A phase sequence protection method and device

Abstract

The present invention discloses a phase sequence protection method and device, which includes sampling the operation data of the system; calculating the real part and the imaginary part of the three-phase voltage of the electrical quantity according to the sampled operation data, including the electrical quantity and the switching quantity, and determining the phase sequence of the electrical quantity according to the preset voltage phase sequence determination rule by the real part and the imaginary part of the three-phase voltage; determining the phase sequence determined by the operation condition of the input quantity; comparing the phase sequence obtained by the electrical quantity calculation with the phase sequence determined by the input quantity. If the two are the same, it is judged that the phase sequence is normal; if the two are different, it is judged that the phase sequence is abnormal, and the phase sequence protection action execution mechanism is controlled to execute the protection action. The present invention realizes phase sequence protection by comparing the phase sequence calculation of the electrical quantity with the phase sequence determination of the operation condition of the input quantity. The principle is simple and reliable, and there is no need to set the electrical quantity setting value. Even in the non-power frequency state, the phase sequence protection can be effectively realized.

Description

Technical Field

[0001] The present invention relates to a phase sequence protection method and device, belonging to the technical field of power systems. Background Art

[0002] The generating motor of a pumped storage power station has two main operating conditions: power generation and pumping. The phase sequences of the two operating conditions are different. The pumped storage unit realizes the phase sequence switching of the entire system through a phase change switch. To avoid the reverse rotation of the generating motor caused by the inconsistency between the voltage phase sequence and the actual operating condition, which may lead to equipment damage, phase sequence protection is set.

[0003] Conventional phase sequence protection introduces the three-phase voltage at the machine terminal and comprehensively judges whether the current phase sequence is normal by using negative sequence voltage and the current operating condition. However, under the same operating condition, negative sequence voltage may also be generated due to system faults, frequency offsets, etc. The setting values of the negative sequence voltage are not very different, so it may be misjudged as inconsistent phase sequence, resulting in misoperation of the phase sequence protection. Summary of the Invention

[0004] The present invention provides a phase sequence protection discrimination method and device, which solves the problems disclosed in the background art.

[0005] To achieve the above object, the present invention is implemented by the following technical solutions:

[0006] In a first aspect, the present invention provides a phase sequence protection method, including:

[0007] Obtain the operation data sampled from the system in advance, where the operation data includes electrical quantities and input signals;

[0008] Calculate the real part and the imaginary part of the three-phase voltage of the electrical quantity, and determine the phase sequence of the electrical quantity according to the preset voltage phase sequence determination rule from the real part and the imaginary part of the three-phase voltage: phase sequence ABC or phase sequence ACB;

[0009] Determine the phase sequence according to the preset determination rule from the input signal operation condition: phase sequence ABC or phase sequence ACB;

[0010] Judge whether the phase sequence calculated from the electrical quantity is the same as the phase sequence determined by the input signal. If the two are the same, it is judged that the phase sequence is normal; if the two are different, it is judged that the phase sequence is abnormal.

[0011] Further, the calculation of the real part and the imaginary part of the three-phase voltage of the electrical quantity, and the determination of the phase sequence of the electrical quantity according to the preset voltage phase sequence determination rule from the real part and the imaginary part of the three-phase voltage, includes:

[0012] Obtain the pre - collected voltage data as the data in the original data area, and perform correction processing on the voltage data to obtain the data in the corrected data area. Among them, if the system frequency is the same as the set value, use the data in the original data area; if the system frequency deviates from the set value, use the data in the corrected data area.

[0013] Use the conventional Fourier algorithm to calculate U ΦΦRe and U ΦΦIm ; where, U ΦΦRe =U ABRe ,U BCRe ,U CARe , is the real part of the three - phase line voltage; U ΦΦIm =U ABIm ,U BCIm ,U CAIm , is the imaginary part of the three - phase line voltage; A, B, C are three phases.

[0014] Determine the phase sequence of electrical quantities according to the preset voltage phase - sequence determination rule.

[0015] Furthermore, the preset voltage phase - sequence determination rule includes:

[0016] If the following conditions are met, calculate as phase sequence ABC;

[0017]

[0018] If the following conditions are met, calculate as phase sequence ACB;

[0019]

[0020] In the above formula, U AB ,U BC ,U CA are the amplitudes of the three - phase line voltage; U Low is the low - threshold value of the line voltage; α and β are threshold values;

[0021] ref1, ref2, ref3, ref4 are intermediate variables, where,

[0022] ref1 = U ABRe *U BCRe +U ABIm *U BCIm

[0023] ref2 = U ABRe *U CARe +U ABIm *U CAIm

[0024] ref3 = U ABIm *U BCRe -U ABRe *UBCIm

[0025] ref4 = U ABIm *U CARe -U ABRe *U CAIm 。

[0026] Further, the three-phase voltage of the electrical quantity is the three-phase line voltage or the three-phase phase voltage.

[0027] Further, determining the phase sequence according to the operating conditions of the input signals based on a preset determination rule includes:

[0028] The protection device introduces the input signal of the phase-changing switch, including the generating potential of the phase-changing switch, the pumping water level of the phase-changing switch, and the fully open position of the phase-changing switch;

[0029] Preprocess the input signals to obtain the effective data of the input signals after removing interference;

[0030] The rule for determining the phase sequence is:

[0031] When the generating potential of the phase-changing switch or the fully open position of the phase-changing switch in the input signals is valid, while the pumping water level of the phase-changing switch is invalid, it is judged as the ABC phase sequence; when both the generating potential of the phase-changing switch and the fully open position of the phase-changing switch in the input signals are invalid, while the pumping water level of the phase-changing switch is valid, it is judged as the ACB phase sequence.

[0032] Further, the sampled operating data is not limited to voltage.

[0033] In a second aspect, the present invention provides a phase sequence protection device, including:

[0034] Sampling module: Sampling the operating data of the system, where the operating data includes electrical quantities and input signals, and among them, the electrical quantity data is voltage or current;

[0035] Calculation module: Calculating the phase sequence determined by the electrical quantity phase sequence and the input signals according to the sampled operating data;

[0036] Phase sequence judgment module: Within a set time, if the phase sequence determined by the electrical quantity phase sequence and the input signals is consistent, the phase sequence is normal; if not, the phase sequence is abnormal, and the phase sequence protection action program is started.

[0037] In a third aspect, the present invention provides a phase sequence protection device, including a processor and a storage medium;

[0038] The storage medium is used to store instructions;

[0039] The processor is used to operate according to the instructions to execute the steps of the method according to any one of the foregoing.

[0040] Fourthly, the present invention provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the steps of the method described in any one of the foregoing are implemented.

[0041] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0042] The present invention provides a phase sequence protection method and device, which realizes phase sequence protection by comparing the phase sequence calculation of three-phase voltages of electrical quantities with the phase sequence determination of the operating conditions of the input signals. The principle is simple and reliable, and there is no need to set the electrical quantity setting value. Even in a non-power frequency state, phase sequence protection can be effectively realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a flowchart of a phase sequence protection method provided by an embodiment of the present invention;

[0044] Figure 2 is a logic block diagram of phase sequence protection provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0046] Embodiment 1

[0047] This embodiment introduces a phase sequence protection method, including:

[0048] Obtain the operation data sampled from the system in advance, where the operation data includes electrical quantities and input signals;

[0049] Calculate the real part and the imaginary part of the three-phase voltages of the electrical quantities, and determine the phase sequence of the electrical quantities according to the preset voltage phase sequence determination rule from the real part and the imaginary part of the three-phase voltages: phase sequence ABC or phase sequence ACB;

[0050] Determine the phase sequence according to the operating conditions of the input signals according to the preset determination rule: phase sequence ABC or phase sequence ACB;

[0051] Judge whether the phase sequence calculated from the electrical quantities is the same as the phase sequence determined by the input signals. If the two are the same, it is judged that the phase sequence is normal; if the two are different, it is judged that the phase sequence is abnormal.

[0052] As Figure 1 shown, for the phase sequence protection method provided in this embodiment, the application process specifically involves the following steps:

[0053] Step 1, sample the operation data of the system (i.e., the power system);

[0054] Step 2: Calculate the real and imaginary parts of the three-phase voltage of the electrical quantity according to the sampled operation data, and determine the phase sequence of the electrical quantity according to the preset voltage phase sequence determination rule: phase sequence ABC or phase sequence ACB;

[0055] Step 3: Determine the phase sequence according to the preset determination rule based on the operation condition of the input quantity according to the sampled operation data: phase sequence ABC or phase sequence ACB;

[0056] Step 4: For the phase sequence calculated from the electrical quantity and the phase sequence determined by the input quantity, if the two are the same, it is judged that the phase sequence is normal; if the two are different, it is judged that the phase sequence is abnormal.

[0057] The above method is applied to the phase sequence protection side. By comparing the phase sequence calculated from the electrical quantity and the phase sequence determined by the input quantity, it can quickly judge whether the current phase sequence is normal, and can avoid the wrong judgment of the system phase sequence caused by the negative sequence voltage generated by the system fault, frequency offset, etc. in the conventional phase sequence protection.

[0058] The phase sequence protection side samples the operation data of the system. The operation data here are the electrical quantity data and input quantity data during the system operation. The sampling frequency is 1200 Hz, and the data window length of each round of sampling is 1 fundamental wave period, and the fundamental wave period is 20 ms.

[0059] According to the sampled data, the steps for calculating the phase sequence of the three-phase voltage are as follows:

[0060] First step: Process the collected voltage data by using the method described in the patent "A Microcomputer Protection Method and Device Adapted to the Frequency Conversion Characteristics of Electrical Equipment" (authorization announcement number: CN110535091B). If the system frequency is 50 Hz, use the data in the original data area; if the system frequency deviates from 50 Hz, use the data in the corrected data area;

[0061] Second step: Use the conventional Fourier algorithm to calculate U ΦΦRe and U ΦΦIm ; where U ΦΦRe =U ABRe ,U BCRe ,U CARe , is the real part of the three-phase line voltage; U ΦΦIm =U ABIm ,U BCIm ,U CAIm , is the imaginary part of the three-phase line voltage; A, B, and C are the three phases;

[0062] Third step: Determine the phase sequence of the electrical quantity according to the preset voltage phase sequence determination rule:

[0063] (1) If the following conditions are met, it is calculated as phase sequence ABC

[0064]

[0065] (2) If the following conditions are met, the calculation is for the phase sequence ACB

[0066]

[0067] In the above formula, U AB , U BC , U CA are the amplitudes of the three-phase line voltages; U Low is the low threshold value of the line voltage; α and β are the threshold values;

[0068] ref1, ref2, ref3, ref4 are intermediate variables, where,

[0069] ref1 = U ABRe * U BCRe + U ABIm * U BCIm

[0070] ref2 = U ABRe * U CARe + U ABIm * U CAIm

[0071] ref3 = U ABIm * U BCRe - U ABRe * U BCIm

[0072] ref4 = U ABIm * U CARe - U ABRe * U CAIm

[0073] The value range of the threshold value α is 1.1 to 1.2, and the value range of β is 0.8 to 0.9.

[0074] The three-phase voltage of the electrical quantity is the three-phase line voltage or the three-phase phase voltage.

[0075] The phase sequence steps determined according to the sampling data and the operating conditions of the input signals:

[0076] First step, the protection device introduces the input signals of the phase change switch generating potential, the phase change switch pumping water level, and the phase change switch fully open position;

[0077] Second step, preprocess the input signals by using the method described in "A Method and Device for Identifying the Working State of a Pumped-Storage Unit" (authorization announcement number: CN111456888B);

[0078] Third step, the rule for determining the phase sequence is:

[0079] When the incoming signal of the phase conversion switch's generating potential or the fully open position of the phase conversion switch is valid, while the incoming signal of the phase conversion switch's pumping water level is invalid, it is determined as the ABC phase sequence; when both the incoming signal of the phase conversion switch's generating potential and the fully open position of the phase conversion switch are invalid, while the incoming signal of the phase conversion switch's pumping water level is valid, it is determined as the ACB phase sequence.

[0080] The present invention realizes phase sequence protection by comparing the phase sequence calculation of the electrical quantity of three-phase voltage with the phase sequence determination of the operating conditions of the incoming signals. The principle is simple and reliable, without the need to set electrical quantity setting values. Even in a non-power frequency state, phase sequence protection can be effectively realized.

[0081] In some specific implementation application examples, taking a certain pumped-storage unit as an example, when the unit is normally started for power generation, the operator miscloses the phase conversion switch to the pumping water level. At this time, the measured three-phase line voltages at the machine terminal are: The frequency is 40Hz, the threshold value α is taken as 0.9, β is taken as 1.2, U Low is taken as 40V, combined with the phase sequence protection logic block diagram (such as Figure 2 ), the discrimination is as follows:

[0082] The method described in the patent "A Microcomputer Protection Method and Device Adapted to the Frequency Conversion Characteristics of Electrical Equipment" (authorization announcement number: CN110535091B) is used to process the collected voltage data. Since the frequency is less than 50Hz, the data source pointer points to the corrected data area.

[0083] The conventional Fourier algorithm is used to calculate U ΦΦRe and U ΦΦIm using the data in the corrected data area. The real-time calculation is as follows:

[0084] U ABRe = 28.5

[0085] U ABIm = 49.362

[0086] U BCRe = 28.5

[0087] U BCIm = -49.362

[0088] U CARe = -57.0

[0089] U CAIm = 0.0

[0090] ref1 = U ABRe * U BCRe + U ABIm * U BCIm = 28.5 * 28.5 - 49.362 * 49.362 = -1624.35

[0091] ref2 = U ABRe *U CARe +U ABIm *U CAIm = -28.5 * 57.0 + 49.362 * 0.0 = -1624.5

[0092] ref3 = U ABIm *U BCRe -U ABRe *U BCIm = 49.362 * 28.5 + 28.5 * 49.362 = 2813.63

[0093] ref4 = U ABIm *U CARe -U ABRe *U CAIm = -49.362 * 57 - 28.5 * 0.0 = -2813.6

[0094]

[0095]

[0096]

[0097] According to the above judgment conditions, the electrical quantity is calculated as phase sequence ABC.

[0098] According to the input signal judgment rule, at this time, both the generating potential of the phase change switch of the pumped storage unit or the fully open position of the phase change switch are invalid. When the pumped water level of the phase change switch is effective, it is judged as phase sequence ACB. Figure 2 It can be seen that within the set time of the phase sequence protection, if the continuously measured three-phase voltages are calculated as phase sequence ABC, while the continuously determined input signals are judged as phase sequence ACB, it is determined that the phase sequence is abnormal and the phase sequence protection action procedure is started.

[0099] The electrical quantity data sampled in this embodiment is not limited to voltage, and can also be current;

[0100] Embodiment 2

[0101] This embodiment provides a phase sequence protection device, including:

[0102] Sampling module: Sampling the operation data of the system, where the operation data includes electrical quantity and input signals, and the electrical quantity data is voltage or current;

[0103] Calculation module: Calculating the phase sequence determined by the electrical quantity phase sequence and the input signals according to the sampled operation data;

[0104] Phase sequence judgment module: within a set time, if the phase sequence determined by the electrical quantity is consistent with the phase sequence determined by the input, the phase sequence is normal; if not, the phase sequence is abnormal and the phase sequence protection action program is started.

[0105] Embodiment 3

[0106] This embodiment provides a phase sequence protection device, including a processor and a storage medium;

[0107] The storage medium is used to store instructions;

[0108] The processor is used to operate according to the instructions to execute the steps of the method according to any one of Embodiment 1.

[0109] Embodiment 4

[0110] This embodiment provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the steps of the method according to any one of Embodiment 1 are implemented.

[0111] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A phase sequence protection method, characterized in that, it includes: Obtain the operation data sampled from the system in advance, where the operation data includes electrical quantities and input signals; Calculate the real part and imaginary part of the three-phase voltage of the electrical quantity, and determine the phase sequence of the electrical quantity according to the preset voltage phase sequence determination rule from the real part and imaginary part of the three-phase voltage: phase sequence ABC or phase sequence ACB; the preset voltage phase sequence determination rule includes: If the following conditions are met, it is calculated as phase sequence ABC; If the following conditions are met, it is calculated as phase sequence ACB; In the above formula, U AB , U BC , U CA are the amplitudes of the three-phase line voltages; U Low is the low threshold of the line voltage; α and β are the threshold values; ref1, ref2, ref3, ref4 are intermediate variables, where, ref1 = U ABRe *U BCRe +U ABIm *U BCIm ; ref2 = U ABRe *U CARe +U ABIm *U CAIm ; ref3 = U ABIm *U BCRe -U ABRe *U BCIm ; ref4 = U ABIm *U CARe -U ABRe *U CAIm ; Among them, U ABRe , U BCRe , U CARe , is the real part of the three-phase line voltage; U ABIm , U BCIm , U CAIm , is the imaginary part of the three-phase line voltage; A, B, and C are the three phases; Determine the phase sequence according to the operation condition of the input signal according to the preset determination rule: phase sequence ABC or phase sequence ACB; Judge whether the phase sequence obtained by calculating the electrical quantity is the same as the phase sequence determined by the input signal. If the two are the same, it is judged that the phase sequence is normal; if the two are different, it is judged that the phase sequence is abnormal.

2. The phase sequence protection method according to claim 1, characterized in that: The calculation of the real part and imaginary part of the three-phase voltage of the electrical quantity, and determining the phase sequence of the electrical quantity according to the preset voltage phase sequence determination rule from the real part and imaginary part of the three-phase voltage includes: Obtain the voltage data collected in advance as the data in the original data area, perform correction processing on the voltage data to obtain the data in the corrected data area. Among them, if the system frequency is the same as the set value, use the data in the original data area; if the system frequency deviates from the set value, use the data in the corrected data area; Calculate U using the conventional Fourier algorithm ΦΦRe and U ΦΦIm ; where, U ΦΦRe = U ABRe , U BCRe , U CARe , is the real part of the three-phase line voltage; U ΦΦIm = U ABIm , U BCIm , U CAIm , is the imaginary part of the three-phase line voltage; A, B, and C are the three phases; Determine the phase sequence of the electrical quantity according to the preset voltage phase sequence determination rule.

3. The phase sequence protection method according to claim 1, characterized in that: The three-phase voltage of the electrical quantity is three-phase line voltage or three-phase phase voltage.

4. The phase sequence protection method according to claim 1, characterized in that: The determination of the phase sequence according to the operation condition of the input signal according to the preset determination rule includes: The protection device introduces the generating potential of the input signal commutation switch, the pumping water level of the commutation switch, and the fully open position of the commutation switch; Perform preprocessing on the input signal to obtain the effective data of the input signal after removing interference; The rule for determining the phase sequence is: When the generating potential of the input signal commutation switch or the fully open position of the commutation switch is valid and the pumping water level of the commutation switch is invalid, it is judged as phase sequence ABC; when the generating potential of the input signal commutation switch and the fully open position of the commutation switch are both invalid and the pumping water level of the commutation switch is valid, it is judged as phase sequence ACB.

5. The phase sequence protection method according to claim 1, characterized in that: The sampled electrical quantity data is not limited to voltage.

6. A phase sequence protection device, characterized in that, it includes: Sampling module: Sample the operation data of the system. The operation data includes electrical quantities and input signals, where the electrical quantity data is voltage or current; Calculation module: Calculate the phase sequence of the electrical quantity and the phase sequence determined by the input signal according to the sampled operation data; if the following conditions are met, it is calculated as phase sequence ABC; If the following conditions are met, it is calculated as phase sequence ACB; In the above formula, U AB , U BC , U CA are the amplitudes of the three-phase line voltages; U Low is the low threshold of the line voltage; α and β are the threshold values; ref1, ref2, ref3, ref4 are intermediate variables, where, ref1 = U ABRe *U BCRe +U ABIm *U BCIm ; ref2 = U ABRe *U CARe +U ABIm *U CAIm ; ref3 = U ABIm *U BCRe -U ABRe *U BCIm ; ref4 = U ABIm *U CARe -U ABRe *U CAIm ; Among them, U ABRe , U BCRe , U CARe , is the real part of the three-phase line voltage; U ABIm , U BCIm , U CAIm , is the imaginary part of the three-phase line voltage; A, B, and C are the three phases; Phase sequence judgment module: Within the set time, if the phase sequence of the electrical quantity is consistent with the phase sequence determined by the input signal, the phase sequence is normal; if not, the phase sequence is abnormal, and start the phase sequence protection action program.

7. A phase sequence protection device, characterized in that: it includes a processor and a storage medium; the storage medium is used for storing instructions; the processor is used for operating according to the instructions to execute the steps of the method according to any one of claims 1 to 5.

8. A computer-readable storage medium, on which a computer program is stored, characterized in that: when the program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 5.

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