A temperature control system and control method for a box transformer for energy storage

Abstract

The present invention relates to the technical field of box-type substations for energy storage, and specifically, to a temperature control system and control method for box-type substations for energy storage. It includes a temperature monitoring module, a graded threshold module, a speed control module and a fault alarm module. The present invention monitors the temperature inside the substation in real time through the temperature monitoring module to obtain accurate temperature, temperature deviation and temperature change rate, uses the graded threshold module to establish a graded temperature threshold model, and optimizes and adjusts the model. The speed control module adopts a fuzzy control algorithm to obtain an accurate correction amount for the initial speed of the fan, sets the association rule between the temperature threshold of the graded control and the speed control unit, synchronizes the consistency of the graded switching and the fan speed adjustment, realizes the graded regulation of the fan, and reduces the power consumption under the premise of ensuring heat dissipation.

Description

Technical Field

[0001] The present invention relates to the technical field of box-type substations for energy storage, and in particular to a temperature control system and a control method for a box-type substation for energy storage. Background Art

[0002] Energy storage box transformer, also known as energy storage box substation, is a substation that integrates energy storage technology and power system requirements. It uses an efficient and intelligent power management system to store and release electricity, effectively solving the problem of insufficient or excessive power supply in the power system due to seasonal power fluctuations, unbalanced loads and other factors. The temperature control system of the energy storage box transformer is a key component to ensure the safe and efficient operation of the energy storage system. It protects batteries and other important components from excessively high or low temperatures by controlling the temperature inside the box.

[0003] At present, the temperature control system of some large-scale box-type substations for energy storage monitors the temperature inside the substation. When the temperature reaches a certain threshold, it starts multiple fans at the same time and uses the air cooling principle to cool down the inside of the substation. Since the internal temperature of the substation gradually increases when it is working, if multiple fans are started when the internal temperature of the substation just reaches the threshold, although the internal temperature of the substation can be quickly reduced, starting multiple fans will consume a lot of electricity. In order to be able to perform graded control of the fans according to the temperature changes inside the substation, at the same time, when the temperature reaches different thresholds, the speed of the fans is dynamically adjusted according to the temperature deviation and the temperature change rate, while saving electricity, the temperature in the substation is accurately regulated. Therefore, we propose a temperature control system and control method for box-type substations for energy storage. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the box-type substation for energy storage cannot effectively control the number of fan starts and the fan speed according to the internal temperature changes, and cannot achieve the unity of energy saving and temperature control. In order to be able to realize hierarchical control of the fan according to the temperature changes in the substation and dynamically adjust the fan speed according to the temperature deviation and the temperature change rate, the temperature in the substation can be accurately controlled while saving electricity.

[0005] To achieve the above object, the present invention provides a temperature control system for a box transformer for energy storage, comprising a temperature monitoring module, a grading threshold module, a speed control module and a fault alarm module;

[0006] The temperature monitoring module evenly distributes multiple groups of temperature sensors in a grid form inside the box-type substation for energy storage, monitors the overall temperature inside the substation in real time, and monitors the surface temperature of the heat sink of the transformer, reactor, and power semiconductor device inside the substation, and monitors the temperature near the chip position to accurately monitor its working temperature, and uses an amplification and filtering circuit to amplify and filter the electrical signal detected by the temperature sensor to obtain accurate temperature, temperature deviation and temperature change rate, and transmits them to the classification threshold module and the speed control module respectively;

[0007] The hierarchical threshold module determines the primary threshold of the temperature through the normal working temperature range of the equipment inside the substation, determines the secondary threshold according to the balance between the heating power of the equipment and the heat dissipation power of the cooling equipment, and determines the tertiary threshold according to the thermal stability of the equipment and the maximum heat dissipation capacity of the cooling equipment. The hierarchical temperature threshold model is described by a piecewise function. The previous temperature control data is collected and substituted into the hierarchical temperature threshold model, and the results are compared with the actual situation, so as to adjust the model parameters and the model control strategy.

[0008] The speed control module adopts a fuzzy control algorithm, takes the temperature deviation and temperature change rate obtained by the temperature monitoring module as input, obtains an accurate correction amount for the initial speed of the fan, sets the association rules between the temperature threshold of the graded control and the speed control unit according to the graded temperature threshold model established by the graded threshold module, synchronizes the consistency of graded switching and fan speed adjustment, and uses a feedback mechanism to dynamically adjust the fan speed parameters and optimize the synchronization effect;

[0009] The fault alarm module sets monitoring points in the hardware devices of hierarchical control and intelligent speed control. When one of the control modes fails, it immediately sends out an alarm signal. At the same time, it starts a fault compensation strategy based on another mode to ensure that the internal temperature of the box transformer can still be effectively controlled in the event of a fault.

[0010] Preferably, the fault alarm module collects the transformer coil temperature and the transformer chamber temperature through the thermostat, compares them with the graded temperature threshold determined by the graded threshold module, determines the fan start-up status, and whether the temperature reaches the alarm threshold. If the threshold is reached, the measurement and control device outputs a trip signal.

[0011] Preferably, when the fault alarm module performs temperature control on the dry-type transformer, an auxiliary thermostat is added, which has two sets of over-temperature dry contacts, trips the high-voltage switch through the measurement and control device, and directly trips the high-voltage switch using another set of over-temperature dry contacts.

[0012] Preferably, the grading threshold module includes a model building unit and a model optimization unit;

[0013] The model building unit determines the graded temperature threshold value according to the normal operating temperature range of the internal equipment of the substation, the heating power of the equipment and the heat dissipation power of the cooling equipment, the thermal stability of the equipment and the maximum heat dissipation capacity of the cooling equipment;

[0014] The model optimization unit collects multiple sets of temperature-time data, finds the minimum value of the sum of squares of the error between the actual temperature and the model predicted temperature by the least squares method, adjusts the model parameters in a certain proportion according to the error size, and adjusts the temperature threshold by monitoring the startup status of the fan.

[0015] Preferably, the model building unit calculates the rate of change of the device temperature over time through a heat balance equation, and determines the threshold of the secondary temperature based on the upper limit of the normal operating temperature range of the device and the temperature change rate, taking into account the time that the device can allow the temperature to exceed the normal range without being damaged, wherein the formula of the heat balance equation is:

[0016]

[0017] in, It's heat. is the mass of the object, is the specific heat capacity, It's the temperature change.

[0018] Preferably, the model optimization unit monitors the fan startup frequency and temperature variation pattern, plots a curve of equipment temperature variation over time, calculates the delay time between the fan startup moment and the temperature variation, and re-evaluates the temperature threshold.

[0019] Preferably, the speed control module includes an initial speed unit and a switching and speed regulation unit;

[0020] The initial speed unit adopts a fuzzy control algorithm, takes the temperature deviation and the temperature change rate as input, adopts a triangular membership function, and uses the maximum and minimum reasoning method to determine the membership function of the output fuzzy set according to the fuzzy rule base to obtain an accurate correction value for the initial speed of the fan;

[0021] The switching and speed regulation unit starts the corresponding cooling equipment according to the hierarchical control strategy, and also determines the initial speed regulation strategy of the speed regulation unit at the same time, and uses the feedback mechanism to determine whether it is necessary to further adjust the hierarchical strategy or perform the next level of hierarchical switching in advance.

[0022] Preferably, the fuzzy rule base of the initial speed unit is in the form of:

[0023]

[0024] in, is the fuzzy set of temperature deviation, is the fuzzy set of temperature change rate, is the fuzzy set of fan speed correction is the fan speed correction, is the temperature, is the rate of temperature change.

[0025] Among them, the output of the fuzzy control algorithm is defuzzified using the center of gravity method to obtain an accurate correction value for the fan speed, and the formula is:

[0026]

[0027] in, is the membership function, For the domain, is the fan speed correction, To find the differential.

[0028] Preferably, the temperature monitoring module includes an amplifying and filtering unit, and the amplifying and filtering unit includes an amplifying and filtering circuit, wherein the amplifying and filtering circuit includes a transistor Q1, a transistor Q2 and an operational amplifier A;

[0029] The base of the transistor Q1 is connected to one end of the resistor R1 and one end of the resistor R2, the other end of the resistor R1 is connected to the positive electrode of the input voltage UI, the emitter of the transistor Q1 is connected to the negative electrode of the input voltage UI, the collector of the transistor Q1 is connected to one end of the resistor R3 and one end of the resistor R4, the other end of the resistor R4 is connected to pin 2 of the operational amplifier A and one end of the resistor R6 and one end of the capacitor C1, the pin 3 of the operational amplifier A is connected to one end of the resistor R5, the other end of the resistor R5 is grounded, the pin 1 of the operational amplifier A is connected to the base of the transistor Q2 and one end of the resistor R6 and the other end of the capacitor C1, the collector of the transistor Q2 is connected to one end of the resistor R7 and the positive electrode of the output voltage UO, the resistor R7 is connected in parallel to the resistor R3 and the resistor R2 to the power supply VCC, and the emitter of the transistor Q2 is connected to the negative electrode of the output voltage UO.

[0030] A second object of the present invention is to provide a temperature control method for a box transformer for energy storage, comprising a temperature control system for a box transformer for energy storage as described in any one of the above, comprising the following steps:

[0031] S1. Use the temperature monitoring module to monitor the temperature inside the substation in real time to obtain accurate temperature, temperature deviation and temperature change rate;

[0032] S2. Establish a graded temperature threshold model using a graded threshold module, and optimize and adjust the model;

[0033] S3, the speed control module adopts fuzzy control algorithm to obtain accurate correction of the initial speed of the fan, set the association rule between the temperature threshold of the graded control and the speed control unit, and synchronize the consistency of graded switching and fan speed adjustment;

[0034] S4. Monitor the temperature control system through the fault alarm module, issue an alarm in case of a fault, and start a fault compensation strategy.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The temperature control system and control method of the box transformer for energy storage use a temperature monitoring module to monitor the temperature inside the substation in real time, and use an amplifying and filtering circuit to amplify and filter the electrical signal detected by the temperature sensor to obtain accurate temperature, temperature deviation and temperature change rate. A graded temperature threshold model is established using a graded threshold module, and the first-level temperature threshold is determined by the normal working temperature range of the equipment inside the substation, and the second-level threshold is determined according to the balance between the heating power of the equipment and the heat dissipation power of the cooling equipment. The third-level threshold is determined according to the thermal stability of the equipment and the maximum heat dissipation capacity of the cooling equipment. The temperature in the substation is monitored in the threshold range, and the number of fans started is regulated to achieve graded regulation of the fans, thereby reducing power consumption while ensuring heat dissipation.

[0037] The speed control module uses a fuzzy control algorithm to obtain an accurate correction of the initial speed of the fan, set the association rule between the temperature threshold of the graded control and the speed control unit, synchronize the graded switching and the fan speed adjustment consistency, and use the feedback mechanism to dynamically adjust the fan speed parameters to achieve the speed consistency between different fans when the fans are graded switched;

[0038] The temperature control system is monitored by the fault alarm module. When one of the control methods fails, an alarm signal is immediately issued and a fault compensation strategy based on another method is started to ensure that the internal temperature of the box transformer can still be effectively controlled in the event of a fault. In addition, an auxiliary thermostat is added, which has two sets of over-temperature dry contacts. Not only can the high-voltage switch be tripped by the measurement and control device, but another set of over-temperature dry contacts can be used to directly trip the high-voltage switch, avoiding overheating and burning of the transformer due to failure to cut off the main return pressure device when the measurement and control device fails. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is the overall flow chart of the present invention;

[0040] Figure 2 It is the overall flow chart of the fault alarm of the present invention;

[0041] Figure 3 It is the overall detailed flow chart of the present invention;

[0042] Figure 4 It is a flow chart of the speed control module of the present invention;

[0043] Figure 5 The amplifying and filtering circuit diagram of the present invention;

[0044] Figure 6 The figure is a flowchart of the method of the present invention.

[0045] The meaning of each number in the figure is:

[0046] 100, temperature monitoring module; 110, amplification and filtering unit; 200, classification threshold module; 210, model building unit; 220, model optimization unit; 300, speed control module; 310, initial speed unit; 320, switching and speed regulation unit; 400, fault alarm module DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] At present, the box-type substation for energy storage cannot effectively control the number of fans started and the fan speed according to the internal temperature changes, and cannot achieve the unity of energy saving and temperature control. In order to be able to implement hierarchical control of fans according to temperature changes in the substation and dynamically adjust the fan speed according to temperature deviation and temperature change rate, it is necessary to save energy while accurately controlling the temperature in the substation.

[0049] Therefore, the present invention proposes to monitor the temperature inside the substation in real time through a temperature monitoring module to obtain accurate temperature, temperature deviation and temperature change rate, establish a graded temperature threshold model using a graded threshold module, and optimize and adjust the model, and use a fuzzy control algorithm in the speed control module to obtain an accurate correction amount for the initial speed of the fan, set the association rule between the temperature threshold of the graded control and the speed regulation unit, synchronize the consistency of the graded switching and the fan speed adjustment, monitor the temperature control system through a fault alarm module, issue an alarm in the event of a fault, and start a fault compensation strategy.

[0050] Embodiment 1, as Figure 1 As shown, one of the purposes of the present invention is to provide a temperature control system for a box transformer for energy storage, including a temperature monitoring module 100, a grading threshold module 200, a speed control module 300 and a fault alarm module 400;

[0051] The temperature monitoring module 100 evenly distributes multiple groups of temperature sensors in a grid form inside the box-type substation for energy storage, monitors the overall temperature inside the substation in real time, and monitors the surface temperature of the heat sink of the transformer, reactor, and power semiconductor device inside the substation, and monitors the temperature near the chip position to accurately monitor its working temperature. The electrical signal detected by the temperature sensor is amplified and filtered by the amplifying and filtering circuit to obtain accurate temperature, temperature deviation and temperature change rate, and transmits them to the classification threshold module 200 and the speed control module 300 respectively;

[0052] The hierarchical threshold module 200 determines the primary threshold of the temperature through the normal working temperature range of the internal equipment of the substation, determines the secondary threshold according to the balance between the heating power of the equipment and the heat dissipation power of the cooling equipment, determines the tertiary threshold according to the thermal stability of the equipment and the maximum heat dissipation capacity of the cooling equipment, and uses a piecewise function to describe the hierarchical temperature threshold model. By collecting previous temperature control data, it is substituted into the hierarchical temperature threshold model, and the results are compared with the actual situation, and then the model parameters are adjusted, and the model control strategy is adjusted;

[0053] The speed control module 300 adopts a fuzzy control algorithm, takes the temperature deviation and temperature change rate obtained by the temperature monitoring module 100 as input, obtains an accurate correction amount for the initial speed of the fan, sets the association rules between the temperature threshold of the graded control and the speed control unit according to the graded temperature threshold model established by the graded threshold module 200, synchronizes the consistency of graded switching and fan speed adjustment, and uses a feedback mechanism to dynamically adjust the fan speed parameters and optimize the synchronization effect;

[0054] The fault alarm module 400 sets monitoring points in the hardware devices of the hierarchical control and the intelligent speed control. When a fault occurs in one of the control modes, an alarm signal is immediately issued. At the same time, a fault compensation strategy based on another mode is started to ensure that the internal temperature of the box transformer can still be effectively controlled in the event of a fault.

[0055] like Figure 2 As shown, the fault alarm module 400 collects the transformer coil temperature and the transformer chamber temperature collected by the thermostat, and compares them with the graded temperature threshold determined by the graded threshold module 200 to determine the fan start-up state and whether the temperature reaches the alarm threshold. If the threshold is reached, the measurement and control device outputs a trip signal;

[0056] Compare the collected transformer coil temperature with the set value. If it reaches the set value, the transformer body fan will be started. If it does not reach the set value, the transformer body fan will not be started. Compare the collected transformer room temperature with the set value. If it reaches the set value, the transformer room fan will be started. If it does not reach the set value, the transformer room fan will not be started. When the body fan fails and the shell fan fails, the temperature of the transformer body and the temperature in the transformer room will rise. When the temperature reaches the alarm threshold, it will be transmitted to the background of the measurement and control device. At the same time, the measurement and control device outputs a trip signal.

[0057] At the same time, the backup temperature control is used to collect the coil temperature of the transformer and compare it with the set value. When the coil temperature reaches the set value, it is directly divided into high and low voltage side switches and transmits the signal to the background of the measurement and control device;

[0058] Among them, the thermostat and backup temperature control module protection set value r dry transformer high temperature alarm: 130℃, dry transformer over-temperature trip: 15o℃ dry transformer body fan (6+2 units): fan start value: 90℃, fan stop value: 80℃, transformer room fan (10 units): fan start value: 45℃, fan stop value: 40℃ backup temperature control module; over-temperature trip: 150℃.

[0059] In order to avoid the situation that the transformer loses the temperature control and over-temperature tripping functions at the same time when the main thermostat fails, causing the transformer to overheat and burn, the fault alarm module 400 adds an auxiliary thermostat when performing temperature control on the dry-type transformer. The auxiliary thermostat has two sets of over-temperature dry contacts, which can not only trip the high-voltage switch through the measurement and control device, but also directly trip the high-voltage switch using another set of over-temperature dry contacts;

[0060] The main thermostat integrates three-phase winding temperature detection and fan control, ambient temperature detection and fan control, over-temperature dry contact, fault power-off dry contact, high-temperature dry contact, RS485 communication function, and 4-20mA output, while the auxiliary thermostat only has temperature detection and over-temperature dry contact, fault power-off dry contact, so the cost of the auxiliary thermostat is much lower than the main thermostat. At the same time, it avoids the transformer overheating and burning due to the inability to cut off the main back pressure device when the measurement and control device fails.

[0061] like Figure 3 As shown, the grading threshold module 200 includes a model building unit 210 and a model optimization unit 220;

[0062] The model building unit 210 determines the graded temperature threshold value according to the temperature range of normal operation of the internal equipment of the substation, the heating power of the equipment and the heat dissipation power of the cooling equipment, as well as the thermal stability of the equipment and the maximum heat dissipation capacity of the cooling equipment;

[0063] The model optimization unit 220 collects multiple sets of temperature-time data, finds the minimum value of the sum of squares of the error between the actual temperature and the temperature predicted by the model through the least square method, adjusts the model parameters according to a certain proportion according to the error size, and adjusts the temperature threshold by monitoring the start-up state of the fan;

[0064] The first level temperature threshold is mainly used to start preliminary cooling measures when the device temperature just starts to rise and approaches the upper limit of the normal operating temperature range. Set the safety margin temperature value based on the thermal sensitivity of the equipment and the response time of the cooling equipment, using the formula:

[0065]

[0066] in, is the safety margin temperature value, It is the first level temperature threshold.

[0067] The heating power of the device determines the temperature rise trend during normal operation. If the heating power is low, the temperature of the device rises slowly within the normal operating range, and the normal operating temperature range may be wider, thus affecting the division of the first-level temperature threshold. The lower heating power can enable the device to withstand higher ambient temperature or load changes during normal operation without exceeding the first-level temperature threshold. For example, when the ambient temperature rises by 10°C, a device with low heating power may still be able to operate normally within the first-level temperature threshold, while a device with high heating power may approach or exceed the first-level threshold.

[0068] In order to more accurately determine the threshold of the secondary temperature, the model building unit 210 calculates the rate of change of the device temperature over time through the heat balance equation, and determines the threshold of the secondary temperature based on the upper limit of the normal operating temperature range of the device and the temperature change rate, taking into account the time that the device can allow the temperature to exceed the normal range without being damaged. The formula of the heat balance equation is:

[0069]

[0070] in, It's heat. is the mass of the object, is the specific heat capacity, It's the temperature change.

[0071] When the device's heat generation power is greater than the heat dissipation power of the cooling device, the device temperature will begin to rise. The greater the heat generation power, the faster the temperature rises. Under the same mass and specific heat capacity, the greater the heat generation power, the greater the temperature change per unit time. For the determination of the secondary temperature threshold, the size of the device's heat generation power determines the range from the upper limit of the normal operating temperature range to the temperature range where performance degradation or damage may occur. For example, if device A has a heat generation power of 80W and device B has a heat generation power of 120W, and the heat dissipation power of their cooling devices is 60W, assuming that the devices have the same thermal capacity, the temperature of device B will rise faster, and its secondary temperature threshold range may be narrower than that of device A because it approaches the temperature at which the device may fail more quickly.

[0072] In extreme cases, high heat generation power may cause the device to approach its thermal stability limit or the maximum heat dissipation capacity of the cooling device more quickly. If the heat generation power of the device continues to increase and the cooling device cannot effectively dissipate heat, the device temperature will rise sharply and quickly reach the device's maximum tolerance temperature. This requires that when determining the third-level temperature threshold, for devices with high heat generation power, the maximum heat dissipation capacity of the cooling device and the thermal stability of the device itself must be considered more strictly. It may be necessary to set the third-level temperature threshold relatively low to avoid damage to the device.

[0073] In order to optimize the hierarchical temperature threshold model, the model optimization unit 220 monitors the fan startup frequency and temperature change law, plots the device temperature change curve over time, calculates the delay time between the fan startup time and the temperature change, and re-evaluates the temperature threshold;

[0074] Based on the collected data, draw a curve of the equipment temperature changing over time. Observe the changing trend of the temperature curve, such as whether the temperature rises gradually, fluctuates, or has obvious periodic changes. At the same time, draw the fan start-up frequency curve and calculate the number of fan starts per unit time, such as the number of fan starts per hour. The time axis can be divided into the same time period (such as one hour as a time period), the number of fan starts in each time period is counted, and then the curve is drawn. For example, when analyzing the data, it is found that the equipment temperature will show a clear upward trend between 9 am and 11 am and 2 pm and 4 pm every day, and the fan start-up frequency will also increase significantly in these two time periods. After each fan start, the temperature will drop by a certain amount, and then gradually rise again;

[0075] According to the data analysis results, if the fan start-up frequency is too high and the temperature fluctuation is small, consider raising the temperature threshold appropriately, use the thermal model of the device (if available) or simulate through a simple thermal balance equation, simulate the change of device temperature and the fan start-up frequency according to the heating power of the device, the heat dissipation power of the cooling device and the adjusted temperature threshold, and gradually adjust the temperature threshold in the actual device operation. The amplitude of each adjustment should not be too large, for example, adjust 1℃-2℃ each time, and then observe the fan start-up frequency and device temperature changes, continue to collect data and analyze, until a suitable temperature threshold is found, so that the fan start-up frequency is reasonable and the device temperature can be effectively controlled.

[0076] like Figure 4 As shown, the speed control module 300 includes an initial speed unit 310 and a switching and speed regulation unit 320;

[0077] The initial speed unit 310 adopts a fuzzy control algorithm, takes the temperature deviation and the temperature change rate as input, adopts a triangular membership function, and uses the maximum and minimum reasoning method to determine the membership function of the output fuzzy set according to the fuzzy rule base to obtain an accurate correction value for the initial speed of the fan;

[0078] The switching and speed regulating unit 320 starts the corresponding cooling equipment according to the hierarchical control strategy, and also determines the initial speed regulating strategy of the speed regulating unit at the same time, and uses the feedback mechanism to determine whether it is necessary to further adjust the hierarchical strategy or to perform the next level of hierarchical switching in advance;

[0079] When the temperature reaches the first level threshold (T1) of hierarchical control, some cooling equipment is started according to the hierarchical control strategy, and intelligent speed control is turned on at the same time. For example, after starting some fans, the intelligent speed control system preliminarily adjusts the fan speed based on factors such as the deviation between the current temperature and T1 and the temperature change rate. If the temperature is close to T1, the speed can be set to a lower initial value; if the temperature has exceeded T1 to a certain extent, the speed is quickly increased to a suitable value to enhance the heat dissipation effect;

[0080] When the hierarchical control switches levels (such as from T1 to T2), the intelligent speed control also makes corresponding adjustments. When the temperature reaches T2, the hierarchical control starts more cooling devices, and the intelligent speed control redistributes the operating speed of each device according to the performance of the newly added devices and the current temperature status. For example, for the newly started fan, its initial speed is determined according to the deviation between the temperature and T2 and the heat dissipation requirements of the system; at the same time, the speed of the running fan is appropriately adjusted so that all cooling devices work together to achieve better heat dissipation effect;

[0081] Intelligent speed control can dynamically adjust the operating speed of the cooling equipment according to temperature changes in real time, thereby optimizing the effect of hierarchical control. For example, at a certain stage of hierarchical control, if the temperature drops quickly, intelligent speed control can appropriately reduce the speed of the cooling equipment to avoid excessively low temperatures and reduce energy consumption; on the contrary, if the temperature drops slowly or has an upward trend, intelligent speed control can increase the speed and enhance the heat dissipation capacity.

[0082] Define the fuzzy sets of input variables. The fuzzy set of temperature deviation is {negative large (NB), negative small (NS), zero (ZO), positive small (PS), positive large (PB)}, and the fuzzy set of temperature change rate is {negative large (NB), negative small (NS), zero (ZO), positive small (PS), positive large (PB)};

[0083] In order to use the fuzzy control algorithm more accurately, the fuzzy rule base of the initial speed unit 310 is in the form of:

[0084]

[0085] in, is the fuzzy set of temperature deviation, is the fuzzy set of temperature change rate, is the fuzzy set of fan speed correction, is the fan speed correction, is the temperature, is the rate of temperature change.

[0086] If the temperature deviation is "Negative Large (NB)" and the temperature change rate is "Negative Large (NB)", then the fan speed correction is "Negative Large (NB)", that is, the fan speed is greatly reduced;

[0087] After obtaining the precise values ​​of temperature deviation and temperature change rate, the membership of each fuzzy set is obtained through fuzzification, and then fuzzy reasoning is performed according to the fuzzy rule base. For example, assuming that the temperature deviation is 3, after fuzzification, the membership of "positive small (PS)" is 0.6, and the membership of "zero (ZO)" is 0.4; the temperature change rate is 1.5, the membership of "positive large (PB)" is 0.5, and the membership of "positive small (PS)" is 0.5.

[0088] In order to obtain a more accurate correction value for the fan speed, the initial speed unit 310 uses the centroid method to defuzzify the fuzzy output to obtain an accurate correction value for the fan speed, and the formula is:

[0089]

[0090] in, is the membership function, For the domain, is the fan speed correction, To find the differential.

[0091] This precise fan speed correction can be used to adjust the actual fan speed, thereby achieving precise control of temperature.

[0092] Set the initial speed regulation rule based on the temperature threshold, T1, and the initial startup and low-speed operation rule: Set the first-level temperature threshold T1 to a position close to the upper limit of the normal operating temperature range, such as ,in, It is a safety margin that can be determined based on the thermal sensitivity of the equipment and the heat dissipation response time, and is generally 5%-10% of the normal operating temperature range. When the temperature reaches T1, some cooling equipment (such as some fans) are started and their speed is set to a lower initial value. This initial speed can be determined based on the heat dissipation power of the heat dissipation equipment at this speed;

[0093] T2. Increase cooling and moderate speed-up rules: Set T2 between T1 and the limit temperature. When the temperature reaches T2, start more cooling equipment. At the same time, adjust the speed of the started and newly started cooling equipment. For the started equipment, increase its speed moderately according to the deviation between the temperature and T2, the equipment heating power, and the performance curve of the cooling equipment. For example, if the temperature exceeds T2 by a small margin, the speed of the started equipment can be increased to 60%-70% of the rated speed; if the excess is large, the speed can be increased to 80%-90% of the rated speed. For newly started equipment, its initial speed can be determined based on the equipment's heat dissipation power requirements and the current temperature status to ensure that the total heat dissipation power can meet the requirements of temperature control;

[0094] T3, full cooling and high-speed operation rules: When the temperature reaches T3, all cooling equipment is started and its speed is increased to a higher level. For example, the fan speed can be increased to 90%-100% of the rated speed, so that the cooling equipment can run at full capacity to avoid overheating of the equipment. At the same time, other measures may need to be considered, such as reducing the load of the box transformer to reduce the heat power.

[0095] In order to increase the influence of the temperature change rate on the speed regulation strategy, the switching and speed regulation unit 320 increases the influence of the temperature change rate on the speed regulation strategy in the association rule between the temperature threshold and the speed regulation unit;

[0096] If the temperature rises or falls slowly, the speed control unit can adopt a relatively mild speed control strategy at each stage of graded control. For example, when the temperature rate approaches T1, the initial speed of the fan after starting can be set to 20%-30% of the rated speed; when the temperature approaches T2 at the same slow rate, the speed increase of the started fan can be smaller, such as increasing the rated speed by 10%-15% each time;

[0097] When the temperature change rate is high, the speed control unit should adjust the speed more actively when each temperature threshold is reached. For example, when the temperature rises rapidly and approaches T1, the initial speed of the fan after starting can be directly set to 40%-50% of the rated speed; when the temperature rises rapidly and reaches T2, not only more fans should be started quickly, but the speed of the started fans can be directly increased to 70%-80% of the rated speed to quickly control the temperature rise trend.

[0098] In order to monitor accurate temperature data, the temperature monitoring module 100 includes an amplifying and filtering unit 110, and the amplifying and filtering unit 110 includes an amplifying and filtering circuit, such as Figure 5 As shown, the amplifying and filtering circuit includes a transistor Q1, a transistor Q2 and an operational amplifier A;

[0099] The base of transistor Q1 is connected to one end of resistor R1 and one end of resistor R2 in parallel, the other end of resistor R1 is connected to the positive electrode of input voltage UI, the emitter of transistor Q1 is connected to the negative electrode of input voltage UI, the collector of transistor Q1 is connected to one end of resistor R3 and one end of resistor R4 in parallel, the other end of resistor R4 is connected to pin 2 of operational amplifier A and one end of resistor R6 and one end of capacitor C1 in parallel, pin 3 of operational amplifier A is connected to one end of resistor R5, the other end of resistor R5 is grounded, pin 1 of operational amplifier A is connected to the base of transistor Q2 and one end of resistor R6 and the other end of capacitor C1, the collector of transistor Q2 is connected to one end of resistor R7 and the positive electrode of output voltage UO, resistor R7 is connected in parallel to resistor R3 and resistor R2 to power supply VCC, and the emitter of transistor Q2 is connected to the negative electrode of output voltage UO;

[0100] In this circuit, a first-stage amplifier circuit is formed by transistor Q1 and resistors R1, R2, R3 and R4, wherein when the input voltage UI changes slightly, the base current of transistor Q1 will change. According to the current amplification function of transistor Q1, the collector current of transistor Q1 will be amplified. As the collector current of transistor Q1 increases, the voltage on resistor R4 will increase, thereby realizing the first-stage amplification of input voltage UI. The voltage after low-pass filtering by the filter circuit is secondarily amplified by a diode amplifier circuit formed by transistor Q2 and resistor R7. The principle is the same as that of the amplifier circuit, and the output voltage UO is obtained.

[0101] The input voltage UI enters the first-stage amplifier circuit for amplification to obtain an amplified voltage signal, which then enters the low-pass filter circuit. Since the capacitive reactance of the capacitor decreases with increasing frequency, high-frequency noise signals are more easily bypassed to the ground through the capacitor, thereby filtering out high-frequency noise and allowing only low-frequency useful signals to pass. The filtered signal then enters the second-stage amplifier circuit for further amplification to a suitable amplitude for subsequent processing. Filtering first and then amplifying the next stage can effectively suppress the influence of high-frequency noise, improve the quality of the output signal of the entire circuit, and ensure the accuracy and reliability of the current signal detection of the mobile substation power interface.

[0102] The second object of the present invention is to provide a temperature control method for a box transformer for energy storage, including a temperature control system for a box transformer for energy storage according to any one of the above, such as Figure 6 As shown, the following steps are included:

[0103] S1. Monitor the temperature inside the substation in real time through the temperature monitoring module 100 to obtain accurate temperature, temperature deviation and temperature change rate;

[0104] S2. Using the classification threshold module 200 to establish a classification temperature threshold model, and optimizing and adjusting the model;

[0105] S3, the speed control module 300 adopts the fuzzy control algorithm to obtain the accurate correction value of the initial speed of the fan, set the association rule between the temperature threshold of the graded control and the speed control unit, and synchronize the consistency of the graded switching and the fan speed adjustment;

[0106] S4. Monitor the temperature control system through the fault alarm module 400, issue an alarm when a fault occurs, and start a fault compensation strategy.

[0107] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A temperature control system for a box transformer for energy storage, characterized in that: It comprises a temperature monitoring module (100), a classification threshold module (200), a speed control module (300) and a fault alarm module (400); The temperature monitoring module (100) evenly distributes multiple groups of temperature sensors in a grid form inside the box-type substation for energy storage, monitors the overall temperature inside the substation in real time, and simultaneously monitors the surface temperature of the heat sink of the transformer, reactor, and power semiconductor device inside the substation, and monitors the temperature near the chip position to accurately monitor its operating temperature, and uses an amplification and filtering circuit to amplify and filter the electrical signal detected by the temperature sensor to obtain accurate temperature, temperature deviation, and temperature change rate, and transmits them to the classification threshold module (200) and the speed control module (300) respectively; The hierarchical threshold module (200) determines the primary threshold of temperature through the normal operating temperature range of the equipment inside the substation, determines the secondary threshold according to the balance between the heating power of the equipment and the heat dissipation power of the cooling equipment, determines the tertiary threshold according to the thermal stability of the equipment and the maximum heat dissipation capacity of the cooling equipment, and uses a piecewise function to describe the hierarchical temperature threshold model, collects previous temperature control data, substitutes it into the hierarchical temperature threshold model, and compares the result with the actual situation, thereby adjusting the model parameters and the model control strategy; The speed control module (300) adopts a fuzzy control algorithm, takes the temperature deviation and temperature change rate obtained by the temperature monitoring module (100) as input, obtains an accurate correction amount for the initial speed of the fan, sets the association rules between the temperature threshold of the graded control and the speed control unit according to the graded temperature threshold model established by the graded threshold module (200), synchronizes the consistency of graded switching and fan speed adjustment, and uses a feedback mechanism to dynamically adjust the fan speed parameters to optimize the synchronization effect; The fault alarm module (400) sets monitoring points in the hardware devices of the hierarchical control and the intelligent speed control, and when a fault occurs in one of the control modes, immediately issues an alarm signal, and at the same time, activates a fault compensation strategy based on another mode, so as to ensure that the internal temperature of the box transformer can still be effectively controlled in the event of a fault; The grading threshold module (200) includes a model building unit (210) and a model optimization unit (220); The model building unit (210) determines the graded temperature threshold value according to the temperature range of normal operation of the equipment inside the substation, the heating power of the equipment and the heat dissipation power of the cooling equipment, as well as the thermal stability of the equipment and the maximum heat dissipation capacity of the cooling equipment; The model optimization unit (220) collects multiple sets of temperature-time data, finds the minimum value of the sum of squares of the error between the actual temperature and the temperature predicted by the model through the least square method, adjusts the model parameters according to a certain proportion according to the error size, and adjusts the temperature threshold by monitoring the start-up state of the fan; The model optimization unit (220) monitors the fan startup frequency and temperature change law, plots a curve of the device temperature change over time, calculates the delay time between the fan startup time and the temperature change, and re-evaluates the temperature threshold; The speed control module (300) comprises an initial speed unit (310) and a switching and speed regulation unit (320); The initial speed unit (310) adopts a fuzzy control algorithm, takes the temperature deviation and the temperature change rate as input, adopts a triangular membership function, and uses the maximum and minimum reasoning method to determine the membership function of the output fuzzy set according to the fuzzy rule base to obtain an accurate correction value of the initial speed of the fan; The switching and speed regulation unit (320) starts the corresponding cooling equipment according to the hierarchical control strategy, and also determines the initial speed regulation strategy of the speed regulation unit at the same time, and uses the feedback mechanism to determine whether it is necessary to further adjust the hierarchical strategy or to perform hierarchical switching to the next level in advance.

2. The temperature control system for the energy storage box transformer according to claim 1 is characterized in that: The fault alarm module (400) collects transformer coil temperature and transformer chamber temperature collected by the thermostat, compares them with the graded temperature threshold determined by the graded threshold module (200), determines the fan startup state, and whether the temperature reaches the alarm threshold; if the threshold is reached, the measurement and control device outputs a trip signal.

3. The temperature control system of the energy storage box transformer according to claim 2 is characterized in that: When the fault alarm module (400) performs temperature control on the dry-type transformer, an auxiliary temperature controller is added, which has two sets of over-temperature dry contacts, trips the high-voltage switch through the measurement and control device, and directly trips the high-voltage switch using another set of over-temperature dry contacts.

4. The temperature control system for the energy storage box transformer according to claim 3 is characterized in that: The model building unit (210) calculates the rate of change of the device temperature over time through a heat balance equation, and determines the threshold of the secondary temperature based on the upper limit of the normal operating temperature range of the device and the temperature change rate, taking into account the time that the device can allow the temperature to exceed the normal range without being damaged, wherein the formula of the heat balance equation is: in, It's heat. is the mass of the object, is the specific heat capacity, It's the temperature change.

5. The temperature control system of the energy storage box transformer according to claim 4 is characterized in that: The fuzzy rule base of the initial speed unit (310) is in the form of: in, is the fuzzy set of temperature deviation, is the fuzzy set of temperature change rate, is the fuzzy set of fan speed correction, is the fan speed correction, is the temperature, is the temperature change rate; Among them, the output of the fuzzy control algorithm is defuzzified using the center of gravity method to obtain an accurate correction value for the fan speed, and the formula is: in, is the membership function, For the domain, is the fan speed correction, To find the differential.

6. The temperature control system for the energy storage box transformer according to claim 1 is characterized in that: The temperature monitoring module (100) comprises an amplifying and filtering unit (110), wherein the amplifying and filtering unit (110) comprises an amplifying and filtering circuit, wherein the amplifying and filtering circuit comprises a transistor Q1, a transistor Q2 and an operational amplifier A; The base of the transistor Q1 is connected to one end of the resistor R1 and one end of the resistor R2, the other end of the resistor R1 is connected to the positive electrode of the input voltage UI, the emitter of the transistor Q1 is connected to the negative electrode of the input voltage UI, the collector of the transistor Q1 is connected to one end of the resistor R3 and one end of the resistor R4, the other end of the resistor R4 is connected to pin 2 of the operational amplifier A and one end of the resistor R6 and one end of the capacitor C1, the pin 3 of the operational amplifier A is connected to one end of the resistor R5, the other end of the resistor R5 is grounded, the pin 1 of the operational amplifier A is connected to the base of the transistor Q2 and one end of the resistor R6 and the other end of the capacitor C1, the collector of the transistor Q2 is connected to one end of the resistor R7 and the positive electrode of the output voltage UO, the resistor R7 is connected in parallel to the resistor R3 and the resistor R2 to the power supply VCC, and the emitter of the transistor Q2 is connected to the negative electrode of the output voltage UO.

7. A method for implementing temperature control of a box transformer for energy storage, comprising a temperature control system for a box transformer for energy storage according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Real-time monitoring of the temperature inside the substation is performed through a temperature monitoring module (100) to obtain accurate temperature, temperature deviation, and temperature change rate; S2, using the classification threshold module (200) to establish a classification temperature threshold model, and optimizing and adjusting the model; S3, the speed control module (300) adopts a fuzzy control algorithm to obtain an accurate correction value of the initial speed of the fan, set the association rule between the temperature threshold of the graded control and the speed control unit, and synchronize the consistency of the graded switching and the fan speed adjustment; S4. The temperature control system is monitored through the fault alarm module (400), an alarm is issued when a fault occurs, and a fault compensation strategy is initiated.

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