CN104242338B - A kind of transformer station's micro-grid system containing distributed power source and control method - Google Patents

Abstract

The invention relates to a substation micro-grid system and control method including distributed power sources, which belong to the field of micro-grid technology. The control method based on power electronics technology enables the substation micro-grid to realize intelligent and flexible control, and achieves the formation of the station micro-grid. "plug and play"function; when the load changes, coordinate and control various distributed power sources in the station microgrid to ensure that the station microgrid meets the power quality requirements of the load in different operating modes; , power outage, etc., the local information collected by the microgrid is automatically transferred to the independent operation state, which is coordinated by the power grid; according to the change of sunshine intensity and load, the working state of the battery pack is switched and adjusted. On the one hand, the adjusted electric energy is directly sent to the To the DC or AC load; on the other hand, the excess power is sent to the battery pack; when the power generation cannot meet the needs of the load, the controller sends the power of the battery to the load to ensure the continuity and stability of the entire system.

Description

Microgrid system and control method for substation with distributed power supply

technical field

The invention belongs to the technical field of micro-grids, and in particular relates to a micro-grid system and a control method for substations including distributed power sources.

Background technique

With the rapid development of the global economy and science and technology, many countries in the world have focused on photovoltaic power generation, and technological progress in the photovoltaic industry has made solar energy applications possible. At present, my country's photovoltaic power generation application market is in its infancy. In 2010, my country's newly installed photovoltaic power generation capacity was about 500MW, with a total of 800MW. my country's photovoltaic manufacturing industry; the photovoltaic power generation market is currently mainly used for rural electrification in remote areas, communications and industrial applications, and solar photovoltaic products, including solar street lights, lawn lights, solar traffic lights and solar landscape lighting, etc., but the photovoltaic industry has not been applied to substations , as a means of responding to emergencies in substations.

The substation power system is the key to ensure the safe and reliable transmission of substation power, and it is also an important guarantee for continuous power supply to users. In the current power system, 110kV and above substations have an important position and are the pivot point of the power system. After the power failure of the whole station, it will cause a large-scale power outage or system collapse, and it plays an important role in the regional power supply system. However, most of these substation power systems use the secondary side of the substation to reduce the voltage to 380V through the station transformer to supply power to the load and monitoring devices in the station. The method is single and unreliable, and the backup power supply cannot continue to supply power. The model aspect is not perfect yet. In terms of energy saving, since the traditional power grid uses fossil fuels to produce electricity, the electricity consumed by the internal loads of the substation is also provided by it, and renewable energy cannot be fully utilized for its power supply. Once the power system of the station or the grid system fails, it will directly affect the safe operation of the primary and secondary equipment of the power system, and in severe cases, it will cause a large-scale power outage and cause huge economic losses. If the backup power supply cannot provide continuous and reliable power supply, it will not be able to provide subsequent power supply during the fault period, and important equipment such as internal communication, lighting, and monitoring in the substation will therefore not be able to work normally. Moreover, with the continuous reform and development of the power system, there are more and more unattended substations. When the station transformer with load loses power, it is necessary for the on-duty personnel of the centralized control station to operate in the substation to restore the occupied power system. Therefore, there are many potential safety hazards in the traditional substation power system.

Contents of the invention

Aiming at the shortcomings of the prior art, the present invention proposes a substation micro-grid system and control method including distributed power sources to achieve intelligent and flexible control of the substation micro-grid and improve the continuity and stability of the entire system.

A microgrid system for a substation with distributed power sources, including a first transformer, a second transformer, a third transformer, a first circuit breaker, a second circuit breaker, a third circuit breaker, a fourth circuit breaker, a Fifth circuit breaker, sixth circuit breaker, seventh circuit breaker, eighth circuit breaker, ninth circuit breaker, tenth circuit breaker, eleventh circuit breaker, twelfth circuit breaker, thirteenth circuit breaker, fourteenth circuit breaker Breaker, Breaker 15, Breaker 16, Breaker 17, Breaker 18, Breaker 19, Breaker 20, Breaker 21, Breaker 22 Circuit breaker, twenty-third circuit breaker, twenty-fourth circuit breaker, twenty-fifth circuit breaker, twenty-sixth circuit breaker, first dual power switch, second dual power switch, controller and display, wherein,

The first transformer is set between the wall photovoltaic panel and the first grid-connected inverter in the grid, and the second transformer is set between the roof photovoltaic panel and the second grid-connected inverter in the grid , the third transformer is set between the micro-grid battery in the power grid and the first bidirectional inverter, the first transformer output terminal, the second transformer output terminal and the third transformer output terminal are connected to the input of the controller through the bus end;

One end of the first circuit breaker is connected to the 380V/AC busbar of the microgrid, and the other end is connected to the 380V/AC busbar of the substation; one end of the second circuit breaker is connected to the first grid-connected inverter, and the other end is connected to the 380V/AC busbar of the microgrid; One end of the third circuit breaker is connected to the second grid-connected inverter, and the other end is connected to the microgrid 380V/AC bus; one end of the fourth circuit breaker is connected to the first bidirectional inverter, and the other end is connected to the microgrid 380V/AC busbar; the fifth circuit breaker One end is connected to the microgrid 380V/AC busbar, and the other end is connected to one end on the double-head side of the first dual power switch; one end of the sixth circuit breaker is connected to the microgrid 380V/AC busbar, and the other end is connected to one end on the double-head side of the second dual power switch; One end of the seventh circuit breaker is connected to the 380V/AC bus of the substation, and the other end is connected to the AC feeder for the station. One end of the eighth circuit breaker is connected to the 380V/AC bus of the substation, and the other end is connected to the AC feeder for the station. One end of the ninth circuit breaker is connected to the 380V/AC substation Busbar, the other end is connected to the AC feeder for the station, one end of the tenth circuit breaker is connected to the 380V/AC busbar of the substation, and the other end is connected to the AC feeder for the station; one end of the eleventh circuit breaker is connected to the 380V/AC busbar of the microgrid, and the other end is connected to the standby transformer 380V /AC busbar, one end of the twelfth circuit breaker is connected to the microgrid 380V/AC busbar, and the other end is connected to communication, monitoring or lighting equipment, one end of the thirteenth circuit breaker is connected to the microgrid 380V/AC busbar, and the other end is connected to communication, monitoring or lighting Equipment; one end of the fourteenth circuit breaker is connected to the spare transformer 380V/AC busbar, and the other end is simultaneously connected to the second end of the double-head side of the first double power switch and the second end of the double-head side of the second double power switch; the fifteenth circuit breaker One end is connected to the single head side of the second double power switch, the other end is connected to the input end of the second bidirectional inverter in the power grid, and the single head side of the second double power switch is connected to the charger input end in the power grid; the sixteenth circuit breaker One end is connected to the output end of the charger in the grid, the other end is connected to the 220V/DC busbar of the first substation, one end of the seventeenth circuit breaker is connected to the battery for the first station in the grid, and the other end is connected to the 220V/DC busbar of the first substation One end of the eighteenth circuit breaker is connected to the second bidirectional inverter in the power grid, and the other end is connected to the 220V/DC bus bar of the second substation. One end of the nineteenth circuit breaker is connected to the battery for the second station in the power grid, and the other end is connected to the second station The 220V/DC busbar of the second-section substation; one end of the 20th circuit breaker is connected to the 220V/DC busbar of the first-section substation, the other end is connected to the station DC feeder, one end of the 21st circuit breaker is connected to the 220V/DC busbar of the first-section substation, and One end is connected to the DC feeder for the station, one end of the 22nd circuit breaker is connected to the 220V/DC busbar of the first substation, the other end is connected to the DC feeder for the station, one end of the 23rd circuit breaker is connected to the 220V/DC busbar of the second substation, and the other end is connected to the 220V/DC busbar of the second substation. One end is connected to the DC feeder for the station, one end of the twenty-fourth circuit breaker is connected to the 220V/DC busbar of the second substation, the other end is connected to the DC feeder for the station, one end of the twenty-fifth circuit breaker is connected to the second substation 220V/DC Busbar, the other end is connected to the DC feeder for the station; one end of the twenty-sixth circuit breaker is connected to the 220V/DC busbar of the first substation, and the other end is connected to the 220V/DC busbar of the second substation;

The output end of the current transformer of the first circuit breaker, the output end of the current transformer of the second circuit breaker, the output end of the current transformer of the third circuit breaker, the output end of the current transformer of the fourth circuit breaker, the fifth circuit breaker The current transformer output terminal of the circuit breaker, the current transformer output terminal of the sixth circuit breaker, the current transformer output terminal of the seventh circuit breaker, the current transformer output terminal of the eighth circuit breaker, the current transformer output of the ninth circuit breaker terminal, output terminal of the current transformer of the tenth circuit breaker, output terminal of the current transformer of the eleventh circuit breaker, output terminal of the current transformer of the twelfth circuit breaker, output terminal of the current transformer of the thirteenth circuit breaker, the output terminal of the current transformer of the thirteenth circuit breaker, The output end of the current transformer of the fourteenth circuit breaker, the output end of the current transformer of the fifteenth circuit breaker, the output end of the current transformer of the sixteenth circuit breaker, the output end of the current transformer of the seventeenth circuit breaker, the output end of the eighteenth circuit breaker The current transformer output end of the circuit breaker, the current transformer output end of the nineteenth circuit breaker, the current transformer output end of the twentieth circuit breaker, the current transformer output end of the twenty-first circuit breaker, the twenty-second The current transformer output terminal of the circuit breaker, the current transformer output terminal of the twenty-third circuit breaker, the current transformer output terminal of the twenty-fourth circuit breaker, the current transformer output terminal of the twenty-fifth circuit breaker and the second The output ends of the current transformers of the sixteen circuit breakers are connected to the controller through the bus;

The current transformer output terminal of the circuit breaker at the station transformer output end in the power grid and the current transformer output end of the backup transformer output circuit breaker are connected to the controller through the bus;

The output terminal of the controller is respectively connected to the control terminal of each circuit breaker through the bus;

The output end of the controller is connected with the input end of the display.

The output terminal of the current transformer of the first dual power switch and the output terminal of the current transformer of the second dual power switch are also connected to the controller through the bus.

A control method for realizing a substation micro-grid system including a distributed power supply includes the following steps:

Step 1. Use the controller to control the eleventh circuit breaker, the fourteenth circuit breaker, and the backup transformer output end circuit breaker to be in the sub-position state, and control the switch blades of the first dual power switch and the second dual power switch to be at the main transformer end. And control other circuit breakers to be in the closing state, so that the system enters the working state of the main transformer;

Step 2. Use the third transformer to collect the current value of the input terminal of the microgrid battery in real time, and judge whether the collected current value reaches the set value. If so, the controller controls the fourth circuit breaker to be in the split state; otherwise, continue real-time collection;

The current transformer of the seventeenth circuit breaker is used to collect the current value of the input terminal of the storage battery for the first station in real time, and judge whether the collected current value reaches the set value, and if so, the controller controls the seventeenth circuit breaker to be in the positional state ;Otherwise, continue real-time acquisition;

The current transformer of the nineteenth circuit breaker is used to collect the current value of the battery input terminal of the second station in real time, and judge whether the collected current value reaches the set value, and if so, the controller controls the nineteenth circuit breaker to be in the sub-position state ;Otherwise, continue real-time acquisition;

Step 3. When the circuit breaker at the output end of the station transformer detects a failure of the 35KV station transformer, the controller sends a signal to the circuit breaker at the output end of the station transformer, the first circuit breaker, the seventh circuit breaker, the eighth circuit breaker, the The ninth circuit breaker and the tenth circuit breaker are in the sub-position state, and the backup transformer output terminal circuit breaker, the eleventh circuit breaker and the fourteenth circuit breaker are in the closing state, and the first double power switch and the second The switch knife of the dual power switch is in the standby transformer end, so that the system enters the working state of the standby transformer;

Step 4. When the current transformer of the circuit breaker at the output end of the backup transformer detects that the current value suddenly changes to 0, control the fifth circuit breaker, the eleventh circuit breaker, and the fourteenth circuit breaker to be in the split state, and control the twenty The six circuit breakers are closed, and the first dual power switch is controlled to be disconnected, and the switch knife of the second dual power switch is connected to the main transformer end, so that the system enters the working state of the microgrid;

Step 5. When the system enters the working state of the microgrid, set the priority of the DC load according to the actual demand, and disconnect the circuit breaker corresponding to the DC load with a lower priority according to the priority;

Step 6. Use the first transformer to collect the current value output by the photovoltaic panel on the wall in real time, and use the second transformer to collect the current value output by the photovoltaic panel on the roof in real time. If the collected current value is greater than 0, the system works normally. If the current value is equal to 0, the second circuit breaker and the third circuit breaker are controlled to be in the sub-position state, and the fourth circuit breaker, the seventeenth circuit breaker and the nineteenth circuit breaker are controlled to be in the closing state;

Step 7. When the 35KV substation transformer resumes power supply, the circuit breaker at the output end of the station transformer will detect the voltage difference between the two ends. If the voltage difference is 0, it will remain unchanged; otherwise, adjust each grid-connected inverter in the power grid. The output voltage phase of the transformer, so that the frequency and phase of the 380V/AC bus voltage of the microgrid are the same as the frequency and phase of the 380V/AC bus voltage of the substation, or within the allowable range, and control the circuit breaker and the first circuit breaker at the output end of the station transformer The circuit breaker, the seventh circuit breaker, the eighth circuit breaker, the ninth circuit breaker and the tenth circuit breaker are in the closed state, the twenty-sixth circuit breaker is in the sub-position state, and the control switch of the first double power switch is located at the main transformer end. Put all the station DC loads into operation.

According to the priority in step 5, the circuit breakers corresponding to the DC loads with low priority are disconnected, the number of disconnected circuit breakers is set according to actual needs, and the priority of communication, monitoring and lighting equipment is the highest.

The allowable range described in step 7 is set according to actual needs.

Advantages of the present invention:

The present invention is a substation micro-grid system and control method including distributed power sources. The control method based on power electronics technology enables the substation micro-grid to realize intelligent and flexible control, and achieves the "plug and play" function of the station micro-grid. ; When the load in the station microgrid changes, through effective coordinated control of various distributed power sources in the station microgrid to ensure that the station microgrid can meet the power quality requirements of the load in different operating modes ; The control of the microgrid for the station responds autonomously to the information in the grid according to the system information. For voltage drops, faults, power outages, etc., the local information collected by the microgrid is automatically transferred to an independent operating state, and the grid coordinates and dispatches in a unified manner; according to the sunshine Intensity and load changes, constantly switch and adjust the working state of the battery pack: on the one hand, the adjusted electric energy is directly sent to the DC or AC load; on the other hand, the excess electric energy is sent to the battery pack for storage; the power generation cannot meet When the load needs it, the controller sends the electric energy of the battery to the load, which ensures the continuity and stability of the whole system.

Description of drawings

Fig. 1 is a system overall structural block diagram of an embodiment of the present invention;

Fig. 2 is a controller circuit schematic diagram of an embodiment of the present invention;

Fig. 3 is a flow chart of power generation and internal power consumption of the microgrid system according to an embodiment of the present invention;

Fig. 4 is a flowchart of a control method of a substation microgrid system including distributed power sources according to an embodiment of the present invention.

detailed description

An embodiment of the present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 1, the substation microgrid system with distributed power sources in the embodiment of the present invention includes the first transformer CT ₁ , the second transformer CT ₂ , the third transformer CT ₃ , and the first circuit breaker QF ₁ , the second circuit breaker QF ₂ , the third circuit breaker QF ₃ , the fourth circuit breaker QF ₄ , the fifth circuit breaker QF ₅ , the sixth circuit breaker QF ₆ , the seventh circuit breaker QF ₇ , the eighth circuit breaker QF ₈ , Ninth circuit breaker QF ₉ , tenth circuit breaker QF ₁₀ , eleventh circuit breaker QF ₁₁ , twelfth circuit breaker QF ₁₂ , thirteenth circuit breaker QF ₁₃ , fourteenth circuit breaker QF ₁₄ , fifteenth circuit breaker QF ₁₅ for the sixteenth circuit breaker, QF ₁₆ for the sixteenth circuit breaker, QF ₁₇ for the seventeenth circuit breaker, QF ₁₈ for the eighteenth circuit breaker, QF ₁₉ for the nineteenth circuit breaker, QF 20 for the twentieth circuit breaker, and QF ₂₀ for the twenty-first circuit breaker QF ₂₁ , the twenty-second circuit breaker QF ₂₂ , the twenty-third circuit breaker QF ₂₃ , the twenty-fourth circuit breaker QF ₂₄ , the twenty-fifth circuit breaker QF ₂₅ , the twenty-sixth circuit breaker QF _D , the first Double power switch QF _8-1 , second double power switch QF _8-2 , controller and display;

In Figure 1, 1 represents the microgrid 380V/AC bus; 2 represents the substation 380V/AC bus; 3 represents the backup transformer 380V/AC bus; 4 represents the substation 220V/DC bus section 1; 5 represents the substation 220V/ There are 2 sections of DC bus; T ₁ is the main transformer; T ₂ is the backup transformer.

In the embodiment of the present invention, as shown in Figure 2, the controller adopts 8086 type CPU, wherein, the pins AD15～AD0 are address/data buses _; , QF ₂ , QF ₃ , QF ₁₁ , QF ₁₄ , QF ₁₇ , QF ₁₈ , QF ₁₉ , QF ₂₀ and QF _D adopt LPCPS-100 type circuit breaker, and other circuit breakers adopt LPCPS-45 type; the first double power switch QF _8-1 and the second dual power switch QF _8-2 adopt ABB's OTM200E4C10D380C model; the transformer adopts the upward OPCT18AL model, and the display adopts the Dell S2340L model, and its input terminal is connected to the A19/S6～A16/S3 terminal of the controller.

In the embodiment of the present invention, the controller has control functions of micro power supply management, energy storage device management, load management, grid disconnection and grid connection. Transformers and circuit breakers upload their respective status information through communication lines, including the PCC point (common connection point) grid voltage, current, frequency, and phase angle; the output voltage, current, frequency, and phase angle of each micro power supply; the circuit breaker on and off State; load parameters, including load size, voltage, current, frequency, power factor; according to the obtained data, formulate micro-power switching, working mode switching, power output adjustment, circuit breaker on-off control, and then set the set value And control commands are sent to each regulating device to maintain the normal operation of the microgrid.

In the embodiment of the present invention, as shown in FIG. 3, when the output terminal power P _out is greater than the DC load terminal power P, the local DC load is directly supplied with power; ① When the remaining electric energy (P _out -P) is greater than the AC load terminal power P ′, then directly supply power to the local AC load. At this time, if the remaining electric energy P _left is not 0, the controller sends out a PWM wave to drive the battery to store energy; ② When the remaining electric energy (P _out -P) is less than When the power of the AC load is P′, judge whether the stored energy W of the current battery is greater than the current required electric energy W″. If so, the controller sends out PWM waves to drive the battery to work and supply power to the AC load; otherwise, the controller sends out PWM waves to drive the grid. The controller makes the circuit breaker in the grid-connected controller close, and the power grid supplements the energy gap of the system at this time;

In the embodiment of the present invention, the PCC point uploads the parameters of the power grid through transformers and circuit breakers, including the voltage, current, frequency, and phase angle of the power grid; Compare the voltage and frequency with the current voltage and frequency of the microgrid to analyze whether they are synchronized. If the deviation is within the allowable range, that is, the voltage difference is 10% and the frequency difference is 0.3Hz, the power output of the energy storage device and photovoltaic cells will be adjusted to achieve the fastest Synchronized with the grid; if the deviation exceeds the allowable range, calculate the amount of reactive power compensation, and send this value to the energy storage device, order the energy storage device to send reactive power, and maintain system balance.

In the embodiment of the present invention, when a power quality problem such as voltage disturbance or power supply interruption occurs in the power grid, the microgrid is transferred to the island mode (the microgrid for the station is disconnected from the power grid and operates independently); when the power grid for the station receives power, Detect the voltage, frequency, and phase angle of the current grid and microgrid. If the microgrid is not synchronized with the grid, calculate the parameter difference between the grid and the microgrid, calculate the compensation amount, and send the compensation amount to the microgrid to adjust the power output. Synchronization with the grid.

In the embodiment of the present invention, the power and voltage controller of the photovoltaic panel itself sends the working mode (maximum power point tracking MPPT/constant voltage) to the photovoltaic panel, and outputs voltage, current, frequency, active power, and reactive power to the controller; networking mode In the island mode, when the output power of the photovoltaic panel is greater than the power consumption of the load, the battery is fully charged, and the energy storage device is fully charged, the controller that controls the photovoltaic panel changes its operation mode and works in the constant voltage mode. Otherwise, keep working in MPPT mode; when the output power of the photovoltaic panel is 0, the controller of the photovoltaic panel stops running.

In the embodiment of the present invention, the power and voltage controller of the battery itself sends the current working mode of the energy storage, the voltage and current of charging and discharging, the output active power, reactive power, and state of charge to the controller; in the networking mode: control The inverter controls the battery to only work in the charging mode. When it is detected that the battery is not fully charged, it will continue to charge, and if it is fully charged, it will stop charging; in island mode: when the photovoltaic output power is less than the load consumption power, or the photovoltaic output power is zero. , and it is detected that the battery has energy storage, the battery is discharged; when the output power of the battery is 0, the controller of the battery itself stops running.

In the embodiment of the present invention, in the networking mode, the controller detects the on-off status of the circuit breaker in real time. When the voltage and current of a certain branch or node are too high, it should quickly cut off the circuit breaker of the branch or node, and notify Maintenance personnel quickly remove the fault to ensure the normal power supply of the load; in the island mode, the circuit breaker QF _G quickly disconnects the connection with the grid, and the microgrid enters the island mode; the circuit breaker cuts off the power supply of one load to ensure high priority When the power supply of the microgrid still does not meet the needs of sensitive loads, the loads with lower power supply levels should be cut off to ensure the normal power supply of high priority loads; when the voltage of a load node exceeds the allowable range, That is, 10% of the load rated voltage, the reactive power compensation amount is calculated according to the reactive power compensation algorithm, and the reactive power compensation amount is sent to the reactive power compensator inside the power grid for voltage regulation.

In the embodiment of the present invention, the first transformer CT ₁ is installed between the wall photovoltaic panel and the first grid-connected inverter in the grid, and the second transformer CT ₂ is installed between the roof photovoltaic panel and the second grid-connected inverter in the grid. Between the grid-connected inverters, the third transformer CT ₃ is arranged between the micro-grid battery in the grid and the first bidirectional inverter, the output terminal of the first transformer CT ₁ , the output terminal of the second transformer CT ₂ and The output terminal of the third transformer CT ₃ is connected to the input terminal of the controller through the bus.

In the embodiment of the present invention, the photovoltaic panel is the YL300C35b model of Yingli solar panel; the grid-connected inverter is the power foot DL-3N40KW model, the bidirectional inverter is the CSIC Pengli PECG1/2/3 model; the battery is Hercules 2-800 LBT models.

In the embodiment of the invention, the bidirectional inverter is suitable for various applications that require dynamic energy storage. When the electric energy is surplus, the electric energy is stored, and when the electric energy is insufficient, the stored electric energy is inverted and then output to the grid; it plays an emergency role in the microgrid. Independent inverter action.

In the embodiment of the present invention, the automatic switching of the working mode is realized by the bidirectional inverter; the bidirectional AC/DC converter realizes the mutual support between the distributed DC power supply system and the power grid, and controls the mutual transfer of energy between the DC bus and the power grid; The control goal of the bidirectional converter is to make the energy realize bidirectional operation, which can realize both rectification and inversion; the DC side bus voltage is stable near the rated value, the grid side current waveform is sinusoidal and the power factor is 1; when the DC bus voltage When it is lower than the rated value, the energy is transmitted from the grid to the DC microgrid through the bidirectional AC/DC converter, thereby increasing the DC bus voltage; when the DC bus voltage is higher than the rated value, the energy is transferred from the DC microgrid to the DC microgrid through the bidirectional AC/DC converter Transmission to the power grid, control the DC bus voltage in the DC micro-grid to drop to near the rated value, so as to maintain the stable operation of the DC micro-grid.

In the embodiment of the present invention, the grid-connected inverter converts the DC power in the storage battery into standard 380V mains power and connects it to the low-voltage power grid on the user side or sends it to the high-voltage power grid through a step-up transformer; The same alternating current, according to the sunlight conditions from sunrise to sunset, according to different external temperature and sunlight intensity conditions, make the photovoltaic panel try to maintain the working state of the maximum power output; impact on the power grid; troubleshoot abnormal situations to ensure safe operation of the system; PLL phase-locked loop technology ensures that the output of the inverter is synchronized with the grid; in control, multi-loop feedback is used to control the frequency. When the frequency decreases, the inverter Large active output, and when the frequency increases, reduce the active output.

In the embodiment of the present invention, photovoltaic power generation is applied to the traditional station power grid, and the photovoltaic effect of solar panels is used to convert light energy into electrical energy, then charge the battery pack, and convert direct current into alternating current through the inverter to supply power to the load .

In the embodiment of the present invention, the battery pack (micro-grid battery and station battery) plays two major roles in energy regulation and load balancing in the system at the same time; it converts the electrical energy output by the photovoltaic power generation system into chemical energy and stores it for power supply Use when insufficient.

In the embodiment of the present invention, a battery management system (BMS) is provided: alarms for overvoltage, undervoltage, and overtemperature of a single battery, alarm protection for overcharge, overdischarge, and overcurrent of a battery pack, and cut off. BMS has the function of analyzing and diagnosing battery performance. It can obtain the current capacity of a single battery by analyzing and diagnosing the model based on real-time measurement of battery module voltage, charge and discharge current, temperature, single battery terminal voltage, and calculated internal resistance of the battery. Or the diagnosis of remaining capacity (SOC), the diagnosis of single battery state of health (SOH), the evaluation of the state of the battery pack, and the estimation of the sustainable discharge time under the current state when discharging.

In the embodiment of the present invention, the service time of the storage battery used in the substation can be extended through the double power switch.

In the embodiment of the present invention, one end of the first circuit breaker QF ₁ is connected to the 380V/AC bus bar of the microgrid, and the other end is connected to the 380V/AC bus bar of the substation; one end of the second circuit breaker QF ₂ is connected to the first grid-connected inverter, and the other end is connected to the micro grid 380V/AC busbar; one end of the third circuit breaker QF ₃ is connected to the second grid-connected inverter, and the other end is connected to the microgrid 380V/AC busbar; one end of the fourth circuit breaker QF ₄ is connected to the first bidirectional inverter, and the other end is connected to Microgrid 380V/AC busbar; one end of the fifth circuit breaker QF ₅ is connected to the microgrid 380V/AC busbar, and the other end is connected to one end on the double-head side of the first double power switch QF _8-1 ; one end of the sixth circuit breaker QF ₆ is connected to the microgrid 380V/AC busbar, the other end is connected to one end of the second dual power switch QF _8-2 double-headed side; one end of the seventh circuit breaker QF ₇ is connected to the 380V/AC busbar of the substation, the other end is connected to the AC feeder for the station, and the eighth circuit breaker QF ₈ One end is connected to the 380V/AC busbar of the substation, the other end is connected to the AC feeder for the station, one end of the ninth circuit breaker QF ₉ is connected to the 380V/AC busbar of the substation, the other end is connected to the AC feeder for the station, one end of the tenth circuit breaker QF ₁₀ is connected to the 380V/ AC busbar, the other end is connected to the station AC feeder; one end of the eleventh circuit breaker QF ₁₁ is connected to the microgrid 380V/AC busbar, the other end is connected to the spare transformer 380V/AC busbar, and the other end is connected to the twelfth circuit breaker QF _12. One end is connected to the microgrid 380V/AC busbar. AC bus, the other end is connected to communication, monitoring or lighting equipment; one end of the thirteenth circuit breaker QF ₁₃ is connected to the microgrid 380V/AC bus, and the other end is connected to communication, monitoring or lighting equipment; one end of the fourteenth circuit breaker QF ₁₄ is connected to the spare Transform 380V/AC bus, the other end is connected to the second end of the first double power switch QF _8-1 double head side and the second double power switch QF _8-2 double head side second end; the fifteenth circuit breaker QF ₁₅ one end Connect the single-head side of the second dual power switch QF _8-2 , the other end is connected to the input terminal of the second bidirectional inverter in the grid, and the single-head side of the second dual power switch QF _8-2 is connected to the charger input in the grid One end of the sixteenth circuit breaker QF ₁₆ is connected to the output end of the charger in the power grid, the other end is connected to the 220V/DC bus bar of the first substation, and one end of the seventeenth circuit breaker QF ₁₇ is connected to the battery for the first station in the power grid. The other end is connected to the 220V/DC bus of the first substation, one end of the eighteenth circuit breaker QF ₁₈ is connected to the second bidirectional inverter in the power grid, and the other end is connected to the 220V/DC bus of the second substation, and the nineteenth circuit breaker QF ₁₉ One end is connected to the battery for the second station in the power grid, and the other end is connected to the 220V/DC bus bar of the second substation; one end of the twentieth circuit breaker QF ₂₀ is connected to the 220V/DC bus bar of the first substation, and the other end is connected to the DC feeder for the station. One end of the 21st circuit breaker QF ₂₁ is connected to the 220V/DC busbar of the first substation, the other end is connected to the DC feeder for the station, and the 22nd circuit breaker One end of _{QF 22} is connected to the 220V/DC busbar of the first substation, and the other end is connected to the DC feeder for the station. One end of the fourteenth circuit breaker _{QF 24} is connected to the 220V/DC busbar of the second substation, and the other end is connected to the DC feeder for the station. Feeder; one end of the twenty-sixth circuit breaker QF _D is connected to the 220V/DC bus of the first substation, and the other end is connected to the 220V/DC bus of the second substation;

In the embodiment of the present invention, the output terminal of the current transformer of the first circuit breaker QF1, the output terminal of the current transformer of the _second circuit breaker QF2, the output terminal of the current transformer of the _third circuit breaker QF3, the output terminal _of the current transformer of the fourth circuit breaker QF The current transformer output terminal of ₄ , the current transformer output terminal of the fifth circuit breaker QF ₅ , the current transformer output terminal of the sixth circuit breaker QF ₆ , the current transformer output terminal of the seventh circuit breaker QF ₇ , the eighth circuit breaker The output end of the current transformer of the circuit breaker QF ₈ , the output end of the current transformer of the ninth circuit breaker QF ₉ , the output end of the current transformer of the tenth circuit breaker QF ₁₀ , the output end of the current transformer of the eleventh circuit breaker QF ₁₁ , The current transformer output terminal of the twelfth circuit breaker QF12, the current transformer output terminal of the thirteenth circuit breaker QF ₁₃ , the current transformer output terminal of the fourteenth circuit breaker QF ₁₄ , the current of the fifteenth circuit breaker QF ₁₅ Transformer output terminal, current transformer output terminal of sixteenth circuit breaker QF ₁₆ , current transformer output terminal of seventeenth circuit breaker QF ₁₇ , current transformer output terminal of eighteenth circuit breaker QF ₁₈ , nineteenth Current transformer output of circuit breaker QF ₁₉ , current transformer output of twentieth circuit breaker QF ₂₀ , current transformer output of twenty-first circuit breaker QF ₂₁ , current of twenty-second circuit breaker QF ₂₂ Transformer output terminal, current transformer output terminal of twenty-third circuit breaker QF ₂₃ , current transformer output terminal of twenty-fourth circuit breaker QF ₂₄ , current transformer output terminal of twenty-fifth circuit breaker QF ₂₅ and The output ends of the current transformers of the twenty-sixth circuit breaker QF _D are all connected to the controller through the bus;

In the embodiment of the present invention, the output terminal of the current transformer of the transformer output terminal circuit breaker QF _G in the power grid and the current transformer output terminal of the spare transformer output terminal circuit breaker QF _B are connected to the controller through the bus; the output terminal of the controller The control terminals of each circuit breaker are respectively connected through the bus; the current transformer output terminals of the first dual power switch QF _8-1 and the current transformer output terminals of the second dual power switch QF _8-2 are also connected to the controller through the bus.

Realize the control method of the substation microgrid system including distributed power supply, the flow chart of the method is shown in Figure 4, including the following steps:

Step 1. Use the controller to control the eleventh circuit breaker QF ₁₁ , the fourteenth circuit breaker QF ₁₄ and the backup transformer output terminal circuit breaker QF _B to be in the divided state, and control the first dual power switch QF _8-1 and the second dual The switch knife of the power switch QF _8-2 is at the main transformer end, and controls other circuit breakers to be in the closing state, so that the system enters the working state of the main transformer;

In the embodiment of the present invention, there are two typical operation modes of the station microgrid: under normal circumstances, the station microgrid and the conventional power grid are connected to the grid (interconnected mode); when a grid failure is detected or the power quality does not meet the requirements, The station microgrid will be disconnected from the power grid in time and run independently (island mode); different control strategies will be adopted according to the different operation modes of the station microgrid. Mode adopts V/f control (voltage frequency control).

In the embodiment of the present invention, when the main transformer is in working state, the microgrid 380V/AC busbar is connected in parallel with the substation 380V/AC busbar, and the photovoltaic panel first charges the microgrid battery and the station battery, and when the energy storage reaches the required value (a Shares are 85% of the total capacity), supplying power to the station loads on the 380V/AC bus of the substation and the loads on the station DC bus, giving priority to the use of clean energy for power supply, ensuring the maximum efficiency output and use of solar power generation, photovoltaic power generation The insufficient part is supplemented by the 380V/AC busbar of the substation.

Step 2. Use the third transformer CT ₃ to collect the current value of the input terminal of the microgrid battery in real time, and judge whether the collected current value reaches 85% of the total capacity. If so, the controller controls the fourth circuit breaker QF ₄ to be in the position status; otherwise, continue real-time collection;

The current transformer of the seventeenth circuit breaker QF ₁₇ is used to collect the current value of the input terminal of the storage battery for the first station in real time, and judge whether the collected current value reaches 85% of the total capacity. If so, the controller controls the seventeenth circuit breaker QF ₁₇ is in the quantile state; otherwise, continue to collect in real time;

The current transformer of the nineteenth circuit breaker QF ₁₉ is used to collect the current value of the input terminal of the storage battery for the second station in real time, and judge whether the collected current value reaches 85% of the total capacity. If so, the controller controls the nineteenth circuit breaker QF ₁₉ is in the quantile state; otherwise, continue to collect in real time;

Step 3. When the circuit breaker QF _G at the output end of the station transformer detects a failure of the 35KV station transformer, the controller sends a signal to the circuit breaker QF _G at the output end of the station transformer, the first circuit breaker QF ₁ , and the seventh circuit breaker QF _7. The eighth circuit breaker QF ₈ , the ninth circuit breaker QF ₉ and the tenth circuit breaker QF ₁₀ are placed in the sub-position state to control the backup transformer output terminal circuit breaker QF _B , the eleventh circuit breaker QF ₁₁ and the tenth circuit breaker The four circuit breakers QF ₁₄ are in the closed state, and control the switch blades of the first dual power switch QF _8-1 and the second dual power switch QF _8-2 to be in the standby transformer, so that the system enters the standby transformer working state;

In the embodiment of the present invention, when the circuit breaker QF _G at the output end of the station transformer detects a failure of the 35KV station transformer, it is automatically put into the station backup transformer, QF _G is disconnected, QF ₁₄ is closed, QF ₁₁ is closed, and QF _8-1 double The switch is turned to the _M2 side, the switch QF _D of the DC bus coupling cabinet is closed, and the backup transformer is charged from the 380V/AC bus of the backup transformer to the 220V/DC bus of the second substation through the bidirectional inverter.

Step 4. When the current transformer of the circuit breaker QF _B at the output end of the backup transformer of the station detects that the current value suddenly changes to 0, control the fifth circuit breaker QF ₅ , the eleventh circuit breaker QF ₁₁ and the fourteenth circuit breaker QF ₁₄ In the sub-position state, control the twenty-sixth circuit breaker QF _D to close, and control the first dual power switch QF _{8-1 to} disconnect, and the switch knife of the second dual power switch QF _8-2 to connect to the main transformer end, so that The system enters the working state of the microgrid;

In the embodiment of the present invention, when both the main and backup power sources fail, QF _G and QF ₁₄ are disconnected, the QF _8-2 double-throw switch is cast to the M ₁ side (main transformer end), and the photovoltaic panel is passed by the microgrid 380V/AC bus The second bidirectional inverter supplies power to the DC load of the station. One photovoltaic array operates as a master station to provide reference voltage and frequency, and the other photovoltaic arrays operate as slave stations in PQ mode to provide constant power.

Give priority to supply power to important loads (communication, monitoring and lighting equipment) on the microgrid 380V/AC bus.

Step 5. When the system enters the working state of the microgrid, set the priority of the DC load according to the actual demand, and disconnect the circuit breaker corresponding to the DC load with a lower priority according to the priority;

In the embodiment of the present invention, according to the priority, the circuit breaker corresponding to the DC load with a low priority is disconnected, and the number of circuit breakers to be disconnected is set according to actual needs, and the priority of communication, monitoring and lighting equipment is the highest.

Step 6. Use the first transformer CT ₁ to collect the current value output by the photovoltaic panel on the wall in real time, and use the second transformer CT ₂ to collect the current value output by the photovoltaic panel on the roof in real time. If the collected current value is greater than 0, the system is normal work, if the collected current value is equal to 0, then control the second circuit breaker QF ₂ and the third circuit breaker QF ₃ to be in the divided state, and control the fourth circuit breaker QF ₄ , the seventeenth circuit breaker QF ₁₇ and the nineteenth circuit breaker The circuit breaker QF ₁₉ is in the closing state;

In the embodiment of the present invention, when the AC bus coupler QF ₁ is disconnected at night or in the absence of light, the QF _8-1 double-throw switch is turned to the middle, and the QF _8-2 double-throw switch is turned to the M ₁ side to prevent the power from being used by the station. The AC power provided by the battery through the bidirectional inverter directly flows back to the charger through the QF _8-1 double-throw switch, and the micro-grid battery and station battery can supply power to DC loads and important loads (communication, monitoring and lighting equipment).

The status of the main and standby power sources and the position of the double-throw switch are shown in the table below:

Table 1

Step 7. When the power supply of the system is restored, the circuit breaker QF _G at the output end of the station transformer detects the voltage difference between its two ends. If the voltage difference is 0, it remains unchanged; otherwise, adjust the voltage of each inverter in the power grid. Output voltage phase, so that the microgrid 380V/AC bus voltage frequency and phase are the same as the substation 380V/AC bus voltage frequency and phase, or within the allowable range, that is, the voltage difference is 10%, the frequency difference is 0.3Hz, and the QF is controlled _G , QF ₁ , QF ₇ , QF ₈ , QF ₉ , and QF ₁₀ are in the closed state, QF _D is in the sub-position state, and the first double power switch is controlled at the main transformer end, and all DC loads for the station are put into operation; The allowable range described above is set according to actual needs.

In the embodiment of the present invention, the station microgrid has a self-healing function. When the system resumes power supply, the voltage frequency phase difference at both ends of the circuit breaker is detected by _QFG , and the voltage phase of each inverter in the microgrid system is automatically adjusted to make the microgrid The grid 380V/AC bus voltage frequency and phase are the same as the substation 380V/AC bus voltage frequency and phase, or within the allowable range, the microgrid system changes from the island operation state to the grid-connected operation state.

In the embodiment of the present invention, the real-time detection of the grid data is realized through the display, as follows:

Main interface: after the system starts, the main interface is displayed; in the embodiment of the present invention, the function menu of the monitoring system is added to the main interface by using the menu control under the VC environment, including the main operation interface, serial port settings, inverter data, historical data, Parameter setting and other menu items.

Status operation interface: The main operation interface of the system displays data such as historical total power generation, cumulative power generation time, daily power generation, smoke and dust emission reduction, and instantaneous power real-time curve.

Human-computer interaction interface: design an interactive interface suitable for customer requirements; standard graphic element library, easy to call and combine; real-time data collection and display; automatic logic calculation and processing of data information; remote change and setting of equipment parameters; closing and opening status display and other functions.

Curve and report management settings: trend curves of electrical parameters required by customers; historical trends of power consumption; design of various reports to meet customer needs; automatic generation of daily, monthly, and annual reports for electric energy measurement; templates can be set according to commonly used MSExcel And generate corresponding reports to make it easy for users to use; query reports at any time, display and print.

Background database management: widely used database software such as MSSQL, SQLServer, etc.; establish an open, networked database; store specified years or all data information; support C/S, B/S remote access, and realize data remote transmission.

Communication management settings: Each serial port of the data collector is configured independently, which is easy to operate; the communication protocol and communication baud rate of different devices are independently selected; the system automatically performs unified remote control configuration for each device connected to the corresponding port of the data collector according to the selection result.

Claims (5)

1. A substation microgrid system containing distributed power sources, characterized in that it includes a first transformer, a second transformer, a third transformer, a first circuit breaker, a second circuit breaker, a third circuit breaker, The fourth circuit breaker, the fifth circuit breaker, the sixth circuit breaker, the seventh circuit breaker, the eighth circuit breaker, the ninth circuit breaker, the tenth circuit breaker, the eleventh circuit breaker, the twelfth circuit breaker, the thirteenth circuit breaker Circuit breaker, fourteenth circuit breaker, fifteenth circuit breaker, sixteenth circuit breaker, seventeenth circuit breaker, eighteenth circuit breaker, nineteenth circuit breaker, twentieth circuit breaker, twenty-first circuit breaker circuit breaker, twenty-second circuit breaker, twenty-third circuit breaker, twenty-fourth circuit breaker, twenty-fifth circuit breaker, twenty-sixth circuit breaker, first double power switch, second double power switch, control devices and displays, where, The first transformer is set between the wall photovoltaic panel and the first grid-connected inverter in the grid, and the second transformer is set between the roof photovoltaic panel and the second grid-connected inverter in the grid , the third transformer is set between the micro-grid battery in the power grid and the first bidirectional inverter, the first transformer output terminal, the second transformer output terminal and the third transformer output terminal are connected to the input of the controller through the bus end; One end of the first circuit breaker is connected to the 380V/AC busbar of the microgrid, and the other end is connected to the 380V/AC busbar of the substation; one end of the second circuit breaker is connected to the first grid-connected inverter, and the other end is connected to the 380V/AC busbar of the microgrid; One end of the third circuit breaker is connected to the second grid-connected inverter, and the other end is connected to the microgrid 380V/AC bus; one end of the fourth circuit breaker is connected to the first bidirectional inverter, and the other end is connected to the microgrid 380V/AC busbar; the fifth circuit breaker One end is connected to the microgrid 380V/AC busbar, and the other end is connected to one end on the double-head side of the first dual power switch; one end of the sixth circuit breaker is connected to the microgrid 380V/AC busbar, and the other end is connected to one end on the double-head side of the second dual power switch; One end of the seventh circuit breaker is connected to the 380V/AC bus of the substation, and the other end is connected to the AC feeder for the station. One end of the eighth circuit breaker is connected to the 380V/AC bus of the substation, and the other end is connected to the AC feeder for the station. One end of the ninth circuit breaker is connected to the 380V/AC substation Busbar, the other end is connected to the AC feeder for the station, one end of the tenth circuit breaker is connected to the 380V/AC busbar of the substation, and the other end is connected to the AC feeder for the station; one end of the eleventh circuit breaker is connected to the 380V/AC busbar of the microgrid, and the other end is connected to the standby transformer 380V /AC busbar, one end of the twelfth circuit breaker is connected to the microgrid 380V/AC busbar, and the other end is connected to communication, monitoring or lighting equipment, one end of the thirteenth circuit breaker is connected to the microgrid 380V/AC busbar, and the other end is connected to communication, monitoring or lighting Equipment; one end of the fourteenth circuit breaker is connected to the spare transformer 380V/AC busbar, and the other end is simultaneously connected to the second end of the double-head side of the first double power switch and the second end of the double-head side of the second double power switch; the fifteenth circuit breaker One end is connected to the single head side of the second double power switch, the other end is connected to the input end of the second bidirectional inverter in the power grid, and the single head side of the second double power switch is connected to the charger input end in the power grid; the sixteenth circuit breaker One end is connected to the output end of the charger in the grid, the other end is connected to the 220V/DC busbar of the first substation, one end of the seventeenth circuit breaker is connected to the battery for the first station in the grid, and the other end is connected to the 220V/DC busbar of the first substation One end of the eighteenth circuit breaker is connected to the second bidirectional inverter in the power grid, and the other end is connected to the 220V/DC bus bar of the second substation. One end of the nineteenth circuit breaker is connected to the battery for the second station in the power grid, and the other end is connected to the second station The 220V/DC busbar of the second-section substation; one end of the 20th circuit breaker is connected to the 220V/DC busbar of the first-section substation, the other end is connected to the station DC feeder, one end of the 21st circuit breaker is connected to the 220V/DC busbar of the first-section substation, and One end is connected to the DC feeder for the station, one end of the 22nd circuit breaker is connected to the 220V/DC busbar of the first substation, the other end is connected to the DC feeder for the station, one end of the 23rd circuit breaker is connected to the 220V/DC busbar of the second substation, and the other end is connected to the 220V/DC busbar of the second substation. One end is connected to the DC feeder for the station, one end of the 24th circuit breaker is connected to the 220V/DC busbar of the second substation, the other end is connected to the DC feeder for the station, and one end of the 25th circuit breaker is connected to the 220V/DC substation of the second section Busbar, the other end is connected to the DC feeder for the station; one end of the twenty-sixth circuit breaker is connected to the 220V/DC busbar of the first substation, and the other end is connected to the 220V/DC busbar of the second substation; The output end of the current transformer of the first circuit breaker, the output end of the current transformer of the second circuit breaker, the output end of the current transformer of the third circuit breaker, the output end of the current transformer of the fourth circuit breaker, the fifth circuit breaker The current transformer output terminal of the circuit breaker, the current transformer output terminal of the sixth circuit breaker, the current transformer output terminal of the seventh circuit breaker, the current transformer output terminal of the eighth circuit breaker, the current transformer output of the ninth circuit breaker terminal, output terminal of the current transformer of the tenth circuit breaker, output terminal of the current transformer of the eleventh circuit breaker, output terminal of the current transformer of the twelfth circuit breaker, output terminal of the current transformer of the thirteenth circuit breaker, the output terminal of the current transformer of the thirteenth circuit breaker, The output end of the current transformer of the fourteenth circuit breaker, the output end of the current transformer of the fifteenth circuit breaker, the output end of the current transformer of the sixteenth circuit breaker, the output end of the current transformer of the seventeenth circuit breaker, the output end of the eighteenth circuit breaker The current transformer output end of the circuit breaker, the current transformer output end of the nineteenth circuit breaker, the current transformer output end of the twentieth circuit breaker, the current transformer output end of the twenty-first circuit breaker, the twenty-second The current transformer output terminal of the circuit breaker, the current transformer output terminal of the twenty-third circuit breaker, the current transformer output terminal of the twenty-fourth circuit breaker, the current transformer output terminal of the twenty-fifth circuit breaker and the second The output ends of the current transformers of the sixteen circuit breakers are connected to the controller through the bus; The current transformer output terminal of the circuit breaker at the station transformer output end in the power grid and the current transformer output end of the backup transformer output circuit breaker are connected to the controller through the bus; The output terminal of the controller is respectively connected to the control terminal of each circuit breaker through the bus; The output end of the controller is connected with the input end of the display. 2. The substation micro-grid system containing distributed power sources according to claim 1, characterized in that, the output end of the current transformer of the first dual power switch and the output end of the current transformer of the second dual power switch The controller is also connected via the bus. 3. realize the control method of the substation micro-grid system that contains distributed power source described in claim 1, it is characterized in that, comprise the following steps: Step 1. Use the controller to control the eleventh circuit breaker, the fourteenth circuit breaker, and the backup transformer output end circuit breaker to be in the sub-position state, and control the switch blades of the first dual power switch and the second dual power switch to be at the main transformer end. And control other circuit breakers to be in the closing state, so that the system enters the working state of the main transformer; Step 2. Use the third transformer to collect the current value of the input terminal of the microgrid battery in real time, and judge whether the collected current value reaches the set value. If so, the controller controls the fourth circuit breaker to be in the split state; otherwise, continue real-time collection; The current transformer of the seventeenth circuit breaker is used to collect the current value of the input terminal of the storage battery for the first station in real time, and judge whether the collected current value reaches the set value, and if so, the controller controls the seventeenth circuit breaker to be in the positional state ;Otherwise, continue real-time acquisition; The current transformer of the nineteenth circuit breaker is used to collect the current value of the battery input terminal of the second station in real time, and judge whether the collected current value reaches the set value, and if so, the controller controls the nineteenth circuit breaker to be in the sub-position state ;Otherwise, continue real-time acquisition; Step 3. When the circuit breaker at the output end of the station transformer detects a failure of the 35KV station transformer, the controller sends a signal to the circuit breaker at the output end of the station transformer, the first circuit breaker, the seventh circuit breaker, the eighth circuit breaker, the The ninth circuit breaker and the tenth circuit breaker are in the sub-position state, and the backup transformer output terminal circuit breaker, the eleventh circuit breaker and the fourteenth circuit breaker are in the closing state, and the first double power switch and the second The switch knife of the dual power switch is in the standby transformer end, so that the system enters the working state of the standby transformer; Step 4. When the current transformer of the circuit breaker at the output end of the backup transformer detects that the current value suddenly changes to 0, control the fifth circuit breaker, the eleventh circuit breaker, and the fourteenth circuit breaker to be in the split state, and control the twenty The six circuit breakers are closed, and the first dual power switch is controlled to be disconnected, and the switch knife of the second dual power switch is connected to the main transformer end, so that the system enters the working state of the microgrid; Step 5. When the system enters the working state of the microgrid, set the priority of the DC load according to the actual demand, and disconnect the circuit breaker corresponding to the DC load with a lower priority according to the priority; Step 6. Use the first transformer to collect the current value output by the photovoltaic panel on the wall in real time, and use the second transformer to collect the current value output by the photovoltaic panel on the roof in real time. If the collected current value is greater than 0, the system works normally. If the current value is equal to 0, the second circuit breaker and the third circuit breaker are controlled to be in the sub-position state, and the fourth circuit breaker, the seventeenth circuit breaker and the nineteenth circuit breaker are controlled to be in the closing state; Step 7. When the 35KV substation transformer resumes power supply, the circuit breaker at the output end of the station transformer will detect the voltage difference between the two ends. If the voltage difference is 0, it will remain unchanged; otherwise, adjust each grid-connected inverter in the power grid. The output voltage phase of the transformer, so that the frequency and phase of the 380V/AC bus voltage of the microgrid are the same as the frequency and phase of the 380V/AC bus voltage of the substation, or within the allowable range, and control the circuit breaker and the first circuit breaker at the output end of the station transformer The circuit breaker, the seventh circuit breaker, the eighth circuit breaker, the ninth circuit breaker and the tenth circuit breaker are in the closed state, the twenty-sixth circuit breaker is in the sub-position state, and the control switch of the first double power switch is located at the main transformer end. Put all the station DC loads into operation. 4. The control method according to claim 3, characterized in that, according to the priority in step 5, the circuit breaker corresponding to the DC load with a low priority is disconnected, and the number of disconnected circuit breakers is set according to the actual demand. set, with communication, monitoring and lighting equipment having the highest priority. 5. The control method according to claim 3, characterized in that the allowable range in step 7 is set according to actual needs.