A UPQC control method based on fuzzy variable ring width hysteresis loop space vector

Abstract

This invention discloses a UPQC control method based on fuzzy variable-loop width-hysteresis space vector. It obtains the adaptive value of the hysteresis width vector in real time through a fuzzy inference process and simultaneously controls both parallel and series converters in the UPQC. Specifically, this invention first prepares fuzzy linguistic value conversion rules and fuzzy inference rules for the hysteresis width vector suitable for UPQC control, and sets different switching combination types. Second, this invention obtains the fuzzy linguistic value of the hysteresis width vector through fuzzy inference using real-time measured voltage and current data, and then obtains the corresponding specific value through defuzzification. The parallel and series converters in the UPQC are processed in parallel throughout the entire process. Compared with existing technologies, this invention overcomes the shortcomings of UPQC control based on fixed hysteresis width vectors, enabling adaptive control based on real-time measured current and voltage data, thereby reducing the maximum switching frequency of the devices.

Description

Technical Field

[0001] This invention relates to power quality control methods, and particularly to a UPQC control method based on fuzzy variable loop wide hysteresis space vector. Background Technology

[0002] A Unified Power Quality Regulator (UPQC) is a device that uses series and parallel active power filters coupled via DC-side capacitors to uniformly compensate for and suppress power quality issues in a power system, such as voltage sags, voltage fluctuations, reactive power, and harmonics. The UPQC's control module uses a PWM circuit to generate pulse signals that trigger the switching of power electronic devices, thereby controlling the power electronic switching devices and outputting compensation signals. Different control strategies will affect various performance aspects of the UPQC, including dynamic switching losses, output compensation functionality, and frequency response.

[0003] Existing literature and patents describe trigger control for UPQC devices, including triangular wave carrier comparison control, hysteresis comparison control, and space vector control. Triangular wave carrier comparison control, where the control frequency is determined by the set triangular wave frequency, offers a relatively fast dynamic response, but its following error is large and its modulation bandwidth is limited, making it unsuitable for high-power operating environments.

[0004] Hysteresis comparators typically have a fixed hysteresis width. In fixed-width hysteresis control, taking current compensation as an example, if the difference between the actual compensation current and the commanded current is large or changes rapidly, the UPQC control will suffer from insufficient compensation capability due to the small fixed loop width, failing to effectively track current changes, and the switching frequency of the devices will also be high. Conversely, if the difference between the actual compensation current and the commanded current is small or changes slowly, the UPQC control may suffer from an excessively large compensation current signal due to the large fixed loop width, also affecting the system's compensation effect. These problems become more pronounced when the current crosses zero or reaches its peak. If the load fluctuates significantly, this load variation will affect the compensation effect of the UPQC system and the switching losses of internal power devices.

[0005] Therefore, considering the shortcomings of fixed-loop wide hysteresis current control and the large load variation, it is necessary to consider how to design variable-loop wide hysteresis control. While improving the real-time performance and effectiveness of variable-loop wide hysteresis control, further research is needed on how to combine vector control to reduce switching frequency, reduce switching losses and improve DC voltage utilization, and solve the inter-phase interference problem existing in independent phase control. These are the problems that need to be solved in the UPQC hysteresis control strategy. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a UPQC control method based on fuzzy variable loop width hysteresis vector, which addresses the shortcomings of the prior art.

[0007] The technical solution adopted by the present invention to solve the above problems is: a UPQC control method based on fuzzy variable loop width hysteresis vector, characterized by including the following steps.

[0008] First, preparations before implementing control include steps (1.1) to (1.5) as shown below.

[0009] Step (1.1) defines 7 fuzzy language values, specifically including negative large, negative medium, negative small, zero, positive small, positive medium and positive large, which are labeled using NB, NM, NS, ZO, PS, PM and PB respectively.

[0010] Step (1.2) determines the difference vector X and the rate of change vector. The data in X is fuzzified to obtain the corresponding fuzzy language values; where, for the j-th data x in X, j The specific rules for obtaining the corresponding fuzzy language value through fuzzification are: if x j ∈[-3,-2.667), and the membership function is a trapezoid, then x j The corresponding fuzzy language value is NB; if x j ∈(-3,-1), if the membership function is of Gaussian form, then x j The corresponding fuzzy language value is NM; if x j ∈(-2,0), the membership function is triangular, then x j The corresponding fuzzy language value is NS; if x j ∈(-1,1), the membership function is triangular, then x j The corresponding fuzzy language value is ZO; if x j ∈(0,2), the membership function is taken as a triangle, then x j The corresponding fuzzy language value is PS; if x j ∈(1,3), if the membership function is of Gaussian form, then x j The corresponding fuzzy language value is PM; if x j ∈(2,3], if the membership function is a trapezoid, then x j The corresponding fuzzy language value is PB; j = 1, 2, 3; for The j-th data in The rules for obtaining the corresponding fuzzy language values ​​by performing fuzzification processing are related to x. j The rules for blurring are the same.

[0011] Step (1.3): Determine the fuzzy inference rule, let X or The fuzzy linguistic values ​​corresponding to the j-th data in the dataset are m and m, respectively. Then the j-th data h in the hysteresis width vector H j The corresponding fuzzy inference rule for the fuzzy linguistic value M is: if m is NB, then M is PB; if m is ZO, then M is NB; if m is PB, then M is PB; if m is NM, then M is PB. Let NB, NM, NS, ZO, PS, PM, and PB be the values, then M be PM, PS, ZO, NS, ZO, PS, and PM respectively; if m is NS and... Let NB, NM, NS, ZO, PS, PM, and PB be the values, then M be the values ​​of PS, ZO, NS, NM, NS, ZO, and PS respectively; if m is PS and... Let NB, NM, NS, ZO, PS, PM, and PB be the values, then M be PS, ZO, NS, NM, NS, ZO, and PS respectively; if m is PM and... If NB, NM, NS, ZO, PS, PM, and PB are respectively, then M is PM, PS, ZO, NS, ZO, PS, and PM.

[0012] Step (1.4) assigns six area numbers for the current difference and six area numbers for the parallel reference voltage to the parallel converters in the UPQC. The six area numbers for the current difference are labeled as I-1, I-2, I-3, I-4, I-5, and I-6, and the six area numbers for the parallel reference voltage are labeled as U1-1, U1-2, U1-3, U1-4, U1-5, and U1-6. At the same time, assigns six area numbers for the voltage difference and six area numbers for the series reference voltage to the series converters in the UPQC. The six area numbers for the voltage difference are labeled as V-1, V-2, V-3, V-4, V-5, and V-6, and the six area numbers for the series reference voltage are labeled as U2-1, U2-2, U2-3, U2-4, U2-5, and U2-6.

[0013] Step (1.5) determines the combination of the three-phase upper arm switches, specifically 7 types, denoted as S1, S2, ..., S7; where S1 indicates that the upper arm switch of phase A is closed, and the upper arm switches of phases B and C are open, then the lower arm switch of phase A is open, and the lower arm switches of phases B and C are closed; S2 indicates that the upper arm switches of phases A and B are closed, and the upper arm switch of phase C is open; S3 indicates that the upper arm switch of phase B is closed, and the upper arm switches of phases A and C are open; S4 indicates that the upper arm switches of phases B and C are closed, and the upper arm switch of phase A is open; S5 indicates that the upper arm switch of phase C is closed, and the upper arm switches of phases A and B are open; S6 indicates that the upper arm switches of phases A and C are closed, and the upper arm switch of phase B is open; S7 indicates that the upper arm switches of phases A, B, and C are simultaneously open or simultaneously closed, in which case there is no output from the strain gauge.

[0014] Secondly, based on the current and voltage data measured at the latest sampling time t, after determining the three-phase upper arm switch combination mode of the parallel converter and the series converter in the UPQC, the corresponding type of switch combination mode is executed for the three-phase upper arm of the parallel converter and the three-phase upper arm of the series converter. The three-phase lower arm switch state of the parallel converter and the series converter is the opposite of the switch state of their three-phase upper arms. The specific implementation process includes the following steps (2.1) to (2.3).

[0015] Step (2.1) involves measuring the current and voltage data at the latest sampling time t, specifically including the actual compensation current feedback i of phases A, B, and C of the parallel converter in the UPQC. A i B and i C and compensation current detection quantity and The actual compensation voltage feedback quantity v of phases A, B and C of the series converter in UPQC A v B and v C and compensation voltage detection quantity and Then calculate the difference vector of the parallel converters. The difference vector between the series converter and the series converter

[0016] Step (2.2) obtains the difference vector I of the parallel converter and the series converter at a sampling time t before t. t-1 and V t-1 Then, follow the formula. and Calculate the rate of change vector of the parallel converters respectively and the rate of change vector of the series converter Where t-1 represents a sampling time before t.

[0017] Step (2.3) involves executing schemes (1) and (2) in parallel; where scheme (1) is: setting X = I t and Then, perform steps ① to ⑦ as shown below; Scheme (2) is: set X = V t and Then, proceed with steps ① through ⑥ as shown below.

[0018] Following step ①: Apply the rules described in step (1.2) to X and The data in the image is fuzzified to obtain the corresponding fuzzy language value.

[0019] Step ②: Following the fuzzy inference rules in step (1.3), after obtaining the fuzzy linguistic values ​​corresponding to the three data points in the hysteresis width vector H, defuzzification is performed using the centroid method to obtain the hysteresis width vector H.

[0020] Step ③: Compare the data at the same position in X and H to obtain the polar vector Y; the specific implementation process is: set j = 1, 2, 3 in sequence, and determine x j Is it less than h? j If so, then the j-th data y in Y j Then it equals 1; otherwise, the j-th data y in Y is equal to 1. j Then it equals 0;

[0021] Step 4: Use the three data points y1, y2, y3 in Y to determine the region number corresponding to Y, and then use... Three data points The difference between and judge The corresponding area number; where, when X = I t The rules for determining the region are as follows: if only y1 is greater than 0, then the region number corresponding to Y is I-1; if only y1 and y2 are greater than 0, then the region number corresponding to Y is I-2; if only y2 is greater than 0, then the region number corresponding to Y is I-3; if only y2 and y3 are greater than 0, then the region number corresponding to Y is I-4; if only y3 is greater than 0, then the region number corresponding to Y is I-5; if only y1 and y3 are greater than 0, then the region number corresponding to Y is I-6; when X = V tThe rules for determining the region number are as follows: if only y1 and y3 are greater than 0, then the region number corresponding to Y is V-1; if only y1 is greater than 0, then the region number corresponding to Y is V-2; if only y1 and y2 are greater than 0, then the region number corresponding to Y is V-3; if only y2 is greater than 0, then the region number corresponding to Y is V-4; if only y2 and y3 are greater than 0, then the region number corresponding to Y is V-5; if only y3 is greater than 0, then the region number corresponding to Y is V-6; when... The rule for judging time is: if only and If it is greater than 0, then The corresponding area number is U1-1; if only If it is greater than 0, then The corresponding area number is U1-2; if only and If it is greater than 0, then The corresponding area number is U1-3; if only If it is greater than 0, then The corresponding area number is U1-4; if only and If it is greater than 0, then The corresponding area number is U1-5; if only If it is greater than 0, then The corresponding area number is U1-6; when The rule for judging time is: if only and If it is greater than 0, then The corresponding area number is U2-1; if only If it is greater than 0, then The corresponding area number is U2-2; if only and If it is greater than 0, then The corresponding area number is U2-3; if only If it is greater than 0, then The corresponding area number is U2-4; if only and If it is greater than 0, then The corresponding area number is U2-5; if only If it is greater than 0, then The corresponding area number is U2-6.

[0022] Step 5: Based on Y and The corresponding area number determines the type of three-phase upper bridge arm switch combination; when X = I t and The specific methods for determining the types of three-phase upper bridge arm switch combinations of parallel converters are shown in Table 1; when X = V t and The specific methods for determining the types of three-phase upper bridge arm switch combinations of the series converter are shown in Table 2.

[0023] Table 1: Rules for determining the types of three-phase upper arm switch combinations in parallel converters.

[0024]

[0025] The specific usage of the rules for determining the three-phase upper arm switch combination in Table 2 is as follows: If the area number corresponding to Y is I-1, and... If the corresponding area number is U1-1, then the type of three-phase upper bridge arm switch combination is S1; if the area number corresponding to Y is I-2, then... If the corresponding area number is U1-1, then the type of three-phase upper bridge arm switch combination is S2; if the area number corresponding to Y is I-4, then... If the corresponding area number is U1-1, then the type of three-phase upper bridge arm switch combination is S7; and so on.

[0026] Table 2: Rules for determining the types of three-phase upper arm switch combinations in series converters.

[0027]

[0028] Step 6: Based on the type of three-phase upper arm switch combination, execute the corresponding actions of the A, B, and C phase switches, and execute the corresponding actions of the three-phase lower arm switches A, B, and C in the opposite switching manner, then return to step (2.1).

[0029] The advantages of the method of the present invention, based on the above implementation steps, are as follows.

[0030] This invention's method, by employing a fuzzy inference process to determine the hysteresis width vector in real time, effectively overcomes the shortcomings of UPQC control based on a fixed hysteresis width vector. It enables adaptive control based on real-time measured current and voltage data, thereby reducing the maximum switching frequency of the devices and effectively compensating for power quality issues such as voltage and current fluctuations caused by large load variations. Furthermore, because the control process incorporates space vector control, it can resolve converter phase-to-phase interference problems while maintaining compensation effectiveness, reducing the switching frequency of switching devices, and improving compensation efficiency. Attached Figure Description

[0031] Figure 1 This is a schematic diagram illustrating the implementation process of the method of the present invention.

[0032] Figure 2 This is a basic structure diagram of UPQC.

[0033] Figure 3This is a schematic diagram illustrating the principle of the UPQC control strategy. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1 As shown, this invention discloses a UPQC control method based on fuzzy variable loop width hysteresis vector. The specific implementation of the method of this invention will be illustrated below with a specific application example.

[0036] In such Figure 2 In the UPQC structure diagram shown, the left side represents the series converter, and the right side represents the parallel converter. Therefore, a typical UPQC specifically includes a parallel converter and a series converter. Both the parallel and series converters use a three-phase bridge structure, so both the parallel and series converters have three-phase upper bridge arm switches and three-phase lower bridge arm switches, for a total of six bridge arm switches. Figure 3 This diagram illustrates the principle of implementing the control strategy using the method of the present invention.

[0037] First, preparations before implementing control include steps (1.1) to (1.5) as shown below.

[0038] Step (1.1) defines 7 fuzzy language values, specifically including negative large, negative medium, negative small, zero, positive small, positive medium and positive large, which are labeled using NB, NM, NS, ZO, PS, PM and PB respectively.

[0039] Step (1.2) determines the difference vector X and the rate of change vector. The data in X is fuzzified to obtain the corresponding fuzzy language values; where, for the j-th data x in X, j The specific rules for obtaining the corresponding fuzzy language value through fuzzification are: if x j ∈[-3,-2.667), and the membership function is a trapezoid, then x j The corresponding fuzzy language value is NB; if x j ∈(-3,-1), if the membership function is of Gaussian form, then x j The corresponding fuzzy language value is NM; if x j ∈(-2,0), the membership function is triangular, then x j The corresponding fuzzy language value is NS; if x j ∈(-1,1), the membership function is triangular, then x j The corresponding fuzzy language value is ZO; if x j ∈(0,2), the membership function is taken as a triangle, then x j The corresponding fuzzy language value is PS; if x j∈(1,3), if the membership function is of Gaussian form, then x j The corresponding fuzzy language value is PM; if x j ∈(2,3], if the membership function is a trapezoid, then x j The corresponding fuzzy language value is PB; j = 1, 2, 3; for The j-th data in The rules for obtaining the corresponding fuzzy language values ​​by performing fuzzification processing are related to x. j The rules for blurring are the same.

[0040] Step (1.3): Determine the fuzzy inference rule, let X or The fuzzy linguistic values ​​corresponding to the j-th data in the dataset are m and m, respectively. Then the j-th data h in the hysteresis width vector H j The corresponding fuzzy inference rule for the fuzzy linguistic value M is: if m is NB, then M is PB; if m is ZO, then M is NB; if m is PB, then M is PB; if m is NM, then M is PB. Let NB, NM, NS, ZO, PS, PM, and PB be the values, then M be PM, PS, ZO, NS, ZO, PS, and PM respectively; if m is NS and... Let NB, NM, NS, ZO, PS, PM, and PB be the values, then M be the values ​​of PS, ZO, NS, NM, NS, ZO, and PS respectively; if m is PS and... Let NB, NM, NS, ZO, PS, PM, and PB be the values, then M be PS, ZO, NS, NM, NS, ZO, and PS respectively; if m is PM and... If NB, NM, NS, ZO, PS, PM, and PB are respectively, then M is PM, PS, ZO, NS, ZO, PS, and PM.

[0041] Step (1.4) assigns six area numbers for the current difference and six area numbers for the parallel reference voltage to the parallel converters in the UPQC. The six area numbers for the current difference are labeled as I-1, I-2, I-3, I-4, I-5, and I-6, and the six area numbers for the parallel reference voltage are labeled as U1-1, U1-2, U1-3, U1-4, U1-5, and U1-6. At the same time, assigns six area numbers for the voltage difference and six area numbers for the series reference voltage to the series converters in the UPQC. The six area numbers for the voltage difference are labeled as V-1, V-2, V-3, V-4, V-5, and V-6, and the six area numbers for the series reference voltage are labeled as U2-1, U2-2, U2-3, U2-4, U2-5, and U2-6.

[0042] Step (1.5) determines the combination of the three-phase upper arm switches, specifically 7 types, denoted as S1, S2, ..., S7; where S1 indicates that the upper arm switch of phase A is closed, and the upper arm switches of phases B and C are open, then the lower arm switch of phase A is open, and the lower arm switches of phases B and C are closed; S2 indicates that the upper arm switches of phases A and B are closed, and the upper arm switch of phase C is open; S3 indicates that the upper arm switch of phase B is closed, and the upper arm switches of phases A and C are open; S4 indicates that the upper arm switches of phases B and C are closed, and the upper arm switch of phase A is open; S5 indicates that the upper arm switch of phase C is closed, and the upper arm switches of phases A and B are open; S6 indicates that the upper arm switches of phases A and C are closed, and the upper arm switch of phase B is open; S7 indicates that the upper arm switches of phases A, B, and C are simultaneously open or simultaneously closed, in which case there is no output from the strain gauge.

[0043] Secondly, based on the current and voltage data measured at the latest sampling time t, after determining the three-phase upper arm switch combination mode of the parallel converter and the series converter in the UPQC, the corresponding type of switch combination mode is executed for the three-phase upper arm of the parallel converter and the three-phase upper arm of the series converter. The three-phase lower arm switch state of the parallel converter and the series converter is the opposite of the switch state of their three-phase upper arms. The specific implementation process includes the following steps (2.1) to (2.3).

[0044] Step (2.1) involves measuring the current and voltage data at the latest sampling time t, specifically including the actual compensation current feedback i of phases A, B, and C of the parallel converter in the UPQC. A i B and i C and compensation current detection quantity and The actual compensation voltage feedback quantity v of phases A, B and C of the series converter in UPQC A v B and v C and compensation voltage detection quantity and Then calculate the difference vector of the parallel converters. The difference vector between the series converter and the series converter

[0045] Step (2.2) obtains the difference vector I of the parallel converter and the series converter at a sampling time t before t. t-1 and V t-1 Then, follow the formula. and Calculate the rate of change vector of the parallel converters respectively and the rate of change vector of the series converter Where t-1 represents a sampling time before t.

[0046] Step (2.3) involves executing schemes (1) and (2) in parallel; where scheme (1) is: setting X = I t and Then, perform steps ① to ⑦ as shown below; Scheme (2) is: set X = V t and Then, proceed with steps ① through ⑥ as shown below.

[0047] Following step ①: Apply the rules described in step (1.2) to X and The data in the image is fuzzified to obtain the corresponding fuzzy language value.

[0048] Step ②: Following the fuzzy inference rules in step (1.3), after obtaining the fuzzy linguistic values ​​corresponding to the three data points in the hysteresis width vector H, defuzzification is performed using the centroid method to obtain the hysteresis width vector H.

[0049] The centroid method in step ② above can also be called the weighted average method. Before implementing the centroid method, it is necessary to know the j-th data h in H. j The corresponding fuzzy linguistic value judgment rule is as follows: if h j If h ∈ [1, 1.333), then h j The corresponding fuzzy language value is NB; if h j If ∈(1,1.667), then h j The corresponding fuzzy language value is NM; if h j If h ∈(1.333,2), then h j The corresponding fuzzy language value is NS; if h j If ∈(1.667,2.333), then h j The corresponding fuzzy language value is ZO; if h j If ∈(2,2.667), then h j The corresponding fuzzy language value is PS; if h j If h ∈(2.333,3), then h j The corresponding fuzzy language value is PM; if h j If h ∈(2.667,3], then h j The corresponding fuzzy language value is PB. Meanwhile, the membership functions for all seven fuzzy intervals are triangular.

[0050] Then, using the number n of the corresponding fuzzy rules activated during the fuzzy inference process and the numerical value h in the fuzzy universe... m and membership value u(h) m The following formula (1) is used to perform deblurring, resulting in h. j :

[0051]

[0052] Where m = 1, 2, ..., n. Formula (1) shows that it calculates the weighted average.

[0053] Step ③: Compare the data at the same position in X and H to obtain the polar vector Y; the specific implementation process is: set j = 1, 2, 3 in sequence, and determine x j Is it less than h? j If so, then the j-th data y in Y j Then it equals 1; otherwise, the j-th data y in Y is equal to 1. j Then it equals 0;

[0054] Step 4: Use the three data points y1, y2, y3 in Y to determine the region number corresponding to Y, and then use... Three data points The difference between and judge The corresponding area number; where, when X = I t The rules for determining the region are as follows: if only y1 is greater than 0, then the region number corresponding to Y is I-1; if only y1 and y2 are greater than 0, then the region number corresponding to Y is I-2; if only y2 is greater than 0, then the region number corresponding to Y is I-3; if only y2 and y3 are greater than 0, then the region number corresponding to Y is I-4; if only y3 is greater than 0, then the region number corresponding to Y is I-5; if only y1 and y3 are greater than 0, then the region number corresponding to Y is I-6; when X = V t The rules for determining the region number are as follows: if only y1 and y3 are greater than 0, then the region number corresponding to Y is V-1; if only y1 is greater than 0, then the region number corresponding to Y is V-2; if only y1 and y2 are greater than 0, then the region number corresponding to Y is V-3; if only y2 is greater than 0, then the region number corresponding to Y is V-4; if only y2 and y3 are greater than 0, then the region number corresponding to Y is V-5; if only y3 is greater than 0, then the region number corresponding to Y is V-6; when... The rule for judging time is: if only and If it is greater than 0, then The corresponding area number is U1-1; if only If it is greater than 0, then The corresponding area number is U1-2; if only and If it is greater than 0, then The corresponding area number is U1-3; if only If it is greater than 0, then The corresponding area number is U1-4; if only and If it is greater than 0, then The corresponding area number is U1-5; if only If it is greater than 0, then The corresponding area number is U1-6; when The rule for judging time is: if only and If it is greater than 0, then The corresponding area number is U2-1; if only If it is greater than 0, then The corresponding area number is U2-2; if only and If it is greater than 0, then The corresponding area number is U2-3; if only If it is greater than 0, then The corresponding area number is U2-4; if only and If it is greater than 0, then The corresponding area number is U2-5; if only If it is greater than 0, then The corresponding area number is U2-6.

[0055] Step 5: Based on Y and The corresponding area number determines the type of three-phase upper bridge arm switch combination; when X = I t and The specific methods for determining the types of three-phase upper bridge arm switch combinations of parallel converters are shown in Table 1; when X = V t and The specific methods for determining the types of three-phase upper bridge arm switch combinations of the series converter are shown in Table 2.

[0056] The determination rules listed in Table 1 are detailed below: When the region number corresponding to Y is I-1 and When the corresponding area numbers are U1-1, U1-2, U1-3, U1-4, U1-5, and U1-6, the types of three-phase upper bridge arm switch combinations of the parallel converters are S1, S2, S7, S7, S6, and S1, respectively; when the area number corresponding to Y is I-2, ... When the corresponding area numbers are U1-1, U1-2, U1-3, U1-4, U1-5, and U1-6, the types of three-phase upper bridge arm switch combinations of the parallel converters are S2, S2, S3, S7, S7, and S1, respectively; when the area number corresponding to Y is I-3, and... When the corresponding area numbers are U1-1, U1-2, U1-3, U1-4, U1-5, and U1-6, the types of three-phase upper bridge arm switch combinations of the parallel converters are S2, S3, S3, S4, S7, and S7, respectively; when the area number corresponding to Y is I-4, ... When the corresponding area numbers are U1-1, U1-2, U1-3, U1-4, U1-5, and U1-6, the types of three-phase upper bridge arm switch combinations for the parallel converters are S7, S3, S4, S4, S5, and S7, respectively; when the area number corresponding to Y is I-5, When the corresponding area numbers are U1-1, U1-2, U1-3, U1-4, U1-5, and U1-6, the types of three-phase upper bridge arm switch combinations for the parallel converters are S7, S7, S4, S5, S5, and S6, respectively; when the area number corresponding to Y is I-6, and... When the corresponding area numbers are U1-1, U1-2, U1-3, U1-4, U1-5, and U1-6, the types of three-phase upper bridge arm switch combinations of the parallel converters are S1, S7, S7, S5, S6, and S6, respectively.

[0057] The determination rules listed in Table 2 are detailed below: When the region number corresponding to Y is V-1 and When the corresponding area numbers are U2-1, U2-2, U2-3, U2-4, U2-5, and U2-6, the types of three-phase upper bridge arm switch combinations of the series converter are S1, S7, S7, S5, S6, and S6, respectively; when the area number corresponding to Y is V-2, and... When the corresponding area numbers are U2-1, U2-2, U2-3, U2-4, U2-5, and U2-6, the types of three-phase upper bridge arm switch combinations of the series converter are S1, S2, S7, S7, S6, and S1, respectively; when the area number corresponding to Y is V-3, and... When the corresponding area numbers are U2-1, U2-2, U2-3, U2-4, U2-5, and U2-6, the types of three-phase upper bridge arm switch combinations of the series converter are S2, S2, S3, S7, S7, and S1, respectively; when the area number corresponding to Y is V-4, and... When the corresponding area numbers are U2-1, U2-2, U2-3, U2-4, U2-5, and U2-6, the types of three-phase upper bridge arm switch combinations of the series converter are S2, S3, S3, S4, S7, and S7, respectively; when the area number corresponding to Y is V-5, When the corresponding area numbers are U2-1, U2-2, U2-3, U2-4, U2-5, and U2-6, the types of three-phase upper bridge arm switch combinations of the series converter are S7, S3, S4, S4, S5, and S7, respectively; when the area number corresponding to Y is V-6, and... When the corresponding area numbers are U2-1, U2-2, U2-3, U2-4, U2-5, and U2-6, the types of three-phase upper bridge arm switch combinations of the series converter are S7, S7, S4, S5, S5, and S6, respectively.

[0058] Step 6: Based on the type of three-phase upper arm switch combination, execute the corresponding actions of the A, B, and C phase switches, and execute the corresponding actions of the three-phase lower arm switches A, B, and C in the opposite switching manner, then return to step (2.1).

Claims

1. A UPQC control method based on fuzzy variable-loop wide-hysteresis space vector, characterized in that, Specifically, the following steps are included: First, preparations before implementing control include the following steps (1.1) to (1.5); Step (1.1) defines 7 fuzzy language values, specifically including negative large, negative medium, negative small, zero, positive small, positive medium and positive large, which are labeled using NB, NM, NS, ZO, PS, PM and PB respectively; Step (1.2) determines the difference vector X and the rate of change vector. The data in X is fuzzified to obtain the corresponding fuzzy language values; where, for the j-th data x in X, j The specific rules for obtaining the corresponding fuzzy language value through fuzzification are: if x j ∈[-3,-2.667), and the membership function is a trapezoid, then x j The corresponding fuzzy language value is NB; if x j ∈(-3,-1), if the membership function is of Gaussian form, then x j The corresponding fuzzy language value is NM; if x j ∈(-2,0), the membership function is triangular, then x j The corresponding fuzzy language value is NS; if x j ∈(-1,1), the membership function is triangular, then x j The corresponding fuzzy language value is ZO; if x j ∈(0,2), the membership function is taken as a triangle, then x j The corresponding fuzzy language value is PS; if x j ∈(1,3), if the membership function is of Gaussian form, then x j The corresponding fuzzy language value is PM; if x j ∈(2,3], if the membership function is a trapezoid, then x j The corresponding fuzzy language value is PB; j = 1, 2, 3; for The j-th data in The rules for obtaining the corresponding fuzzy language values ​​by performing fuzzification processing are related to x. j The rules for blurring are the same; Step (1.3): Determine the fuzzy inference rule, let X or The fuzzy linguistic values ​​corresponding to the j-th data in the dataset are m and m, respectively. Then the j-th data h in the hysteresis width vector H j The corresponding fuzzy inference rule for the fuzzy linguistic value M is: if m is NB, then M is PB; if m is ZO, then M is NB; if m is PB, then M is PB; if m is NM, then M is PB. Let NB, NM, NS, ZO, PS, PM, and PB be the values, then M be PM, PS, ZO, NS, ZO, PS, and PM respectively; if m is NS and... Let NB, NM, NS, ZO, PS, PM, and PB be the values, then M be the values ​​of PS, ZO, NS, NM, NS, ZO, and PS respectively; if m is PS and... Let NB, NM, NS, ZO, PS, PM, and PB be the values, then M be PS, ZO, NS, NM, NS, ZO, and PS respectively; if m is PM and... If NB, NM, NS, ZO, PS, PM, and PB are respectively, then M is PM, PS, ZO, NS, ZO, PS, and PM. Step (1.4) assigns six area numbers for the current difference and six area numbers for the parallel reference voltage to the parallel converters in the UPQC. The six area numbers for the current difference are labeled as I-1, I-2, I-3, I-4, I-5 and I-6, and the six area numbers for the parallel reference voltage are labeled as U1-1, U1-2, U1-3, U1-4, U1-5 and U1-6. At the same time, assigns six area numbers for the voltage difference and six area numbers for the series reference voltage to the series converters in the UPQC. The six area numbers for the voltage difference are labeled as V-1, V-2, V-3, V-4, V-5 and V-6, and the six area numbers for the series reference voltage are labeled as U2-1, U2-2, U2-3, U2-4, U2-5 and U2-6. Step (1.5) determines the combination of the three-phase upper arm switches, specifically there are 7 types, denoted as S1, S2, ..., S7; where S1 indicates that the upper arm switch of phase A is closed, and the upper arm switches of phases B and C are open, then the lower arm switch of phase A is open, and the lower arm switches of phases B and C are closed; S2 indicates that the upper arm switches of phases A and B are closed, and the upper arm switch of phase C is open; S3 indicates that the upper arm switch of phase B is closed, and the upper arm switches of phases A and C are open; S4 indicates that the upper arm switches of phases B and C are closed, and the upper arm switch of phase A is open; S5 indicates that the upper arm switch of phase C is closed, and the upper arm switches of phases A and B are open; S6 indicates that the upper arm switches of phases A and C are closed, and the upper arm switch of phase B is open; S7 indicates that the upper arm switches of phases A, B, and C are simultaneously open or simultaneously closed, in which case there is no output from the strain gauge. Secondly, based on the current and voltage data measured at the latest sampling time t, after determining the type of three-phase upper bridge arm switch combination for the parallel converter and the series converter in the UPQC, the corresponding type of switch combination is executed for the three-phase upper bridge arm of the parallel converter and the three-phase upper bridge arm of the series converter. The switch states of the three-phase lower bridge arm of the parallel converter and the series converter are opposite to the switch states of their three-phase upper bridge arms. The specific implementation process includes the following steps (2.1) to (2.3). Step (2.1) involves measuring the current and voltage data at the latest sampling time t, specifically including the actual compensation current feedback i of phases A, B, and C of the parallel converter in the UPQC. A i B and i C and compensation current detection quantity and The actual compensation voltage feedback quantity v of phases A, B and C of the series converter in UPQC A v B and v C and compensation voltage detection quantity and Then calculate the difference vector of the parallel converters. The difference vector between the series converter and the series converter Step (2.2) obtains the difference vector I of the parallel converter and the series converter at a sampling time t before t. t-1 and V t-1 Then, follow the formula. and Calculate the rate of change vector of the parallel converters respectively and the rate of change vector of the series converter Where t-1 represents a sampling time before t; Step (2.3) involves executing schemes (1) and (2) in parallel; where scheme (1) is: setting X = I t and Then, perform steps ① to ⑦ as shown below; Scheme (2) is: set X = V t and Then, proceed with steps ① to ⑥ as shown below; Following step ①: Apply the rules described in step (1.2) to X and The data in the image is fuzzy to obtain the corresponding fuzzy language value; Step ②: Following the fuzzy inference rules in step (1.3), after obtaining the fuzzy linguistic values ​​corresponding to the three data in the hysteresis width vector H, the centroid method is used for defuzzification to obtain the hysteresis width vector H. Step ③: Compare the data at the same position in X and H to obtain the polar vector Y; the specific implementation process is: set j = 1, 2, 3 in sequence, and determine x j Is it less than h? j If so, then the j-th data y in Y j Then it equals 1; otherwise, the j-th data y in Y is equal to 1. j Then it equals 0; Step 4: Use the three data points y1, y2, y3 in Y to determine the region number corresponding to Y, and then use... Three data points The difference between and judge The corresponding area number; where, when X = I t The rules for determining the region are as follows: if only y1 is greater than 0, then the region number corresponding to Y is I-1; if only y1 and y2 are greater than 0, then the region number corresponding to Y is I-2; if only y2 is greater than 0, then the region number corresponding to Y is I-3; if only y2 and y3 are greater than 0, then the region number corresponding to Y is I-4; if only y3 is greater than 0, then the region number corresponding to Y is I-5; if only y1 and y3 are greater than 0, then the region number corresponding to Y is I-6; when X = V t The rules for determining the region are as follows: if only y1 and y3 are greater than 0, then the region number corresponding to Y is V-1; if only y1 is greater than 0, then the region number corresponding to Y is V-2; if only y1 and y2 are greater than 0, then the region number corresponding to Y is V-3; if only y2 is greater than 0, then the region number corresponding to Y is V-4; if only y2 and y3 are greater than 0, then the region number corresponding to Y is V-4; if only y2 and y3 are greater than 0, then the region number corresponding to Y is V-5. If y3 is greater than 0, then the region number corresponding to Y is V-5; if only y3 is greater than 0, then the region number corresponding to Y is V-6; when The rule for judging time is: if only and If greater than 0, then The corresponding area number is U1-1; if only If greater than 0, then The corresponding area number is U1-2; if only and If greater than 0, then The corresponding area number is U1-3; if only If greater than 0, then The corresponding area number is U1-4; if only and If greater than 0, then The corresponding area number is U1-5; if only If greater than 0, then The corresponding area number is U1-6; when The rule for judging time is: if only and If greater than 0, then The corresponding area number is U2-1; if only If greater than 0, then The corresponding area number is U2-2; if only and If greater than 0, then The corresponding area number is U2-3; if only If greater than 0, then The corresponding area number is U2-4; if only and If greater than 0, then The corresponding area code is U2-5; if only If greater than 0, then The corresponding area code is U2-6; Step 5: Based on Y and The corresponding area number determines the type of three-phase upper bridge arm switch combination; when X = I t and The specific methods for determining the types of three-phase upper bridge arm switch combinations of parallel converters are shown in Table 1; when X = V t and The specific methods for determining the types of three-phase upper bridge arm switch combinations of the series converter are shown in Table 2. Table 1: Rules for determining the types of three-phase upper arm switch combinations in parallel converters; Table 2: Rules for determining the types of three-phase upper arm switch combinations in series converters; Step 6: Based on the type of three-phase upper arm switch combination, execute the corresponding actions of the A, B, and C phase switches, and execute the corresponding actions of the three-phase lower arm switches A, B, and C in the opposite switching manner, then return to step (2.1).

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