, and the remaining N-1 inverters are slaves; the master is used for receiving the control signal output by the master controller 200 through the communication bus CNL1, performing grid connection/disconnection according to the control signal, and communicating with each slave through the communication bus CNL1 to control the slave to work.

In this embodiment, the host is directly connected to the master controller 200 through the communication bus CNL1 in a communication manner, receives the control signal sent by the master controller 200, responds to and executes the corresponding control signal, for example, performs a grid-connection operation, and accesses the photovoltaic array 400 for electric energy conversion. The master machine can also control the corresponding slave machines to work according to the master controller 200, for example, control all or part of the slave machines to be connected in a grid mode, or control all or part of the slave machines to be disconnected in a grid mode. When the master controller 200 issues a grid-connected control signal, the master responds, then the master 1 issues to each slave (1-N-1) through the communication bus CNL1, the master and each slave (1-N-1) convert the direct current received from the photovoltaic array 400 into alternating current and output the alternating current, and grid-connected power generation is realized. In addition, the inverter host CAN be connected with each slave (1-N-1) through a CAN bus or a 485 bus, and parameter information of the received photovoltaic array 400 is shared to each inverter slave in real time, so that good dynamic current sharing between the inverter host and each inverter slave is ensured. It can be understood that the master machine and each slave machine (1-N-1) are hung on the bus, so that each slave machine can be independently controlled by the master machine, and compared with a hand-held connection mode between the master machine and the slave machine, the communication between the slave machine and the master machine does not need to depend on the slave machine of the previous stage, so that even if the slave machine in the middle link has a communication fault, the communication of the next stage cannot be influenced, the normal work of other inverters cannot be influenced under the condition that the slave machine cannot normally work, and other inverters (the master machine or the slave machines) continue to normally work to carry out grid-connected power generation, so that the generated energy is not wasted.

Referring to fig. 2, in an embodiment, when the master fails, the remaining N-1 slaves, which are slaves in the inverters, are switched to the master according to a control signal received from the master controller 200, and communicate with each slave through the communication bus CNL1 to control the N-2 slaves to operate.

In this embodiment, the master controller 200 may communicate with the master in real time, and when the master fails, the master may report a failure to the master controller 200, or when the master fails, that is, when the master fails, the master may be switched out from the inverter system, and one of the other slaves is switched to the master, and then the new master controls the other slaves to operate. The novel communication system provided by the utility model can effectively solve the defects of the prior art, when the host fails, the host is removed, the communication of other slave machines below is not affected, grid-connected power generation can still be realized, in addition, the communication of each slave machine is hung on the bus, the problem of long communication line is solved, and the communication quality is ensured. It is understood that all inverters connected in parallel are communicated with each other, for example, if the slave receives a failure signal sent by the master, it can be determined that the master has failed. Therefore, each slave (1-N-1) can judge whether the master is failed or not in time, and the slave becomes a new master according to a preset sequence. When the master computer fails, one slave computer works by using the backup data and is switched to the master computer, and the other slave computers backup the control data of the new master computer again. In a similar way, when one slave machine fails, other slave machines are independently controlled by the host machine and are not influenced by the upper-level inverter, and grid-connected power generation can still be realized.

Referring to fig. 3, in an embodiment, N inverters 100 are hosts, and each host is configured to receive a control signal output by the overall controller 200 through the communication bus CNL1, and perform grid connection/grid disconnection according to the control signal.

In this embodiment, each host (1 to N) is independently controlled by the master controller 200, the master controller 200 can control each inverter to work independently, at this time, the master controller 200 can control the operation state of each inverter independently, and can adjust the output power of each photovoltaic inverter according to the operation state of each photovoltaic inverter, when each inverter is a host, the master controller 200 issues a grid-connected control signal, each host (1 to N) responds simultaneously, each host (1 to N) converts the direct current received from the photovoltaic array 400 into an alternating current and outputs the alternating current, thereby realizing grid-connected power generation. The actions of all the inverters are consistent, the whole field control speed is high, and the precision is high, so that the stability of the system is improved, and the grid-connected friendliness is improved. The new communication system provided by the utility model can effectively solve the defects of the prior art, when one host in the middle breaks down, the host is removed, other lower hosts are directly connected with the master controller 200 through the communication bus CNL1, the communication is not influenced, the grid-connected power generation can still be realized, in addition, the communication of each host (1-N) is hung on the bus, the problem of the long communication line is solved, and the communication quality is ensured.

Referring to fig. 2 or 3, in an embodiment, the inverter parallel system further includes three-channel adapters 300, the number of the three-channel adapters 300 corresponds to the number of the inverters, two terminals of each three-channel adapter 300 are sequentially connected in series to the communication bus CNL1, and a third terminal of each three-channel adapter 300 is connected to a communication terminal of one of the inverters.

In this embodiment, each inverter can communicate with the main controller and other inverters through the three-channel adapter 300, and the inverters can be detachably connected with the three-channel converter, and when any one of the inverters fails, the inverter can be detached from the three-channel converter for maintenance, so that the failure of the other machines due to the failure of one inverter is avoided, the normal grid connection of the generator system is not affected, and the normal operation of the system can be ensured. Through the three-channel adapter 300, hot plugging can be realized in practical application, and the operation of a grid-connected system cannot be influenced by the connection or disconnection of one or more inverters.

Referring to fig. 1, in one embodiment, the dc sides of N inverters 100 are arranged in parallel and the ac sides of N inverters 100 are arranged in parallel.

In the present embodiment, all inverters have their own controllers, respectively; the dc side of each inverter may be connected to a subarray of the pv array 400, the AC side of each inverter may be connected to the grid AC, and since the dc sides of the inverters are connected in parallel and the AC sides are also connected in parallel, the controllers of the inverters may communicate with each other to inform their respective operating states. When the master machine is in failure, one slave machine becomes a new master machine, and the rest slave machines are controlled by the new master machine. When all the inverters are hosts, all the hosts are independently controlled by the master controller 200 through the communication bus CNL1, and are not affected by other hosts. In addition, power lines among the inverters are also connected in parallel, when one of the inverters fails, the inverter can be detached from the system from the power line and the communication bus CNL1, other machines can be normally connected to the grid, power generation is not affected, and after one of the inverters fails, other inverters (a master machine or a slave machine) can continue to normally work to carry out grid-connected power generation, so that power generation amount is not wasted.

In this embodiment, the inverter system may further include a ring network switch, which may be any one of a ring network medium voltage circuit breaker, a medium voltage load switch, or a medium voltage contactor. The looped network switch includes, but is not limited to, various switches capable of implementing grid connection/grid disconnection, and in other embodiments, other looped network switches may also be used to implement the switch, which is not limited herein.

Referring to fig. 1, in an embodiment, each of the inverters includes:

and the controller is connected with the controlled end of the inverter circuit, receives the control signal output by the master controller 200 through the communication bus CNL1 to control the inverter circuit to work, so that direct current accessed from the direct current bus is converted into alternating current and then is output to the power grid AC through the alternating current bus.

In this embodiment, the controller may be implemented by a DSP controller, a single chip, or the like, and the controller may be in communication connection with the main controller 200 through a communication bus CNL1, and control the inverter circuit to operate/stop according to a grid-connected control signal or an off-line control signal sent by the main controller 200.

The inverter circuit can be a three-phase inverter circuit or a single-phase inverter circuit, the three-phase inverter circuit can comprise six power switching devices of which control ends are respectively connected to the controller and a freewheeling diode which is connected to each power switching device in an anti-parallel mode, the six power switching devices respectively form three upper arms and three lower arms, each upper arm and the corresponding lower arm form a phase bridge arm, and the three-phase bridge arms are connected in parallel; the connection parts of the upper arm and the lower arm of each phase of bridge arm of the three-phase bridge circuit are respectively connected to three input ends of a power grid AC through one filter inductor; or the connection positions of the upper arm and the lower arm of any two-phase bridge arm in the three-phase bridge arms of the three-phase bridge circuit are respectively connected to the power grid AC through the filter inductor.

The utility model further provides a grid-connected power generation system.

Referring to fig. 1, the grid-connected power generation system includes a master controller 200 and the inverter parallel system as described above;

the inverter parallel system comprises N inverters 100, and communication terminals of the N inverters 100 are connected with the master controller 200 through the communication bus CNL 1. The overall controller 200 can be implemented by a DSP control system. Each inverter is connected to the communication bus CNL1, that is, each inverter may be connected to the master controller 200 through the communication bus CNL1, and the inverters may be connected to each other through the communication bus CNL1 for signal interaction. Each inverter can be directly controlled by the master controller 200, when all inverters are hosts, the master controller 200 issues a grid-connected control signal, all hosts simultaneously respond to the control signal to carry out grid connection, and all hosts convert direct current received from the photovoltaic array 400 into alternating current and then output the alternating current, so that grid-connected power generation is realized. Or, the inverter can be controlled by other inverters, one of the inverters is a master, the other inverters are slaves, the master is directly controlled by the master controller 200, the slaves are indirectly controlled by the master controller 200, when the master controller 200 issues a grid-connected control signal, the master responds, the master 1 simultaneously issues the grid-connected control signal to each slave (1-N-1) through the communication bus CNL1, and the master and each slave (1-N-1) convert direct current received from the photovoltaic array 400 into alternating current and output the alternating current, so that grid-connected power generation is realized.

Referring to fig. 1, in an embodiment, the grid-connected power generation system further includes:

a Photovoltaic Array 400(Photovoltaic Array), said Photovoltaic Array 400 comprising N Photovoltaic sub-arrays, each said Photovoltaic sub-Array connected to the dc side of one said inverter by a dc bus.

In this embodiment, in practical applications of the photovoltaic array 400, solar energy can be converted into direct current electric energy by the photovoltaic effect of the solar cells, but the current that can be generated by one photovoltaic module or one photovoltaic panel is limited, so several photovoltaic modules or photovoltaic panels are connected together to form the photovoltaic array 400 to generate more current. Therefore, in this embodiment, the photovoltaic array 400 can be used for connecting a plurality of photovoltaic modules or connecting more photovoltaic cells.

The photovoltaic array 400 and the photovoltaic inverters can form a photovoltaic power station, each photovoltaic inverter can be connected with a corresponding photovoltaic sub-array in the photovoltaic array 400, each photovoltaic inverter converts direct current electric energy generated by the connected photovoltaic sub-array into alternating current electric energy, and the alternating current electric energy obtained by conversion is converged into an alternating current bus; in some embodiments, the grid-connected power generation system may further include a booster station, such as a transformer, where the AC bus transmits the AC power to the booster station, the AC power is boosted to an AC power meeting the AC requirement of the power grid, and the grid-connected point on the high-voltage bus is connected to the power grid AC to complete the boosting process from low voltage to medium voltage or high voltage, and the transformation ratio, the voltage level, the power level, and the type of the transformer are different according to the system; the transformer may be a double split transformer or a double winding transformer, and is not limited herein.

The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. The utility model provides an inverter parallel system, is applied to in the power generation system that is incorporated into the power networks, the power generation system that is incorporated into the power networks includes total controller, its characterized in that, inverter parallel system includes:

the communication bus is used for being connected with the master controller;

2. The inverter parallel system according to claim 1, wherein one of the N inverters is a master, and the remaining N-1 inverters are slaves; the host is used for receiving the control signal output by the master controller through the communication bus, carrying out grid connection/grid disconnection according to the control signal, and communicating with each slave machine through the communication bus so as to control the slave machines to work.

3. The parallel inverter system as claimed in claim 2, wherein when the master fails, the remaining N-1 slaves of the inverters as slaves are switched to the master according to a control signal received from the master controller, and communicate with the slaves via the communication bus to control the operation of the N-2 slaves.

4. The parallel inverter system of claim 1, wherein N inverters are hosts, and each host is configured to receive a control signal output by the master controller via the communication bus and perform grid connection/grid disconnection according to the control signal.

5. The inverter parallel system according to claim 1, further comprising three-channel adapters, the number of the three-channel adapters corresponding to the number of the inverters, two terminals of each of the three-channel adapters being connected in series to the communication bus in turn, and a third terminal of each of the three-channel adapters being connected to a communication terminal of one of the inverters.

6. The inverter parallel system of claim 1, wherein the dc sides of N of the inverters are arranged in parallel and the ac sides of N of the inverters are arranged in parallel.

7. The inverter parallel system according to any one of claims 1 to 6, wherein each of the inverters comprises:

8. The inverter parallel system according to any one of claims 1 to 6, wherein the communication bus is a CAN communication bus, or wherein the communication bus is a 485 communication bus.

9. A grid-connected power generation system, characterized in that the grid-connected power generation system comprises a master controller and the inverter parallel system according to any one of claims 1 to 8;

10. The grid-connected power generation system according to claim 9, further comprising: