CN117200363A - Control method for AC/DC coordinated interaction micro-grid group - Google Patents
Control method for AC/DC coordinated interaction micro-grid group Download PDFInfo
- Publication number
- CN117200363A CN117200363A CN202311045113.9A CN202311045113A CN117200363A CN 117200363 A CN117200363 A CN 117200363A CN 202311045113 A CN202311045113 A CN 202311045113A CN 117200363 A CN117200363 A CN 117200363A
- Authority
- CN
- China
- Prior art keywords
- micro
- grid
- area
- power
- 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
- 230000003993 interaction Effects 0.000 title claims abstract description 28
- 238000000034 method Methods 0.000 title claims abstract description 21
- 238000012423 maintenance Methods 0.000 claims abstract description 22
- 238000004891 communication Methods 0.000 claims abstract description 10
- 238000005457 optimization Methods 0.000 claims abstract description 7
- 238000012546 transfer Methods 0.000 claims description 37
- 238000004146 energy storage Methods 0.000 claims description 29
- 238000011217 control strategy Methods 0.000 claims description 16
- 230000002452 interceptive effect Effects 0.000 claims description 13
- 238000010521 absorption reaction Methods 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 4
- 238000004364 calculation method Methods 0.000 claims description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 2
- 230000002159 abnormal effect Effects 0.000 claims description 2
- 238000012544 monitoring process Methods 0.000 claims description 2
- 238000010248 power generation Methods 0.000 claims description 2
- 238000012797 qualification Methods 0.000 claims description 2
- 230000009133 cooperative interaction Effects 0.000 abstract description 3
- 238000000354 decomposition reaction Methods 0.000 abstract description 3
- 238000004088 simulation Methods 0.000 description 11
- 238000010586 diagram Methods 0.000 description 7
- 238000007599 discharging Methods 0.000 description 4
- 238000010276 construction Methods 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 238000012795 verification Methods 0.000 description 3
- 241000124033 Salix Species 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000013589 supplement Substances 0.000 description 2
- 230000001360 synchronised effect Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000016507 interphase Effects 0.000 description 1
- 230000006855 networking Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Landscapes
- Supply And Distribution Of Alternating Current (AREA)
Abstract
The invention provides a control method of an alternating current/direct current coordinated interaction micro-grid group, which is applied to a scene that a plurality of low-voltage stations are flexibly interconnected to form the micro-grid group, and realizes micro-grid group control under four main operation modes including an on-line control mode, an off-line control mode, a scheduled maintenance mode and a grid fault mode based on a cloud-side-end integrated three-layer cooperative control architecture. The flexible resources such as distributed light, storage, charging and the like in the micro-grid group are considerable, measurable, adjustable and controllable, and the aims of transparent power grid, main-distribution coordination and source-load interaction are realized. The invention realizes the strategy optimization decomposition of the equipment-level control layer, the district autonomous control layer and the main station coordination control layer, realizes the layered cooperative regulation and control independent of the on-site lateral communication, improves the cooperative interaction capability of the distributed resource consumption capability and the source network charge storage, and has the popularization advantages of strong scale expansibility and good function reusability.
Description
Technical Field
The invention relates to the field of operation and control of power systems, in particular to a control method of an alternating current-direct current coordinated interaction micro-grid group.
Background
Future distribution networks will exhibit the following basic features: the method comprises the steps of large-scale access of a distributed power supply (DG), large-scale access of an energy storage system, large-scale construction application of charging stations and charging piles, gradual application of flexible alternating-current and direct-current series-parallel connection and the like. The conventional distribution network is a binary structure based on a power grid-load, namely a unidirectional power distribution network between power grid power supply and user power consumption. With the new form of the future power distribution network, the binary structure of the traditional power distribution network gradually transits to a quaternary structure of source-network-load-storage, and a powerful foundation is provided for the development of micro-grids. The micro-grid can independently perform networking operation by means of distributed new energy, and the power supply is dispersed, the load is dispersed, and the on-site electric energy consumption is dominant. With the development of power electronics technology, a plurality of micro-grids can rely on flexible interconnection devices to form a micro-grid group with an alternating current/direct current coordination interaction function, so that the maximization on-site consumption of a distributed power supply is realized, and the problem of flexible and stable electricity utilization of local users is solved for areas where a large power grid cannot reach.
At present, there are still several problems to be solved in the interactive application of source network charges stored in micro-grid clusters:
firstly, the capacity of the distributed power supply is still improved. The distribution power system put into operation can raise the distribution line voltage even surpass the warning line under the condition of low local area load such as holidays. The power distribution network lacks flexible regulation means, and can only roughly limit power or cut off, so that the construction recovery period of the distributed power supply is prolonged, and the construction income of users is damaged.
And secondly, the energy storage device has single application function, the energy storage systems independently operate, and the utilization rate of equipment still needs to be improved. Most of the built energy storage devices are configured and applied only aiming at single problems, so that the requirements of improving the electric energy quality and reducing the electricity cost of users are not effectively met, and the advantages of the energy storage devices are not fully exerted.
Thirdly, the ordered management and control of the random load of the electric automobile and the like still need to be improved. The fast charging time of the electric automobile is shorter, the charging power is larger, and the influence of the large-scale charging station on the load fluctuation of the power grid is larger. The analysis management of the system level of a large number of charging stations in the regional power distribution network can effectively improve the influence of the charging behavior of the user on the power distribution network.
Fourth, the source network and the load storage lack the mutual coordination of the distribution network layers. The source-network-charge storage is fully coordinated and embodied at the micro-grid level at the present stage, the mutual coordination interaction at the power distribution network level is weak, the source-charge storage basically performs independent operation control or interaction with the power grid according to respective targets, and the effective coordination and coordination of the integrity are not formed yet, namely the flexible regulation and control potential of the source-charge storage is not fully utilized.
In view of the foregoing, it is highly desirable to invent a control method suitable for a micro-grid group, so as to realize the maximum consumption of distributed energy, fully exert the control potential of flexible loads such as energy storage and electric vehicles, and realize the optimal coordination control effect of source-grid charge storage.
Disclosure of Invention
Aiming at the problems of insufficient distributed energy consumption capability, insufficient flexible resource regulation and control potential, insufficient coordination and interaction capability and the like existing in the interactive application of the existing source network load stored in the micro-grid group, the invention provides a control method of an alternating current-direct current coordination and interaction micro-grid group.
A control method of an alternating current-direct current coordinated interaction micro-grid group is applied to a scene that a plurality of low-voltage stations are flexibly interconnected to form the micro-grid group, the micro-grid group has an alternating current-direct current coordinated interaction function, the micro-grid group adopts an integrated three-layer coordinated control architecture and a three-layer information interaction architecture, and different control strategies are adopted in four main operation modes of an on-line control mode, an off-line control mode, a planned maintenance mode and a grid fault mode.
Further, the micro-grid group is composed of a plurality of low-voltage transformer areas in a 10kV medium-voltage alternating-current circuit, the plurality of low-voltage alternating-current transformer areas are flexibly interconnected on a direct-current side through a flexible interconnection device, and each transformer area has micro-grid autonomous capability; each station area is provided with a micro-grid controller, and is used for issuing control instructions to adjustable resources in the station area downwards, collecting the resource information in the station area and receiving the control instructions issued by the cloud master station upwards; the micro-grid controllers of all the transformer areas establish communication with a common cloud master station, and receive unified coordination allocation of the cloud master station; the platform area contains common AC/DC load and light, storage and charging flexible load.
Further, the three-layer cooperative control architecture includes: a device-level control layer, a district autonomous control layer and a master station coordination control layer;
wherein the device level control layer comprises: the flexible interconnection device is connected with adjustable resources and other adjustable resources in the station area through the direct current output port;
the micro-grid controller receives a main station instruction and a control mode or an autonomous strategy forming control instruction from the platform area homemade control layer and issues the control instruction to the adjustable resource;
the main station coordination control layer relies on real-time power generation data, relies on an optimization model to form a demand for issuing a regulation and control command or receiving a station area, and forms a control command for issuing according to the demand.
Further, the three-layer information interaction architecture is a cloud-side-end integrated three-layer information interaction architecture;
wherein the end comprises: the system comprises a flexible interconnection device, a secondary standard interface cabinet and an energy storage vehicle, wherein the flexible interconnection device is responsible for collecting basic information of a body and direct current equipment information connected in a local area; the secondary standard interface cabinet is used for collecting information of the access energy storage vehicle and information of the access switch;
the side comprises a micro-grid controller configured for each area, is responsible for collecting terminal equipment information, completes an autonomous coordination control function in the area, transmits all terminal equipment information and states in the area to a master station, and simultaneously receives a regulation command of the master station to form a issuing control command;
the cloud comprises Yun Zhuzhan of a micro-grid group, and a cloud master station is responsible for monitoring platform area information and coordinated control among the platforms and sends out regulation and control instructions to a micro-grid controller.
Further, the online control mode is defined as: the power grid normally operates, communication between the station areas and the cloud master station is normal, normal information interaction, control instruction issuing, receiving and executing can be performed, and under unified coordination and allocation of the cloud master station, the functions of economic optimal operation, distributed resource maximized consumption and power supply quality optimization management among the station areas are realized.
Further, the offline control mode is defined as: the power grid normally operates, communication between the master station and the micro-grid controller is abnormal, the master station cannot receive information of micro-grid control within 15 minutes, and the off-line platform area finishes the autonomous of the micro-grid in the platform area by means of the micro-grid controller of the platform area, so that the local photovoltaic maximum absorption is realized.
Further, the planned maintenance mode is defined as: the main station issues maintenance instructions to a single platform area in advance, other operations are completed by the micro-grid controller and the local interface cabinet, and the flexible interconnection device is utilized to transfer power to support a mode of maintaining the local load of the platform area, so that the zero power failure maintenance of the platform area is realized.
Further, the grid-side fault mode is defined as: the medium-voltage side line breaks down, the cloud master station controls the micro-grid controller to timely cut off relevant transformer areas in the fault section, and the transformer areas are mutually balanced through the flexible interconnection device, so that loads in the transformer areas are supported, and the shortest power failure of the cut-off transformer areas is realized.
Further, the control strategy is agreed and constrained as follows:
1) When the platform area does not need external support, the platform area micro-grid controller automatically operates according to the platform area, and when the external support is needed, the platform area micro-grid controller sends a request to the master station, and the master station forms a control instruction to issue;
2) The autonomous operation of the platform area comprises the following operation modes: a) Economic operation: optimizing the line loss of the transformer area; b) Low carbon operation: preferentially absorbing clean energy in the station area; c) Optimizing power supply quality: the electric energy quality such as low voltage, harmonic wave and the like is treated, and the power supply quality level is improved;
3) Inter-station power comprises: a) A heavy load transfer mode, wherein when a certain area is heavy load, another area can be mutually used by flexible interconnection transfer; b) The zero power failure maintenance mode realizes the zero power failure of a maintenance platform area; c) And under the condition of large photovoltaic heat, the cross-platform low-carbon operation mode of the cross-platform region realizes the cross-platform region absorption of the distributed photovoltaic.
Further, the initial running condition, instruction sending and power matching principle of the micro-grid group are as follows:
1) In the aspect of primary equipment, the alternating current and the direct current of the transformer area are all connected in a grid mode, the power electronic transformer is a VF node, and the rest is a PQ node;
2) In the aspect of secondary equipment, n micro-grid control lines are arranged, wherein n is more than or equal to 1 and less than or equal to 5;
3) The master station transmits node voltage ranges of each platform region, wherein the node voltage ranges of each platform region are derived from power flow calculation and state estimation results, or voltage qualification rate ranges of +7% to-10%, or manually set ranges;
4) Uploading by a micro-grid controller: the power demand of the power supply area, the grading supply condition of the AC/DC power supply and the grading supply condition of the load are sent up for 15min, wherein the grading supply condition of the AC/DC power supply is graded according to the supply stability, the power of an AC main network is predefined in TTU to be 1 grade, the energy storage is 2 grade, the photovoltaic is 3 grade, the V2G is 4 grade, the grading supply condition of the load is graded according to the importance of the load, the important load is 1 grade, the general load is 2 grade, and the interruptible load is 3 grade;
5) The principle of inter-station power matching is as follows: preferentially meeting a single station area, preferentially selecting a side 10kV line station area, preferentially meeting power supply-load stability;
6) The main station performs the power matching in the following manner: the power is issued to a TTU of an A station area, and the A station area sends out certain kW power to a direct current bus; the power is sent to a TTU of a B station area, and the B station area absorbs certain kW power from a direct current bus; the TTU of each platform region participating in the matching controls the flexible interconnection device to execute;
7) Switching of a master station to a station control mode: an online and offline control mode;
8) And (3) prefabricating a table of VF node switching sequences aiming at the faults of the flexible interconnection device, and switching the flexible interconnection device on line according to the sequences when the power electronic transformer fails.
The invention is mainly applied to micro-grid groups with alternating current and direct current coordination interaction function, and based on a cloud-side-end integrated three-layer cooperative control architecture, the micro-grid group control under four main operation modes including an on-line control mode, an off-line control mode, a scheduled maintenance mode and a grid fault mode is realized; the method realizes the strategy optimization decomposition of the equipment-level control layer, the district autonomous control layer and the master station coordination control layer, realizes layered cooperative regulation and control independent of local side transverse communication, fully exploits the flexible resource regulation and control potential, improves the cooperative interaction capability of distributed resource absorption capability and source network load storage, and has the popularization advantages of strong scale expansibility and good function reusability.
Drawings
FIG. 1 is a diagram of a cloud-edge-end integrated three-layer information interaction architecture according to an embodiment of the present invention;
FIG. 2 is an overall topology of an exemplary project of a local AC/DC coordinated interactive micro grid group;
FIG. 3 is a flow chart of an on-line control mode control strategy;
FIG. 4 is a flow chart of an offline control mode control strategy;
FIG. 5 is a flow chart of a control strategy for a scheduled maintenance mode in an embodiment of the present invention, taking a T5 zone as an example;
FIG. 6 is a flowchart of a control strategy for a grid-side failure mode using a T5 bay as an example in an embodiment of the present invention;
FIG. 7 is a diagram of the simulation verification result of the T5 area;
fig. 8 is a diagram of T4 zone simulation verification results.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. 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.
The invention is described by taking a certain AC/DC coordinated interactive micro-grid group demonstration project as an embodiment.
The micro-grid group builds flexible low-voltage direct-current interconnection devices on the low-voltage sides of 5 transformer areas, meanwhile, 1 on-load capacity-regulating voltage-regulating transformer is deployed to replace the existing transformer, 1 power electronic transformer, and builds a direct-current distribution transformer area with a certain scale by taking the flexible low-voltage direct-current interconnection devices as cores, so that an active power distribution network with flexible switching and power mutual aid is built. The specific topology is shown in fig. 2. T4 and T5 districts are respectively led out from the 122# pole tower and the 124# pole tower of the 10kV willow 611 line, T1, T2, T3 and the non-interconnected districts are led out from the 74# pole tower of the 10kV east 14 line, and 4 districts are connected through a branch switch. The T1, T2 and T3 areas are connected through the ring main unit. The 124# pole of the 10kV willow 611 line is connected with the 74# pole of the 10kV east 14 line through a tie switch. The T1, T2, T3, T4 and T5 areas form flexible interconnection through a direct current bus. The configuration of the photovoltaic, energy storage, charging piles, and flexible interconnection devices of each bay is shown in detail in fig. 2, wherein the energy storage vehicle is accessed through a secondary standard interface cabinet. The micro-grid group adopts a three-layer cooperative control architecture, and comprises an equipment-level control layer, a platform autonomous control layer and a master station cooperative control layer; the micro-grid group adopts a three-layer information interaction architecture, which is a cloud-side-end integrated three-layer information interaction architecture, as shown in fig. 1.
The control strategies of the various control modes in the present embodiment will be described in detail below.
1. On-line control mode
Step 1: the master station firstly issues a voltage range instruction when each station area operates normally.
Step 2: and the micro-grid controller of each area calculates photovoltaic output power, energy storage, charging piles and load power in the area.
Judgment 1: judging whether the voltage of the platform area is out of limit, if so, entering the step 3, and if not, entering the step 3.
Step 3: the micro-grid controller calculates reactive power supplement or harmonic supplement instruction values of the transformer area.
Judging 2: and (4) judging whether the flexible interconnection device and other adjustable converters connected on the lead have redundant capacity, if not, lifting hands to help the master station to transfer power, releasing the capacity by the flexible interconnection device, and participating in node voltage regulation, and if so, entering step (4).
Step 4: and the micro-grid controller issues reactive power compensation or harmonic compensation command values.
Judging 3: and judging whether the photovoltaic output Ppv is larger than the load requirement Pload, if so, entering a judgment 4, otherwise, entering a judgment 9.
Judging 4: and judging whether the energy storage has a charging condition, if so, charging the energy storage, otherwise, entering a step 5.
Step 5: the micro-grid controller informs the cloud master station of the need of actively transferring power by hand, the cloud master station searches for a power shortage platform area, and the next step is to judge 5.
Judging 5: and judging whether the non-same 10kV power supply station area has power shortage, if so, entering a judgment 6, and if not, entering a judgment 7.
Judging 6: judging whether a transfer condition is met, if so, the cloud master station transmits a transfer instruction to a micro-grid controller of a transfer station area, and the micro-grid controller controls the flexible interconnection device to receive power so as to finish heavy-load transfer. If not, enter decision 7.
Judging 7: if the 10kV power supply station area has power shortage, the judgment 8 is entered, otherwise, the heavy load transfer cannot be completed.
Judging 8: and judging whether a transfer condition is met, if so, the cloud master station transmits a transfer instruction to a micro-grid controller of a transfer station area, and the micro-grid controller controls the flexible interconnection device to receive power so as to finish heavy-load transfer. If not, the heavy load transfer cannot be completed.
Judging 9: is the energy storage provided with discharge conditions? And if so, the energy storage discharges and the charging pile stops charging. If not, go to step 6.
Step 6: the micro-grid controller informs the cloud master station of requesting power mutual aid of other stations by hand, and the cloud master station searches for a power surplus station. The next step is to enter decision 10.
Judging 10: and judging whether the power surplus exists in the non-same 10kV power supply station area, if so, entering a judgment 11, and if not, entering a judgment 12.
Judgment 11: judging whether the transfer condition is provided. If yes, the cloud master station issues a power transferring instruction to the micro-grid controller of the power transferring station area, and the micro-grid controller controls the flexible interconnection device to transfer power to finish heavy load transfer. If not, go to decision 12.
Judging 12: judging whether the same 10kV power supply station area has surplus power, if so, entering a judgment 13, otherwise, failing to finish heavy load transfer.
Judging 13: judging whether the transfer condition is provided. If yes, the cloud master station issues a power transferring instruction to the micro-grid controller of the power transferring station area, and the micro-grid controller controls the flexible interconnection device to transfer power to finish heavy load transfer. If not, the heavy load transfer cannot be completed.
The logic diagram of the specific control strategy is shown in fig. 3.
2. Offline control mode
Taking a T5 zone as an example
Step 1: and the micro-grid controller of the T5 area calculates photovoltaic output power and load power. The next step is to enter decision 1.
Judgment 1: judging whether the photovoltaic output of the platform area is 0, if so, not outputting the photovoltaic output, and stepping into a judgment 4, otherwise, entering a judgment 2.
Judging 2: and judging whether the photovoltaic output is larger than the load power demand. If yes, entering a step 2; if not, enter decision 4.
Step 2: and (5) outputting photovoltaic power to a T5 area, and guiding the charging vehicle to charge. The next step is to go to decision 3.
Judging 3: and judging whether the stored energy is fully charged or not. If yes, charging energy storage through photovoltaic; if not, the photovoltaic reversely transmits power to the 10kV power grid, and after the communication is normal, the micro-grid controller lifts a hand to send a power output request to the main station.
Judging 4: and judging whether the stored energy is discharged or not. If yes, entering a judgment 5; if not, the energy storage stops discharging.
Judging 5: and judging whether the voltage of the energy storage supporting load is qualified or not. If yes, enter the judgement 6, if not, enter the energy storage and stop discharging.
Judging 6: judging whether the frequency of the energy storage supporting load is qualified or not. If yes, discharging the energy storage to the No. 5 area, otherwise, stopping discharging the energy storage.
The logic diagram of the specific control strategy is shown in fig. 4.
3. Planned maintenance mode
1) Taking T5 area maintenance as an example
Step 1: the main station issues a planned maintenance instruction in advance.
Step 2: and the micro-grid controller of the T5 station area calculates photovoltaic power Ppv5, charging pile power Pv2g5 and direct current load power Pload5 in the station area, and reports the calculation result to the master station. The next step is to enter decision 1.
Judgment 1: judging whether Ppv5 is greater than ppv2g5+pload5? If not, the step 3 is carried out, and if yes, the step 6 is carried out.
Step 3: the T5 zone microgrid controller requests a zone power mutual aid from the master station.
Step 4: and the micro-grid controller of the T5 station area calculates the power shortage Pc5=Ppv 5-Pv2g5-Pload5 of the station area and reports the power shortage Pc5=Ppv 5-Pv2g5-Pload5 to the master station.
Step 5: the master station issues instructions to the micro-grid controllers of the areas participating in the mutual aid of functions, and Pc5 power is transferred to other areas by using the flexible interconnection device. The next step goes to step 8.
Step 6: and (5) controlling direct current load and charging piles in the photovoltaic active supporting platform area in the platform area by the micro-grid controller in the T5 platform area, and next stepping into judgment 2.
Judging 2: determine whether the stored energy can be charged? If yes, storing energy for charging, otherwise, entering step 7.
Step 7: and the micro-grid controller of the T5 station area requests support from the cloud master station by hand, and transfers the redundant photovoltaic in the T5 station area to other station areas.
Step 8: the micro-grid controller in the T5 area monitors the current Iac5 at the inlet side of the transformer, and the next step is judged 3.
Judging 3: it is determined whether Iac5 is less than the interruptible value I0. If yes, go to step 9, otherwise go to step 8.
Step 9: the micro-grid controller issues a mode switching instruction to the flexible interconnection device, and the flexible interconnection device is switched into a V/F control mode.
Step 10: the micro-grid controller sends an instruction for disconnecting the outgoing line switch of the transformer to the secondary interface cabinet, and the secondary interface cabinet controls the disconnection of the outgoing line switch of the transformer.
Step 11: and (5) entering a planned maintenance. The next step is to go to decision 4.
Judging 4: and judging whether the overhaul is finished or not. If yes, go to step 12; if not, go to step 11.
Step 12: the micro-grid controller sends a request to the master station to inform that the overhaul is completed.
Step 13: the master station issues an instruction for returning to a normal state to the micro-grid controller, and the micro-grid controller issues an instruction for switching on the outgoing line switch of the transformer to a secondary interface, and the secondary interface forwards the instruction to detect the outgoing line switch of the transformer in synchronization with the instruction.
Step 14: the low-voltage flexible interconnection device is switched to a P/Q mode and is restored to a master station control state. And (5) after the overhaul is finished, recovering the system.
The logic diagram of the specific control strategy is shown in fig. 5.
T4 and other station area maintenance are similar to the control strategy of the T5 station area (shown in figure 6), the following principle is that the local load power of the station area is supported by other station areas, the power supply of the alternating current side is disconnected, the zero power failure maintenance is realized, and the control strategy is the protection scope of the patent.
4. Grid side failure mode
Take the fault of the alternating current 10kV side of the T5 transformer area as an example
Step 1: and an inter-phase short circuit fault occurs on the medium-voltage side of the power grid, the photovoltaic anti-islanding protection action of the T5 area is realized, and the photovoltaic alternating current grid-connected switch is immediately disconnected.
Step 2: and setting the active adjustment instruction of the flexible interconnection device to zero.
Step 3: and the T5 transformer area micro-grid controller is used for disconnecting the low-voltage side breaker of the transformer area and the direct-current bus switch through a secondary standard interface cabinet.
Step 4: and the micro-grid controller of the T5 platform area switches the energy storage vehicle to enter a V/F working mode through a secondary standard interface cabinet, supports the voltage of the platform area, and discharges alternating current load in the support platform area.
Step 5: and the micro-grid controller of the T5 platform region controls the photovoltaic alternating current grid-connected switch to be switched on and grid-connected, and the photovoltaic participates in supporting the load of the platform region.
Judgment 1: and judging whether the output force and the photovoltaic output force of the energy storage vehicle are larger than the load of the platform area. If yes, go to step 9, otherwise go to step 6.
Step 6: and the T5 area micro-grid controller controls the flexible interconnection device to be switched into a V/F mode, simultaneously closes a direct current bus switch and requests a main station for power mutual aid. The cloud master station searches for a power surplus station area. The next step is to enter decision 2.
Judging 2: whether the different 10kV power supply station area has power surplus or not. If yes, enter decision 3, otherwise enter decision 4.
Judging 3: and judging whether a transfer condition is met, if so, the cloud master station transmits a power transfer instruction to the micro-grid controller of the power transfer station area, and the micro-grid controller controls the flexible interconnection device to transfer power and enters the step 7. If not, enter decision 4.
Judging 4: and whether the 10kV power supply station area has surplus power or not. If yes, enter the judgement 5, otherwise, can't finish the mutual aid of power.
Judging 5: judging whether the transfer condition is provided. If yes, the cloud master station issues a power transferring instruction to the micro-grid controller of the power transferring area, and the micro-grid controller controls the flexible interconnection device to transfer power and enters the step 7. If not, the power mutual aid cannot be achieved.
Step 7: and waiting for the power grid fault to clear.
Judging 6: and judging whether the power grid fault is cleared. If yes, go to step 8, otherwise go to step 7.
Step 8: and the micro-grid controller of the T5 area controls the low-voltage flexible interconnection device to be switched into a P/Q mode, and the micro-grid controller of the T5 area detects the low-voltage outgoing circuit breaker of the transformer of the area in synchronous closing through a secondary standard interface cabinet, so that fault recovery is completed.
Step 9: the T5 micro-grid controller controls the flexible interconnection device to be switched into a V/F mode, a hand is lifted to Yun Zhuzhan to apply for transferring photovoltaic surplus power, and meanwhile, the direct current bus switch is closed. The cloud master station searches for a power shortage station area. The next step is to enter decision 7.
Judging 7: determine if there is a power shortage in the non-same 10kV power supply station region? If yes, go to decision 8, otherwise go to decision 9.
Judging 8: whether or not a transfer condition is provided. If yes, go to step 10, otherwise go to decision 9.
Judging 9: determine if there is a power shortage in the same 10kV power supply station region? If yes, the method proceeds to a judgment 10, otherwise, the photovoltaic surplus power transfer cannot be completed.
Judging 10: judging whether the transfer condition is provided. If yes, go to step 10; otherwise, photovoltaic surplus power transfer cannot be completed.
Step 10: the cloud master station issues a transferred instruction to a micro-grid controller of a transferred platform region, and the micro-grid controller controls the flexible interconnection device to finish transfer of photovoltaic surplus power of the T5 platform region. The recovery is completed. The logic diagram of the specific control strategy is shown in fig. 6.
Simulation verification
In order to effectively verify the implementation effect, a discretization simulation model is built by means of an RT-LAB real-time simulation system according to a medium-low voltage active power distribution network comprising an alternating current-direct current coordination interaction micro-grid in the implementation mode, and control strategies under two scenes of fault and overhaul are comprehensively verified.
(1) Grid fault mode
In the simulation, 10kV power grid faults of the transformer areas T4 and T5 occur at 0.438s, when the power grid sides of the transformer areas T4 and T5 are in faults, the power grid side switch is turned off, off-grid operation is carried out, the transformer area T4 flexible interconnection device is converted from a constant power mode to an alternating voltage mode to supply alternating current loads in the transformer areas, and the power electronic transformer of the transformer area T4 stops operating. The constant power mode of the station area T1 is changed into the constant voltage mode to control the total direct current bus voltage to be maintained at 750V, and the direct current loads of the station areas T4 and T5 are all powered by the total direct current bus. The zones T2, T3 still operate in constant power mode.
After the power grid faults of the transformer areas T4 and T5 are recovered, the power electronic transformer of the transformer area T4 is recovered to operate, the flexible interconnection device of the transformer area T1 is converted into a constant alternating current power mode from a constant voltage mode, the transformer area T5 is converted into a constant power mode from an alternating current voltage mode, the power grid voltage is tracked, the alternating current output voltage is controlled to be consistent with the power grid voltage amplitude, frequency and phase, a transformer area alternating current side switch is closed, and the transformer area T5 is recovered to normally operate from an off-grid to a grid-connected integral system. In the simulation, the 10kV power grid fault is recovered to 0.76s, the platform area T5 is ready for grid connection, and the 0.789s platform area T5 flexible interconnection device is used for grid connection off conversion. The simulation results are shown in the form of relevant waveforms of the platform area T5, particularly shown in fig. 7, and conform to the expected results, so that the accuracy of the implementation is proved.
(2) Maintenance mode
In the simulation, a main station issues maintenance control instructions at 0.832s, a power electronic transformer in a transformer area T4 stops running, all flexible interconnection devices in other transformer areas autonomously control the power flow and direction of the power electronic transformer, so that the power and the current of each power grid side are gradually reduced to 0, after the power of a port of the power grid side meets the requirement, the power grid side switches are respectively disconnected, the power grid side switches are converted from a constant alternating current power mode to an alternating current voltage mode and enter an off-grid state, and at the moment, the direct current buses of each transformer area are supported by energy storage or photovoltaics.
In the simulation, after the overhaul of the power grid is finished in 0.957s, the master station issues a control command, the power electronic transformer in the transformer area T4 is put into operation to support the total direct current bus voltage, all the flexible interconnection devices track the power grid voltage, after the power grid side output voltage and the power grid voltage are controlled to be synchronous, the power grid side switches are respectively closed, the alternating current voltage mode is converted into a constant power mode, the grid-connected operation is shifted, and the system is restored to normal operation. The simulation result is shown in the form of the relevant waveform of the station area T4, particularly shown in fig. 8, and is consistent with the expected result, so that the accuracy of the implementation mode is proved.
The invention has the following advantages:
1. the invention realizes the strategy optimization decomposition of the equipment-level control layer, the district autonomous control layer and the main station coordination control layer, realizes the layered cooperative regulation and control independent of the on-site lateral communication, fully exploits the flexible resource regulation and control potential, and improves the cooperative interaction capability of the distributed resource absorption capability and the source network charge storage.
2. Based on the analysis of the embodiment, the control method provided by the invention has universality and rationality, can be applied to micro-grid groups with AC/DC coordination interaction functions, and has the popularization advantages of strong scale expansibility and good function reusability.
The foregoing is merely illustrative embodiments of the present invention, and the present invention is not limited thereto, and any changes or substitutions that may be easily contemplated by those skilled in the art within the scope of the present invention should be included in the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.
Claims (10)
1. A control method of an alternating current-direct current coordinated interaction micro-grid group is characterized by being applied to a scene that a plurality of low-voltage stations are flexibly interconnected to form the micro-grid group, the micro-grid group has an alternating current-direct current coordinated interaction function, the micro-grid group adopts an integrated three-layer cooperative control architecture and a three-layer information interaction architecture, and different control strategies are adopted in four main operation modes of an online control mode, an offline control mode, a planned maintenance mode and a grid fault mode.
2. The method for controlling an ac/dc coordinated interactive micro grid group according to claim 1, wherein:
the micro-grid group consists of a plurality of low-voltage transformer areas in a 10kV medium-voltage alternating-current circuit, the plurality of low-voltage alternating-current transformer areas form flexible interconnection on a direct-current side through a flexible interconnection device, and each transformer area has micro-grid autonomous capability; each station area is provided with a micro-grid controller, and is used for issuing control instructions to adjustable resources in the station area downwards, collecting the resource information in the station area and receiving the control instructions issued by the cloud master station upwards; the micro-grid controllers of all the transformer areas establish communication with a common cloud master station, and receive unified coordination allocation of the cloud master station; the platform area contains common AC/DC load and light, storage and charging flexible load.
3. The method for controlling an ac/dc coordinated interactive micro grid group according to claim 1, wherein:
the three-layer cooperative control architecture comprises: a device-level control layer, a district autonomous control layer and a master station coordination control layer;
wherein the device level control layer comprises: the flexible interconnection device is connected with adjustable resources and other adjustable resources in the station area through the direct current output port;
the micro-grid controller receives a main station instruction and a control mode or an autonomous strategy forming control instruction from the platform area homemade control layer and issues the control instruction to the adjustable resource;
the main station coordination control layer relies on real-time power generation data, relies on an optimization model to form a demand for issuing a regulation and control command or receiving a station area, and forms a control command for issuing according to the demand.
4. The method for controlling an ac/dc coordinated interactive micro grid group according to claim 1, wherein:
the three-layer information interaction architecture is a cloud-side-end integrated three-layer information interaction architecture;
wherein the end comprises: the system comprises a flexible interconnection device, a secondary standard interface cabinet and an energy storage vehicle, wherein the flexible interconnection device is responsible for collecting basic information of a body and direct current equipment information connected in a local area; the secondary standard interface cabinet is used for collecting information of the access energy storage vehicle and information of the access switch;
the side comprises a micro-grid controller configured for each area, is responsible for collecting terminal equipment information, completes an autonomous coordination control function in the area, transmits all terminal equipment information and states in the area to a master station, and simultaneously receives a regulation command of the master station to form a issuing control command;
the cloud comprises Yun Zhuzhan of a micro-grid group, and a cloud master station is responsible for monitoring platform area information and coordinated control among the platforms and sends out regulation and control instructions to a micro-grid controller.
5. The method for controlling an ac/dc coordinated interactive micro grid group according to claim 1, wherein:
the online control mode is defined as: the power grid normally operates, communication between the station areas and the cloud master station is normal, normal information interaction, control instruction issuing, receiving and executing can be performed, and under unified coordination and allocation of the cloud master station, the functions of economic optimal operation, distributed resource maximized consumption and power supply quality optimization management among the station areas are realized.
6. The method for controlling an ac/dc coordinated interactive micro grid group according to claim 1, wherein:
the offline control mode is defined as: the power grid normally operates, communication between the master station and the micro-grid controller is abnormal, the master station cannot receive information of micro-grid control within 15 minutes, and the off-line platform area finishes the autonomous of the micro-grid in the platform area by means of the micro-grid controller of the platform area, so that the local photovoltaic maximum absorption is realized.
7. The method for controlling an ac/dc coordinated interactive micro grid group according to claim 1, wherein:
the planned overhaul mode is defined as: the main station issues maintenance instructions to a single platform area in advance, other operations are completed by the micro-grid controller and the local interface cabinet, and the flexible interconnection device is utilized to transfer power to support a mode of maintaining the local load of the platform area, so that the zero power failure maintenance of the platform area is realized.
8. The method for controlling an ac/dc coordinated interactive micro grid group according to claim 1, wherein:
the grid-side failure mode is defined as: the medium-voltage side line breaks down, the cloud master station controls the micro-grid controller to timely cut off relevant transformer areas in the fault section, and the transformer areas are mutually balanced through the flexible interconnection device, so that loads in the transformer areas are supported, and the shortest power failure of the cut-off transformer areas is realized.
9. The method for controlling an ac/dc coordinated interactive micro grid group according to claim 1, wherein:
the conventions and constraints of the control strategy are:
1) When the platform area does not need external support, the platform area micro-grid controller automatically operates according to the platform area, and when the external support is needed, the platform area micro-grid controller sends a request to the master station, and the master station forms a control instruction to issue;
2) The autonomous operation of the platform area comprises the following operation modes: a) Economic operation: optimizing the line loss of the transformer area; b) Low carbon operation: preferentially absorbing clean energy in the station area; c) Optimizing power supply quality: the electric energy quality such as low voltage, harmonic wave and the like is treated, and the power supply quality level is improved;
3) Inter-station power comprises: a) A heavy load transfer mode, wherein when a certain area is heavy load, another area can be mutually used by flexible interconnection transfer; b) The zero power failure maintenance mode realizes the zero power failure of a maintenance platform area; c) And under the condition of large photovoltaic heat, the cross-platform low-carbon operation mode of the cross-platform region realizes the cross-platform region absorption of the distributed photovoltaic.
10. The method for controlling an ac/dc coordinated interactive micro grid group according to claim 1, wherein:
the initial running conditions, instruction sending and power matching principles of the micro-grid group are as follows:
1) In the aspect of primary equipment, the alternating current and the direct current of the transformer area are all connected in a grid mode, the power electronic transformer is a VF node, and the rest is a PQ node;
2) In the aspect of secondary equipment, n micro-grid control lines are arranged, wherein n is more than or equal to 1 and less than or equal to 5;
3) The master station transmits node voltage ranges of each platform region, wherein the node voltage ranges of each platform region are derived from power flow calculation and state estimation results, or voltage qualification rate ranges of +7% to-10%, or manually set ranges;
4) Uploading by a micro-grid controller: the power demand of the power supply area, the grading supply condition of the AC/DC power supply and the grading supply condition of the load are sent up for 15min, wherein the grading supply condition of the AC/DC power supply is graded according to the supply stability, the power of an AC main network is predefined in TTU to be 1 grade, the energy storage is 2 grade, the photovoltaic is 3 grade, the V2G is 4 grade, the grading supply condition of the load is graded according to the importance of the load, the important load is 1 grade, the general load is 2 grade, and the interruptible load is 3 grade;
5) The principle of inter-station power matching is as follows: preferentially meeting a single station area, preferentially selecting a side 10kV line station area, preferentially meeting power supply-load stability;
6) The main station performs the power matching in the following manner: the power is issued to a TTU of an A station area, and the A station area sends out certain kW power to a direct current bus; the power is sent to a TTU of a B station area, and the B station area absorbs certain kW power from a direct current bus; the TTU of each platform region participating in the matching controls the flexible interconnection device to execute;
7) Switching of a master station to a station control mode: an online and offline control mode;
8) And (3) prefabricating a table of VF node switching sequences aiming at the faults of the flexible interconnection device, and switching the flexible interconnection device on line according to the sequences when the power electronic transformer fails.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311045113.9A CN117200363A (en) | 2023-08-17 | 2023-08-17 | Control method for AC/DC coordinated interaction micro-grid group |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311045113.9A CN117200363A (en) | 2023-08-17 | 2023-08-17 | Control method for AC/DC coordinated interaction micro-grid group |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117200363A true CN117200363A (en) | 2023-12-08 |
Family
ID=89002548
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311045113.9A Pending CN117200363A (en) | 2023-08-17 | 2023-08-17 | Control method for AC/DC coordinated interaction micro-grid group |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117200363A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117762043A (en) * | 2024-02-22 | 2024-03-26 | 国网上海能源互联网研究院有限公司 | flexible-straight interconnection hardware-in-loop simulation system and testing method |
-
2023
- 2023-08-17 CN CN202311045113.9A patent/CN117200363A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117762043A (en) * | 2024-02-22 | 2024-03-26 | 国网上海能源互联网研究院有限公司 | flexible-straight interconnection hardware-in-loop simulation system and testing method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107612051B (en) | AC/DC hybrid system based on dual-redundancy power electronic transformer | |
| CN110601248B (en) | Multi-mode coordination control method of annular alternating current-direct current hybrid micro-grid system | |
| CN107394829B (en) | Direct current power supply system coordination control system and method based on non-interconnection communication | |
| CN104505867B (en) | Alternating current and direct current hybrid micro-grid system and control strategy thereof | |
| CN104281977B (en) | A kind of mixed type micro-capacitance sensor application platform and its control method | |
| CN108539776B (en) | Coordination control method for low-voltage flexible distribution network power supply system | |
| CN108539777B (en) | Power control method for low-voltage flexible distribution network power supply system | |
| CN112117767B (en) | Power supply and distribution system based on multi-station fusion | |
| JP2020530974A (en) | Methods and equipment for bidirectional storage and renewable power converters | |
| CN105811458A (en) | Microgrid energy storage system and energy management method thereof | |
| CN107404119B (en) | Control method of electric vehicle load transfer system | |
| CN107681700B (en) | Method for converting operation modes of alternating current-direct current hybrid micro-grid | |
| CN207753466U (en) | A kind of Ac/dc Power Systems based on dual redundant electric power electric transformer | |
| CN209913508U (en) | Micro-grid layered coordination control device | |
| CN105244909A (en) | Direct-current micro-grid system and grid-connection self-balancing control strategy | |
| CN115441498A (en) | Platform area micro-grid system based on flexible direct current interconnection and control method thereof | |
| CN117200363A (en) | Control method for AC/DC coordinated interaction micro-grid group | |
| CN115882602A (en) | Energy storage coordination control system | |
| CN115714436A (en) | Stable power supply method of multi-energy storage power supply system suitable for traffic system | |
| Chen et al. | Engineering design and practice of grouped distribution station areas based on flexible DC interconnection | |
| CN109617098B (en) | Internal three-phase unbalance disturbance suppression method suitable for micro-grid group | |
| CN108711875B (en) | Distributed energy storage unit coordination control system and control method | |
| CN116937680A (en) | Flexible ring closing device operation mode division and power instruction generation method | |
| CN112491098A (en) | Multi-port intelligent micro-grid energy exchanger and control method and system thereof | |
| CN116780589A (en) | Distribution network flexible-direct interconnection-wind-light-storage-charging-conversion integrated power energy station |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication |