Source-load interaction grading stability control system based on micro-grid architecture

Abstract

The invention, which belongs to the technical field of micro-grid operation control, provides a source-load interaction grading stability control system based on a micro-grid architecture, and the system comprises a distributed energy module, an energy storage module, a control module, a communication module, a monitoring module, a communication interruption processing module and a load. The distributed energy module is used for supplying power to a load and the energy storage module, the energy storage module is used for storing standby power and performing supplementary power supply on the load, the control module controls power supply of the load and charging of the energy storage module, and the communication module realizes data communication among the modules. The monitoring module collects parameter information of the system and sends the parameter information to the control module, and the communication interruption processing module determines a processing strategy according to an interruption level to track a deviation level and protect a load when communication interruption occurs. The method has the beneficial effects that the composite stability control architecture of SOC dynamic monitoring and multi-level threshold triggering is combined with a three-level communication degradation strategy, so that the response speed, the control precision and the anti-disturbance capability of the system can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of microgrid operation control, and specifically relates to a source-load interaction hierarchical stability control system based on a microgrid architecture. Background Art

[0002] With the development of distributed generation, microgrids have received increasing attention. Microgrids have high flexibility and can not only operate independently but also achieve grid-connected operation efficiently, so they are highly favored. However, microgrids are greatly affected by the environment and have insufficient anti-disturbance ability under harsh working conditions, which seriously restricts the development of microgrids.

[0003] In order to improve the anti-disturbance ability of microgrids, many experts and scholars have conducted research and achieved some results, but there are still deficiencies.

[0004] Although Patent CN118944099A proposes source-grid interaction load control, it does not involve energy storage dynamic strategies, cannot handle scenarios of SOC changes, relies on a static rule library, does not implement a multi-level threshold trigger mechanism, and the response delay still exceeds the second level.

[0005] Patent CN116862042A only uses the LSTM model to predict the load and does not combine hardware architecture optimization, so it cannot handle abnormal working conditions such as communication interruptions.

[0006] Patent CN117200363A focuses on the interaction between power grids and it is difficult to provide necessary protection for the load side under harsh working conditions. Summary of the Invention

[0007] To solve the problems in the above background art, the present invention provides a source-load interaction hierarchical stability control system based on a microgrid architecture, which can improve the response speed, control accuracy, and anti-disturbance ability of the system.

[0008] To achieve the above object, the present invention provides a source-load interaction hierarchical stability control system based on a microgrid architecture, including a distributed energy module, an energy storage module, a control module, a communication module, a monitoring module, a communication interruption processing module, and a load;

[0009] The distributed energy module is used to supply power to the load and also to charge the energy storage module;

[0010] The energy storage module is used to store backup power and supply supplementary power to the load according to the instructions of the control module;

[0011] The control module is used to control the power supply amounts of the distributed energy module and the energy storage module, manage the power supply to the load according to the deviation level, and control the charge and discharge of the energy storage module according to the charging power error of the lithium battery pack in the energy storage module;

[0012] The communication module is used to implement data communication between the control module and the distributed energy module, the energy storage module, and the load.

[0013] The monitoring module uses sensors to collect the power, voltage, and frequency information of the system, and sends the data to the control module through the communication module.

[0014] The communication interruption processing module is used to determine the processing strategy according to the interruption level to track the deviation level and protect the load when a communication interruption occurs.

[0015] Furthermore, in the distributed energy module, the total penetration rate of wind power and photovoltaic power generation is ≥ 30%, and a maximum power point tracking controller is equipped.

[0016] Furthermore, the power supply management steps of the control module for the load are as follows:

[0017] S301 Classify the load, and divide the load into critical load, adjustable load, and standby load;

[0018] S302 Determine the priority of each type of load, specifically: the critical load is non-interruptible, the adjustable load is dynamically adjusted, and the standby load is cuttable;

[0019] S303 When the deviation level is 1, adjust the adjustable load. When the deviation level is 2, enable energy storage discharge and diesel generator. When the deviation level is 3, cut the non-critical load.

[0020] Furthermore, the strategy of the control module for the charge and discharge control of the energy storage module is:

[0021] P ess = k p (P pred - P real ) + k i ∫(P pred - P real )dt;

[0022] Among them, P ess is the charge and discharge power, P pred is the power prediction value, P real is the actual power value. When P ess is positive, it means charging. When P ess is negative, it means discharging. k p and k i are positive real numbers. When k p takes 0.8 and k i takes 0.05, the effect is better.

[0023] Further, in step S303, when the state of charge (SOC) of the battery is less than 20%, the diesel generator is preferentially started, and when the SOC of the battery is greater than 80%, the energy storage is forced to discharge.

[0024] The state of charge (SOC) of the battery can be expressed as:

[0025]

[0026] Further, the steps for determining the deviation level are as follows:

[0027] S601 Obtain power, voltage, frequency and other power parameter information of the system. Then, the deviation parameter of the system is:

[0028]

[0029] where ΔX% is the deviation parameter, and X a1 and X n1 are the actual value and the nominal value of the power respectively, X a2 and X n2 are the actual value and the nominal value of the voltage respectively, X a3 and X n3 are the actual value and the nominal value of the frequency respectively;

[0030] S602 The deviation levels are sequentially divided into 0, 1, 2, and 3. The system determines the deviation level according to the deviation parameter. When 0 < ΔX% ≤ 10%, the deviation level is tentatively set to 0. When 10% < ΔX% ≤ 15%, the deviation level is tentatively set to 1. When 15% < ΔX% ≤ 20%, the deviation level is tentatively set to 2. When ΔX% > 20%, the deviation level is tentatively set to 3;

[0031] S603 Further correct the deviation level with the frequency change rate and the fuzzy control parameter. The fuzzy control parameter is expressed as:

[0032]

[0033] where β is the fuzzy control parameter, F b is the absolute value of the frequency change rate, and F bmax is the maximum value of the absolute value of the allowable frequency change rate;

[0034] S604 Judge the magnitude of β. When β > 1, increase the deviation level by one level. The highest deviation level is level 3.

[0035] Further, the energy storage module uses a lithium battery pack to store electrical energy. The monitoring accuracy of the state of charge (SOC) of the lithium battery pack is ±1%, and it supports charging and discharging through a bidirectional converter.

[0036] Further, the communication interruption processing module divides the interruption level according to the interruption time. When the interruption time is less than 10 s, it is the first-level degradation; when the interruption time is between 10 and 30 s, it is the second-level degradation; when the interruption time is greater than 30 s, it is the third-level degradation;

[0037] When the first-level degradation occurs, the local LSTM neural network model is enabled to track the deviation level, predict the current deviation level, and perform corresponding operations;

[0038] When the second-level degradation occurs, switch to the ARIMA model to track the deviation level and perform corresponding operations;

[0039] When the third-level degradation occurs, set the deviation level to 3 and perform the operation of cutting off non-critical loads.

[0040] Further, the success rate of the communication interruption processing module in processing communication interruptions is ≥92%;

[0041] The success rate of the communication interruption processing refers to the success rate of the overall operation of the system during communication interruptions.

[0042] The present invention also provides a storage medium for storing program codes for implementing the system.

[0043] Beneficial effects: The present invention proposes a composite stability control architecture for SOC dynamic monitoring and multi-level threshold triggering, combined with a three-level communication degradation strategy, which can improve the response speed, control accuracy and anti-disturbance ability of the system, and effectively improve the energy storage cycle efficiency. Description of the Drawings

[0044] The following further describes the present invention with reference to the drawings and embodiments:

[0045] Figure 1 It is the system control block diagram of the present invention;

[0046] Figure 2 It is the multi-level stability control strategy flow chart of the present invention;

[0047] Figure 3 It is the processing strategy flow chart of the communication interruption processing module of the present invention;

[0048] Figure 4 It is the voltage comparison diagram under extreme working conditions of the present invention;

[0049] Figure 5 It is the effect diagram of the charge and discharge strategy of the energy storage module of the present invention. Detailed Embodiments

[0050] Embodiment 1

[0051] As Figures 1 to 3As shown in the figure, a hierarchical stability control system for source-load interaction based on a microgrid architecture includes a distributed energy module, an energy storage module, a control module, a communication module, a monitoring module, a communication interruption handling module, and a load;

[0052] The distributed energy module is used to supply power to the load and also to charge the energy storage module. Among them, the total penetration rate of wind power and photovoltaic power generation is ≥ 30%, and a maximum power point tracking controller is equipped;

[0053] The energy storage module uses a lithium battery pack to store electrical energy. The monitoring accuracy of the state of charge (SOC) of the lithium battery pack during charging is ±1%. It supports bidirectional inverter charging and discharging, is used to store backup power, and supplies supplementary power to the load according to the instructions of the control module;

[0054] The control module is used to control the power supply of the distributed energy module and the energy storage module, manage the power supply to the load according to the deviation level, and control the charging and discharging of the energy storage module according to the charging power error of the lithium battery pack in the energy storage module;

[0055] The communication module is used to realize data communication between the control module and the distributed energy module, the energy storage module, and the load;

[0056] The monitoring module uses sensors to collect power, voltage, and frequency information of the system, and sends the data to the control module through the communication module;

[0057] The communication interruption handling module is used to decide on a handling strategy according to the interruption level to predict the deviation level and protect the load when a communication interruption occurs. The division of the interruption level is determined by the interruption time. When the interruption time is less than 10 s, it is a first-level downgrade. When the interruption time is between 10 and 30 s, it is a second-level downgrade. When the interruption time is greater than 30 s, it is a third-level downgrade;

[0058] When a first-level downgrade occurs, the local LSTM neural network model is enabled to track the deviation level, predict the current deviation level, and perform corresponding operations;

[0059] When a second-level downgrade occurs, switch to the ARIMA model to track the deviation level and perform corresponding operations;

[0060] When a third-level downgrade occurs, set the deviation level to 3 and perform the operation of cutting off non-critical loads;

[0061] The success rate of communication interruption handling is ≥ 92%. The success rate of communication interruption handling refers to the success rate of the overall operation of the system during communication interruption.

[0062] Furthermore, the steps of the control module for power supply management of the load are as follows:

[0063] Classify the S301 load and divide the load into critical load, adjustable load, and standby load;

[0064] S302 Determine the priority of each type of load, specifically: the critical load is non-interruptible, the adjustable load is dynamically adjustable, and the standby load is cuttable;

[0065] S303 When the deviation level is 1, adjust the adjustable load. When the deviation level is 2, enable energy storage discharge and diesel generator. Among them, when the state of charge (SOC) of the battery < 20%, the diesel generator is preferentially started. When the state of charge (SOC) of the battery > 80%, forced energy storage discharge is performed. When the deviation level is 3, cut the non-critical load;

[0066] The state of charge (SOC) of the battery can be expressed as:

[0067]

[0068] The strategy of the control module for charging and discharging control of the energy storage module is:

[0069] P ess = k p (P pred - P real ) + k i ∫(P pred - P real )dt;

[0070] Among them, P ess is the charging and discharging power, P pred is the power prediction value, P real is the actual power value. When P ess is positive, it means charging. When P ess is negative, it means discharging. k p and k i are positive real numbers. When k p takes 0.8 and k i takes 0.05, the effect is better.

[0071] Furthermore, the steps for determining the deviation level are:

[0072] S601 Obtain the power, voltage, frequency and other electrical parameter information of the system. Then the deviation parameter of the system is:

[0073]

[0074] Among them, ΔX% is the deviation parameter, X a1 , X n1 are the actual value and the system nominal value of the power respectively, X a2 , X n2 are the actual value and the system nominal value of the voltage respectively, Xa3 , X n3 are the actual value and the system nominal value of the frequency, respectively;

[0075] The deviation levels of S602 are divided into 0, 1, 2, and 3 in sequence. The system determines the deviation level according to the deviation parameter. When 0 < ΔX% ≤ 10%, the deviation level is tentatively set to 0. When 10% < ΔX% ≤ 15%, the deviation level is tentatively set to 1. When 15% < ΔX% ≤ 20%, the deviation level is tentatively set to 2. When ΔX% > 20%, the deviation level is tentatively set to 3;

[0076] S603 further corrects the deviation level with the frequency change rate and the fuzzy control parameter. The fuzzy control parameter is expressed as:

[0077]

[0078] where β is the fuzzy control parameter, F b is the absolute value of the frequency change rate, and F bmax is the maximum value of the absolute value of the allowable frequency change rate;

[0079] S604 judges the magnitude of β. When β > 1, the deviation level is raised by one level. The highest deviation level is 3. For example, when the currently tentative deviation level is 1, but the fuzzy control parameter is 1.2, the deviation level is adjusted to 2 at this time. When the currently tentative deviation level is 3 and the fuzzy control parameter is 1.2, the deviation level remains 3.

[0080] Embodiment 2

[0081] Combined with Embodiment 1, a source-load interaction hierarchical stable control system model based on the microgrid architecture is built on SIMULINK. The system parameters are set as follows: Photovoltaic capacity: 10 MW, energy storage system: 5 MW / 20 MWh lithium battery, adjustable load: 3 MW flexible production line, extreme condition: typhoon scenario. The simulation results are as Figures 4 to 5 shown. It can be seen from this that in the extreme condition of the present invention, the fluctuation range of the per-unit voltage is only 2%, which is much smaller than 8% of the traditional method, and has good anti-disturbance ability. And the response time of the energy storage dynamic compensation is ≤ 300 ms, and the response speed is relatively fast. At the same time, the charge and discharge strategy of the energy storage module of the present invention can effectively improve the energy storage cycle efficiency.

[0082] Embodiment 3

[0083] Verify the effect of communication interruption, and the results are shown in Table 1.

[0084] Table 1 Communication Interruption Fault Tolerance Test As can be seen from the table, the three-level degradation processing strategy used by the communication interruption processing module of the present invention has high tracking accuracy and has a good protection effect on the device.

[0085] Embodiment 4

[0086] The present invention also provides a storage medium for storing program codes for implementing the system.

[0087] The above embodiments are only the preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. The protection scope of the present invention should be the technical solutions recited in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recited in the claims. That is, the equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A source-load interaction hierarchical stability control system based on a microgrid architecture, characterized in that: It includes a distributed energy module, an energy storage module, a control module, a communication module, a monitoring module, a communication interruption handling module, and a load; The distributed energy module is used to supply power to the load and also to charge the energy storage module; The energy storage module is used to store backup power and supplement power to the load according to the instructions of the control module; The control module is used to control the power supply amounts of the distributed energy module and the energy storage module, manage the power supply to the load according to the deviation level, and control the charge and discharge of the energy storage module according to the charging power error of the lithium battery pack in the energy storage module; The communication module is used to realize data communication between the control module, the distributed energy module, the energy storage module, and the load; The monitoring module uses sensors to collect the power, voltage, and frequency information of the system and sends the data to the control module through the communication module; The communication interruption handling module is used to determine the handling strategy according to the interruption level to track the deviation level and protect the load when a communication interruption occurs.

2. The system according to claim 1, wherein: In the described distributed energy module, the total penetration rate of wind power and photovoltaic power generation is ≥ 30%, and it is equipped with a maximum power point tracking controller.

3. The system according to claim 1, wherein: The steps for the control module to manage the power supply to the load are as follows: S301 Classify the load, and divide the load into critical load, adjustable load, and standby load; S302 Determine the priority of each type of load, specifically: the critical load is non-interruptible, the adjustable load is dynamically adjustable, and the standby load is cuttable; S303 When the deviation level is 1, adjust the adjustable load. When the deviation level is 2, enable the energy storage to discharge and the diesel generator. When the deviation level is 3, cut off the non-critical load.

4. The system according to claim 1, wherein: The strategy for the control module to control the charge and discharge of the energy storage module is as follows: Among them, P ess is the charge-discharge power, P pred is the power prediction value, and P real is the actual power value. When P ess is positive, it indicates charging. When P ess is negative, it indicates discharging. k p and k i are positive real numbers. When k p takes 0.8 and k i takes 0.05, the effect is better.

5. The system according to claim 3, wherein: In step S303, when the state of charge (SOC) of the battery < 20%, the diesel generator is preferentially started. When the state of charge (SOC) of the battery > 80%, the energy storage is forced to discharge; The state of charge (SOC) of the battery can be expressed as:

6. The system according to claim 1 or 3, characterized in that: The steps for determining the deviation level are as follows: S601 Obtain the power, voltage, frequency and other power parameter information of the system, then the deviation parameter of the system is: Among them, ΔX% is the deviation parameter, and X a1 and X n1 are the actual value and the system nominal value of the power respectively, and X a2 and X n2 are the actual value and the system nominal value of the voltage respectively, and X a3 and X n3 are the actual value and the system nominal value of the frequency respectively; S602 The deviation levels are successively divided into 0, 1, 2, 3. The system determines the deviation level according to the deviation parameter. When 0 < ΔX% ≤ 10%, the deviation level is tentatively set to 0. When 10% < ΔX% ≤ 15%, the deviation level is tentatively set to 1. When 15% < ΔX% ≤ 20%, the deviation level is tentatively set to 2. When ΔX% > 20%, the deviation level is tentatively set to 3; S603 Further correct the deviation level with the frequency change rate and the fuzzy control parameter, and the fuzzy control parameter is expressed as: Among them, β is the fuzzy control parameter, F b is the absolute value of the frequency change rate, and F bmax is the maximum value of the absolute value of the allowable frequency change rate; S604 Judge the magnitude of β. When β > 1, raise the deviation level by one level, and the highest deviation level is 3 levels.

7. The system according to claim 1, characterized in that: For the described energy storage module, a lithium battery pack is used to store electrical energy. The monitoring accuracy of the state of charge (SOC) of the lithium battery pack is ±1%, and it supports bidirectional converter charge and discharge.

8. The system according to claim 1, characterized in that: For the described communication interruption handling module, the interruption level is divided according to the interruption time. When the interruption time is less than 10s, it is the first-level degradation. When the interruption time is between 10 and 30s, it is the second-level degradation. When the interruption time is greater than 30s, it is the third-level degradation; When a first-level degradation occurs, the local LSTM neural network model is enabled to track the deviation level, predict the current deviation level, and perform corresponding operations; When a second-level degradation occurs, switch to the ARIMA model to track the deviation level and perform corresponding operations; When a third-level degradation occurs, set the deviation level to 3 and perform the operation of cutting off non-critical loads.

9. The system according to claim 8, wherein: For the communication interruption handling module described above, the success rate of communication interruption handling is ≥ 92%; The success rate of communication interruption handling described above refers to the success rate of the overall system maintaining operation during communication interruption.

10. A storage medium, characterized in that: Store the program code for implementing the system described in claims 1-9.

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