A method for correcting power distribution errors in parallel operation of energy storage

Abstract

This invention discloses a power distribution error correction method for energy storage in parallel operation, relating to the field of energy storage device power control technology. First, initial power allocation is performed based on the device's state of charge. Then, a dynamic grouping and cyclic redistribution mechanism handles excess power to ensure the safe operation of each device. Next, error correction is performed by comparing the actual and target total power. Based on fluctuation monitoring, dynamic or static error thresholds are intelligently switched to achieve a balance between high precision and stability. This invention solves the problem of uneven power distribution through dynamic grouping and cyclic redistribution mechanisms, improving system safety and output capacity. Combined with dual-threshold correction and variance monitoring, it intelligently balances precision and stability, eliminating errors while reducing equipment losses, thereby improving overall operating efficiency and lifespan.

Description

Technical Field

[0001] This invention relates to the field of power control technology for energy storage devices, specifically a method for correcting power distribution errors in parallel operation of energy storage systems. Background Technology

[0002] In parallel energy storage systems, whether it is a photovoltaic-storage integrated system for residential and commercial scenarios or a larger-scale industrial and commercial energy storage system, when multiple devices are operating in parallel and in coordination, they all face a core and common technical challenge: power distribution. In order to achieve a rapid and accurate response of the total system power to the upper-level scheduling command, the total power target must be reasonably, efficiently and safely distributed to each parallel-operating energy storage unit. This is not only related to the overall control accuracy and energy conversion efficiency of the system, but also the key to ensuring equipment safety and extending battery life.

[0003] For example, the power control method for hybrid energy storage systems used for new energy prediction error compensation provided in Chinese Patent Publication No. CN114899850A generates an allowable error domain for the output of new energy power plants based on short-term and ultra-short-term prediction data of new energy power output. Combined with real-time new energy power output data, it obtains the total power that the hybrid energy storage system needs to compensate for. It selects reasonable wavelet basis functions and wavelet decomposition level k; implements initial power allocation for the hybrid energy storage system based on real-time wavelet transform; designs the charging and discharging operating areas of battery energy storage and flywheel energy storage; and corrects power commands in real-time based on the state of charge of battery energy storage and the energy state of flywheel energy storage, thereby achieving coordinated power control of the hybrid energy storage system. This control method is adaptable to different new energy power plants and can achieve coordinated power control of hybrid energy storage systems in new energy power prediction error compensation scenarios, improving the prediction accuracy of new energy power plants.

[0004] In grid-connected energy storage systems, allocating power solely based on the battery's state of charge has significant drawbacks. Some devices may fail to operate due to power allocation exceeding their maximum limits, while others may fail to reach their optimal operating point due to insufficient power allocation. Furthermore, since the devices themselves inevitably have output errors, these errors accumulate and amplify when multiple devices are connected in parallel, lacking secondary error control. Additionally, directly discarding excess power during the allocation process also generates extra errors. Summary of the Invention

[0005] Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a power distribution error correction method for energy storage in parallel operation. This method solves the problems in current grid-connected energy storage systems where power distribution is based solely on the state of charge ratio, which can easily lead to equipment overload or underload. Furthermore, the lack of closed-loop processing for parallel error accumulation and the discarding of overloaded power results in a decrease in system control accuracy.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a power allocation error correction method for energy storage in parallel operation, comprising the following specific steps: Step 1: Based on historical experiments, set the target total power, dynamic total power error threshold, and static total power error threshold, and acquire energy storage device data, including the number of devices, the state of charge (SOC) of each device, and the maximum operating power of each device; Step 2: Calculate the SOC power allocation ratio based on the number of devices and the SOC of each device, and then calculate the actual operating power initially allocated to each device in conjunction with the target total power; Step 3: Define an over-limit set and a non-over-limit set, classify the initially allocated devices as over-limit or not, and calculate... Step 3: Distribute excess power to the set of devices that have not exceeded the limit, and assign a reasonable power to each device in the set of devices that have exceeded the limit. This process is repeated until all excess power has been distributed. Step 4: Sum the actual operating power of each device to obtain the actual total power. Analyze whether the absolute value of the difference between the actual total power and the target total power exceeds the static total power error threshold. If the analysis shows that it exceeds the threshold, a correction is made; otherwise, no correction is made. Step 5: Monitor the fluctuation of the difference between the actual total power and the target total power. If the fluctuation exceeds the set range, switch to the dynamic total power error threshold; otherwise, use the static total power error threshold.

[0008] Furthermore, the specific method for obtaining the initial allocated actual operating power of each device is as follows: sum the states of charge of each device to obtain the total state of charge; calculate the quotient between the state of charge of any device and the total state of charge to obtain the state of charge power allocation ratio, wherein the total state of charge is not zero; and multiply the state of charge power allocation ratio with the target total power to obtain the initial allocated actual operating power of each device.

[0009] Furthermore, the specific method for classifying the initially allocated equipment as exceeding the limit is as follows: compare the actual operating power of each initially allocated equipment with the maximum operating power of each equipment. If the actual operating power of each initially allocated equipment is greater than the maximum operating power of each equipment, it is classified into the exceeding limit set; if the actual operating power of each initially allocated equipment is less than or equal to the maximum operating power of each equipment, it is classified into the non-exceeding limit set.

[0010] Furthermore, the specific method for obtaining the excess power is as follows: the difference between the actual operating power initially allocated to each device in the over-limit set and the maximum operating power of each device is calculated, and then the difference is summed according to the number of devices to obtain the excess power.

[0011] Furthermore, the specific method for obtaining the actual operating power of each device after secondary allocation is as follows: Calculate the actual operating power of each non-over-limit device after secondary allocation based on the state of charge and excess power of each device in the non-over-limit set, and assign the maximum operating power of each device to each device in the over-limit set to obtain the actual operating power of each over-limit device after secondary allocation. Combine the actual operating power of each non-over-limit device with the actual operating power of each over-limit device after secondary allocation to obtain the actual operating power of each device after secondary allocation.

[0012] Furthermore, the specific method for obtaining the actual operating power of each non-over-limit device in the secondary allocation is as follows: sum the states of charge of each device in the non-over-limit set to obtain the total non-over-limit states of charge; quotient the states of charge of each device in the non-over-limit set with the total non-over-limit states of charge to obtain the power allocation ratio of the non-over-limit states of charge, wherein the total non-over-limit states of charge are not zero; multiply the power allocation ratio of the non-over-limit states of charge with the excess power to obtain the actual operating power of each non-over-limit device in the secondary allocation.

[0013] Furthermore, the specific steps for making the correction are as follows: calculate the difference between the actual total power and the target total power to obtain the gap power; count the number of devices in the set that have not exceeded the limit to obtain the number of devices that have not exceeded the limit; calculate the quotient between the gap power and the number of devices that have not exceeded the limit to obtain the average gap power; and add the average gap power to the actual operating power of each device that has not exceeded the limit and is re-allocated.

[0014] Furthermore, the specific method for monitoring the fluctuation of the difference between the actual total power and the target total power is as follows: the fluctuation value of the actual total power in the time series is calculated by the variance method, the fluctuation threshold is set according to historical experiments, and the fluctuation value is compared with the fluctuation threshold. If the fluctuation value is greater than the fluctuation threshold, it means that the fluctuation exceeds the set range. If the fluctuation value is less than or equal to the fluctuation threshold, it means that the fluctuation does not exceed the set range.

[0015] Furthermore, the specific steps for calculating the fluctuation value of the actual total power in the time series using the variance method are as follows: equally extract the time series to obtain average time periods; count the number of times the absolute value of the difference between the actual total power and the target total power in each average time period exceeds the static total power error threshold, obtain the number of times exceeding the threshold in each average time period; count the number of time periods to obtain the number of time periods; sum the number of times exceeding the threshold in each average time period based on the number of time periods and then average them to obtain the average number of times exceeding the threshold in each average time period; take the square root of the difference between the number of times exceeding the threshold in each average time period and the average number of times exceeding the threshold in each average time period, and then sum them to obtain the total fluctuation value; finally, calculate the quotient between the total fluctuation value and the number of time periods.

[0016] Beneficial effects

[0017] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0018] 1. By introducing a dynamic division of over-limit and non-over-limit equipment sets and a cyclical secondary allocation mechanism for surplus power, the problem of uneven power distribution caused by the maximum power limit of equipment is effectively solved. This not only avoids the overload or underload operation of a single equipment and significantly improves system safety and equipment utilization, but also maximizes the overall output capacity of the energy storage system while ensuring the safe operation of each device.

[0019] 2. By adopting a dual correction strategy that combines static and dynamic error thresholds, and monitoring power fluctuations in real time based on the variance method, this design can intelligently sense the system's operating status and achieve the best balance between accuracy and stability: it can eliminate accumulated errors through closed-loop correction to ensure that the output power accurately follows the scheduling instructions, and avoid excessively frequent corrections when fluctuations are severe, thereby reducing equipment wear and improving the overall operating efficiency and lifespan of the system.

[0020] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0021] Figure 1 This invention provides a flowchart of a power distribution error correction method for energy storage in parallel operation. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0024] Example 1:

[0025] like Figure 1 As shown, this embodiment of the invention provides a method for correcting power distribution errors in parallel operation of energy storage systems, including the following specific steps:

[0026] Step 1: Initialize the power allocation of the energy storage devices to ensure that the initial power allocation of all devices is zero, so as to avoid the interference of the previously allocated power to the current power allocation. Based on historical experiments, set the target total power, dynamic total power error threshold and static total power error threshold. The premise of the target total power is to ensure that the allocated power does not exceed the sum of the maximum operating power of all devices. Obtain the energy storage device data, including the number of devices, the state of charge of each device and the maximum operating power of each device. The state of charge is the current battery power of the device.

[0027] Step 2: Calculate the power allocation ratio based on the number of devices and the state of charge of each device. Then, combine this with the target total power to calculate the actual operating power initially allocated to each device. Allocating power according to the state of charge can maximize the utilization of high-power devices while protecting low-power devices from excessive wear, thereby optimizing the overall system performance and extending device battery life.

[0028] Step 3: Define the over-limit set and the non-over-limit set. The over-limit set is used to filter out the set of devices whose allocated power exceeds their maximum operating power, and the non-over-limit set is used to filter out the set of devices whose allocated power does not exceed their maximum operating power. The devices initially allocated are divided into over-limit and non-over-limit sets. The excess power is calculated based on the actual operating power initially allocated to each device in the over-limit set and the maximum operating power of each device. The excess power is then redistributed to the devices in the non-over-limit set, and each device in the over-limit set is assigned a reasonable power. The actual operating power of each device is then obtained. Step 3 is executed repeatedly until the excess power is distributed. By redistributing the excess power to the devices that still have capacity according to the state of charge ratio, the overall output capacity of the system is maximized while ensuring safety.

[0029] Step 4: Sum the actual operating power of each device after secondary allocation to obtain the actual total power. Compare the absolute value of the difference between the actual total power and the target total power with the static total power error threshold. If the absolute value of the difference between the actual total power and the target total power is greater than the static total power error threshold, then the actual operating power of each device after secondary allocation is corrected to eliminate calculation accumulation and random errors, ensuring that the final output power of the system is strictly consistent with the scheduling command, thereby achieving high-precision control; otherwise, no correction is made.

[0030] Step 5: Due to the large fluctuations in the actual total power when multiple devices in the energy storage system are operating in parallel, frequent corrections are triggered. That is, when the absolute value of the difference between the actual total power and the target total power is greater than the static total power error threshold, the actual operating power of each device is corrected after secondary allocation. However, frequent corrections would increase the resource consumption of the devices and affect their operating efficiency. Therefore, the fluctuation of the difference between the actual total power and the target total power is monitored. When the fluctuation exceeds the set range, the system switches to the dynamic total power error threshold, which represents the fluctuation range. Fluctuations within this range indicate that the fluctuation has not exceeded the set range. Otherwise, the static total power error threshold is used, which helps to intelligently balance the control accuracy and system stability.

[0031] Example 2 differs from Example 1 in that:

[0032] The specific method for obtaining the initial allocated actual operating power for each device is as follows:

[0033] The state of charge (SOC) of each device is summed to obtain the total SOC. The SOC of any device is then divided by the total SOC to obtain the SOC power allocation ratio. The total SOC is not zero, meaning no power is allocated when the SOC of all devices is zero. The SOC power allocation ratio is then multiplied by the target total power to obtain the initial operating power allocated to each device.

[0034] ;

[0035] in, This indicates the initial actual operating power allocated to each device. Indicates the first The state of charge of the equipment. Indicates the total state of charge. This represents the target total power.

[0036] The specific method for determining whether the initially allocated equipment exceeds the limit is as follows:

[0037] The initial allocated actual operating power of each device is compared with its maximum operating power. If the initial allocated actual operating power of a device is greater than its maximum operating power, it is classified into the over-limit set. ,in Denotes an overbounded set. Indicates the first Taiwan equipment, This indicates the initial actual operating power allocated to each device. This indicates the maximum operating power of each device;

[0038] If the actual operating power initially allocated to each device is less than or equal to the maximum operating power of each device, then it is included in the set that has not exceeded the limit. ,in, Represents a set that is not overbounded. Indicates the first Taiwan equipment, This indicates the initial actual operating power allocated to each device. This indicates the maximum operating power of each device.

[0039] The specific methods for obtaining excess power are as follows:

[0040] The difference between the initial allocated actual operating power and the maximum operating power of each device in the over-limit set is calculated, and then summed according to the number of devices to obtain the excess power.

[0041] The specific method for obtaining the actual operating power of each device after secondary allocation is as follows:

[0042] The actual operating power of each non-over-limit device is calculated based on its state of charge and excess power in the non-over-limit set. The maximum operating power of each device is then assigned to each device in the over-limit set to obtain the actual operating power of each over-limit device. Finally, the actual operating power of each non-over-limit device and the actual operating power of each over-limit device are combined to obtain the actual operating power of each device in the secondary allocation.

[0043] The specific method for obtaining the actual operating power of each non-over-limit device through secondary allocation is as follows:

[0044] The state of charge of each device in the set of devices not exceeding the limit is summed to obtain the total state of charge of devices not exceeding the limit. The state of charge of each device in the set of devices not exceeding the limit is divided with the total state of charge of devices not exceeding the limit to obtain the power allocation ratio of the state of charge of devices not exceeding the limit. The total state of charge of devices not exceeding the limit is not zero. The power allocation ratio of the state of charge of devices not exceeding the limit is multiplied with the excess power to obtain the actual operating power of each device not exceeding the limit being secondary allocated.

[0045] ;

[0046] in, This indicates the actual operating power of each device that did not exceed its limits, which was then reassigned. This represents the state of charge of each device in the set that has not exceeded the limit. This represents the sum of states of charge that have not exceeded their limits. This indicates excess power.

[0047] The specific steps for correcting the actual operating power of each device after secondary allocation are as follows:

[0048] The difference between the actual total power and the target total power is calculated to obtain the gap power. The number of devices in the set that do not exceed the limit is counted to obtain the number of devices that do not exceed the limit. The gap power is divided by the number of devices that do not exceed the limit to obtain the average gap power. The average gap power is added to the actual operating power of each device that does not exceed the limit after secondary allocation.

[0049] ;

[0050] in, This represents the power that is adjusted after the actual operating power of each piece of equipment that has not exceeded its limits is re-allocated. Indicates the actual total power. Indicates the target power. This indicates the number of devices that have not exceeded the limit. This represents the actual operating power of each piece of equipment that has not exceeded its limits, which has been reassigned. If the target total power is greater than the actual total power, that is, the actual total power is less, then The difference is positive, that is Some additional power is needed. If the target total power is less than the actual total power, meaning the actual total power is too high, then... The difference is negative, that is A portion of the power needs to be removed. If the target total power equals the actual total power, then... The difference is zero, that is No power needs to be added or removed.

[0051] The specific method for monitoring the fluctuation of the difference between the actual total power and the target total power is as follows:

[0052] The fluctuation value of the actual total power in the time series is calculated by the variance method. The fluctuation threshold is set according to historical experiments. The fluctuation value is compared with the fluctuation threshold. If the fluctuation value is greater than the fluctuation threshold, it means that the fluctuation exceeds the set range. If the fluctuation value is less than or equal to the fluctuation threshold, it means that the fluctuation does not exceed the set range.

[0053] The specific steps for calculating the fluctuation value of the actual total power over a time series using the variance method are as follows:

[0054] The time series is equally extracted to obtain average time periods. The number of times the absolute value of the difference between the actual total power and the target total power exceeds the static total power error threshold in each average time period is counted to obtain the number of times the value exceeds the threshold in each average time period. The number of time periods is counted to obtain the number of time periods. The number of times the value exceeds the threshold in each average time period is summed and then averaged to obtain the average number of times the value exceeds the threshold in each average time period. The square root of the difference between the number of times the value exceeds the threshold in each average time period and the average number of times the value exceeds the threshold in each average time period is summed to obtain the total fluctuation value. Finally, the quotient is calculated based on the total fluctuation value and the number of time periods.

[0055] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for power distribution error correction in energy storage parallel operation state, characterized in that: The method comprises the following specific steps: Step 1: setting a target total power, a dynamic total power error threshold and a static total power error threshold according to historical experiments, and obtaining energy storage device data, including the number of devices, the state of charge of each device and the maximum operating power of each device; Step 2: calculating a state of charge power allocation ratio according to the number of devices and the state of charge of each device, and then calculating the actual operating power initially allocated to each device in combination with the target total power; Step 3: defining an overrun set and a non-overrun set, dividing the devices initially allocated into the overrun set and the non-overrun set, and calculating excess power, which is then secondarily allocated to the non-overrun set, and each device in the overrun set is assigned a reasonable power, so as to obtain the actual operating power secondarily allocated to each device, and step 3 is repeatedly executed until the excess power is allocated; Step 4: summing the actual operating power secondarily allocated to each device to obtain an actual total power, and analyzing whether the absolute value of the difference between the actual total power and the target total power exceeds the static total power error threshold, and if so, performing correction, otherwise, not performing correction; Step 5: monitoring the fluctuation of the difference between the actual total power and the target total power, and switching to the dynamic total power error threshold when the fluctuation exceeds a set range, wherein the dynamic total power error threshold represents a fluctuation interval, and the fluctuation within the interval indicates that the fluctuation does not exceed the set range; otherwise, the static total power error threshold is used; The specific way of monitoring the fluctuation of the difference between the actual total power and the target total power is as follows: The fluctuation value of the actual total power in the time sequence is calculated by the variance method, the fluctuation threshold is set according to historical experiments, and the fluctuation value is compared with the fluctuation threshold, if the fluctuation value is greater than the fluctuation threshold, it indicates that the fluctuation exceeds the set range, if the fluctuation value is less than or equal to the fluctuation threshold, it indicates that the fluctuation does not exceed the set range; The specific steps of calculating the fluctuation value of the actual total power in the time sequence by the variance method are as follows: The time sequence is equally intercepted to obtain an average time period, the number of times that the absolute value of the difference between the actual total power and the target total power in each average time period is greater than the static total power error threshold is counted to obtain the exceeding number of each average time period, the number of time periods is counted to obtain the time period number, the exceeding number of each average time period is summed and then averaged according to the time period number to obtain the average exceeding number of each average time period, the difference between the exceeding number of each average time period and the average exceeding number of each average time period is squared and then summed to obtain a total fluctuation value, and finally the total fluctuation value is divided by the time period number.

2. The method for power distribution error correction in energy storage parallel operation state according to claim 1, characterized in that: The specific way of obtaining the actual operating power initially allocated to each device is as follows: The state of charge of each device is summed to obtain a total state of charge, the state of charge of any device is divided by the total state of charge to obtain a state of charge power allocation ratio, wherein the total state of charge is not zero, the state of charge power allocation ratio is multiplied by the target total power to obtain the actual operating power initially allocated to each device.

3. The method for power distribution error correction in energy storage parallel operation state according to claim 1, characterized in that: The specific way of whether the primary allocated equipment is over-limit is as follows: The actual running power of each equipment is compared with the maximum running power of each equipment, if the actual running power of each equipment is greater than the maximum running power of each equipment, it is divided into the over-limit set; if the actual running power of each equipment is less than or equal to the maximum running power of each equipment, it is divided into the non-over-limit set.

4. The method for power distribution error correction in energy storage parallel operation state according to claim 1, characterized in that: The specific way of obtaining the excess power is as follows: The actual running power of each equipment in the over-limit set is subtracted from the maximum running power of each equipment, and the sum is calculated according to the number of equipment to obtain the excess power.

5. The method for power distribution error correction in energy storage parallel operation state according to claim 1, characterized in that: The specific way of obtaining the actual running power of each equipment after secondary allocation is as follows: The actual running power of each non-over-limit equipment after secondary allocation is calculated according to the state of charge of each equipment in the non-over-limit set and the excess power, and the maximum running power of each equipment is assigned to each equipment in the over-limit set to obtain the actual running power of each over-limit equipment after secondary allocation, and the actual running power of each non-over-limit equipment after secondary allocation is combined with the actual running power of each over-limit equipment after secondary allocation to obtain the actual running power of each equipment after secondary allocation.

6. The method for power distribution error correction in energy storage parallel operation state according to claim 5, characterized in that: The specific way of obtaining the actual running power of each non-over-limit equipment after secondary allocation is as follows: The state of charge of each equipment in the non-over-limit set is summed to obtain the total state of charge, the state of charge of each equipment in the non-over-limit set is divided by the total state of charge to obtain the power allocation proportion of the non-over-limit state of charge, wherein the total state of charge is not zero, the power allocation proportion of the non-over-limit state of charge is multiplied by the excess power to obtain the actual running power of each non-over-limit equipment after secondary allocation.

7. The method for power distribution error correction in energy storage parallel operation state according to claim 1, characterized in that: The specific steps of the correction are as follows: The actual total power is subtracted from the target total power to obtain the gap power, the number of equipment in the non-over-limit set is counted to obtain the number of non-over-limit equipment, the gap power is divided by the number of non-over-limit equipment to obtain the average gap power, and the average gap power is added to the actual running power of each non-over-limit equipment after secondary allocation.

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