CN117639075A - Multi-mode flexible switching coordination control system and method for AC/DC interconnection micro-grid - Google Patents
Multi-mode flexible switching coordination control system and method for AC/DC interconnection micro-grid Download PDFInfo
- Publication number
- CN117639075A CN117639075A CN202311637813.7A CN202311637813A CN117639075A CN 117639075 A CN117639075 A CN 117639075A CN 202311637813 A CN202311637813 A CN 202311637813A CN 117639075 A CN117639075 A CN 117639075A
- Authority
- CN
- China
- Prior art keywords
- grid
- micro
- converter
- bidirectional
- control
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 35
- 230000002457 bidirectional effect Effects 0.000 claims abstract description 71
- 230000001105 regulatory effect Effects 0.000 claims abstract description 12
- 230000005540 biological transmission Effects 0.000 claims abstract description 8
- 230000008859 change Effects 0.000 claims abstract description 7
- 238000006243 chemical reaction Methods 0.000 claims description 12
- 239000003990 capacitor Substances 0.000 claims description 10
- 230000001360 synchronised effect Effects 0.000 claims description 9
- 230000001276 controlling effect Effects 0.000 claims description 8
- 238000004146 energy storage Methods 0.000 claims description 8
- 230000001939 inductive effect Effects 0.000 claims description 6
- 238000007665 sagging Methods 0.000 claims description 5
- 238000011217 control strategy Methods 0.000 description 4
- 238000010248 power generation Methods 0.000 description 4
- 230000003068 static effect Effects 0.000 description 4
- 238000013178 mathematical model Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000008439 repair process Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000011426 transformation method Methods 0.000 description 1
Landscapes
- Inverter Devices (AREA)
Abstract
The invention discloses a multimode flexible switching coordination control system and method of an AC/DC interconnection micro-grid, wherein the system comprises an AC sub-micro-grid, a DC sub-micro-grid and an interconnection converter connected between the AC sub-micro-grid and the DC sub-micro-grid, the interconnection converter is a bidirectional AC/DC converter, droop control is adopted during switching between the AC sub-micro-grid and the DC sub-micro-grid, and the power transmission quantity is regulated and controlled according to the change of bus voltage and frequency of the AC sub-micro-grid and the DC sub-micro-grid connected with the bidirectional AC/DC converter. When the AC/DC hybrid micro-grid is switched between the grid-connected mode and the island mode, the bidirectional AC/DC converter adopts droop control, and the presynchronization method is adopted to eliminate the difference between the AC/DC hybrid micro-grid and the public power grid, so that the grid-connected mode and the island mode are switched seamlessly, the electric energy quality in the system is improved, the seamless switching of the grid connection and the grid disconnection is realized, the overcurrent or overvoltage impact is avoided, and the internal loss of the micro-grid system is effectively reduced.
Description
Technical Field
The invention relates to the technical field of micro-grids, in particular to a multi-mode flexible switching coordination control system and method for an AC/DC interconnection micro-grid, which are suitable for sharing an energy storage power station.
Background
At present, the microgrid structure studied at home and abroad comprises an alternating current microgrid, a direct current microgrid and an alternating current/direct current hybrid microgrid. The AC/DC hybrid can effectively manage and control the distributed power supply and can meet the power supply requirements of different loads, so that the distributed power supply becomes a hot spot for the research of the power distribution technology and has been rapidly developed in recent years. For example, the Hachnohe microgrid in Japan is formed by connecting an energy storage device to an alternating current bus through an inverter, so that the earliest alternating current-direct current coupling microgrid is formed. United states scholars in 2010 put forward an ac-dc hybrid stratified distribution system, which considers convenience and economy of different types of load access for the first time. The university of southern kenyao of singapore researches a time average model of an alternating current-direct current hybrid micro-grid and provides a coordination control strategy of the model, but the control strategy is simpler and is only suitable for controlling the alternating current-direct current hybrid micro-grid with small scale and small capacity.
The AC/DC hybrid micro-grid is a small power generation and distribution system formed by integrating a distributed power supply, an energy storage device, an energy conversion device, related loads and a monitoring and protecting device, and is an autonomous system capable of realizing self-control, protection and management. The AC/DC hybrid micro-grid comprises an AC sub-grid and a DC sub-grid, and the AC sub-grid and the DC sub-grid are connected by adopting an interconnection converter.
The AC/DC hybrid micro-grid generally operates in a grid-connected mode, and when a public power grid fails or overhauls, the hybrid micro-grid is actively disconnected from the public power grid and is switched to an island mode from the grid-connected mode in order to ensure continuous power supply of important loads in the micro-grid and reduce the influence caused by the public power grid failure; and when the public power grid repair problem and the overhaul are completed, the hybrid micro-grid is connected again so as to realize the efficient utilization of the distributed power generation units. Due to the frequency, phase and voltage amplitude differences of the public power grid and the hybrid micro-grid system, over-current or over-voltage impact can be caused at the switching moment of two modes in the AC/DC hybrid micro-grid, and the stable operation of the micro-grid system can be influenced when serious. Therefore, it is highly desirable to eliminate the difference between the hybrid micro-grid and the public grid at the time of on-grid/off-grid, and realize on-grid/off-grid seamless switching.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides a multi-mode flexible switching coordination control system and method for an AC/DC interconnection micro-grid based on the problems that the AC/DC interconnection micro-grid is inflexible in operation mode, and overcurrent or overvoltage impact is caused at the moment of switching when AC/DC or DC/AC is forced, and the stable operation of the micro-grid system is affected when the switching is serious.
The technical scheme adopted is as follows:
in one aspect, the invention provides a multimode flexible switching coordination control system of an alternating current/direct current interconnection micro-grid, which comprises an alternating current/direct current hybrid micro-grid formed by an alternating current sub-micro-grid and a direct current sub-micro-grid and an interconnection converter connected between the alternating current sub-micro-grid and the direct current sub-micro-grid, and is characterized in that the interconnection converter is a bidirectional AC/DC converter, the bidirectional AC/DC converter adopts a sagging control alternating current/direct current hybrid micro-grid during parallel/off-grid switching, and the power transmission quantity is controlled according to the change of bus voltage and frequency of the alternating current sub-micro-grid and the direct current sub-micro-grid connected with the bidirectional AC/DC converter.
Further, the bidirectional AC/DC converter is of a three-phase voltage source type bridge topology structure, and includes a switching tube Sa1, a switching tube Sa2, a switching tube Sb1, a switching tube Sb2, a switching tube Sc1, and a switching tube Sc2, wherein an emitter of the switching tube Sa1 is connected with a collector of the switching tube Sa2 to form a bridge frame a, an emitter of the switching tube Sb1 is connected with a collector of the switching tube Sb2 to form a bridge frame b, an emitter of the switching tube Sc1 is connected with a collector of the switching tube Sc2 to form a bridge frame c, the bridge frame a, the bridge frame b and the bridge frame c are respectively connected with corresponding AC sub-micro-grid buses, collectors of the switching tube Sa1, the switching tube Sb1, and the switching tube Sc1 are connected with positive nodes of the DC sub-micro-grid buses, and emitters of the switching tube Sa2, the switching tube Sb2, and the switching tube Sc2 are connected with negative nodes of the DC sub-micro-grid buses. And a capacitor Cdc connected with the bridge frame a in parallel is further arranged in the system, and two ends of the capacitor Cdc are respectively connected with the positive electrode node and the negative electrode node of the direct current sub-micro-grid bus.
Further, the bidirectional AC/DC converter further includes constant power PQ control and constant voltage and constant frequency control; when the system operates in a grid-connected mode, the bidirectional AC/DC converter adopts constant-power PQ to control an AC/DC hybrid micro-grid; when the system operates in an island mode, the bidirectional AC/DC converter adopts a constant-voltage constant-frequency control AC/DC hybrid micro-grid, and when the system is in a parallel/off-grid switching mode, the bidirectional AC/DC converter adopts a droop control AC/DC hybrid micro-grid.
Preferably, the power supply sides of the ac sub-micro-network and the dc sub-micro-network are connected with corresponding ac power supply and dc power supply, which specifically includes: one or more of photovoltaic power stations, wind power stations, super capacitors, energy storage power stations, public power grids and loads.
On the other hand, the invention also provides a multi-mode flexible switching coordination control method of the AC/DC interconnection micro-grid, when the AC/DC hybrid micro-grid is switched between a grid-connected mode and an island mode, the bidirectional AC/DC converter adopts drooping control of the AC/DC hybrid micro-grid, and adjusts and controls the power transmission quantity according to the change of the bus voltage and the frequency of the AC sub-micro-grid and the DC sub-micro-grid connected with the bidirectional AC/DC converter, so that the difference between the AC/DC hybrid micro-grid and a public grid is eliminated, and the grid-connected mode and the island mode are switched seamlessly.
Further, when operating in grid-connected mode, the bidirectional AC/DC converter adopts constant power PQ to control the AC/DC hybrid micro-grid; when the bidirectional AC/DC converter operates in the island mode, the bidirectional AC/DC converter adopts a constant voltage and constant frequency to control an AC/DC hybrid micro-grid; and when the parallel/off-grid switching mode is adopted, the bidirectional AC/DC converter adopts a droop control AC/DC hybrid micro-grid.
Further, the bidirectional AC/DC converter adopts a presynchronization method to eliminate the difference between the AC/DC hybrid micro-grid and the public grid, and the specific method is as follows:
detecting the voltage amplitude, phase and frequency of a public power grid;
the voltage amplitude is controlled and regulated by a secondary voltage regulating method, so that the voltage amplitude is synchronous with the voltage of the AC/DC hybrid micro-grid;
and regulating the voltage phase and frequency through a proportional integral PI regulator, so that the AC/DC hybrid micro-grid is synchronous with the public grid.
Further, the specific method for controlling the alternating current-direct current hybrid micro-grid by the constant-power PQ is as follows:
calculating a power value according to the power grid voltage and the grid-connected point current, and obtaining a current control instruction;
negative feedback and PI regulation are carried out on the current control instruction;
the control modulation wave obtained through d-q conversion is transmitted to a bidirectional AC/DC converter, so that constant power PQ control is realized.
Further, the specific method for controlling the AC/DC hybrid micro-grid by the constant voltage constant frequency V/F comprises the following steps:
collecting voltage amplitude and frequency output by a bidirectional AC/DC converter;
the voltage amplitude and the frequency are controlled through negative feedback and PI regulation;
the control modulation wave obtained through d-q conversion is transmitted to a bidirectional AC/DC converter, so that constant voltage constant frequency V/F control is realized.
Further, the specific method for controlling the AC/DC hybrid micro-grid by sagging is as follows:
constructing a single-phase equivalent circuit when the bidirectional AC/DC converter operates;
calculating active power and reactive power of the bidirectional AC/DC converter;
the equivalent impedance of the distributed power supply is set to be inductive through a control algorithm, and droop control over voltage amplitude and frequency is realized according to droop control characteristics of inductive loads.
The technical scheme of the invention has the following advantages:
A. the interconnection converter adopts a bidirectional AC/DC converter, and the bidirectional AC/DC converter is used as an important pivot of the AC/DC hybrid micro-grid, so that the interconnection converter is a key for maintaining the stable operation of the AC/DC hybrid micro-grid; the invention is beneficial to improving the electric energy quality in the system, realizing the parallel/off-grid seamless switching, effectively reducing the internal loss of the micro-grid system and having important significance for improving the new energy acceptance capacity and the economic operation level of the power distribution system and supporting the application and development of the zero-carbon power grid construction through a control strategy of the bidirectional AC/DC converter with reasonable design.
B. The invention adopts a presynchronization method to eliminate the difference between the AC/DC hybrid micro-grid and the public power grid in the bidirectional AC/DC converter, and synchronizes the AC/DC hybrid micro-grid and the public power grid, thereby avoiding the overcurrent or overvoltage impact caused by the difference of frequency, phase and voltage amplitude of the public power grid and the hybrid micro-grid system at the moment of parallel/separation switching, and greatly improving the stable operation of the micro-grid system.
Drawings
In order to more clearly illustrate the embodiments of the present invention, the drawings that are required for the embodiments will be briefly described, and it will be apparent that the drawings in the following description are some embodiments of the present invention and that other drawings may be obtained according to the drawings without inventive effort for a person skilled in the art.
Fig. 1 is a topology structure of an ac/dc hybrid micro-grid system provided by the invention.
Fig. 2 is a schematic diagram of a bi-directional AC/DC converter topology provided by the present invention.
The meaning of the symbols in the drawings is as follows:
1-a photovoltaic power station; 2-a wind farm; 3-an energy storage power station; 4-public power grid; 5-load
6-a circuit breaker; 7-a power line; 8-interconnected converters.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in the structures of fig. 1 and fig. 2, the invention provides a multi-mode flexible switching coordination control system for an AC/DC interconnection microgrid, which comprises an AC/DC hybrid microgrid composed of an AC sub-microgrid and a DC sub-microgrid and an interconnection converter connected between the AC sub-microgrid and the DC sub-microgrid, wherein the interconnection converter is a bidirectional AC/DC converter, and when in parallel/off-grid switching, the droop control of the AC/DC hybrid microgrid is adopted, and the control of the power transmission quantity is adjusted according to the bus voltage and frequency changes of the AC sub-microgrid and the DC sub-microgrid connected with the bidirectional AC/DC converter. The bidirectional AC/DC converter adopts a three-phase voltage source type bridge topology structure and comprises a switching tube S a1 Switch tube S a2 Switch tube S b1 Switch tube S b2 Switch tube S c1 Switch tube S c2 Switch tube S a1 Emitter and switching tube S of (C) a2 Form bridge a after the collector connection of (a) and switch tube S b1 Emitter and switching tube S of (C) b2 Form bridge b after connecting the collector electrodes of (a) and switch tube S c1 Emitter and switching tube S of (C) c2 After the collecting electrodes of the transformer are connected, a bridge frame c is formed, the bridge frame a, the bridge frame b and the bridge frame c are respectively connected with corresponding AC sub-micro-grid buses, and the switching tube S a1 Switch tube S b1 Switch tube S c1 The collector of the switch tube S is connected with the positive electrode node of the DC sub-micro-grid bus after being connected a2 Switch tube S b2 Switch tube S c2 The emitter of the direct current sub micro-grid busbar is connected with the negative electrode node of the direct current sub-micro-grid busbar after being connected; the system is also provided with a capacitor C connected with the bridge a in parallel dc The capacitor C dc And the two ends of the direct current sub micro-grid bus are respectively connected with the positive electrode node and the negative electrode node of the direct current sub-micro-grid bus.
As a core device in the AC/DC hybrid micro grid, a structural model of the bidirectional AC/DC converter is shown in fig. 2. L, R, C in the figure are the AC/DC converter AC test equivalent filter inductance, resistance and capacitance, respectively. C (C) dc Is a direct current filter capacitor, U dc Is the DC side voltage, i dc Is a direct current side current; u (U) a 、U b 、U c The AC/DC converter AC side A, B, C three-phase voltages, i La 、i Lb 、i Lc Three-phase currents on the ac side A, B, C of the inverter, respectively; uoa, uob, uoc are the three-phase voltages of the parent bus A, B, C, respectively; s is S a1 、S a2 、S b1 、S b2 、S c1 、S c2 Is a device that controls the AC/DC converter switches to achieve power transfer.
In order to convert the alternating current quantity into the direct current quantity which is relatively easy to control, so that the subsequent PI control link is more effective, the three-dimensional transformation method is adopted to convert the three-phase static coordinate system into the two-phase synchronous d-q coordinate system, and the specific method is as follows: and (3) carrying out phase number simplification by using Clark conversion to obtain a two-phase static coordinate coefficient model, further converting the two-phase static coordinate system mathematical model into a two-phase synchronous rotation coordinate coefficient model by Park conversion, and combining the mathematical model obtained by Clark conversion with the mathematical model obtained by Park conversion to obtain a conversion matrix from the three-phase static coordinate system to the two-phase rotation synchronous coordinate system.
According to the condition that the AC/DC hybrid micro-grid is connected with the public power grid, the operation modes of the hybrid micro-grid can be divided into two modes, namely a grid-connected mode and an island mode. However, due to the flexibility of the micro grid system, there is also a mutual switching of the on/off grid modes between the grid-connected mode and the island mode. Therefore, according to different operation modes, the distributed power generation and the reasonable exchange of energy between two sub-networks are realized through the AC/DC converter, and the stable operation of the AC/DC hybrid micro-grid system is realized. According to the working characteristics of the AC/DC hybrid micro-grid in different operation modes, the stable operation of the system is realized by applying different control modes to the bidirectional AC/DC converter. The control method of the bidirectional AC/DC converter provided by the invention is divided into three types according to different operation modes: constant power PQ control, constant voltage constant frequency V/F control, and droop control.
(1) Constant power PQ control
The constant power PQ control mode is a control mode adopted when the constant power PQ control mode operates in a grid-connected mode by inputting or outputting constant active power and reactive power through the bidirectional AC/DC converter according to the value of a preset working point. The specific method for constant power PQ control is as follows:
calculating a power value according to the power grid voltage and the grid-connected point current, and obtaining a current control instruction; negative feedback and PI regulation are carried out on the current control instruction; the control modulation wave obtained through d-q conversion is transmitted to a bidirectional AC/DC converter, so that constant power PQ control is realized.
Under constant power PQ control, the bidirectional AC/DC converter cannot participate in bus frequency and voltage regulation; in the running mode, the voltage and frequency of the AC sub-micro-grid are supported by the public power grid, the DC sub-micro-grid completely flows the rest electric energy into the public power grid through the AC/DC converter according to a preset working point, or the public power grid transmits the loss power into the DC sub-micro-grid through the AC/DC converter according to the loss condition in the DC sub-micro-grid, so that the energy balance in the system is realized.
(2) Constant voltage and constant frequency control
The invention applies constant voltage and constant frequency control to the operation in island mode, and the specific control method is as follows: collecting voltage amplitude and frequency output by a bidirectional AC/DC converter; the voltage amplitude and the frequency are controlled through negative feedback and PI regulation; the control modulation wave obtained through d-q conversion is transmitted to a bidirectional AC/DC converter, so that constant voltage constant frequency V/F control is realized. When the AC/DC hybrid micro-grid operates in an island mode, the voltage and the frequency of the AC sub-micro-grid lose the support of the public power grid, so that the voltage and the frequency fluctuate, and the voltage and the frequency of the two sub-micro-grids can be stabilized by adopting constant voltage and constant frequency control through the bidirectional AC/DC converter. The constant voltage constant frequency control adopts a double closed loop structure, the voltage outer loop ensures the stability of the output voltage of the bidirectional AC/DC converter, the current follow-up characteristic of the current inner loop can quickly resist system disturbance, and the anti-interference capability is strong.
(3) Sagging control
The sagging control is realized by simulating the frequency modulation characteristic of a traditional generator set, and the power transmission quantity is regulated and controlled according to the change of the voltage and the frequency of two sub-microgrid buses of the bidirectional AC/DC converter, and the specific method is as follows:
constructing a single-phase equivalent circuit when the bidirectional AC/DC converter operates; calculating active power and reactive power of the bidirectional AC/DC converter; the equivalent impedance of the distributed power supply is set to be inductive through a control algorithm, and droop control over voltage amplitude and frequency is realized according to droop control characteristics of inductive loads. Droop control may be set to operate in island mode and grid-tie mode.
Of course, the invention preferably adopts droop control during the network switching and does not need control algorithm switching during the network switching, which has the advantages of not causing overload condition of other power supplies in the system and realizing redistribution through energy management in the system.
The AC/DC hybrid micro-grid generally operates in a grid-connected mode, and when the public power grid fails or overhauls, the AC/DC hybrid micro-grid is actively disconnected from the public power grid and is switched to an island mode from the grid-connected mode in order to ensure continuous power supply of important loads in the micro-grid and reduce the influence caused by the public power grid failure; and after the public power grid repair problem and the overhaul are completed, the AC/DC hybrid micro-grid is connected again so as to realize the efficient utilization of the distributed power generation units, and then the island mode is switched to the grid-connected mode. Because of the frequency, phase and voltage amplitude differences of the public power grid and the AC/DC hybrid micro-grid system, the invention adds a presynchronization technology in the bidirectional AC/DC converter, eliminates the difference between the hybrid micro-grid and the public power grid, and realizes the seamless switching between the hybrid micro-grid and the public power grid, thereby avoiding the problem of overcurrent or overvoltage impact caused by the instant switching of two modes in the AC/DC hybrid micro-grid and ensuring that the micro-grid system operates stably. The adopted presynchronization method is as follows: detecting the voltage amplitude, phase and frequency of a public power grid; the voltage amplitude is controlled and regulated by a secondary voltage regulating method, so that the voltage amplitude is synchronous with the voltage of the AC/DC hybrid micro-grid; and regulating the voltage phase and frequency through a proportional integral PI regulator, so that the AC/DC hybrid micro-grid is synchronous with the public grid.
The power supply sides of the alternating current sub-micro network and the direct current sub-micro network are connected with corresponding alternating current power supplies and direct current power supplies, and the method specifically comprises the following steps: the photovoltaic power station, the wind power station, the super capacitor, the energy storage power station, the public power grid and the load are connected through a circuit breaker and a power line.
The invention also provides a multi-mode flexible switching coordination control method for the AC/DC interconnection micro-grid of the shared energy storage power station, when the AC/DC hybrid micro-grid is switched between a grid-connected mode and an island mode, the bidirectional AC/DC converter adopts droop control, and the power transmission quantity is regulated according to the change of the bus voltage and the frequency of the AC sub-micro-grid and the DC sub-micro-grid which are connected with the bidirectional AC/DC converter, so that the difference between the AC/DC hybrid micro-grid and a public grid is eliminated, and the grid-connected mode and the island mode are switched seamlessly.
Of course, the invention further controls the way: when the bidirectional AC/DC converter operates in a grid-connected mode, the bidirectional AC/DC converter adopts a constant-power PQ control mode; when the bidirectional AC/DC converter operates in the island mode, the bidirectional AC/DC converter is controlled by adopting constant voltage and constant frequency V/F; the bi-directional AC/DC converter uses droop control during the on/off switching mode.
The system is beneficial to improving the electric energy quality in the system, realizing the parallel/off-grid seamless switching, effectively reducing the internal loss of the micro-grid system and having important significance for improving the new energy acceptance capacity and the economic operation level of the power distribution system and supporting the application and development of the zero-carbon power grid construction through a control strategy of the bidirectional AC/DC converter with reasonable design.
The invention is applicable to the prior art where nothing is mentioned.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While obvious variations or modifications are contemplated as falling within the scope of the present invention.
Claims (10)
1. The alternating current/direct current interconnection microgrid multimode flexible switching coordination control system comprises an alternating current/direct current hybrid microgrid formed by an alternating current sub-microgrid and a direct current sub-microgrid and an interconnection converter connected between the alternating current sub-microgrid and the direct current sub-microgrid, and is characterized in that the interconnection converter is a bidirectional AC/DC converter, the bidirectional AC/DC converter adopts droop control to control the alternating current/direct current hybrid microgrid during parallel/off-grid switching, and the power transmission quantity is controlled according to the change of bus voltage and frequency of the alternating current sub-microgrid and the direct current sub-microgrid connected with the bidirectional AC/DC converter.
2. The AC/DC interconnection micro-grid multimode flexible switching coordination control system according to claim 1, wherein the bidirectional AC/DC converter is a three-phase voltage source type bridge topology structure, and comprises a switching tube S a1 Switch tube S a2 Switch tube S b1 Switch tube S b2 Switch tube S c1 Switch tube S c2 The switch tube S a1 Emitter and switching tube S of (C) a2 Form a bridge a after the connection of the collector electrodes of the switch tube S b1 Emitter and switching tube S of (C) b2 Form bridge b after connection of the collector electrodes of the switch tube S c1 Emitter and switching tube S of (C) c2 The collecting electrodes of the bridge frame are connected to form a bridge frame c, the bridge frame a, the bridge frame b and the bridge frame c are respectively connected with corresponding AC sub-micro-grid buses, and the switch tube S a1 Switch tube S b1 Switch tube S c1 The collector electrode of the switch tube S is connected with the positive electrode node of the DC sub-micro-grid bus after being connected a2 Switch tube S b2 Switch tube S c2 The emitter of the direct current sub-micro-grid busbar is connected with the negative electrode node of the direct current sub-micro-grid busbar after being connected; the system is also provided with a capacitor C connected with the bridge a in parallel dc The capacitor C dc And the two ends of the direct current sub-micro-grid bus are respectively connected with the positive electrode node and the negative electrode node of the direct current sub-micro-grid bus.
3. The AC/DC interconnection micro-grid multi-mode flexible switching coordination control system of claim 2, wherein the bidirectional AC/DC converter further comprises constant power PQ control and constant voltage constant frequency control; when the system operates in a grid-connected mode, the bidirectional AC/DC converter adopts constant-power PQ to control an AC/DC hybrid micro-grid; when the system operates in an island mode, the bidirectional AC/DC converter adopts a constant-voltage constant-frequency control AC/DC hybrid micro-grid, and when the system is in a parallel/off-grid switching mode, the bidirectional AC/DC converter adopts a droop control AC/DC hybrid micro-grid.
4. The ac/dc interconnection micro-grid multimode flexible switching coordination control system according to claim 1, wherein the power supply sides of the ac sub-grid and the dc sub-grid are connected with corresponding ac power supply and dc power supply, specifically comprising: one or more of photovoltaic power stations, wind power stations, super capacitors, energy storage power stations, public power grids and loads.
5. A multi-mode flexible switching coordination control method for an AC/DC interconnection micro-grid is characterized in that when the AC/DC hybrid micro-grid is switched between a grid-connected mode and an island mode, a bidirectional AC/DC converter adopts a drooping control AC/DC hybrid micro-grid, and adjusts and controls power transmission quantity according to the change of bus voltage and frequency of an AC sub-micro-grid and a DC sub-micro-grid connected with the bidirectional AC/DC converter, so that the difference between the AC/DC hybrid micro-grid and a public grid is eliminated, and the grid-connected mode and the island mode are switched seamlessly.
6. The method for multi-mode flexible switching coordination control of an AC/DC interconnection micro-grid according to claim 5, wherein the bidirectional AC/DC converter uses constant power PQ to control the AC/DC hybrid micro-grid when operating in grid-connected mode; when the bidirectional AC/DC converter operates in the island mode, the bidirectional AC/DC converter adopts a constant voltage and constant frequency to control an AC/DC hybrid micro-grid; and when the parallel/off-grid switching mode is adopted, the bidirectional AC/DC converter adopts a droop control AC/DC hybrid micro-grid.
7. The method for coordinated multi-mode flexible switching control of an AC/DC interconnection micro-grid according to claim 6, wherein the bidirectional AC/DC converter adopts a presynchronization method to eliminate the difference between the AC/DC hybrid micro-grid and the public grid, and the specific method is as follows:
detecting the voltage amplitude, phase and frequency of a public power grid;
the voltage amplitude is controlled and regulated by a secondary voltage regulating method, so that the voltage amplitude is synchronous with the voltage of the AC/DC hybrid micro-grid;
and regulating the voltage phase and frequency through a proportional integral PI regulator, so that the AC/DC hybrid micro-grid is synchronous with the public grid.
8. The method for controlling the ac/dc interconnection micro-grid to flexibly switch and coordinate in a multi-mode manner according to claim 6, wherein the specific method for controlling the ac/dc hybrid micro-grid by the constant power PQ is as follows:
calculating a power value according to the power grid voltage and the grid-connected point current, and obtaining a current control instruction;
negative feedback and PI regulation are carried out on the current control instruction;
the control modulation wave obtained through d-q conversion is transmitted to a bidirectional AC/DC converter, so that constant power PQ control is realized.
9. The method for flexibly switching and coordinated control of the ac/dc interconnection micro-grid in a multi-mode manner according to claim 6, wherein the specific method for controlling the ac/dc hybrid micro-grid by using the constant voltage constant frequency V/F is as follows:
collecting voltage amplitude and frequency output by a bidirectional AC/DC converter;
the voltage amplitude and the frequency are controlled through negative feedback and PI regulation;
the control modulation wave obtained through d-q conversion is transmitted to a bidirectional AC/DC converter, so that constant voltage constant frequency V/F control is realized.
10. The method for coordinated multi-mode flexible switching control of the ac/dc interconnection micro-grid according to claim 6, wherein the specific method for controlling the ac/dc hybrid micro-grid by sagging is as follows:
constructing a single-phase equivalent circuit when the bidirectional AC/DC converter operates;
calculating active power and reactive power of the bidirectional AC/DC converter;
the equivalent impedance of the distributed power supply is set to be inductive through a control algorithm, and droop control over voltage amplitude and frequency is realized according to droop control characteristics of inductive loads.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311637813.7A CN117639075A (en) | 2023-12-01 | 2023-12-01 | Multi-mode flexible switching coordination control system and method for AC/DC interconnection micro-grid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311637813.7A CN117639075A (en) | 2023-12-01 | 2023-12-01 | Multi-mode flexible switching coordination control system and method for AC/DC interconnection micro-grid |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117639075A true CN117639075A (en) | 2024-03-01 |
Family
ID=90024950
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311637813.7A Pending CN117639075A (en) | 2023-12-01 | 2023-12-01 | Multi-mode flexible switching coordination control system and method for AC/DC interconnection micro-grid |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117639075A (en) |
-
2023
- 2023-12-01 CN CN202311637813.7A patent/CN117639075A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| She et al. | DC zonal micro-grid architecture and control | |
| CN110912242B (en) | Large disturbance transient stability coordination control method for hybrid energy storage direct current micro-grid | |
| CN110601248A (en) | Multi-mode coordination control method of annular alternating current-direct current hybrid micro-grid system | |
| Zhu et al. | Operation and control of the smart transformer in meshed and hybrid grids: Choosing the appropriate smart transformer control and operation scheme | |
| Khajesalehi et al. | Modeling and control of quasi Z-source inverters for parallel operation of battery energy storage systems: Application to microgrids | |
| CN106712024A (en) | Energy Internet for electric car charging station | |
| WO2019075879A1 (en) | Running mode conversion method for alternating-current/direct-current hybrid microgrid | |
| CN111711196A (en) | Seamless switching control method for operation modes of alternating current-direct current hybrid power distribution network | |
| Zhou et al. | The study of power electronic transformer on power flow control and voltage regulation in DC micro-grid | |
| CN104393591A (en) | Power supply system | |
| Deng et al. | Coordinated control and application of multi-terminal DC distribution system | |
| Tong et al. | Flexible substation and its control for AC and DC hybrid power distribution | |
| Madichetty et al. | Modeling and design of solid state smart transformer for microgrid | |
| CN117639075A (en) | Multi-mode flexible switching coordination control system and method for AC/DC interconnection micro-grid | |
| Thakur et al. | Grid forming energy router: A utility interface for renewable energy sources and energy storage grid integration applications | |
| CN103178547A (en) | Micro-network system with two-way inverter, and operating method of micro-network system | |
| Wu et al. | Power transfer and multi-control mode of a distribution network based on a flexible interconnected device | |
| Wu et al. | A power router based on modular multilevel converter integrating ultracapacitor energy storage system | |
| CN203398800U (en) | Energy storing device for clean energy | |
| CN111555336A (en) | Power distribution system based on energy router | |
| Dias et al. | Power electronics in the context of renewables, power quality and smart grids | |
| Guo et al. | Feasibility study on new energy multi-feed direct current grid connection | |
| Fu et al. | Coordinated control strategy for improving fault ride-though performance of photovotaic/battery microgrid | |
| Wang et al. | Review of coordinated control strategy for AC/DC hybrid microgrid | |
| Li et al. | Study on Topology Structure Optimization Technology Requirements for Large-scale Offshore Wind Power Integration |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |