Elevator energy storage device performance monitoring method and system

Abstract

The present invention discloses a performance monitoring method for an elevator energy storage device. The energy storage device stores regenerative energy during elevator regenerative operation and provides the stored energy to a drive motor during elevator electric operation to achieve elevator energy saving. The monitoring method comprises the following steps: selecting a charge and discharge process of the energy storage device; obtaining a first terminal voltage, a second terminal voltage and a charge and discharge current of the energy storage device during the charge and discharge process; the first terminal voltage is the terminal voltage of the energy storage device at the start of the charge and discharge process, and the second terminal voltage is the terminal voltage of the energy storage device at the end of the charge and discharge process; calculating the net charged energy of the energy storage device during the charge and discharge process by using the first terminal voltage, the second terminal voltage and the charge and discharge current; calculating the square difference between the second terminal voltage and the first terminal voltage; calculating the capacitance calculated value of the energy storage device; and evaluating the performance of the energy storage device according to the deviation between the capacitance calculated value and the capacitance nominal value.

Description

Technical Field

[0001] The present invention relates to the field of elevators, and in particular to a performance monitoring method and a monitoring system for an energy storage device for achieving energy saving in elevators. Background Art

[0002] Traction elevators usually have two modes in operation: electric and regenerative. When the elevator is heavily loaded upward or lightly loaded downward, the elevator drive motor works in electric mode. At this time, the drive motor will use the electric energy from the power grid to drive the elevator, and the electric energy is converted into the potential energy of the elevator. When the elevator is lightly loaded upward or heavily loaded downward, the elevator drive motor works in regenerative mode. At this time, the drive motor converts the potential energy of the elevator into electric energy (i.e., regenerative energy) and enters the main circuit of the elevator. At present, one of the processing methods for the regenerative energy generated in the elevator regenerative mode is to use an energy storage device to store the regenerative energy and send it to the drive motor through an inverter when the elevator is powered to drive the elevator. This effectively solves the problem of regenerative energy processing and reduces the energy consumption of the elevator by reusing the regenerative energy, thus achieving elevator energy saving, such as: CN00137058.8, CN00137464.8, CN200410002268.5, and CN200580013464.5.

[0003] After a long period of use, the performance of the energy storage device will decline to varying degrees, which is manifested as: 1) reduced capacity, increased equivalent resistance, increased leakage current, etc. The performance degradation of the energy storage device will seriously affect its ability to handle regenerative energy and the energy-saving effect of the elevator. Therefore, it is necessary to monitor the performance of the elevator energy storage device so that appropriate treatment measures (such as replacement and maintenance) can be taken in time when its performance declines to a certain extent.

[0004] In the prior art, CN201980095367.7 aims at the problem of battery deterioration in contactless power-supply elevators without accompanying cables, and uses at least one of the number of battery charging cycles, the operating time or elapsed time after the last charge of the battery, the number of door opening and closing actions, and the power consumption of the equipment in the car to estimate the battery deterioration and detect the battery life, that is, to estimate the battery deterioration according to the action of the elevator device, to detect the battery life, and to promote the replacement of the battery; CN201210567493.8 aims at the battery used for parking operation, by cutting off the power supplied to the motor from the commercial main power supply in the test mode and the battery is used to power the drive motor, and judging whether the battery needs to be replaced according to the voltage value of the battery before and after the elevator car moves the maximum moving distance. Although both patents involve the problem of battery life prediction, the battery in the former is used as the power source of the elevator car, and the latter is used as the power source of the drive motor when the commercial power supply is cut off. Both are single power sources for electrical equipment and are aimed at the problem of whether power can be supplied. They are not aimed at the performance monitoring of energy storage devices used to process regenerative energy and achieve energy saving in elevators. In addition, both solutions estimate the deterioration of the battery based on the specific number of elevator operation actions or the corresponding power consumption, and cannot be applied to the performance monitoring of energy storage devices used for storage and reuse of regenerative energy. In this application, when the elevator is powered, both the commercial power supply and the energy storage device serve as the source of power. Therefore, the deterioration of the battery cannot be estimated based on the specific number of elevator operation actions or the corresponding power consumption, and no technical inspiration for solving this application is given.

[0005] Thus, how to effectively monitor the performance of energy storage devices used to process regenerative energy and achieve elevator energy saving becomes a technical problem to be solved. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method and system which can effectively realize the performance monitoring of an energy storage device for processing regenerative energy and realizing energy saving of elevators.

[0007] In order to solve the above technical problems, the present invention provides a method for monitoring the performance of an elevator energy storage device.

[0008] A method for monitoring the performance of an elevator energy storage device, wherein the energy storage device stores regenerative energy during elevator regenerative operation and provides the stored energy to a drive motor during elevator electric operation to achieve elevator energy saving, wherein the monitoring method comprises the following steps:

[0009] Step S1, selecting a charge and discharge process of the energy storage device;

[0010] Step S2, determining the start time, the end time, and n times between the start time and the end time of the charge and discharge process of the energy storage device, where n is a non-negative integer;

[0011] Step S3: Obtain the energy storage device terminal voltage u corresponding to each moment i and the charge and discharge current i i , where i∈[1,2,…,n+2];

[0012] Step S4, calculating the net charged energy of the energy storage device in at least one time pair of the energy storage device using the terminal voltage and the charge and discharge current of the energy storage device in the time pair, wherein the time pair is composed of any two different time points among the optional time points consisting of the start time, the end time, and n time points between the start time and the end time;

[0013] Step S5, calculating the voltage square difference between the two terminal voltages in the moment pair;

[0014] Step S6, calculating the capacitance calculated value of the energy storage device using the net charged energy obtained in step S4 and the voltage square difference obtained in step S5;

[0015] Step S7: Evaluate the performance of the energy storage device according to the deviation between the calculated capacitance value and the nominal capacitance value.

[0016] Preferably, the charging and discharging process located in the moment pair satisfies at least one of the following conditions:

[0017] a) the difference between the first terminal voltage and the second terminal voltage during the charge and discharge process is not less than a preset voltage threshold, and the first terminal voltage and the second terminal voltage are respectively the terminal voltages of the energy storage device at two moments corresponding to the moment pair during the charge and discharge process;

[0018] b) the absolute value of the average value of the charge and discharge current during the charge and discharge process is not less than a preset current threshold;

[0019] c) the duration of the charging and discharging process or the length of the moment pair is greater than a preset time threshold;

[0020] d) The energy in the energy storage device at the beginning of the charge and discharge process does not exceed the minimum energy threshold, the energy in the energy storage device at the end of the charge and discharge process is not less than the maximum energy threshold, or the net charged energy during the entire charge and discharge process is not less than the net charged energy threshold.

[0021] Preferably, the charging and discharging process is one of a regenerative operation mode or an electric operation mode when the elevator is in an unbalanced load.

[0022] Preferably, the charging and discharging process is when the elevator is in a uniform speed running state.

[0023] Preferably, the step S6 respectively calculates the capacitance calculation value of the elevator in the regenerative operation mode when the elevator is in an unbalanced load and the capacitance calculation value of the elevator in the electric operation mode when the elevator is in an unbalanced load, and the step S7 uses the average of the two capacitance calculation values ​​as the final capacitance calculation value, and evaluates the performance of the energy storage device according to the deviation between the average and the nominal capacitance value.

[0024] Preferably, during the two calculations, the first terminal voltage in the regenerative operation mode is equal to the second terminal voltage in the electric operation mode, or the second terminal voltage in the regenerative operation mode is equal to the first terminal voltage in the electric operation mode, or the charge and discharge current in the regenerative operation mode is equal to the corresponding charge and discharge current in the electric operation mode after being arranged in reverse order.

[0025] Preferably, the deviation is a difference obtained by subtracting the nominal capacitance value from the calculated capacitance value, and step S7 evaluates the performance of the energy storage device according to the difference and a difference threshold.

[0026] Preferably, the time pair preferably selects the time pair with the largest voltage difference at the terminals of the corresponding energy storage device.

[0027] Preferably, when the number of moments n between the start moment and the end moment is greater than 0, the step S6 calculates at least two capacitance calculation values, the step S7 first draws a capacitance calculation value curve using at least two capacitance calculation values, then draws a reference curve using the capacitance nominal value, and finally evaluates the performance of the energy storage device based on the capacitance calculation value curve and the reference curve.

[0028] Preferably, step S7 evaluates the performance of the energy storage device according to the distance between the capacitance calculation value curve and the reference curve and a distance threshold, or according to the relationship between the slope of the capacitance calculation value curve and a slope threshold.

[0029] Preferably, the distance between the curve and the reference curve refers to the root mean square of the distance between the calculated capacitance value and the nominal capacitance value at each moment between the curve and the reference curve.

[0030] The present invention also discloses a performance monitoring system for an elevator energy storage device, the monitoring system comprising:

[0031] A selection unit, used for selecting a primary charge and discharge process of the energy storage device;

[0032] An acquisition unit, used to acquire the terminal voltage ui and the charge and discharge current ii of the energy storage device at each moment in the charge and discharge process, where i∈[1,2,…,n+2];

[0033] A calculation unit, used to calculate the net charged energy of the energy storage device at least one time pair, the voltage square difference of two terminal voltages, and the calculated capacitance value of the energy storage device;

[0034] A storage unit, used to store the nominal value of the capacitance of the energy storage device;

[0035] An evaluation unit is configured to evaluate the performance of the energy storage device according to a deviation between the calculated capacitance value and the nominal capacitance value.

[0036] The present invention also discloses a performance monitoring system for an elevator energy storage device, the monitoring system comprising:

[0037] A selection unit, used for selecting a primary charge and discharge process of the energy storage device;

[0038] An acquisition unit, used to acquire the terminal voltage ui and the charge and discharge current ii of the energy storage device at each moment in the charge and discharge process, where i∈[1,2,…,n+2];

[0039] A calculation unit, used to calculate the net charged energy of the energy storage device at least two time pairs, the voltage square difference of two terminal voltages, and the calculated capacitance value of the energy storage device;

[0040] A fitting unit, used for plotting the capacitance calculation values ​​of at least two time pairs into a capacitance calculation value curve;

[0041] A storage unit, used to store a reference curve of the energy storage device, wherein the reference curve is drawn using a nominal value of capacitance;

[0042] An evaluation unit is used to evaluate the performance of the energy storage device according to the distance between the capacitance calculation value curve and the reference curve and the distance threshold, or according to the relationship between the slope of the capacitance calculation value curve and the slope threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of a driving structure of an elevator system including an energy storage device in the prior art;

[0044] Figure 2 A schematic diagram of a driving structure of an elevator system including an energy storage device to which the present invention is applied;

[0045] Figure 3 This is a schematic diagram of the structure of the elevator energy storage device performance monitoring system of Example 1;

[0046] Figure 4 This is a schematic diagram of the steps of the elevator energy storage device performance monitoring method of Example 1;

[0047] Figures 5 to 8are various schematic diagrams of the curve drawn in step S7 of Example 2 and the reference curve;

[0048] Fig. 9 This is a schematic diagram of the structure of the elevator energy storage device performance monitoring system of Example 2. DETAILED DESCRIPTION

[0049] The following describes the implementation of the present invention through specific specific embodiments in conjunction with the accompanying drawings, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. In the following description, specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented or applied through other different specific embodiments, and the various details in this specification can also be based on different viewpoints and applications. Those skilled in the art can make various similar generalizations and substitutions without departing from the spirit of the present invention.

[0050] Embodiment 1

[0051] like Figure 1 As shown, in the prior art elevator system drive structure diagram including an energy storage device, the energy storage device 20 is connected to the DC bus 6 of the elevator main circuit via the charge and discharge circuit 19, and the charge and discharge controller 18 controls the charge and discharge circuit 19 according to the DC bus voltage detected by the DC bus voltage detection unit 4 and the terminal voltage of the energy storage device 20 detected by the energy storage device state detector 21 (i.e., the terminal voltage). In fact, in order to achieve a better control effect, the charge and discharge controller 18 usually adopts a voltage and current double closed-loop control, the outer loop is a voltage loop control, and the inner loop is a current loop control. The voltage loop controller controls the bus voltage according to the DC bus voltage and the terminal voltage, and outputs the current command value of the current controller under the premise that the terminal voltage of the energy storage device is within its allowable range, so that the DC bus voltage tracks the bus voltage command value; the current loop controller controls according to the current command value and the current detection value detected by the current detection unit (not shown in the figure), so that the charging current entering the energy storage device 20 tracks the current command value. Under such control, the energy stored in the energy storage device 20 (expressed as its terminal voltage) is within the allowable range. When the elevator drive motor 9 is in the regenerative state, the regenerative energy generated enters the DC bus 6 through the inverter 7 and then enters the energy storage device 20 through the charge and discharge circuit 19. When the elevator drive motor 9 is in the electric state, the energy in the energy storage device 20 enters the DC bus 6 through the charge and discharge circuit 19 under the control of the charge and discharge controller 18 and further reaches the drive motor 9 through the inverter 7, thereby providing it with the required electrical energy.

[0052] Figure 2 The schematic diagram of the driving structure of the elevator system including the energy storage device of the present invention is shown in FIG. Figure 1 The elevator energy storage device performance monitoring system 22 is further included.

[0053] like Figure 3 As shown, this embodiment provides an elevator energy storage device performance monitoring system, wherein the energy storage device stores regenerative energy during elevator regenerative operation and provides the stored energy to a drive motor during elevator electric operation to achieve elevator energy saving, and the monitoring system 22 includes:

[0054] A selection unit, used for selecting a primary charge and discharge process of the energy storage device;

[0055] An acquisition unit is used to acquire the terminal voltage u of the energy storage device at each moment during the charging and discharging process. i and the charge and discharge current i i , where i∈[1,2,…,n+2];

[0056] A calculation unit, used to calculate the net charged energy of the energy storage device at least one time pair, the voltage square difference of two terminal voltages, and the calculated capacitance value of the energy storage device;

[0057] A storage unit, used to store the nominal value of the capacitance of the energy storage device;

[0058] An evaluation unit is configured to evaluate the performance of the energy storage device according to a deviation between the calculated capacitance value and the nominal capacitance value.

[0059] like Figure 4 As shown, this embodiment also provides a method for monitoring the performance of an elevator energy storage device, wherein the energy storage device stores regenerative energy during elevator regenerative operation and provides the stored energy to a drive motor during elevator electric operation to achieve elevator energy saving, and the monitoring method comprises the following steps:

[0060] Step S1, selecting a charge and discharge process of the energy storage device;

[0061] Step S2, determining the start time, the end time, and n times between the start time and the end time of the charge and discharge process of the energy storage device, where n is a non-negative integer;

[0062] Step S3: Obtain the energy storage device terminal voltage u corresponding to each moment i and the charge and discharge current i i , where i∈[1,2,…,n+2];

[0063] Step S4, calculating the net charged energy of the energy storage device in at least one time pair of the energy storage device using the terminal voltage and the charge and discharge current of the energy storage device in the time pair, wherein the time pair is composed of any two different time points among the optional time points consisting of the start time, the end time, and n time points between the start time and the end time;

[0064] Step S5, calculating the voltage square difference between the two terminal voltages in the moment pair;

[0065] Step S6, calculating the capacitance calculated value of the energy storage device using the net charged energy obtained in step S4 and the voltage square difference obtained in step S5;

[0066] Step S7: Evaluate the performance of the energy storage device according to the deviation between the calculated capacitance value and the nominal capacitance value.

[0067] The deviation is a difference obtained by subtracting the nominal capacitance value from the calculated capacitance value, and step S7 evaluates the performance of the energy storage device according to the difference and the difference threshold.

[0068] The time pair preferably selects the time pair with the largest voltage difference at the terminals of the corresponding energy storage device, such as the start time and the end time of a charge and discharge process.

[0069] More specifically, Figure 2 As shown. In order to control the charge and discharge of the energy storage device, it is usually necessary to detect the charge and discharge current of the energy storage device. At the same time, in order to ensure the safety of the energy storage device (such as the terminal voltage of the energy storage device will not be too high due to charging), the terminal voltage of the energy storage device is usually detected. In this embodiment, the performance monitoring of the energy storage device only requires the charge and discharge current and terminal voltage of the energy storage device, so there will be no hardware changes to the original elevator energy-saving system based on the energy storage device. Since the energy stored in the energy storage device can be calculated by the following formula:

[0070]

[0071] Where E is the energy stored in the energy storage device, C is the capacitance value of the energy storage device, and u is the terminal voltage of the energy storage device.

[0072] When the energy storage device undergoes a certain charging and discharging process, taking one moment pair as an example, the terminal voltage in the moment pair changes from u1 to u2, where u1 is the terminal voltage at the start moment of the moment pair, which is defined as the first terminal voltage, and u2 is the terminal voltage at the end moment of the moment pair, which is defined as the second terminal voltage. Then the change in energy stored in the energy storage device is:

[0073]

[0074] Where ΔE is the change in energy stored in the energy storage device, that is, the net charged energy.

[0075] On the other hand, since the charge and discharge current of the energy storage device during the charge and discharge process is also known (obtained through detection), the energy charged into the energy storage device (or released from the energy storage device) can be calculated using the charge and discharge current of the energy storage device, the terminal voltage of the energy storage device, and the time of the charge and discharge process, that is:

[0076] ΔE=∫u(t)i(t)dt (3)

[0077] Where i is the charge and discharge current.

[0078] If we combine formulas (2) and (3), we get:

[0079]

[0080] Obviously, the capacitance calculation value of the energy storage device can be obtained using the above formula.

[0081] When the deviation between the capacitance calculated by formula (4) and the nominal capacitance is too large, it can be determined that the performance of the energy storage device has been degraded.

[0082] In order to obtain better results, the charge and discharge process may be further limited by one or more of the following:

[0083] For example, the charging and discharging process satisfies at least one of the following conditions:

[0084] a) the difference between the first terminal voltage and the second terminal voltage during the charge and discharge process is not less than a preset voltage threshold, and the first terminal voltage and the second terminal voltage are respectively the terminal voltages of the energy storage device at two moments corresponding to the moment pair during the charge and discharge process;

[0085] b) the absolute value of the average value of the charge and discharge current during the charge and discharge process is not less than a preset current threshold;

[0086] c) the duration of the charging and discharging process or the length of the moment pair is greater than a preset time threshold;

[0087] d) The energy in the energy storage device at the beginning of the charge and discharge process does not exceed the minimum energy threshold, the energy in the energy storage device at the end of the charge and discharge process is not less than the maximum energy threshold, or the net charged energy during the entire charge and discharge process is not less than the net charged energy threshold.

[0088] For example, the charging and discharging process is one of the regenerative operation mode or the electric operation mode when the elevator is in an unbalanced load (ie, it cannot be partially electric and partially regenerative).

[0089] For example, the charging and discharging process is when the elevator is in a uniform speed running state.

[0090] In the above description, the capacitance value is calculated only once using formula (4). Step S5 can also be used to calculate the capacitance calculation value in the regenerative operation mode when the elevator is in an unbalanced load and the capacitance calculation value in the electric operation mode when the elevator is in an unbalanced load. Step S6 uses the average of the two capacitance calculation values ​​as the final elevator calculation value, and evaluates the performance of the energy storage device based on its deviation from the nominal capacitance value.

[0091] Or further limit the two calculations, the first terminal voltage in the regenerative operation mode is equal to the second terminal voltage in the electric operation mode, or the second terminal voltage in the regenerative operation mode is equal to the first terminal voltage in the electric operation mode, or the charge and discharge current in the regenerative operation mode is equal to the corresponding charge and discharge current in the electric operation mode after reverse arrangement.

[0092] This embodiment makes full use of the application feature that the energy change of the energy storage device can be calculated from the terminal voltage and the nominal value of the capacitance, and can also be calculated from the charge and discharge current and the terminal voltage. The two calculations are linked together using the energy change as a bridge. The capacitance calculation value of the current energy storage device is calculated only based on the charge and discharge current and the terminal voltage of the energy storage device, and the performance of the energy storage device is evaluated based on the capacitance calculation value and the nominal value of the capacitance before the performance of the energy storage device is reduced.

[0093] Example 2

[0094] In Example 1, the capacitance value of the energy storage device is calculated only once (or twice in certain cases). Considering the interference and noise that are bound to exist in the detection process, there will inevitably be a certain deviation between the detected terminal voltage and charge and discharge current and their true values, which will cause the calculated value of the capacitance value obtained therefrom to also have random errors. In order to reduce or eliminate these errors in the results, this embodiment increases the number of detections and calculations on the basis of Example 1, and performs performance evaluation based on the calculated results of the capacitance values ​​of a series of energy storage devices obtained.

[0095] In this embodiment, based on the embodiment 1, when the number of moments n between the start moment and the end moment is greater than 0, the step S6 calculates at least two capacitance calculation values, the step S7 first draws a capacitance calculation value curve using the at least two capacitance calculation values, then draws a reference curve using the capacitance nominal value, and finally evaluates the performance of the energy storage device according to the capacitance calculation value curve and the reference curve. Figure 5 As shown, the solid line is the capacitance calculation value curve, and the dotted line is the reference curve.

[0096] In order to obtain better effects, one or more limitations may be made to the charging and discharging process, which are the same as those in the embodiment.

[0097] In step S7, a capacitance calculation value curve is drawn using multiple capacitance calculation values, with the square difference of the terminal voltage as the horizontal coordinate and the net charged energy at the corresponding moment as the vertical coordinate in the coordinate system. In essence, this is curve fitting or modeling based on known data pairs. The specific method can be least squares fitting, neural network, machine learning, etc., as long as a model or formula suitable for these data pairs can be obtained.

[0098] In a specific implementation, the interval formed by the minimum and maximum values ​​of the terminal voltage of the energy storage device can be evenly divided into n intervals (the terminal voltage difference of each interval is equal); when the elevator is in regeneration mode to charge the energy storage device, the terminal voltage of the energy storage device gradually increases from the minimum value to the maximum value, and the terminal voltage and charging and discharging current corresponding to each interval are recorded in turn.

[0099] If the data of each interval is used to calculate the net charged energy from the start time of the charge and discharge process to the current time and the square difference of the terminal voltage between the start time and the current time; the net charged energy and the square difference thus obtained are fitted to obtain a curve. Obviously, if interference, errors and performance degradation of the energy storage device are not considered, the obtained curve should be a straight line with a fixed slope, and the slope corresponds to the capacitance value of the energy storage device. When the performance of the energy storage device (mainly the capacitance value) decreases, there will inevitably be a certain distance between the straight line obtained according to the detection body and the reference curve. Step S7 evaluates the performance of the energy storage device according to the slope of the curve and the slope of the pre-set reference curve. Figure 5 As shown, the dotted line is the reference curve and the solid line is the curve obtained by data fitting.

[0100] Figure 6 The same is based on the fitting results of the data. Figure 5 The difference is that in this fitting, considering that the data at both ends obviously have different rules from the data in the middle section, three straight lines are fitted according to the actual situation of the data. Considering that the slope of the straight line corresponds to the capacitance value, it is obvious that the capacitance value at both ends is significantly smaller than the capacitance value in the middle section. This situation shows that after a long period of use, the capacitance value at both ends of the terminal voltage is smaller than the capacitance value in the middle section. Therefore, when evaluating the performance of the energy storage device according to the obtained curve, it can be evaluated according to the change of the capacitance value at both ends relative to the capacitance value in the middle section in the absence of a reference curve. When evaluating, it can be evaluated based on the change of the slope of the two ends relative to the slope of the middle section, it can be evaluated based on the length of the straight lines at both ends where the slope changes relative to the middle section, and it can also be evaluated by combining the two methods.

[0101] If the capacitance value of the energy storage device is directly calculated using the data of each interval, that is, taking the starting point of each interval as the initial value and the end point of each interval as the termination value, the net charged energy of the energy storage device in the interval and the square difference of the corresponding terminal voltage are calculated respectively, and then each interval is used as the horizontal coordinate and the ratio of the net charged energy to the square difference is used as the vertical coordinate. At this time, the straight lines corresponding to each interval are of equal length. Obviously, if interference, error and performance degradation of the energy storage device are not considered, the heights of these straight lines corresponding to each interval must be equal. However, when there is interference, error, etc., there is a certain height difference between different straight lines corresponding to each interval, and when considering the performance degradation of the energy storage device, the height difference between each line segment corresponding to each interval and the reference curve is used to evaluate the performance of the energy storage device. Since there are multiple interval line segments, there will be many height differences between them and the reference curve. Therefore, the height differences between the interval line segments and the reference curve can be calculated separately, and then the performance of the energy storage device is evaluated based on the relationship between the root mean square of these height differences and the distance threshold. That is, step S7 evaluates the performance of the energy storage device based on the relationship between the root mean square of the distance between the curve and the reference curve and the distance threshold.

[0102] like Figure 7 As shown in the figure, the dotted line is the reference curve. When evaluating, the actual curve is evaluated based on whether it is in the middle of the reference curve. Of course, you can also refer to the above slope method. When the height of the straight lines at the two ends is obviously lower than the height of the straight line in the middle (such as Figure 8 It is determined that the performance of the energy storage device at both ends has significantly decreased. The evaluation can also be performed based on the height decrease degree and / or the ratio of the length of the interval where the decrease occurs to the length of the middle section.

[0103] Alternatively, after the curve is obtained in a non-interval manner, a differential curve of the curve is further plotted, and then the performance of the energy storage device is evaluated based on the relationship between the obtained differential curve and a threshold value (the threshold value in this case is a single parameter value).

[0104] Furthermore, the charging and discharging process is when the elevator is in a regenerative operation mode when an unbalanced load occurs; when the step S7 evaluates the performance of the energy storage device according to the relationship between the slope of the curve and the slope threshold, the first terminal voltage is less than the minimum voltage threshold, and the second terminal voltage is greater than the maximum voltage threshold.

[0105] When step S7 evaluates the performance of the energy storage device according to the relationship between the slope of the curve and the slope threshold, the energy in the energy storage device does not exceed the minimum energy threshold at the start of the charge and discharge process, and the energy in the energy storage device is not less than the maximum energy threshold at the end of the charge and discharge process, or the net charged energy in the entire charge and discharge process is not less than the net charged energy threshold.

[0106] Furthermore, the charging and discharging process is when the elevator is in an electric operation mode when an unbalanced load occurs; when the step S7 evaluates the performance of the energy storage device according to the relationship between the slope of the curve and the slope threshold, the first terminal voltage is greater than the maximum voltage threshold, and the second terminal voltage is less than the minimum voltage threshold.

[0107] When step S7 evaluates the performance of the energy storage device according to the relationship between the slope of the curve and the slope threshold, the energy in the energy storage device at the start of the charge and discharge process is not less than the maximum energy threshold, the energy in the energy storage device at the end of the charge and discharge process does not exceed the minimum energy threshold, or the net charged energy in the entire charge and discharge process is not less than the net charged energy threshold.

[0108] Correspondingly, such as Fig. 9 As shown, a system for monitoring the performance of an elevator energy storage device corresponding to the method of embodiment 2, wherein the energy storage device stores regenerative energy during elevator regenerative operation and provides the stored energy to a drive motor during elevator electric operation to achieve elevator energy saving, and the monitoring system comprises:

[0109] A selection unit, used for selecting a primary charge and discharge process of the energy storage device;

[0110] An acquisition unit is used to acquire the terminal voltage u of the energy storage device at each moment during the charging and discharging process. i and the charge and discharge current i i , where i∈[1,2,…,n+2];

[0111] A calculation unit, used to calculate the net charged energy of the energy storage device at least two time pairs, the voltage square difference of two terminal voltages, and the calculated capacitance value of the energy storage device;

[0112] A fitting unit, used for plotting the capacitance calculation values ​​of at least two time pairs into a capacitance calculation value curve;

[0113] A storage unit, used to store a reference curve of the energy storage device, wherein the reference curve is drawn using a nominal value of capacitance;

[0114] An evaluation unit is used to evaluate the performance of the energy storage device according to the distance between the capacitance calculation value curve and the reference curve and the distance threshold, or according to the relationship between the slope of the capacitance calculation value curve and the slope threshold.

[0115] The present invention is described in detail above through specific embodiments, which are only preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Without departing from the principle of the present invention, equivalent substitutions and improvements made by those skilled in the art should be regarded as within the technical scope protected by the present invention.

Claims

1. A method for monitoring the performance of an elevator energy storage device, wherein the energy storage device stores regenerative energy during elevator regenerative operation and provides the stored energy to a drive motor during elevator electric operation to achieve elevator energy saving, characterized in that: The monitoring method comprises the following steps: Step S1, selecting a charge and discharge process of the energy storage device; Step S2, determining the start time, the end time, and n times between the start time and the end time of the charge and discharge process of the energy storage device, where n is a non-negative integer; Step S3: Obtain the terminal voltage of the energy storage device corresponding to each moment u i and charge and discharge current i i , where i∈[1, 2,…, n+2]; Step S4, calculating the net charged energy of the energy storage device in at least one time pair of the energy storage device using the terminal voltage and the charge and discharge current of the energy storage device in the time pair, wherein the time pair is composed of any two different time points among the optional time points consisting of the start time, the end time, and n time points between the start time and the end time; Step S5, calculating the voltage square difference between the two terminal voltages in the moment pair; Step S6, calculating the capacitance calculated value of the energy storage device using the net charged energy obtained in step S4 and the voltage square difference obtained in step S5; Step S7: Evaluate the performance of the energy storage device according to the deviation between the calculated capacitance value and the nominal capacitance value.

2. The elevator energy storage device performance monitoring method according to claim 1, characterized in that: The charging and discharging process located in the time pair satisfies at least one of the following conditions: The difference between the first terminal voltage and the second terminal voltage in the charging and discharging process is not less than a preset voltage threshold, and the first terminal voltage and the second terminal voltage are respectively the terminal voltages of the energy storage device at two moments in the charging and discharging process corresponding to the moment pair; The absolute value of the average value of the charge and discharge current during the charge and discharge process is not less than a preset current threshold; The duration of the charging and discharging process or the length of the moment pair is greater than a preset time threshold; The energy in the energy storage device at the start of the charge and discharge process does not exceed the minimum energy threshold, the energy in the energy storage device at the end of the charge and discharge process is not less than the maximum energy threshold, or the net charged energy in the entire charge and discharge process is not less than the net charged energy threshold.

3. The elevator energy storage device performance monitoring method according to claim 1 or 2, characterized in that: The charging and discharging process is one of a regenerative operation mode or an electric operation mode when the elevator is in an unbalanced load.

4. The elevator energy storage device performance monitoring method according to claim 3, characterized in that: The charging and discharging process is when the elevator is in a uniform speed running state.

5. The elevator energy storage device performance monitoring method according to claim 4, characterized in that: The step S6 respectively calculates the capacitance calculation value in the regenerative operation mode when the elevator is in an unbalanced load and the capacitance calculation value in the electric operation mode when the elevator is in an unbalanced load. The step S7 uses the average of the two capacitance calculation values ​​as the final capacitance calculation value, and evaluates the performance of the energy storage device according to the deviation between the average and the nominal capacitance value.

6. The elevator energy storage device performance monitoring method according to claim 5, characterized in that: During the two calculations, the first terminal voltage in the regenerative operation mode is equal to the second terminal voltage in the electric operation mode, or the second terminal voltage in the regenerative operation mode is equal to the first terminal voltage in the electric operation mode, or the charge and discharge current in the regenerative operation mode is equal to the corresponding charge and discharge current in the electric operation mode after being arranged in reverse order.

7. The elevator energy storage device performance monitoring method according to claim 1, characterized in that: The deviation is a difference obtained by subtracting the nominal capacitance value from the calculated capacitance value, and step S7 evaluates the performance of the energy storage device according to the difference and the difference threshold.

8. The elevator energy storage device performance monitoring method according to claim 7, characterized in that: The time pair preferably selects the time pair with the largest voltage difference at the terminals of the corresponding energy storage device.

9. The elevator energy storage device performance monitoring method according to claim 1, characterized in that: When the number of moments n between the start moment and the end moment is greater than 0, the step S6 calculates at least two capacitance calculation values, the step S7 first draws a capacitance calculation value curve using the at least two capacitance calculation values, then draws a reference curve using the capacitance nominal value, and finally evaluates the performance of the energy storage device based on the capacitance calculation value curve and the reference curve.

10. The elevator energy storage device performance monitoring method according to claim 9, characterized in that: The step S7 evaluates the performance of the energy storage device according to the distance between the capacitance calculation value curve and the reference curve and the distance threshold, or according to the relationship between the slope of the capacitance calculation value curve and the slope threshold.

11. The elevator energy storage device performance monitoring method according to claim 10, characterized in that: The distance between the capacitance calculation value curve and the reference curve refers to the root mean square of the distance between the capacitance calculation value and the capacitance nominal value at each moment between the capacitance calculation value curve and the reference curve.

12. An elevator energy storage device performance monitoring system, characterized in that: The elevator energy storage device performance monitoring method according to claim 1 is applied, and the monitoring system comprises: A selection unit, used for selecting a primary charge and discharge process of the energy storage device; An acquisition unit is used to acquire the terminal voltage of the energy storage device at each moment during the charging and discharging process. u i and charge and discharge current i i , where i∈[1, 2, …, n+2]; A calculation unit, used to calculate the net charged energy of the energy storage device at least one time pair, the voltage square difference of two terminal voltages, and the calculated capacitance value of the energy storage device; A storage unit, used to store the nominal value of the capacitance of the energy storage device; An evaluation unit evaluates the performance of the energy storage device according to a deviation between the calculated capacitance value and the nominal capacitance value.

13. An elevator energy storage device performance monitoring system, characterized in that: The elevator energy storage device performance monitoring method according to claim 10 is applied, and the monitoring system comprises: A selection unit, used for selecting a primary charge and discharge process of the energy storage device; An acquisition unit is used to acquire the terminal voltage of the energy storage device at each moment during the charging and discharging process. u i and charge and discharge current i i , where i∈[1, 2, …, n+2]; A calculation unit, used to calculate the net charged energy of the energy storage device at least two time pairs, the voltage square difference of two terminal voltages, and the calculated capacitance value of the energy storage device; A fitting unit, used for plotting the capacitance calculation values ​​of at least two time pairs into a capacitance calculation value curve; A storage unit, used to store a reference curve of the energy storage device, wherein the reference curve is drawn using a nominal value of capacitance; An evaluation unit is used to evaluate the performance of the energy storage device according to the distance between the capacitance calculation value curve and the reference curve and the distance threshold, or according to the relationship between the slope of the capacitance calculation value curve and the slope threshold.

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