Diesel-storage photoelectric network system and fault control method of diesel-storage photoelectric network system

Abstract

The invention discloses a diesel storage photoelectric network system which comprises a photovoltaic system, a diesel generator set, a load, an energy storage device and a control unit. The control unit comprises a monitoring module, and the monitoring module is connected with the diesel generator set, the photovoltaic system, the load and the energy storage device. The monitoring module is connected with a control module, and the control module is connected with a switching execution module and a communication module; the switching execution module is connected with the diesel generator set and the energy storage device. The communication module is connected with a diesel generator controller, a photovoltaic inverter, an energy storage BMS, a load management system and a control center. The invention further discloses a control method of the diesel storage photoelectric network system. The control method comprises a diesel generator set fault control method and a photovoltaic power sudden drop control method. According to the system and the method, rapid cooperation of the energy storage and the diesel generator can be realized, seamless switching between power supplies is ensured when the system encounters a fault, and continuous and stable power supply of a key load is ensured.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of multi-source hybrid power supply, and particularly relates to a diesel storage photovoltaic grid system, and also relates to a fault control method of the diesel storage photovoltaic grid system. BACKGROUND

[0002] In modern multi-source power supply systems, diesel generator sets, energy storage devices and renewable energy (typically represented by photovoltaic) work together to provide power support for loads. This kind of system integrates multiple energy sources to improve power supply stability and sustainability, but it faces many complex fault challenges during operation.

[0003] As an important power supply unit, the diesel generator set may be mechanically damaged due to long-term wear and tear of mechanical parts, such as piston ring damage, crankshaft fracture, etc., so that the unit cannot operate normally; problems in the fuel supply system, such as fuel filter blockage and oil pump failure, can also cause the unit to stop working; abnormal control system, such as sensor failure and controller program error, can also cause the unit to run disorderly or even stop.

[0004] The photovoltaic system is highly dependent on weather conditions. When clouds block the sun, the light intensity decreases significantly, and the power generation of the photovoltaic panel will also decrease sharply; in rainy weather, rainwater adheres to the surface of the photovoltaic panel, affecting light absorption, and even may cause circuit short circuit due to water accumulation, resulting in power generation of the photovoltaic system decreasing to zero output.

[0005] In the face of the above faults, the existing multi-source power supply system exposes a series of problems. In the power switching link, due to the delay in detecting faults, starting standby power and other processes, it will cause the load to be temporarily powered off. This may cause data loss, equipment damage and other serious consequences for sensitive equipment such as data center servers, medical precision equipment and other highly sensitive equipment that require continuous power supply. There is a lack of effective cooperative control mechanism between energy storage devices and diesel generator sets, which cannot dynamically optimize the power supply strategy according to the real-time load demand of the power grid, the power generation state of each power source and other factors, making it difficult to achieve optimal system power supply efficiency. When the system fails, it is difficult to quickly and accurately identify critical loads and prioritize their power supply. SUMMARY

[0006] The purpose of the present application is to provide a diesel storage photovoltaic grid system, which can realize the rapid cooperation of energy storage and diesel generator, and ensure seamless switching between power sources when the system encounters a fault, and ensure continuous and stable power supply for critical loads.

[0007] Another technical solution of the present application is a control method of the diesel storage photovoltaic grid system.

[0008] The technical scheme adopted by the present application is a diesel storage photoelectric power grid system, comprising a photovoltaic system, a diesel generator set, a load, an energy storage device, and a control unit. The control unit comprises a monitoring module connected with the diesel generator set, the photovoltaic system, the load, and the energy storage device; the monitoring module is connected with a control module, the control module is connected with a switching execution module and a communication module; the switching execution module is connected with the diesel generator set and the energy storage device; and the communication module is connected with a diesel generator controller, a photovoltaic inverter, an energy storage BMS, a load management system, and a control center.

[0009] The present application has the following characteristics: The monitoring module is used for collecting the operating parameters of the diesel generator set, the photovoltaic system, the load, and the energy storage device, judging the fault information according to the operating data, and transmitting the fault information to the control module; the monitoring module has a fault judgment system embedded therein, which is specifically as follows: When the rotating speed of the diesel generator set is lower than 70% of the rated value and lasts for 3 seconds, or the current oil temperature exceeds the alarm threshold and lasts for 5 seconds, it is determined that the diesel generator set is faulty; when the output power of the photovoltaic system is lower than the threshold, it is determined that the photovoltaic system has a sudden drop in power; The control module is used for receiving the data of the monitoring module and sending instructions to the switching module and the communication module to complete the power grid system regulation and control and fault response; the control module has a decision logic embedded therein, which is specifically as follows: For the diesel generator set fault, first detect the SOC of the energy storage device, if the SOC is greater than or equal to 20%, switch to the energy storage device for power supply, otherwise start the standby diesel generator set; for the sudden drop in photovoltaic power, the control module first calculates the power gap and the proportion of the key load, dynamically adjusts the charging and discharging strategy of the energy storage device and the start and stop of the diesel generator set to maintain system balance; The switching execution module is used for realizing the on-off of the power supply circuit in the fault scenario; The communication module is used for realizing data sharing and collaborative control between the monitoring module, the control module, the switching execution module, and external devices, and uploading information to the monitoring center.

[0010] Another technical scheme adopted by the present application is a diesel storage photoelectric power grid system fault control method, comprising a diesel generator set fault control method and a photovoltaic power sudden drop control method.

[0011] The diesel generator set fault control method has the following characteristics: The diesel generator set fault control method comprises the following steps: Step A1: The monitoring module collects the operating parameters of the diesel generator set in real time, judges whether the diesel generator set has a fault according to the operating parameters, and transmits the fault information to the control module if the diesel generator set has a fault; Step A2: The control module judges the SOC of the energy storage device. If the SOC is greater than or equal to 20%, the switching execution module performs the following operation: opens the diesel generator fault unit output switch and closes the energy storage device output switch. Step A3: The monitoring module monitors the energy storage device discharge power in real time and the SOC. If the predicted SOC will be lower than 10% and the total load power > the energy storage device can use the discharge power , the control module starts the standby diesel generator unit. Step A4: After the standby diesel generator unit is started, the grid-connected condition is verified. After the grid-connected condition is met, the switching execution module closes the standby diesel generator unit output switch, and the control module gradually reduces the energy storage device output power, and the diesel generator unit bears the main load.

[0012] In step A1, whether the diesel generator unit has failed is judged. Specifically, when any of the following conditions is met, it is determined to be a failure: Condition a: the oil temperature is out of limit, and the duration Δ t ≥ 5s, wherein, is the current oil temperature ， is the preset alarm temperature; Condition b: the speed drops suddenly, using the speed change rate measure: ≤−30% , wherein, is the rated speed.

[0013] In step A3, the grid-connected condition is that after the standby diesel generator unit is started, the voltage deviation is less than or equal to 5% and the frequency deviation is less than or equal to 5%, which is expressed as:

[0014] In the formula, represents the output voltage of the standby diesel generator unit; represents the rated voltage of the system;

[0015] In the formula, represents the output voltage frequency of the standby diesel generator unit; represents the rated voltage frequency of the system.

[0016] In step A4, the control module gradually reduces the energy storage device output power, according to the following rules:

[0017] In the formula, represents the diesel generator unit output power; represents the energy storage discharge power, and is:

[0018] wherein, k represents the attenuation coefficient, represents the maximum discharge power of the energy storage device.

[0019] The photovoltaic power sudden drop control method specifically comprises the following steps: Step B1: After the monitoring module detects that the photovoltaic output power is lower than the threshold value, the fault information is transmitted to the control module; Step B2: The control module calculates the total power of the load and the power gap If > 0 and the proportion of the critical load power to the total load power is greater than or equal to 70%, the control module sends an instruction to the load management system through the communication module, so that the non-critical load performs current limiting; at the same time, the SOC of the energy storage device is less than 30% or > 0.8 The control module immediately starts the standby diesel generator set; Step B3: After the standby diesel generator set meets the voltage deviation ≤ 5% and the frequency deviation ≤ 5%, the switching execution module integrates it into the system to form a collaborative power supply mode with the photovoltaic system and the energy storage device, and the total power is represented as:

[0020] wherein, represents the total power, represents the diesel generator set power, represents the photovoltaic system power, P ESS represents the energy storage power; Step B4: The control module dynamically reduces the diesel generator set power, and controls the charging power of the energy storage device.

[0021] In step B2, the power gap is represented as:

[0022] wherein, represents the photovoltaic system power, represents the energy storage discharge power; The current limiting is performed on the non-critical load power , which is represented as:

[0023] wherein, represents the non-critical load power after current limiting, represents the power current limiting ratio of the non-critical load, and the value is , and when When =0, the non-critical load power remains unchanged; when α When =0.5 (i.e. 50%), the non-critical load power is limited to 50% of the original value; when α When =1, the non-critical load is completely cut off.

[0024] In step B4, the control module dynamically reduces the power of the diesel generator set according to the following rules: ; In the formula, P0 represents the initial output of the diesel generator set; The charging power of the energy storage device is controlled as follows: The control module judges the SOC of the energy storage device. If SOC<80%, the energy storage device absorbs the excess photovoltaic power, i.e. the charging power is:

[0025] In the formula, Pex represents the excess power of the photovoltaic system, Pmax represents the maximum charging power of the energy storage device.

[0026] The beneficial effects of the present application are: The diesel storage photovoltaic grid system and the control method for diesel generator fault and photovoltaic power drop of the system of the present application, through the deployment of high-precision sensors and monitoring modules, real-time acquisition of data of the diesel generator set, the energy storage device and the photovoltaic system and the load, combined with the intelligent decision algorithm carried by the system, can deeply analyze the real-time monitoring data. When detecting diesel engine mechanical failure, photovoltaic power drop abnormality, quickly combining the load demand, the state of each power supply, and formulating the optimal power supply strategy. The control module is responsible for efficient execution of the decision instruction, realizes the rapid collaborative switching of the energy storage device and the diesel generator set, ensures the seamless connection of the power supply, and ensures that the critical load always obtains stable power supply. From data acquisition, intelligent analysis to instruction execution, the system's fault response capability in complex working conditions is comprehensively improved, and the power supply reliability and stability defense line is built. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a structural diagram of the diesel storage photovoltaic system diesel generator fault and photovoltaic power drop collaborative control system of the present application; Figure 2 is a diesel generator set fault response method flow chart in the diesel storage photovoltaic system diesel generator fault and photovoltaic power drop collaborative control method of the present application; Figure 3 is a response method flow chart when the photovoltaic power drops in the diesel storage photovoltaic system diesel generator fault and photovoltaic power drop collaborative control method of the present application. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] The diesel storage photovoltaic power grid system of the present invention is as follows: Figure 1 As shown, the system includes a photovoltaic system, a diesel generator set, a load, an energy storage device, and a control unit. The control unit is used to respond to system failures and consists of four core components: a monitoring module (system perception unit), a control module (core decision-making unit), a switching execution module (rapid response unit), and a communication module (data exchange unit). Specifically, the monitoring module is connected to the diesel generator set, the photovoltaic system, the load, and the energy storage device; the monitoring module is connected to the control module, which is connected to the switching execution module and the communication module; the switching execution module is connected to the diesel generator set and the energy storage device respectively; the communication module is connected to the diesel generator controller (for monitoring and managing the operating status of the diesel generator set); the photovoltaic inverter (for converting the DC power output of the solar panels into AC power, etc.); the energy storage BMS (for monitoring, controlling, and protecting the battery pack to ensure safe and efficient operation and optimize battery performance); the load management system (for controlling and optimizing the load of electrical equipment to achieve rational power resource allocation, improve energy efficiency, and stabilize the grid); and the control center. The modules work together to form a complete "monitoring-decision-execution-feedback" closed-loop control system, ensuring that the multi-source power supply system can maintain stable operation under various fault conditions.

[0030] The monitoring module is used to collect operating parameters of the diesel generator set, photovoltaic system, load, and energy storage device. It realizes real-time monitoring of the entire system status through a multi-dimensional sensor cluster, determines fault information based on operating data, and transmits the fault information to the control module. In the diesel generator set monitoring, a Hall current sensor with an accuracy of ±0.2% and a PT100 temperature sensor with a range of -50~150℃ are used to collaboratively collect key parameters such as the speed, voltage, and oil temperature of the diesel generator set. In conjunction with an electromagnetic fuel flow meter with an error of ≤0.5%, an energy efficiency model is constructed (for example, in relation to the power system output power). P out ( t ), fuel energy input power P fuel ( t ), speed n ( t ), torque T ( t ) and other parameters coupling to calculate the energy conversion efficiency ), and the mechanical state is double-diagnosed by the oil pressure sensor and the crankshaft speed sensor. The energy storage device is monitored by the BMS (Battery Management System) to track the SOC (State of Charge), SOH (State of Health) and the charge / discharge rate in real time, and the risk of overcharging / overdischarging is prevented by the high-precision voltage sampling module (±1 mV) and the distributed temperature monitoring network (single cell temperature difference ≤2℃). The photovoltaic system is configured with an MPPT (Maximum Power Point Tracking) tracker and an I-V (current-voltage) curve scanner to capture the power drop of more than 30% caused by cloud cover in real time, and the power fluctuation traceability analysis is realized in combination with the irradiance sensor. The 0.5S level intelligent electric meter is deployed on the load side for accurate power measurement, and the RFID (Radio Frequency Identification) tag identification technology is integrated to divide the load into Level 1~3 priorities (Level 1 critical load power supply, Level 2 continuity but non-core important load, Level 3 non-critical and interruptible auxiliary load), providing hierarchical decision basis for energy scheduling. The monitoring module is embedded with a fault judgment system: when the speed of the diesel generator set is lower than 70% of the rated value and lasts for 3 seconds, or the current oil temperature exceeds the alarm threshold and lasts for 5 seconds, it is determined that the diesel generator fails; when the output power of the photovoltaic system is lower than the threshold (for example, 30% of the normal value), it is determined that the photovoltaic system has a sudden drop. The monitoring module transmits the fault information to the control module, and the network integrates the professional technologies such as Hall effect current detection, three-wire PT100 temperature measurement and coulomb metering through the multi-protocol communication architecture such as CAN FD and Modbus TCP, forms a digital perception system covering the whole link of “generation-storage-distribution-use”, and finally realizes millisecond-level data fusion through the edge computing node to provide high-time-effectiveness data support for system optimization control.

[0031] The control module is used for receiving data of the monitoring module and sending instructions to the switching module and the communication module to complete grid system regulation and fault response; its built-in intelligent algorithm dynamically evaluates the operating state of each power source. Once receiving fault information from the monitoring module, the control module immediately starts the intelligent decision logic: for diesel generator failure, first detect the SOC state of the energy storage system, if higher than 20%, quickly switch to the energy storage device for power supply, otherwise start the standby diesel generator set; in the face of photovoltaic power drop, the control module accurately calculates the power gap, dynamically adjusts the energy storage charging and discharging strategy or diesel generator output power to maintain system balance. At the same time, the control module strictly follows the load grading management principle, and when the system power is insufficient, it prioritizes the power supply of Level 1 critical load, and if necessary, limits the flow or temporarily removes Level 3 non-critical load, ensuring the continuous and stable operation of important loads. Through this intelligent decision mechanism, the control module realizes accurate regulation and rapid response of the multi-source power supply system.

[0032] The switching execution module is composed of high-performance execution elements such as fast switches, contactors, and solid-state relays, and can complete the fast switching operation of the power supply system within milliseconds. Through precise timing control, the switching execution module ensures seamless power switching in various fault scenarios: when a diesel generator set failure is detected, the switching execution module will immediately open the diesel generator set output switch, and simultaneously close the energy storage system output switch, realizing instantaneous switching of the power supply system; after the standby diesel generator set starts and reaches a stable operating state, this module can also realize smooth grid connection of the standby diesel generator set by precisely adjusting voltage and frequency, thereby ensuring the continuity and stability of the entire power supply system. This fast and reliable switching mechanism effectively avoids load power failure risks and provides uninterrupted power supply for critical equipment.

[0033] The communication module uses industrial standard communication protocols such as Modbus and CAN bus to build an efficient and reliable data interaction network. The communication module establishes real-time communication connections with the diesel generator set controller, photovoltaic inverter, energy storage BMS, and load management system, realizing data sharing and collaborative control between subsystems. Through millisecond-level data transmission, the communication module ensures the rapid transmission of control instructions and the timely feedback of execution feedback. At the same time, the communication module continuously uploads the operating state, fault alarm, and other key information of each subsystem of the power grid system to the monitoring center, providing a remote monitoring interface for operation and maintenance personnel, enabling them to real-time monitor system dynamics, quickly locate and handle faults, and greatly improve operation and maintenance response speed and management efficiency. This two-way, real-time communication architecture provides solid data support for the intelligent management and stable operation of the entire power supply system.

[0034] During the operation of the diesel storage photoelectric power grid system, diesel generator set failure and photovoltaic power sudden drop may occur. Through overall collaborative control of the control unit, rapid collaborative switching of the energy storage device and the diesel generator set is realized, seamless connection of the power supply is ensured, and stable power supply to the key load is ensured.

[0035] Specifically, the diesel generator set failure control method, as shown in the figure, specifically includes the following steps: Figure 2 Step A1: The monitoring module collects diesel generator set operating parameters in real time, determines whether the diesel generator set has failed according to the operating parameters, and transmits the fault information to the control module if a failure occurs, otherwise continuously monitors the parameter data of each subsystem. Determine whether the diesel generator set has failed according to the parameters of the diesel generator set collected by the monitoring module, including oil temperature, speed, etc.: when any of the following conditions is met, it is determined to be a failure; Condition a: oil temperature exceeds the limit, and the duration Δ t ≥ 5s, wherein, is the current oil temperature ， is the preset alarm temperature; Condition b: speed drop, using speed change rate measurement: ≤−30% , wherein, is the rated speed.

[0036] Step A2: After the control module receives the fault information of the monitoring module, it determines the SOC of the energy storage device. If the SOC is greater than or equal to 20%, the switching execution module performs the following operations: open the diesel generator set output switch, close the energy storage device output switch; if the SOC is less than 20%, the control module adjusts the energy storage discharge power to meet the power distribution requirements of the power grid system; Step A3: The monitoring module monitors the energy storage device discharge power and SOC in real time. If the predicted SOC is lower than 10% and the total power of the load > energy storage device available discharge power , the control module starts the standby diesel generator set; otherwise, the control module adjusts the energy storage discharge power to meet the power distribution requirements of the power grid system.

[0037] Under normal circumstances, the SOC can be predicted according to the remaining time of the energy storage and the load demand time , assuming that the energy storage device discharge power is constant, and the battery energy efficiency η is a constant: the current available energy of the energy storage ， is the rated capacity;​ Time to SOC 10% ; Time to SOC 10% ; Risk: If , then SOC will drop below 10% within the demand time.

[0038] Step A4: After the standby diesel generator set is started, the grid-connected condition is verified, and after the grid-connected condition is met, the switch of the standby diesel generator set is closed, and the output power of the energy storage device is gradually reduced by the control module.

[0039] The grid-connected condition is that the standby diesel generator set is started, and at the same time, the voltage deviation is less than or equal to 5%, and the frequency deviation is less than or equal to 5%, which is expressed as:

[0040] In the formula, represents the output voltage of the standby diesel generator set; represents the rated voltage of the system;

[0041] In the formula, represents the output voltage frequency of the standby diesel generator set; represents the rated voltage frequency of the system.

[0042] After the grid-connected operation is implemented, the output power of the energy storage device is gradually reduced by the control module according to the following rules:

[0043] In the formula, represents the output power of the diesel generator set; represents the discharge power of the energy storage device, and is:

[0044] In the formula, k represents the attenuation coefficient, represents the maximum discharge power of the energy storage device.

[0045] The photovoltaic power sudden drop control method, as shown in Figure 3 , specifically includes the following steps: Step B1: After the monitoring module detects that the photovoltaic output power is lower than the threshold value, the fault information is transmitted to the control module, for example, if the output power is lower than 30% of the normal value, it is determined as a photovoltaic power sudden drop fault.

[0046] Step B2: The control module calculates the total load power and the power gap , if >0 and the critical load power accounts for ≥70% of the total load power, the communication module sends instructions to the load management system to limit the current or temporarily cut off the non-critical loads; at the same time, the energy storage device SOC <30% or >0.8 , the control module immediately starts the standby diesel generator set.

[0047] Power gap , which is expressed as follows:

[0048] Where, Indicates the photovoltaic system power, Indicates the energy storage discharge power.

[0049] Non-critical load current limiting: If the critical load power accounts for ≥ 70% of the total load power, the non-critical load power Limit to:

[0050] Where, Indicates the power current limit ratio of non-critical loads, the value is , and when =0, the power of non-critical loads remains unchanged; when α =0.5 (i.e. 50%), the power of non-critical loads is limited to 50% of the original value; when α =1, non-critical loads are completely cut off. Example: When the PV power drops suddenly and the system power is insufficient (such as the critical load power accounts for ≥70% of the total load power), by setting α The threshold value (e.g. α =50%), the system can dynamically reduce the power of non-critical loads to give priority to ensuring the power supply of critical loads.

[0051] Diesel engine start decision: If SOC < 30% or >0.8 ( Indicates the maximum power of the diesel generator set), start the standby diesel generator set. Otherwise, do not start the standby diesel generator set temporarily.

[0052] Step B3: After the standby diesel generator meets the voltage deviation ≤ 5% and the frequency deviation ≤ 5%, the switch execution module is integrated into the system to form a coordinated power supply mode with the photovoltaic system and energy storage device. The total power is expressed as:

[0053] Where, Indicates the total power, Indicates the power of the diesel generator set. Indicates the photovoltaic system power, PESS Indicates the energy storage power; Step B4: During the PV power recovery process, the control module dynamically reduces the power of the diesel generator set and controls the charging power of the energy storage device.

[0054] When the PV system recovers and transitions, the control module dynamically reduces the power of the diesel generator set according to an exponential decay function, as shown below: ; Where, Indicates the initial output of the diesel generator set; Control the charging power of the energy storage device, specifically: The control module determines the SOC of the energy storage device. If the SOC is less than 80%, the energy storage absorbs the excess photovoltaic power, i.e. the charging power for:

[0055] Where, Indicates excess power of the photovoltaic system, Indicates the maximum charging power of the energy storage device. If the energy storage SOC is close to the upper limit (such as 95%), It will be dynamically reduced to prevent overcharging.

[0056] At the same time, the system power balance error Δ is calculated in real time P :

[0057] If Δ P >5% , triggering the proportional-integral (PI) control algorithm:

[0058] In the formula K p and K i is the control parameter.

[0059] Example 1 This embodiment provides a diesel storage photovoltaic grid system, such as Figure 1 As shown, it includes photovoltaic system, diesel generator set, load, energy storage device and control unit; The control unit includes a monitoring module, which is connected to the diesel generator set, photovoltaic system, load and energy storage device respectively; the monitoring module is connected to the control module, which is connected to the switching execution module and the communication module; the switching execution module is connected to the diesel generator set and the energy storage device respectively; the communication module is connected to the diesel generator controller, photovoltaic inverter, energy storage BMS, load management system and control center.

[0060] The monitoring module is used for collecting operation parameters of the diesel generator set, the photovoltaic system, the load and the energy storage device, judging fault information according to the operation data and transmitting the fault information to the control module; the monitoring module is embedded with a fault judgment system, and the specific steps are as follows: When the diesel generator set speed is lower than 70% of the rated value and lasts for 3 seconds, or the current oil temperature exceeds the alarm threshold and lasts for 5 seconds, it is determined that the diesel generator set is faulty; when the photovoltaic system output power is lower than the threshold, it is determined that the photovoltaic system is suddenly reduced; The control module is used for receiving data of the monitoring module and sending instructions to the switching module and the communication module to complete grid system regulation and fault response; the control module is embedded with decision logic, and the specific steps are as follows: For the diesel generator set fault, first detect the SOC of the energy storage device, if the SOC is greater than or equal to 20%, switch to the energy storage device power supply, otherwise start the standby diesel generator set; for the photovoltaic power sudden drop, the control module first calculates the power gap and the proportion of the key load, and dynamically adjusts the energy storage device charging and discharging strategy and the diesel generator set start-stop to maintain system balance; The switching execution module is used for realizing the on-off of the power supply circuit in the fault scene; The communication module is used for realizing data sharing and cooperative control among the monitoring module, the control module, the switching execution module and external devices, and uploading information to the monitoring center.

[0061] Embodiment 2 The embodiment provides a fault control method of a diesel storage photovoltaic grid system, specifically a diesel generator set fault control method, and specifically includes the following steps: Step A1: The monitoring module collects diesel generator set operation parameters in real time, judges whether the diesel generator set has a fault according to the operation parameters, and transmits fault information to the control module if the diesel generator set has a fault; Step A2: The control module judges the SOC of the energy storage device, if the SOC is greater than or equal to 20%, the switching execution module performs the following operations: disconnects the diesel generator set output switch, and closes the energy storage device output switch; Step A3: The monitoring module monitors the energy storage device discharge power in real time and the SOC, if the predicted SOC is lower than 10% and the total power of the load > the energy storage device can use the discharge power , the control module starts the standby diesel generator set; Step A4: After the standby diesel generator set is started, the grid connection condition is verified, and after the grid connection condition is met, the switching execution module closes the standby diesel generator set output switch, and the control module gradually reduces the energy storage device output power, and the diesel generator set bears the main load.

[0062] Embodiment 3 On the basis of embodiment 2, it is judged in step A1 whether the diesel generator unit has a fault, specifically: when any of the following conditions is met, it is determined to be a fault; Condition a: oil temperature over-limit, and the duration Δ t ≥ 5s, wherein, is the current oil temperature ， is the preset alarm temperature; Condition b: sudden drop in speed, using the speed change rate measure: ≤ -30% , wherein, is the rated speed.

[0063] In step A3, the grid-connected condition is that after the standby diesel generator unit is started, the voltage deviation ≤ 5% and the frequency deviation ≤ 5% are simultaneously satisfied, which is expressed as:

[0064] In the formula, represents the output voltage of the standby diesel generator unit; represents the system rated voltage;

[0065] In the formula, represents the output voltage frequency of the standby diesel generator unit; represents the system rated voltage frequency.

[0066] In step A4, the control module gradually reduces the output power of the energy storage device according to the following rules:

[0067] In the formula, represents the output power of the diesel generator unit; represents the energy storage discharge power, and is:

[0068] In the formula, k represents the attenuation coefficient, represents the maximum discharge power of the energy storage device.

[0069] Embodiment 4 The embodiment provides a fault control method of a diesel storage photovoltaic grid system and a photovoltaic power sudden drop control method, specifically including the following steps: Step B1: After the monitoring module detects that the photovoltaic output power is lower than the threshold value, the fault information is transmitted to the control module; Step B2: The control module calculates the total load power and the power gap , if >0 and the critical load power ratio is greater than or equal to 70% of the total load power, the control module sends an instruction to the load management system through the communication module to make the non-critical load execute current limiting; at the same time, the SOC of the energy storage device is less than 30% or >0.8 , the control module immediately starts the standby diesel generator set; Power gap , which is represented as follows:

[0070] In the formula, represents the power of the photovoltaic system, represents the discharge power of the energy storage device.

[0071] The non-critical load power is executed current limiting, which is represented as:

[0072] In the formula, represents the non-critical load power after current limiting, represents the power current limiting ratio of the non-critical load, which is taken as , and when =0, the non-critical load power remains unchanged; when α =0.5 (i.e. 50%), the non-critical load power is limited to 50% of the original value; when α =1, the non-critical load is completely cut off.

[0073] Step B3: After the standby diesel generator set meets the voltage deviation ≤5% and the frequency deviation ≤5%, the switching execution module is switched into the system, forming a collaborative power supply mode with the photovoltaic system and the energy storage device, and the total power is represented as:

[0074] In the formula, represents the total power, represents the diesel generator set power, represents the photovoltaic system power, P ESS represents the energy storage power; Step B4: The control module dynamically reduces the diesel generator set power and controls the energy storage device charging power.

[0075] The control module dynamically reduces the diesel generator set power according to the following rules: ; In the formula, represents the initial output of the diesel generator set; The control module controls the energy storage device charging power, which is specifically: The control module judges the SOC of the energy storage device. If the SOC < 80%, the energy storage device absorbs the excess photovoltaic power, i.e. charging power is:

[0076] wherein, represents the excess power of the photovoltaic system, represents the maximum charging power of the energy storage device.

[0077] Example 5 This example includes a power supply system of two 2.4 MW diesel generator units, a 1500 kW energy storage device and a photovoltaic system. In response to the shutdown of one diesel generator unit due to a fuel pump failure, the response and control process of each module of the system is as follows: Step A1: The monitoring module detects a sudden drop in the rotating speed and the fuel quantity is 0, which determines that the diesel generator is faulty, and transmits the fault information to the control module. Step A2: The control module checks that the SOC of the energy storage device is 35%, and instructs the switching execution module to disconnect the faulty diesel generator switch and close the energy storage switch. At this time, the load is powered by the energy storage.

[0078] Step A3: The monitoring module monitors the load power of 1200 kW and the energy storage discharging power of 1200 kW, and predicts that the SOC will drop to 10% in 12 minutes. The control module starts another diesel generator unit, which stabilizes after 2 minutes, and the switching execution module integrates it. The control module adjusts the energy storage discharging power to 200 kW, and the diesel generator unit bears 1000 kW, and the system stabilizes.

[0079] This example shows the complete process of switching power supply by energy storage, monitoring the load and energy storage state, starting a standby diesel generator and adjusting the power to ultimately restore system stability when the diesel generator fails.

[0080] Example 6 This example provides a control method for photovoltaic power drop, which specifically includes: Step B1: The photovoltaic system power drops from 1000 kW to 200 kW (sudden heavy rain), and the photovoltaic power drop fault information appears. The monitoring module transmits the fault information to the control module. Step B2: The control module calculates the total load power of 1500 kW, the power gap of 1300 kW. The energy storage SOC is 40%, and the discharging power is 1500 kW. The critical load power is 1000 kW, and the control module informs the load management system to reduce the non-critical load from 500 kW to 200 kW. Since the energy storage can meet the remaining power (1500 kW - 200 kW = 1300 kW ≤ 1500 kW) and the SOC is sufficient, the standby diesel generator unit is not started. After the photovoltaic power is restored, the control module adjusts the energy storage to stop discharging, and the system operates normally.

Claims

1. The diesel-storage-photovoltaic grid system is characterized by: Including photovoltaic system, diesel generator set, load, energy storage device and control unit; The control unit includes a monitoring module, which is respectively connected to the diesel generator set, photovoltaic system, load and energy storage device; the monitoring module is connected to the control module, which is connected to the switching execution module and the communication module; the switching execution module is respectively connected to the diesel generator set and the energy storage device; the communication module is connected to the diesel generator controller, photovoltaic inverter, energy storage BMS, load management system and control center.

2. The diesel-storage-photovoltaic grid system according to claim 1, characterized in that: The monitoring module is used to collect operating parameters of the diesel generator set, photovoltaic system, load and energy storage device, determine fault information based on the operating data, and transmit the fault information to the control module; the monitoring module has an embedded fault judgment system, which is as follows: When the diesel generator speed is lower than 70% of the rated value for 3 seconds, or the current oil temperature exceeds the alarm threshold for 5 seconds, it is determined to be a diesel generator failure; when the photovoltaic system output power is lower than the threshold, it is determined to be a photovoltaic sag; The control module is used to receive data from the monitoring module and send instructions to the switching module and communication module to complete the power grid system regulation and fault response; the control module has embedded decision logic, which is as follows: In the event of a diesel generator failure, the system first checks the energy storage device's SOC. If the SOC is ≥ 20%, power is switched to the energy storage device; otherwise, the backup diesel generator is activated. In the event of a sudden drop in PV power, the control module first calculates the power gap and the proportion of critical loads, and dynamically adjusts the energy storage device's charging and discharging strategy and the diesel generator's start and stop to maintain system balance. The switching execution module is used to realize the switching of the power circuit in a fault scenario; The communication module is used to realize data sharing and collaborative control among the monitoring module, the control module, the execution switching module and the external devices, and upload the information to the monitoring center.

3. The fault control method of the diesel-storage-photovoltaic grid system according to any one of claims 1 to 2, characterized in that: It includes diesel generator set fault control method and photovoltaic power sag control method.

4. The method for coordinated control of diesel generator failure and photovoltaic power sag in a diesel-storage-solar system according to claim 3, characterized in that: The diesel generator set fault control method specifically comprises the following steps: Step A1: The monitoring module collects the operating parameters of the diesel generator set in real time, determines whether the diesel generator set has a fault based on the operating parameters, and transmits the fault information to the control module if a fault occurs; Step A2: The control module determines the SOC of the energy storage device. If the SOC is ≥ 20%, the switch execution module performs the following operations: disconnect the output switch of the faulty diesel generator unit and close the output switch of the energy storage device; Step A3: The monitoring module monitors the discharge power of the energy storage device in real time If the SOC is predicted to be less than 10% and the total load power >Energy storage device can use discharge power , the control module starts the standby diesel generator set; Step A4: After the standby diesel generator set is started, the grid connection conditions are checked. If the grid connection conditions are met, the execution module switches to close the output switch of the standby diesel generator set. The control module gradually reduces the output power of the energy storage device, and the diesel generator set bears the main load.

5. The method for coordinated control of diesel generator failure and photovoltaic power drop in a diesel-storage-photovoltaic system according to claim 4 is characterized in that: In step A1, it is determined whether the diesel generator set has a fault. Specifically, if any of the following conditions is met, it is determined to be a fault; Condition a: Oil temperature exceeds the limit, And duration Δ t ≥5s, where Current oil temperature ， It is the preset alarm temperature; Condition b: Speed ​​drops suddenly, use speed change rate measure: ≤−30% ,in, is the rated speed.

6. The method for coordinated control of diesel generator failure and photovoltaic power sag in a diesel-storage-photovoltaic system according to claim 5, characterized in that: The grid connection condition in step A3 is that after the standby diesel generator set is started, the voltage deviation is ≤5% and the frequency deviation is ≤5%, which can be expressed as: Where, Indicates the output voltage of the standby diesel generator set; Indicates the system rated voltage; Where, Indicates the output voltage and frequency of the standby diesel generator set; Indicates the system rated voltage and frequency.

7. The method for coordinated control of diesel generator failure and photovoltaic power sag in a diesel-storage-photovoltaic system according to claim 6, characterized in that: In step A4, the control module gradually reduces the output power of the energy storage device according to the following rules: Where, Indicates the output power of the diesel generator set; represents the energy storage discharge power and is: Where, k represents the attenuation coefficient, Indicates the maximum discharge power of the energy storage device.

8. The method for coordinated control of diesel generator failure and photovoltaic power sag in a diesel-storage-photovoltaic system according to claim 7, characterized in that: The photovoltaic power sag control method specifically comprises the following steps: Step B1: After the monitoring module detects that the photovoltaic output power is lower than the threshold, it transmits the fault information to the control module; Step B2: The control module calculates the total load power With power gap ,like >0 and the critical load power accounts for ≥70% of the total load power, the communication module sends instructions to the load management system to limit the current of non-critical loads; at the same time, the energy storage device SOC <30% or >0.8 , the control module immediately starts the standby diesel generator set; Step B3: After the standby diesel generator meets the voltage deviation ≤ 5% and the frequency deviation ≤ 5%, the switch execution module is integrated into the system to form a coordinated power supply mode with the photovoltaic system and energy storage device. The total power is expressed as: Where, Indicates the total power, Indicates the power of the diesel generator set. Indicates the photovoltaic system power, P ESS Indicates energy storage power; Step B4: The control module dynamically reduces the power of the diesel generator set and controls the charging power of the energy storage device at the same time.

9. The method for coordinated control of diesel generator failure and photovoltaic power sag in a diesel-storage-solar system according to claim 8, characterized in that: In step B2, the power gap , which is expressed as follows: Where, Indicates the photovoltaic system power, Indicates the energy storage discharge power; For non-critical load power Execute current limiting, expressed as: Where, Indicates the non-critical load power after current limiting, Indicates the power current limit ratio of non-critical loads, the value is , and when =0, the power of non-critical loads remains unchanged; when α =0.5 (i.e. 50%), the power of non-critical loads is limited to 50% of the original value; when α =1, non-critical loads are completely cut off.

10. The method for coordinated control of diesel generator failure and photovoltaic power sag in a diesel-storage-solar system according to claim 9, characterized in that: In step B4, the control module dynamically reduces the power of the diesel generator set according to the following rules: ； Where, Indicates the initial output of the diesel generator set; Control the charging power of the energy storage device, specifically: The control module determines the SOC of the energy storage device. If the SOC is less than 80%, the energy storage device absorbs excess photovoltaic power, i.e., charging power. for: Where, Indicates excess power of the photovoltaic system, Indicates the maximum charging power of the energy storage device.

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