Intelligent energy storage inverter adjusting system with peak clipping and valley filling functions

Abstract

The invention relates to the technical field of energy storage inverters, and particularly discloses a peak-load shifting intelligent energy storage inverter adjusting system which comprises an energy storage device used for being connected with an energy storage inverter. A data acquisition module; an electric energy quality evaluation module; a central control module; a driving module; through cooperation of the data acquisition module, the electric energy quality evaluation module, the central control module and the driving module, a preset current waveform can be dynamically adjusted according to real-time power grid parameters, and when the power grid frequency fluctuates, the frequency of the preset waveform is correspondingly adjusted to be synchronous with the power grid frequency; when the output characteristics of the energy storage device are changed due to aging of the energy storage device, the amplitude or other parameters of the preset waveform are adjusted according to the real-time state of the energy storage device so as to ensure that the output power of the inverter is matched with the actual demand, the risk of failure of the preset waveform is reduced, and the adjustment precision is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage inverters, and particularly relates to a peak shaving and valley filling intelligent energy storage inverter regulation system. Background Technique

[0002] As a key device connecting the energy storage system with the power grid or load, the performance of the intelligent energy storage inverter directly affects the operation efficiency, power quality, and stability of the energy storage system. In order to ensure that the energy storage inverter stably outputs high-quality electric energy under different working conditions, it is necessary to regulate the output power of the energy storage inverter to reduce the influence of voltage fluctuations or harmonic interference on the normal operation of the power grid or load equipment.

[0003] Currently, the power regulation method of intelligent energy storage inverters is usually harmonic governance or power quality optimization regulation based on power quality assessment. For example, Chinese patent document application number 202410021015.X discloses a method for regulating the output power of an energy storage inverter and a computer device, including: determining the busbar boxes and problem busbar boxes in the busbar box using reliability, obtaining the output current waveforms of the inverters connected to different busbar boxes, and determining the output reliability of different inverters and the problem inverter based on the phase of the output current waveform of the inverter and the preset current waveform. According to the output power of the energy storage device, the reliability of the reliable busbar box, and the similarity of the output current waveforms, the output reliability of the inverter and the similarity of the output current waveforms are used to determine the output power of different busbar boxes and inverters, ensuring the reliability of the energy storage device while reducing the harmonic content.

[0004] However, the above technical solution uses the preset current waveform as the only reference standard, which is not convenient for adapting to the dynamic changes of the grid demand or the real-time state of the energy storage device. When the grid frequency fluctuates or the energy storage device ages, the preset waveform may fail, affecting the accuracy of the assessment, and thus the accuracy of the output power regulation of the energy storage inverter is not ideal. Therefore, we need to propose a peak shaving and valley filling intelligent energy storage inverter regulation system to solve the above problems, enabling it to dynamically adjust the preset waveform according to real-time grid parameters, reducing the probability of the preset waveform failure, and improving the accuracy of the output power regulation of the energy storage inverter. Summary of the Invention

[0005] The purpose of the present invention is to provide a peak shaving and valley filling intelligent energy storage inverter regulation system, which can dynamically adjust the preset waveform according to real-time grid parameters, reduce the probability of the preset waveform failure, and improve the accuracy of the output power regulation of the energy storage inverter, so as to solve the problems raised in the above background technique.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A peak shaving and valley filling intelligent energy storage inverter regulation system, including an energy storage device for connecting with the energy storage inverter, the energy storage device is used to store electric energy, and cooperate with the energy storage inverter to achieve the peak shaving and valley filling function, and suppress the power fluctuation of the power grid;

[0008] A data acquisition module, which acquires grid parameters and the status information of the energy storage device;

[0009] A power quality assessment module, which assesses the current power quality according to the grid parameters acquired by the data acquisition module;

[0010] A central control module, which calculates the target output power of the energy storage inverter according to the status information of the energy storage device, the assessment result of the power quality assessment module, the preset peak shaving and valley filling strategy and the grid demand, and dynamically adjusts the preset current waveform according to the real-time grid parameters at the same time, so that the preset waveform can adapt to the actual situation of the power grid and the energy storage device;

[0011] A drive module, which drives the power device of the energy storage inverter to adjust the output power of the energy storage inverter according to the instruction issued by the central control module.

[0012] Preferably, the data acquisition module includes a parameter acquisition unit for acquiring grid parameters and a status acquisition unit for acquiring the status information of the energy storage device. The parameter acquisition unit is electrically connected to the power quality assessment module, and the status acquisition unit is electrically connected to the central control module.

[0013] Preferably, the process of the power quality assessment module for power quality assessment is as follows:

[0014] A1. Compare the actual voltage value acquired by the data acquisition module with the rated voltage value of the power grid, and calculate the voltage deviation;

[0015] A2. Extract the actual frequency value from the acquired grid parameters, and compare it with the standard frequency value of the power grid to calculate the frequency deviation;

[0016] A3. Use Fourier transform to convert the voltage signal in the time domain into a frequency domain signal, then analyze the amplitude and phase of each harmonic, and further calculate the harmonic voltage content;

[0017] A4. Calculate the positive sequence voltage effective value and negative sequence voltage effective value according to the instantaneous values of the three-phase voltages, and then calculate the three-phase unbalance degree according to the positive sequence voltage effective value and negative sequence voltage effective value.

[0018] Preferably, the peak shaving and valley filling strategy divides a day into peak hours, valley hours, and normal hours according to the load characteristics of the power grid. During peak hours, the energy storage system discharges at a certain power to support the power grid and relieve the load pressure of the power grid. During valley hours, it charges at an appropriate power to store excess electric energy. During normal hours, small-power charge and discharge adjustments are made according to the actual situation to maintain the stability of the power grid.

[0019] Preferably, the calculation process of the target output power of the energy storage inverter by the central control module is as follows:

[0020] C1. Determine the available capacity and safe operating range of the energy storage device according to the state of charge and temperature information of the energy storage device;

[0021] C2. Based on the results of the power quality evaluation module, judge the current power quality status of the power grid. If the voltage is too high, increase the charging power of the energy storage device to absorb excess electric energy. If the voltage is too low, increase the discharge power to boost the power grid voltage;

[0022] C3. Combine the preset peak shaving and valley filling strategy and the power grid demand to determine the power that the energy storage inverter should output under the current power grid load;

[0023] C4. Calculate the target output power of the energy storage inverter based on the power that the energy storage inverter should output.

[0024] Preferably, in step C2, the power quality status judgment process is as follows:

[0025] C21. Define the standard limits of each power quality index;

[0026] C22. Compare the real-time monitored voltage deviation value with the standard limit. If the deviation value is within the allowable range, it means the voltage quality is qualified. If the voltage exceeds the allowable range, it means the voltage quality is unqualified;

[0027] C23. Compare the monitored frequency deviation with the allowable range. If the frequency deviation is within the allowable range, the frequency quality meets the standard. If the frequency deviation exceeds the allowable range, it indicates that the frequency is abnormal;

[0028] C24. Compare the content of each harmonic voltage with the corresponding standard value. If the content of one or more harmonic voltages exceeds the specified value, it means the harmonic pollution exceeds the standard and the power quality is affected. If the content of multiple harmonic voltages does not exceed the specified value, it means there is no harmonic pollution;

[0029] C25. Compare the measured three-phase unbalance degree with the standard value. If it does not exceed the minimum value of the standard value, it means the three-phase balance condition is good. If it is within the standard value range, it belongs to a short-term unbalance situation. If it exceeds the maximum value of the standard value, the three-phase unbalance problem is relatively serious;

[0030] C26. Comprehensively consider the judgment results of various indicators, and comprehensively evaluate the power quality status. If all indicators are within the standard range, the power quality of the power grid is good; if one or more indicators exceed the standard, judge that the power quality is poor according to the degree of exceeding and the impact on the power grid operation and equipment.

[0031] Preferably, in step C4, the calculation formula for the target output power is:

[0032] P ta = P0 + k1ΔU + k2Δf + k3TD + k4ε + f(SOC), where P ta is the target output power of the energy storage inverter, P0 is the power that the energy storage inverter should output, ΔU is the voltage deviation, k1 is the weight coefficient of the voltage deviation, Δf is the frequency deviation, k2 is the weight coefficient of the frequency deviation, k3 is the weight coefficient of the harmonic voltage content, TD is the harmonic voltage content index, k4 is the weight coefficient of the three-phase unbalance degree, ε is the three-phase unbalance degree, and f(SOC) is a function of the state of charge of the energy storage device, which is used to adjust the target output power according to the current state of charge of the energy storage device.

[0033] Preferably, the process of the central control module for dynamically adjusting the preset current waveform is as follows:

[0034] D1. Obtain the power grid parameters in real time. The power grid parameters include information on voltage, current, and frequency;

[0035] D2. Analyze the operating state of the current power grid according to the obtained power grid parameters;

[0036] D3. Adjust the preset current waveform according to the power grid operating state according to the preset rules and algorithms.

[0037] Preferably, the drive module includes a signal processing unit for receiving instructions from the central control module, a PWM generation unit for generating PWM signals, a drive unit for converting the PWM signals into drive signals, and a protection unit for protecting the power devices of the inverter. The protection unit and the drive unit are both connected to the power devices of the energy storage inverter.

[0038] Preferably, the energy storage device is composed of a battery pack. The battery pack is connected to the energy storage inverter through a communication line to perform peak shaving during peak load periods of the power grid and valley filling during low load periods of the power grid.

[0039] Compared with the prior art, a peak shaving and valley filling intelligent energy storage inverter regulation system proposed by the present invention has the following advantages:

[0040] 1. Through the coordinated cooperation of the data acquisition module, power quality assessment module, central control module, and drive module, the present invention can dynamically adjust the preset current waveform according to real-time grid parameters. When the grid frequency fluctuates, the frequency of the preset waveform is correspondingly adjusted to keep it synchronized with the grid frequency. When the output characteristics of the energy storage device change due to aging, the amplitude or other parameters of the preset waveform are adjusted according to the real-time state of the energy storage device to ensure that the inverter output power matches the actual demand, reduce the risk of preset waveform failure, and improve the regulation accuracy.

[0041] 2. Through the cooperation of the energy storage inverter, energy storage device, and central control module, the present invention realizes the charge and discharge control of the energy storage device, and further realizes the functions of peak shaving and valley filling and power regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The system block diagram of the regulation system according to an embodiment of the present invention is shown;

[0043] Figure 2 The flowchart of power quality assessment by the power quality assessment module according to an embodiment of the present invention is shown;

[0044] Figure 3 The flowchart of calculating the target output power of the energy storage inverter by the central control module according to an embodiment of the present invention is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0046] The present invention provides a Figures 1-3 peak shaving and valley filling intelligent energy storage inverter regulation system as shown, including an energy storage device, a data acquisition module, a power quality assessment module, a central control module, and a drive module for connecting with the energy storage inverter. The data acquisition module collects grid parameters and the state information of the energy storage device. The grid parameters include voltage, current, and frequency, and the state information includes the state of charge and temperature of the battery.

[0047] The data acquisition module includes a parameter acquisition unit for acquiring grid parameters and a state acquisition unit for acquiring the state information of the energy storage device. The parameter acquisition unit is electrically connected to the power quality assessment module, and the state acquisition unit is electrically connected to the central control module. The parameter acquisition unit and the state acquisition unit provide a real-time and accurate data source for the output power regulation of the energy storage inverter.

[0048] The parameter acquisition unit includes a sensor group, a signal conditioning circuit, and an analog-to-digital converter. The signal conditioning circuit is electrically connected to the sensor group and the analog-to-digital converter respectively. The sensor group includes a voltage sensor, a current sensor, and a frequency sensor. The voltage sensor is connected in parallel to the grid line, the current sensor is connected in series to the grid line, and the frequency sensor is connected to a signal source that can reflect the grid frequency. The real-time voltage of the grid is acquired through the voltage sensor, the real-time current of the grid is acquired through the current sensor, and the grid frequency is acquired in real-time by the frequency sensor. The signal conditioning circuit is used to amplify and filter the signals acquired by the sensor group. The signal conditioning circuit consists of an operational amplifier and an RC filter circuit. The analog signals acquired by the sensor group are amplified by the operational amplifier, and then the amplified signals are filtered by the RC filter circuit to remove interference signals. The analog-to-digital converter converts the adjusted analog signals into digital signals and transmits the converted signals to the power quality assessment module.

[0049] The state acquisition unit includes a current transformer, a temperature sensor, and a microcontroller. The microcontroller is electrically connected to the current transformer and the temperature sensor respectively. The current transformer is connected in series in the battery charge and discharge circuit, and the temperature sensors are distributed at different positions of the battery pack. By measuring the current during the battery charge and discharge process, the microcontroller acquires and integrates the current signals, and updates the SOC of the battery according to the initial state of charge and the current integral value during the charge and discharge process. The overall temperature distribution of the energy storage device is monitored in real-time through the temperature sensor, and the acquired temperature signals are transmitted to the microcontroller for storage and analysis to provide a data source for the preset current waveform adjustment.

[0050] The power quality assessment module evaluates the current power quality according to the grid parameters acquired by the data acquisition module.

[0051] The process of the power quality assessment module for power quality assessment is as follows:

[0052] A1. Compare the actual voltage value acquired by the data acquisition module with the grid rated voltage value, and calculate the voltage deviation. The calculation formula for the voltage deviation is:

[0053] where ΔU is the voltage deviation, U is the actual measured voltage value of the grid, U Eis the rated voltage value of the power grid;

[0054] A2. Extract the actual frequency value from the collected power grid parameters, compare it with the standard frequency value of the power grid, and calculate the frequency deviation. The frequency deviation is the difference between the actually measured frequency value and the standard frequency value of the power grid;

[0055] A3. Use Fourier transform to convert the voltage signal in the time domain into a frequency domain signal, then analyze the amplitude and phase of each harmonic, and further calculate the harmonic voltage content. The formula for calculating the harmonic voltage content is:

[0056] where TD is the harmonic voltage content index, U1 is the effective value of the fundamental wave voltage, and U n is the effective value of the nth harmonic voltage;

[0057] A4. Calculate the positive-sequence voltage effective value and the negative-sequence voltage effective value according to the instantaneous values of the three-phase voltages, and then calculate the three-phase unbalance degree according to the positive-sequence voltage effective value and the negative-sequence voltage effective value. Among them, the formula for calculating the positive-sequence voltage effective value is:

[0058] where U 正 is the positive-sequence voltage effective value, U a , U b and U c are the instantaneous values of the three-phase voltages respectively, a is the rotation factor for rotating the voltage component counterclockwise by 120°, that is a 2 is the rotation factor for rotating the voltage component counterclockwise by 240°;

[0059] The formula for calculating the negative-sequence voltage effective value is:

[0060] where U 负 is the negative-sequence voltage effective value;

[0061] The formula for calculating the three-phase unbalance degree is:

[0062] where ε is the negative-sequence unbalance degree;

[0063] The central control module calculates the target output power of the energy storage inverter according to the state information of the energy storage device collected by the data acquisition module, the evaluation results of the power quality evaluation module, the preset peak shaving and valley filling strategy, and the power grid demand. At the same time, it dynamically adjusts the preset current waveform according to the real-time power grid parameters, so that the preset waveform can adapt to the actual situation of the power grid and the energy storage device;

[0064] The peak shaving and valley filling strategy divides a day into peak hours, valley hours, and normal hours according to the load characteristics of the power grid. During peak hours, the energy storage system discharges at a certain power to support the power grid and relieve the load pressure on the power grid. During valley hours, it charges at an appropriate power to store excess electrical energy. During normal hours, small-power charge and discharge adjustments are made according to the actual situation to maintain the stability of the power grid.

[0065] The preset process of the peak shaving and valley filling strategy is as follows:

[0066] B1. Obtain historical power grid load data, analyze the historical power grid load data, and determine the time ranges and power thresholds for peak, valley, and normal hours. For example, by statistically analyzing the power grid load data of the past year, find the time periods when the daily load exceeds a certain value (such as 120% of the average load) as peak hours, the time periods when it is lower than a certain value (such as 80% of the average load) as valley hours, and the rest as normal hours.

[0067] B2. Set the charge and discharge power limits for different time periods according to the capacity and performance of the energy storage device. For example, during peak hours, set the maximum discharge power of the energy storage device to 80% of its rated power to ensure that while meeting the power grid demand, it will not cause excessive loss to the energy storage device. During valley hours, set the charging power to 60%-80% of the rated charging power to avoid excessive charging affecting the battery life.

[0068] B3. Develop a real-time adjustment strategy to dynamically adjust the charge and discharge power according to the real-time power grid load situation and the state of the energy storage device. For example, during peak hours, if the power grid load continues to increase and the SOC of the energy storage device permits, the discharge power can be appropriately increased. During valley hours, if the power grid load shows an upward trend, the charging power can be reduced in advance to prepare for possible discharge requirements.

[0069] The calculation process of the target output power of the energy storage inverter by the central control module is as follows:

[0070] C1. Determine the available capacity and safe operating range of the energy storage device according to the state of charge (SOC) and temperature information of the energy storage device.

[0071] C2. Based on the results of the power quality assessment module, such as voltage deviation, frequency deviation, harmonic voltage content, and three-phase unbalance degree, judge the current power quality status of the power grid. If the voltage is too high, increase the charging power of the energy storage device to absorb excess electrical energy. If the voltage is too low, increase the discharge power to boost the power grid voltage.

[0072] The process of judging the power quality status is as follows:

[0073] C21. Define the standard limits for various power quality indicators. For example, according to relevant national standards, the voltage deviation is generally required to be within the range of ±5% - ±10% of the rated voltage; the frequency deviation is usually allowed to be between ±0.2 - ±0.5 Hz; the harmonic voltage content has different limit standards according to different voltage levels and electrical equipment. For example, in a low-voltage distribution network, the content rate of each harmonic voltage generally does not exceed 5%; the three-phase unbalance degree is generally required not to exceed 2%, and not to exceed 4% for a short time.

[0074] C22. Compare the real-time monitored voltage deviation value with the standard limit. If the deviation value is within the allowable range, it indicates that the voltage quality is qualified; if the voltage exceeds the allowable range, it indicates that the voltage quality is unqualified. For example, if it exceeds 10% of the rated voltage, it is determined that the voltage is too high; if it is lower than the lower limit value, such as lower than 5% of the rated voltage, it is determined that the voltage is too low.

[0075] C23. Compare the monitored frequency deviation with the allowable range. If the frequency deviation is within the allowable range, the frequency quality meets the standard; if the frequency deviation exceeds the allowable range, it indicates that the frequency is abnormal.

[0076] C24. Compare the content of each harmonic voltage with the corresponding standard value. If the content of one or more harmonics exceeds the specified value, such as exceeding 5% in a low-voltage distribution network, it indicates that the harmonic pollution exceeds the standard and the power quality is affected; if the content of multiple harmonic voltages does not exceed the specified value, it indicates that there is no harmonic pollution.

[0077] C25. Compare the measured three-phase unbalance degree with the standard value. If it does not exceed the minimum value of the standard value, it indicates that the three-phase balance is good; if it is within the standard value range, it belongs to a short-term unbalanced situation; if it exceeds the maximum value of the standard value, the three-phase unbalance problem is relatively serious. For example, if it does not exceed 2%, the three-phase balance is good; if it exceeds 2% but does not exceed 4%, it belongs to a short-term unbalanced situation; if it exceeds 4%, the three-phase unbalance problem is relatively serious.

[0078] C26. Comprehensively consider the judgment results of various indicators and comprehensively evaluate the power quality status. If all indicators are within the standard range, the power quality of the power grid is good; if one or more indicators exceed the standard, according to the degree of exceeding and the impact on the power grid operation and equipment, judge that the power quality is poor. For example, if only the voltage deviation slightly exceeds the standard and other indicators are normal, it may have a certain impact on the operation of some equipment, and the power quality is judged to be average; if the voltage deviation is large and at the same time the harmonic voltage content also exceeds the standard, it may cause electrical equipment to heat up, increase losses and even fail. At this time, the power quality is judged to be poor.

[0079] C3. Determine the power that the energy storage inverter should output under the current grid load condition in combination with the preset peak shaving and valley filling strategy and grid demand. For example, during peak electricity consumption periods, increase the discharge power of the energy storage device to meet the grid load demand; during off-peak electricity consumption periods, charge to store electrical energy.

[0080] C4. Calculate the target output power of the energy storage inverter based on the power that the energy storage inverter should output. The formula for the target output power is:

[0081] P ta = P0 + k1ΔU + k2Δf + k3TD + k4ε + f(SOC), where P ta is the target output power of the energy storage inverter, P0 is the power that the energy storage inverter should output, ΔU is the voltage deviation, k1 is the weight coefficient of the voltage deviation, Δf is the frequency deviation, k2 is the weight coefficient of the frequency deviation, k3 is the weight coefficient of the harmonic voltage content, TD is the harmonic voltage content index, k4 is the weight coefficient of the three-phase unbalance degree, ε is the three-phase unbalance degree, f(SOC) is a function of the state of charge of the energy storage device, which is used to adjust the target output power according to the current state of charge of the energy storage device. For example, when the SOC is relatively high, f(SOC) may increase the target output power so as to output more electrical energy to the grid; when the SOC is relatively low, f(SOC) will limit the target output power to prevent over-discharge. k1, k2, k3, k4, and f(SOC) are reasonably set and optimized according to the specific grid operation conditions, the characteristics of the energy storage device, and the power quality standards to ensure that the calculated target output power can effectively improve the power quality while ensuring the safe and stable operation of the energy storage device;

[0082] The process of the central control module for dynamically adjusting the preset current waveform is as follows:

[0083] D1. Obtain grid parameters in real time. The grid parameters include information on voltage, current, and frequency.

[0084] D2. Analyze the operating state of the current grid based on the obtained grid parameters, such as whether there are voltage fluctuations, frequency offsets, etc.

[0085] D3. Adjust the preset current waveform according to the grid operating state according to the preset rules and algorithms. The preset rules and algorithms are formulated based on the operating requirements of the power system and the characteristics of the energy storage system, and are reasonably selected and combined according to the specific grid operating conditions, the configuration of the energy storage system, and the control objectives to achieve precise control and optimization of the grid parameters and ensure the stable and reliable operation of the grid;

[0086] The drive module drives the power devices of the energy storage inverter to adjust the output power of the energy storage inverter according to the instructions issued by the central control module.

[0087] The driving module includes a signal processing unit for receiving instructions from the central control module, a PWM generating unit for generating PWM signals, a driving unit for converting the PWM signals into driving signals, and a protection unit for protecting the power devices of the inverter. The protection unit and the driving unit are both connected to the power devices of the energy storage inverter. The power devices of the energy storage inverter are set as insulated gate bipolar transistors. The digital signals transmitted from the central control module are received by the signal processing unit, processed, and converted into a signal form suitable for the PWM generating unit to process. The PWM generating unit generates PWM signals according to the processed signals and a specific algorithm. For example, when it is necessary to increase the output power of the inverter, the duty cycle of the PWM signal will increase, making the conduction time of the power device longer; conversely, when it is necessary to reduce the output power, the duty cycle will decrease.

[0088] The driving unit processes the PWM signals such as isolation and amplification, generates driving signals capable of driving power devices (such as IGBTs), and applies them to the control terminals of the power devices to control the switching actions of the IGBTs. By controlling the switching frequency and duty cycle of the IGBTs, the amplitude and frequency of the AC voltage output by the inverter are adjusted, thereby realizing the adjustment of the output power of the energy storage inverter to meet the requirements of the power grid for power quality and power balance. During the whole process, the protection circuit continuously monitors the working state of the power devices. Once an abnormality is detected, protection measures are immediately taken to stop the operation of the power devices and avoid system failures and damages;

[0089] The signal processing unit includes a level conversion chip of model MAX232, an LM358 operational amplifier connected to the level conversion chip, and an LC filter connected to the operational amplifier. The level conversion chip conducts conversions between different level standards to ensure the correct transmission of digital signals between circuits in different voltage domains. The LM358 operational amplifier amplifies the weak input signals to the required amplitude to meet the signal strength requirements of subsequent units. The LC filter filters out the interference noise in the signals to improve the quality and stability of the signals;

[0090] The PWM generating unit includes a digital signal processor with a built-in PWM generating module. By writing the corresponding program for the PWM generating module and utilizing the resources of its internal timer and calculator, PWM signals are generated according to the input signals and a specific algorithm;

[0091] The driving unit includes an optocoupler isolator and a power amplifier. The optocoupler isolator transmits the PWM signals in the form of optical signals, effectively isolating the high voltage in the main circuit. The power amplifier is composed of MOSFETs and amplifies the PWM signals to sufficient power and voltage amplitude to drive the insulated gate bipolar transistors;

[0092] The protection circuit consists of a Hall current sensor, a resistive voltage divider voltage sensor, a thermistor, and a comparator of model LM339. The Hall current sensor, the resistive voltage divider voltage sensor, and the thermistor are all connected to the comparator. The working current of the power device of the energy storage inverter is monitored in real time through the Hall current sensor. The resistive voltage divider voltage sensor converts the high voltage of the main circuit into a low voltage in proportion through a resistor network for the protection circuit to monitor the voltage. When overvoltage or undervoltage is detected, the protection circuit will act. The resistance value of the thermistor changes with temperature, and the temperature information of the power device of the energy storage inverter can be indirectly obtained by measuring its resistance value. When the temperature exceeds the set upper limit, the protection circuit will trigger a protection action to prevent the power device from being damaged due to overheating. The comparator compares the signals detected by the sensors with the preset thresholds. When the detected signal exceeds the threshold, the output state of the comparator changes, thus triggering the corresponding action of the protection circuit.

[0093] The energy storage device is used to store electrical energy and cooperate with the energy storage inverter to achieve the function of peak shaving and valley filling, and smooth the power fluctuations of the power grid.

[0094] The energy storage device consists of a battery pack. The battery pack is connected to the energy storage inverter through a communication line. When the power grid load is at the peak period, peak shaving is carried out. Specifically, the central control module judges whether the preset peak threshold is reached according to the monitored power grid power data. If the peak is reached, the central control module sends a discharge instruction to the energy storage inverter. After receiving the instruction, the energy storage inverter controls the energy storage device to start discharging, converts the direct current in the energy storage device into alternating current matching the voltage and frequency of the power grid, and outputs it to the power grid at a certain power to supplement the shortage of the power grid power and relieve the power supply pressure of the power grid, so as to achieve the purpose of peak shaving. The energy storage inverter also accurately controls the discharge amount of the energy storage device by adjusting its own output power according to the actual needs of the power grid. For example, when the peak load of the power grid changes, the energy storage inverter can adjust the output power in real time to make the discharge power of the energy storage device adapt to it, ensuring the stability of the power grid power.

[0095] During the low valley period of the power grid load, valley filling is carried out. Specifically, when the central control module monitors that the power grid power is lower than the preset valley threshold, it will issue a charging instruction. The energy storage inverter converts the alternating current in the power grid into direct current suitable for charging the energy storage device to charge the energy storage device. At this time, the energy storage device absorbs the excess electrical energy of the power grid and stores it to achieve the function of valley filling and improve the power utilization rate of the power grid. In order to protect the energy storage device and extend its service life, the energy storage inverter will adopt an optimized charging strategy according to the characteristics of the energy storage device and the current state of charge, such as adopting different charging methods in different stages such as constant current charging and constant voltage charging to ensure that the energy storage device is charged quickly and efficiently under the premise of safety.

[0096] The data acquisition module transmits the collected power grid and energy storage device data to the power quality assessment module and the central control module; the power quality assessment module feeds back the assessment results to the central control module; the central control module performs operations and makes decisions based on the received information, and sends control instructions to the drive module; the drive module controls the power output of the energy storage inverter according to the instructions. At the same time, the energy storage inverter is connected to the energy storage device to realize the charge and discharge control of the energy storage device, thereby realizing the functions of peak shaving and valley filling and power regulation. Among them, the central control module also dynamically adjusts the preset current waveform according to the real-time power grid parameters. When the power grid frequency fluctuates, the frequency of the preset waveform is adjusted accordingly to keep it synchronized with the power grid frequency; when the output characteristics of the energy storage device change due to aging, the amplitude or other parameters of the preset waveform are adjusted according to the real-time state of the energy storage device to ensure that the inverter output power matches the actual demand, reduce the risk of preset waveform failure, and improve the regulation accuracy.

[0097] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An intelligent energy storage inverter regulation system with peak shaving and valley filling, characterized in that: It includes an energy storage device for connecting to an energy storage inverter. The energy storage device is used to store electrical energy and cooperate with the energy storage inverter to achieve the function of peak shaving and valley filling, and smooth the power fluctuation of the power grid. A data acquisition module that acquires grid parameters and the status information of the energy storage device. A power quality assessment module that assesses the current power quality based on the grid parameters acquired by the data acquisition module. A central control module that calculates the target output power of the energy storage inverter according to the status information of the energy storage device, the assessment result of the power quality assessment module, the preset peak shaving and valley filling strategy, and the grid demand. At the same time, it dynamically adjusts the preset current waveform according to the real-time grid parameters to make the preset waveform adapt to the actual situation of the power grid and the energy storage device. A drive module that drives the power devices of the energy storage inverter to adjust the output power of the energy storage inverter according to the instructions issued by the central control module.

2. The intelligent energy storage inverter regulation system with peak shaving and valley filling according to claim 1, wherein: The data acquisition module includes a parameter acquisition unit for acquiring grid parameters and a status acquisition unit for acquiring the status information of the energy storage device. The parameter acquisition unit is electrically connected to the power quality assessment module, and the status acquisition unit is electrically connected to the central control module.

3. The intelligent energy storage inverter regulation system with peak shaving and valley filling according to claim 1, wherein: The process of the power quality assessment module for power quality assessment is as follows: A1. Compare the actual voltage value acquired by the data acquisition module with the rated voltage value of the power grid to calculate the voltage deviation. A2. Extract the actual frequency value from the acquired grid parameters and compare it with the standard frequency value of the power grid to calculate the frequency deviation. A3. Use Fourier transform to convert the voltage signal in the time domain into a frequency domain signal, then analyze the amplitude and phase of each harmonic, and further calculate the harmonic voltage content. A4. Calculate the positive-sequence voltage effective value and negative-sequence voltage effective value according to the instantaneous values of the three-phase voltages, and then calculate the three-phase unbalance degree according to the positive-sequence voltage effective value and negative-sequence voltage effective value.

4. A peak shaving and valley filling intelligent energy storage inverter regulation system according to claim 1, characterized in that: The peak shaving and valley filling strategy divides a day into peak hours, valley hours, and normal hours according to the load characteristics of the power grid. During peak hours, the energy storage system discharges at a certain power to support the power grid supply and relieve the load pressure of the power grid. During valley hours, it charges at an appropriate power to store excess electrical energy; during normal hours, small-power charge and discharge adjustments are made according to the actual situation to maintain the stability of the power grid.

5. The intelligent energy storage inverter regulation system with peak shaving and valley filling according to claim 4, wherein: The process of the central control module for calculating the target output power of the energy storage inverter is as follows: C1. Determine the available capacity and safe operating range of the energy storage device according to the state of charge and temperature information of the energy storage device. C2. Based on the result of the power quality assessment module, judge the current power quality status of the power grid. If the voltage is too high, increase the charging power of the energy storage device to absorb excess electrical energy. If the voltage is too low, increase the discharge power to boost the power grid voltage. C3. Combine the preset peak shaving and valley filling strategy and the grid demand to determine the power that the energy storage inverter should output under the current grid load condition. C4. Calculate the target output power of the energy storage inverter in combination with the power that the energy storage inverter should output.

6. The intelligent energy storage inverter regulation system with peak shaving and valley filling according to claim 5, characterized in that: In step C2, the process of judging the power quality status is as follows: C21. Define the standard limits of each power quality index. C22. Compare the real-time monitored voltage deviation value with the standard limit value. If the deviation value is within the allowable range, it indicates that the voltage quality is qualified; if the voltage exceeds the allowable range, it indicates that the voltage quality is unqualified. C23. Compare the monitored frequency deviation with the allowable range. If the frequency deviation is within the allowable range, the frequency quality meets the standard; if the frequency deviation exceeds the allowable range, it indicates that the frequency is abnormal. C24. Compare the content of each harmonic voltage with the corresponding standard value. If the content of one or more harmonic voltages exceeds the specified value, it indicates that the harmonic pollution exceeds the standard and the power quality is affected; if the content of multiple harmonic voltages does not exceed the specified value, it indicates that there is no harmonic pollution. C25. Compare the measured three-phase unbalance degree with the standard value. If it does not exceed the minimum value of the standard value, it indicates that the three-phase balance condition is good; if it is within the standard value range, it belongs to a short-term unbalance situation; if it exceeds the maximum value of the standard value, the three-phase unbalance problem is relatively serious. C26. Comprehensively consider the judgment results of various indicators and comprehensively evaluate the power quality status. If all indicators are within the standard range, the power quality of the power grid is good; if one or more indicators exceed the standard, judge the power quality as poor according to the degree of exceeding and the impact on the power grid operation and equipment.

7. The intelligent energy storage inverter regulation system with peak shaving and valley filling according to claim 6, characterized in that: In step C4, the calculation formula for the target output power is: P ta = P0 + k1ΔU + k2Δf + k3TD + k4ε + f(SOC), where P ta is the target output power of the energy storage inverter, P0 is the power that the energy storage inverter should output, ΔU is the voltage deviation, k1 is the weight coefficient of the voltage deviation, Δf is the frequency deviation, k2 is the weight coefficient of the frequency deviation, k3 is the weight coefficient of the harmonic voltage content, TD is the harmonic voltage content index, k4 is the weight coefficient of the three-phase unbalance degree, ε is the three-phase unbalance degree, and f(SOC) is a function of the state of charge of the energy storage device, which is used to adjust the target output power according to the current state of charge of the energy storage device.

8. A peak shaving and valley filling intelligent energy storage inverter regulation system according to claim 7, characterized in that: The process of the central control module for dynamically adjusting the preset current waveform is as follows: D1. Obtain the power grid parameters in real time. The power grid parameters include information on voltage, current, and frequency. D2. Analyze the current operating state of the power grid according to the obtained power grid parameters. D3. Adjust the preset current waveform according to the operating state of the power grid according to the preset rules and algorithms.

9. The intelligent energy storage inverter regulation system with peak shaving and valley filling according to claim 1, characterized in that: The drive module includes a signal processing unit for receiving instructions from the central control module, a PWM generation unit for generating PWM signals, a drive unit for converting the PWM signals into drive signals, and a protection unit for protecting the power devices of the inverter. The protection unit and the drive unit are both connected to the power devices of the energy storage inverter.

10. A peak shaving and valley filling intelligent energy storage inverter regulation system according to claim 1, characterized in that: The energy storage device consists of a battery pack. The battery pack is connected to the energy storage inverter through a communication line to perform peak shaving during peak grid load periods and valley filling during low grid load periods.

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