A three-phase power supply line fire prevention and control method and storage medium

Abstract

The present invention discloses a fire prevention and control method and storage medium for a three-phase power supply line, and belongs to the field of signal processing technology. In a three-phase circuit (TN-S), after the three-phase total residual current is measured, the insulation resistance and capacitive reactance of each phase relative to ground are obtained by phase splitting and data splitting. The method of the present invention is to realize a 380V three-phase power supply system, and after the three-phase total residual current is measured, the insulation resistance of each phase relative to ground, the leakage capacitance of each phase relative to ground, the resistive residual current of each phase relative to ground, and the capacitive residual current of each phase relative to ground are obtained. The present invention uses residual current phase splitting and data splitting to accurately obtain the resistive current value of each phase relative to ground and the insulation resistance of each phase relative to ground from the total residual current, and performs fire prevention and control early warning on the three-phase power supply line according to the resistive current value of each phase relative to ground and the insulation resistance value of each phase relative to ground, thereby improving the accuracy of early warning, facilitating the online prevention and control of the insulation performance and potential electrical fire hazard of the power supply circuit of the three-phase TN-S power supply system, and effectively preventing the occurrence of electrical fire accidents.

Description

Technical Field

[0001] The present invention relates to the technical field of signal processing, and more particularly to a three-phase power supply line fire prevention and control method and a storage medium. Background Art

[0002] For three-phase power supply lines, in view of the fact that the residual current to ground and the load current cannot be separated in practice, therefore, in actual engineering applications, we can only measure the total residual current of the three-phase power supply line, but cannot obtain the residual current of each phase to ground, and therefore cannot obtain the insulation resistance of each phase to ground. Insulation resistance is an important parameter to reflect whether the power supply line is in a safe state. At present, the method of testing the total residual current of the three phases to reflect whether the power supply line is in a safe state has the following problems:

[0003] 1. In the TN-S three-phase power supply line, Id = Ia + Ib + Ic + In = Ida + Idb + Idc (vector sum), Figure 2 middle:

[0004] Ua is the voltage between phase A and ground, Ub is the voltage between phase B and ground, and Uc is the voltage between phase C and ground;

[0005] Ia is the current of phase A, Ib is the current of phase B, Ic is the current of phase C, and In is the current of phase N;

[0006] Za is the A phase load, Zb is the B phase load, and Zc is the C phase load;

[0007] Ra is the equivalent insulation resistance of phase A to ground, Rb is the equivalent insulation resistance of phase B to ground, and Rc is the equivalent insulation resistance of phase C to ground;

[0008] Ca is the equivalent leakage capacitance of phase A to ground, Cb is the equivalent leakage capacitance of phase B to ground, and Cc is the equivalent leakage capacitance of phase C to ground;

[0009] Id is the total residual current of the three phases; Co is the reference capacitor; Ido is the reference capacitor current;

[0010] Idra is the resistive current between phase A and ground, Idrb is the resistive current between phase B and ground, and Idrc is the resistive current between phase C and ground;

[0011] Idca is the capacitive current of phase A to ground, Idcb is the capacitive current of phase B to ground, and Idcc is the capacitive current of phase C to ground;

[0012] Ida is the residual current between phase A and ground, Idb is the residual current between phase B and ground, and Idc is the residual current between phase C and ground.

[0013] like Figure 2As shown in the figure, if the insulation resistance of each phase decreases evenly, the resistive residual current of each phase will increase at the same time, but the total residual current is very small, which conceals the truth of the fault. Therefore, when the impedance of the three-phase power supply line to the ground is basically symmetrical (this is the normal operation), this defect is particularly serious. The purpose of setting up electrical fire detectors on three-phase power supply lines is to predict the occurrence of faults from the slight changes in the insulation resistance during normal operation, prevent them from happening gradually, and eliminate them in the bud. However, the defect of using the single measurement of the total residual current data of the three phases as an important basis for judgment is that the practical significance of electrical fire as an early warning system is lost.

[0014] 2. Even if the total residual current Id of the three phases is measured, the resistive and capacitive components of the residual current of each phase are unknown. Id = SQR (Idc 2 +Idr 2 ), Id, Idc, and Idr are the total residual current, capacitive residual current, and resistive residual current, respectively. The resistive component is a very important parameter for the safe operation of the power supply line, and the capacitive component reflects the energy exchange between the power supply line and the earth. In general, most of the residual current is capacitive current, and the resistive current component is very small. For example, in the prior art, most people would think that the total residual current of 300mA is better than the total residual current of 500mA in terms of insulation to the ground. However, if 90% of the total residual current of 500mA is capacitive residual current, that is, 450mA capacitive residual current, and 218mA of the resistive residual current is resistive residual current, the insulation resistance to the ground is Rj1=220 / 218≈1000 ohms; and perhaps 30% of the total residual current of 300mA is capacitive residual current, that is, 90mA capacitive residual current, and 286mA of the resistive residual current is resistive residual current, the insulation resistance to the ground is Rj2=220 / 286=769 ohms, and the insulation resistance to the ground of the total residual current of 300mA is Rj2=769 ohms, which is much smaller than the insulation resistance to the ground of the total residual current of 500mA, Rj1=1000 ohms. Therefore, it is unreasonable to use residual current to reflect the insulation of the line to the ground.

[0015] 3. Due to the influence of harmonics, the total residual current cannot reflect the quality of insulation to the ground.

[0016] Due to the limitations of current science and technology and testing methods, it is impossible to implement real-time online testing of the insulation resistance of each phase to ground of a three-phase power supply line both at home and abroad.

[0017] Therefore, in actual engineering, the parameters we can directly measure are only: three-phase voltages Ua, Ub, Uc, total residual current Id and reference capacitor current Ido, but the parameters that need to be obtained are as follows:

[0018] 1) Relative resistive current of each phase: Idra, Idrb, Idrc;

[0019] 2) Insulation resistance of each phase to ground: Ra, Rb, Rc;

[0020] 3) Capacitive currents relative to ground: Idca, Idcb, Idcc

[0021] 4) Leakage capacitance of each phase to ground: Ca, Cb, Cc;

[0022] However, in the prior art, there is no good technical solution to accurately obtain the above parameters, which is not conducive to electrical fire early warning.

[0023] Therefore, how to provide a three-phase power supply line fire prevention and control method and storage medium is a problem that technical personnel in this field urgently need to solve. Summary of the invention

[0024] In view of this, the present invention provides a three-phase power supply line fire prevention and control method and storage medium to solve the problems existing in the above-mentioned prior art.

[0025] In order to achieve the above object, the present invention provides the following technical solutions:

[0026] A three-phase power supply line fire prevention and control method, based on a TN-S three-phase power supply line, comprises the following steps:

[0027] S100: collects the phase voltage, total residual current and reference capacitor current in the TN-S three-phase power supply line;

[0028] S200: Separate the total residual current into resistive residual current and capacitive residual current;

[0029] S300: establishing a phase splitting network function, splitting the resistive residual current and the capacitive residual current respectively, and obtaining the resistive current value of each phase to ground and the capacitive current value of each phase to ground;

[0030] S400: Obtaining each relative-to-ground insulation resistance value according to each relative-to-ground resistive current value and each relative-to-ground capacitive current value;

[0031] S500: Provide fire prevention and control warning for three-phase power supply lines based on the relative ground resistive current values ​​and the relative ground insulation resistance values.

[0032] Optionally, the S100 includes:

[0033] S110: collecting voltage signals of each phase in the TN-S three-phase power supply line through a detector;

[0034] S120: collects the total residual current of the TN-S three-phase power supply line from the residual current transformer in the TN-S three-phase power supply line through the detector;

[0035] S130: Collect reference capacitor current from a reference capacitor current transformer in a TN-S three-phase power supply line through a detector.

[0036] Optionally, the total residual current Id of the TN-S three-phase power supply line in S120 is:

[0037] Id=(Ida+Idb+Idc)=(Ua / Zda+Ub / Zdb+Uc / Zdc);

[0038] Wherein, Zda, Zdb, Zdc are the impedances of phase A, phase B, and phase C to ground respectively; Ua, Ub, Uc are the three-phase voltages.

[0039] Optionally, the S300 includes:

[0040] The total residual current is separated, and the specific formula is:

[0041] Id=Idr+Idc;

[0042] Where: Id: total residual current, Idr: total resistive residual current, Idc: total capacitive residual current;

[0043] To make the three-phase reference capacitance requirements symmetrical, the specific formula is:

[0044] Idr=Id*sinβ, Idc=Id*cosβ;

[0045] Where:

[0046] β is the angle between the reference capacitor current, Ido, and the measured residual current Id, β = ∠(Id, Ido); where:

[0047] Ido=∫ido(i)*ido(i); Id=∫id(i)*id(i);

[0048] β=Acos{∫ido(i)*id(i) / Ido*Id};

[0049] Where: ido(i) and id(i) are the instantaneous values ​​of the reference residual current and the residual current of the measured circuit respectively.

[0050] Optionally, the S300 further includes:

[0051] The total resistive residual current is split into phases, and the specific formula is:

[0052] Idr=Idra+Idrb+Idrc;

[0053] Where, Idra, Idrb, and Idrc are the resistive residual current values ​​of phase A, phase B, and phase C respectively;

[0054] idr=idra+idrb+idrc;

[0055] Where, idr is the total resistive residual current of the line under test, idra, idrb, idrc are the instantaneous values ​​of the residual currents of phase A, phase B, and phase C respectively;

[0056] The total capacitive residual current is split into phases, and the specific formula is:

[0057] Idc=Idca+Idcb+Idcc;

[0058] Where, Idca, Idcb, and Idcc are the compatibility residual currents of phase A, phase B, and phase C respectively;

[0059] The relationship between the parameters is obtained as follows:

[0060] idr*ua=ua*ua / Ra+ub*ua / Rb+uc*ua / Rc;

[0061] Where ua, ub, uc are the instantaneous values ​​of the three-phase voltages, idr is the resistive component of the total residual current in the three-phase circuit, Ra, Rb, Rc are the insulation resistances of the three phases to ground, respectively;

[0062] Perform full-frequency domain ZH network transformation on the above formula to establish the resistive residual current signal split-phase network function and the capacitive residual current signal split-phase network function.

[0063] Optionally, the resistive residual current signal split phase network function is established as follows:

[0064]

[0065] The resistive current value of each phase to ground is obtained according to the resistive residual current signal split phase network function.

[0066] Optionally, the S300 further includes:

[0067] Establish the capacitive residual current signal split phase network function:

[0068]

[0069] Optionally, the S300 includes:

[0070] Establish the capacitive residual current node splitting function, specifically:

[0071]

[0072] The equations for phase splitting of capacitive residual current are:

[0073]

[0074] Solving the system of equations yields: U, V, W;

[0075] According to U = 1 / Ca; V = 1 / Cb; W = 1 / Cc, the relative leakage capacitances Ca, Cb, Cc are obtained;

[0076] According to Idca=Ua / Ca, Idcb=Ub / Cb, Idcc=Uc / Cc, the compatible residual currents Idca, Idcb and Idcc are obtained.

[0077] Optionally, the S400 includes: establishing a resistive residual current node splitting function, specifically:

[0078]

[0079] The equations for resistive residual current phase splitting are:

[0080]

[0081] Solving the system of equations yields: X, Y, Z;

[0082] According to X=1 / Ra; Y=1 / Rb; Z=1 / Rc, the relative insulation resistances Ra, Rb, and Rc are obtained.

[0083] A computer storage medium stores a computer program, which, when executed by a processor, implements the steps of a three-phase power supply line fire prevention and control method.

[0084] It can be seen from the above technical solution that compared with the prior art, the present invention discloses a three-phase power supply line fire prevention and control method and storage medium, which can realize that after the 380V three-phase power supply system measures the three-phase total residual current, the insulation resistance of each phase to the ground, the leakage capacitance of each phase to the ground, the resistive residual current of each phase to the ground, and the capacitive residual current of each phase to the ground are obtained, and these are verified in experiments.

[0085] The present invention has a good demodulation effect and adopts residual current phase splitting and data splitting to solve the problem of being unable to accurately obtain three-phase to ground resistive current, three-phase to ground insulation resistance and three-phase to ground capacitive current. It is beneficial to online prevention and control of the insulation performance and potential electrical fire hazards of the power supply circuit of the three-phase TN-S power supply system, and effectively prevent the occurrence of electrical fire accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0087] Figure 1 It is a schematic diagram of the method flow of the present invention;

[0088] Figure 2 It is the principle diagram of the present invention;

[0089] Figure 3 Schematic diagram of the total residual current phase splitting of the present embodiment 1;

[0090] Figure 4 This is a schematic diagram of the first embodiment of the present invention using the sampled Ido (reference capacitor current) as a reference.

[0091] In the figure:

[0092] Ua: A phase voltage, ub: B phase voltage, Ue: C phase voltage;

[0093] Ia: A phase current, Ib: B phase current, Ic: C phase current, In: neutral line current;

[0094] Zz: A phase load, Zb: B phase load, Zc: C phase load;

[0095] Id: total residual current, Co reference capacitance, 1do: reference capacitance current;

[0096] Ra: equivalent insulation resistance of phase A to ground, Rb: equivalent insulation resistance of phase B to ground, Rc: equivalent insulation resistance of phase C to ground;

[0097] Ca: equivalent leakage capacitance of phase A to ground, Cb: equivalent leakage capacitance of phase B to ground, Cc: equivalent leakage capacitance of phase C to ground;

[0098] Idra: Resistive current of phase A to ground, Idrb: Resistive current of phase B to ground, Idrc: Resistive current of phase C to ground;

[0099] Idca: A phase capacitive current to ground, Idcb: B phase capacitive current to ground, Idcc: C phase capacitive current to ground;

[0100] Ida: Residual current relative to phase A, Idb: Residual current relative to phase B, Idc: Residual current relative to phase C. DETAILED DESCRIPTION

[0101] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0102] Example 1

[0103] See also Figure 1 As shown, the embodiment of the present invention discloses a three-phase power supply line fire prevention and control method, based on a TN-S three-phase power supply line, characterized in that it includes the following steps:

[0104] S100: collects the phase voltage, total residual current and reference capacitor current in the TN-S three-phase power supply line;

[0105] S200: Separate the total residual current into resistive residual current and capacitive residual current;

[0106] S300: establishing a phase splitting network function, splitting the resistive residual current and the capacitive residual current respectively, and obtaining the resistive current value of each phase to ground and the capacitive current value of each phase to ground;

[0107] S400: Obtaining each relative-to-ground insulation resistance value according to each relative-to-ground resistive current value and each relative-to-ground capacitive current value;

[0108] S500: Provide fire prevention and control warning for three-phase power supply lines based on the relative ground resistive current values ​​and the relative ground insulation resistance values.

[0109] Specifically, it also includes:

[0110] The detector collects the voltage signals of each phase in the TN-S three-phase power supply line;

[0111] The detector collects the total residual current in the TN-S three-phase power supply line from the residual current transformer;

[0112] The detector collects the reference capacitor current from the reference capacitor current transformer;

[0113] Separate the total residual current into resistive residual current and capacitive residual current;

[0114] A phase-splitting network function is established to split the resistive residual current and the capacitive residual current into phases to obtain the resistive current value to ground and the capacitive current value to ground of each phase;

[0115] Obtain the insulation resistance value of each phase to ground from the split value;

[0116] Fire prevention and control warning for three-phase power supply lines is carried out according to the resistive current values to ground of each phase and the insulation resistance values to ground of each phase.

[0117] In a specific embodiment, the detector synchronously collects the instantaneous values of three-phase voltage, the total residual current of the loop, and the reference capacitive current in real time, and further calculates the resistive insulation resistances Ra, Rb, Rc to ground of each phase of the effectively grounded three-phase power supply loop and the resistive current values Idra, Idrb, Idrc to ground of each phase by using the split-phase network function of the present invention as the core. The Idra, Idrb, and Idrc are respectively compared with the residual current alarm threshold I0. According to the actual working conditions or relevant national standards (such as the "National Standard GB50054-95 Code for Design of Low-Voltage Distribution"), when the resistive current value to ground of any one of the three phases is greater than I0 for three consecutive cycles (that is, when Idra > I0 or Idrb > I0 or Idrc > I0), a residual current alarm signal is output. At the same time, Ra, Rb, and Rc are also respectively compared with the lower limit alarm threshold R0 of the insulation resistance. According to the actual working conditions or relevant national standards (such as the "GB50303-2002 Code for Acceptance of Construction Quality of Electrical Engineering in Buildings"), when the resistive insulation resistance to ground of any one of the three phases is less than R0 (that is, when Ra < R0 or Rb < R0 or Rc < R0), an insulation performance alarm signal is output, and it is determined that the insulation performance of the power supply loop of the three-phase AC distribution system is damaged, there are grounding short-circuit faults and potential electrical fire hazards, thereby realizing the accurate online prevention and control warning of grounding short-circuit faults and potential electrical fires caused by the reduction of the insulation performance of the cable and load insulation layer and the decrease of the resistive insulation resistance value to ground in the power supply loop of the three-phase AC distribution system.

[0118] In a specific embodiment, first, the total residual current Id is split-phase and split to obtain the resistive current values Idra, Idrb, Idrc to ground of each phase and the capacitive current values Idca, Idcb, Idcc to ground of each phase. Then, the insulation resistances to ground of each phase are obtained from the split values: Ra, Rb, Rc

[0119] Specifically, to achieve the split-phase and data splitting of the residual current, it is necessary to Figure 2 First, establish a digital signal transformation network (network equations group), and then split-phase and split the total residual current. The split residual current components may be much larger than the total residual current because: Id = Ida + Idb + Idc (vector sum), where Id, Ida, Idb, and Idc are the total residual current and the residual currents to ground of phases A, B, and C respectively.

[0120] Specifically, assuming that Ida=300∠0 (mA), Idb=290∠120 (mA), Ida=280∠240 (mA), then Id=SQR{(300+290*cos120+280*cos240)2+(290*sin120+280*sin240)2}=SQR(225+75)=17.3 (mA).

[0121] Specifically, regarding the digital splitting technology, a hitherto unsolved mathematical conjecture of Goldbach is based on the fact that any even number greater than 2 can be split into the sum of two prime numbers, which is the so-called 1 = "1 + 1". Finally, through number theory, it is proved that any sufficiently large even number can be split into the sum of a prime number and an almost prime number, and the almost prime number is equal to the product of two prime numbers. The result can be expressed as: large even number = prime number + prime number × prime number, which is the so-called 1 = "1 + 2", known as Chen's theorem. The prime number and almost prime number after splitting are not greater than their large even number.

[0122] The total residual current is split by phase splitting and data splitting, that is, splitting 1 number into 6 numbers, so-called 1 = "1+1+1+1+1+1". Figure 3 shown.

[0123] To realize the phase splitting and data splitting of residual current, we first need to Figure 2 , establish the phase splitting equations, i.e. the signal transformation network function, and then perform phase splitting on the total residual current. Figure 2 In the circuit, the inductive reactance of the line itself and the ground is very small and can be ignored.

[0124] Separation: Separate the total residual current into resistive residual current and capacitive residual current.

[0125] Phase splitting: split the resistive residual current and capacitive residual current into the resistive residual current of each phase and the capacitive residual current of each phase.

[0126] In an actual three-phase power supply circuit, the leakage capacitance and insulation resistance of each phase to ground are invisible and intangible, and it is impossible to measure them directly and effectively. Figure 2 The impedance to ground is obtained by virtual equivalent. The signal conversion network function is established by using the mutual relationship of the parameters of the three-phase circuit.

[0127] In a specific embodiment, the total residual current Id of the TN-S circuit includes:

[0128] Id=(Ida+Idb+Idc)=(Ua / Zda+Ub / Zdb+Uc / Zdc)(vector sum)

[0129] Among them: Zda, Zdb, Zdc: are the impedances of phase A, B, C to ground respectively; Ua, Ub, Uc are the three-phase voltages.

[0130] The total residual current can be decomposed into: Id=Idr+Idc, where: Id: total residual current, Idr: total resistive residual current, Idc: total capacitive residual current.

[0131] In a specific embodiment, the total resistive residual current is split into phases, and the specific formula is as follows:

[0132] dr=Idra+Idrb+Idrc(1)

[0133] The total capacitive residual current is split into phases, and the specific formula is as follows:

[0134] Idc=Idca+Idcb+Idcc(2)

[0135] Where: Idra, Idrb, Idrc are the resistive residual currents of phases A, B, and C respectively;

[0136] Idca, Idcb, and Idcc are A, B, and C compatibility residual currents respectively;

[0137] by Figure 2 The Ido (reference capacitor current) sampled in is used as a reference, see Figure 4 .

[0138] The measured Idr=Id*sinβ, Idc=Id*cosβ, requirement: the three-phase reference capacitor is symmetrical.

[0139] β=∠(Id, Ido), β is the angle between the reference capacitor current Ido and the measured residual current Id.

[0140] Ido=∫ido(i)*ido(i)Id=∫id(i)*id(i)

[0141] Where: ido(i) and id(i) are the instantaneous values ​​of the reference residual current and the residual current of the measured circuit respectively. β=Acos{∫ido(i)*id(i) / Ido*Id}

[0142] For a three-phase power supply line, the capacitive residual current is as follows:

[0143] Idc=Ua / Ca+Ub / Cb+Uc / Cc (3)

[0144] From (1): idr=idra+idrb+idrc

[0145] Among them: idr, idra, idrb, idrc are the total resistive residual current of the tested line and the instantaneous values ​​of the relative residual currents of A, B, and C respectively.

[0146] idr=ua / Ra+ub / Rb+uc / Rc (4)

[0147] Among them: ua, ub, uc are the instantaneous values ​​of the three-phase voltage, idr is the resistive component of the total residual current of the three-phase circuit, Ra, Rb, Rc are the insulation resistance of the three phases to ground.

[0148] The above formula is subjected to full-frequency domain ZH network transformation, also called full-frequency domain split-phase network transformation, to establish a resistive residual current signal split-phase network function and a capacitive residual current signal split-phase network function.

[0149] In a specific embodiment, the resistive residual current signal split phase network function is established as:

[0150]

[0151] In a specific embodiment, a resistive residual current node splitting function is established, specifically:

[0152]

[0153] The equations for splitting the resistive residual current phase are:

[0154]

[0155] Solving the system of equations yields: X, Y, Z;

[0156] According to X=1 / Ra; Y=1 / Rb; Z=1 / Rc, the relative insulation resistances Ra, Rb, and Rc are obtained.

[0157] In a specific embodiment, the capacitive residual current signal split phase network function is established:

[0158]

[0159] In a specific embodiment, a capacitive residual current node splitting function is established, specifically:

[0160]

[0161] Equations for splitting capacitive residual current after phase splitting

[0162]

[0163] Solving the system of equations yields: U, V, W;

[0164] According to U = 1 / Ca; V = 1 / Cb; W = 1 / Cc, the relative leakage capacitances Ca, Cb, Cc are obtained;

[0165] According to Idca=Ua / Ca, Idcb=Ub / Cb, Idcc=Uc / Cc, the compatible residual currents Idca, Idcb and Idcc are obtained.

[0166] Specifically, the established split phase network function of the resistive residual current signal (split phase network function) and the established split phase network function of the capacitive residual current signal (split phase network function) are a highly sensitive convolution array, which is a ZH transformation. In the process of complex signal processing, due to the start and stop of many loads carried by the TN-S circuit, the operation of nonlinear loads, etc., the transient signal in the circuit often does not meet the conditions of Fourier demodulation or the conditions of the wavelet algorithm. At the same time, the role of harmonics in the circuit (whether positive or negative) should be reflected in the test process to ensure the authenticity of the measurement results. In the complex case of full-wave mixing, the ZH full-wave internal convolution energy consumption method is adopted, that is, in the convolution process between the harmonic voltages and currents, the phases of the same frequency are orthogonal to zero, the integral area of ​​the first half cycle and the integral area of ​​the second half cycle are mutually impacted, the energy of each order is accumulated without leakage (the active power of each harmonic), and the energy of different frequencies is zero, so that within a fundamental wave cycle, the effective output of harmonic interference is minimized, forming a full-wave work internal convolution. Most of the convolution work cancels each other out internally. At the same time, the active power to the harmonics maximizes the output.

[0167] In the ZH transform convolution array, the functions of each node are interrelated, the frequency range is very wide, and different harmonics have active output within the full wave range of the line, which makes the network conversion highly sensitive, so as to meet the slight change of current and slight phase shift under high resistance, and obtain good transformation results. In the ZH transform convolution array, as long as there is a slight change in a certain vibration point, the entire network will interact. At the same time, because the network is highly sensitive and highly interactive, it is also prone to some interference, which has certain requirements for the systematicness of the hardware design and the comprehensive anti-interference ability requirements are also relatively high.

[0168] In order to ensure the correct conversion of the network function, the directly sampled voltage and current signals must first be preprocessed. The angular difference and ratio difference problems of fundamental large current transformers are relatively easy to solve, while the angular difference and ratio difference problems of small current residual current transformers under full wave (including fundamental and harmonic waves) are more difficult to solve. The response sensitivity of the transformer is different at different frequencies, and the iron loss, copper loss and hysteresis loss are also different. For small currents, the relative errors caused by these losses are sometimes very large. Therefore, the first task is to design and manufacture full-wave micro current transformers to reduce the amplitude attenuation and phase shift problems of small signals passing through the transformer; secondly, each acquisition channel must process the signal as it is, and it is not appropriate to use digital filtering technology and hardware filtering networks to process the signal, because these filters have bandwidth limitations, so as to avoid signal distortion, so as to facilitate the offset-free conversion of the original signal in the ZH transform convolution array.

[0169] The split-phase network function satisfies the working conditions of complete symmetry, simple symmetry and asymmetry of the three-phase insulation impedance to ground.

[0170] Through the node function, the contribution of the node energy in the network function is determined, and finally the phase splitting of the total residual current collected is realized, that is, the total residual current is split into the resistive residual current and capacitive residual current of each phase A, B, and C, and the insulation resistance to ground and the leakage capacitance to ground of each phase can be obtained.

[0171] A computer storage medium stores a computer program, which, when executed by a processor, implements the steps of a three-phase power supply line fire prevention and control method.

[0172] Through the above technical scheme, the present invention uses residual current phase splitting and data splitting to accurately obtain each relative ground resistive current value and each relative ground insulation resistance from the total residual current, and performs fire prevention and control early warning on the three-phase power supply line according to each relative ground resistive current value and each relative ground insulation resistance value, thereby improving the accuracy of the early warning, being conducive to online prevention and control of the insulation performance and potential electrical fire hazards of the power supply circuit of the three-phase TN-S power supply system, and effectively preventing the occurrence of electrical fire accidents.

[0173] Example 2

[0174] Experimental verification

[0175] A three-phase TN-S power supply system test bench was established in the laboratory to simulate the "real-time online monitoring of the insulation resistance to ground of the three-phase TN-S power supply system".

[0176] The test bench setting parameters: the first group Ra=80k, Rb=45k, Rc=40k, Ca=Cb=Cc=1uF, that is, the three-phase insulation impedance to ground is modulated to 80k for phase A, 45k for phase B and 40k for phase C, and the three-phase capacitive reactance to ground is 1uF; the second group Ra=100k, Rb=20k, Rc=50k, Ca=Cb=Cc=2.4uF; that is, the three-phase insulation impedance to ground is modulated to 100k for phase A, 20k for phase B and 50k for phase C, and the three-phase capacitive reactance to ground is 2.4uF. Verification tests were carried out by setting parameters of the power supply system environment simulated by the above two groups of test benches. The ground insulation resistance detector used adopted the method of "phase splitting and digital separation technology of three-phase residual current" of the present invention. The measured and calculated data are shown in Tables 1 and 2, wherein Table 1 is a test data record table of the first group of ground insulation resistance detectors provided, and Table 2 is a test data record table of the second group of ground insulation resistance detectors.

[0177] Table 1 Test data record table of the first group of ground insulation resistance detectors

[0178]

[0179] Table 2 Test data record table of the second group of ground insulation resistance detectors

[0180]

[0181]

[0182] Laboratory verification has shown that the present invention has a good demodulation effect, solves the problem of being unable to accurately obtain the three-phase to ground insulation resistance, is beneficial to online prevention and control of the insulation performance and potential electrical fire hazards of the power supply circuit of the three-phase TN-S power supply system, and effectively prevents the occurrence of electrical fire accidents.

[0183] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0184] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A three-phase power supply line fire prevention and control method, based on a TN-S three-phase power supply line, characterized in that: The following steps are involved: S100: collects the phase voltage, total residual current and reference capacitor current in the TN-S three-phase power supply line; S200: Separate the total residual current into resistive residual current and capacitive residual current; S3 00: Establish a phase-splitting network function, split the resistive residual current and the capacitive residual current into phases, and obtain the resistive current value of each phase to ground and the capacitive current value of each phase to ground; S400: Obtaining each relative-to-ground insulation resistance value according to each relative-to-ground resistive current value and each relative-to-ground capacitive current value; S500: Fire prevention and control warning for three-phase power supply lines according to each phase-to-ground resistive current value and each phase-to-ground insulation resistance value; Wherein, the S300 includes: Establish the capacitive residual current signal split phase network function: The S300 further includes: Establish the capacitive residual current node splitting function, specifically: The equations for phase splitting of capacitive residual current are: Solving the system of equations yields: U, V, W; According to U = 1 / Ca; V = 1 / Cb; W = 1 / Cc, the relative leakage capacitances Ca, Cb, Cc are obtained; According to Idca=Ua / Ca, Idcb=Ub / Cb, Idcc=Uc / Cc, the relative capacitive currents Idca, Idcb and Idcc are obtained; The S400 includes: establishing a resistive residual current node splitting function, specifically: The equations for resistive residual current phase splitting are: Solving the system of equations yields: X, Y, Z; According to X=1 / Ra; Y=1 / Rb; Z=1 / Rc, the relative insulation resistances Ra, Rb, and Rc are obtained.

2. A three-phase power supply line fire prevention and control method according to claim 1, characterized in that: The S100 includes: S110: collecting voltage signals of each phase in the TN-S three-phase power supply line through a detector; S120: Collect the total residual current of the TN-S three-phase power supply line through the residual current transformer in the detector; S130: Collect reference capacitor current from a reference capacitor current transformer in a TN-S three-phase power supply line through a detector.

3. A three-phase power supply line fire prevention and control method according to claim 2, characterized in that: The calculation formula of the total residual current Id of the TN-S three-phase power supply line in S120 is: Id=(Ida+Idb+Idc)=(Ua / Zda+Ub / Zdb+Uc / Zdc); Wherein, Zda, Zdb, Zdc are the impedances of phase A, phase B, and phase C to ground respectively; Ua, Ub, Uc are the three-phase voltages.

4. A three-phase power supply line fire prevention and control method according to claim 1, characterized in that: The S300 includes: The total residual current is separated, and the specific formula is: Id=Idr+Idc; Where: Id is the total residual current, Idr is the total resistive residual current, and Idc is the total capacitive residual current; To make the three-phase reference capacitance requirements symmetrical, the specific formula is: Idr=Id*sinβ, Idc=Id*cosβ; Where: β is the angle between the reference capacitor current Ido and the measured residual current Id, β = ∠(Id, Ido); where: Ido=∫ido(i)*ido(i); Id=∫id(i)*id(i); β=Acos{∫ido(i)*id(i) / Ido*Id}; Where: ido(i) and id(i) are the instantaneous values ​​of the reference residual current and the residual current of the measured circuit respectively.

5. A three-phase power supply line fire prevention and control method according to claim 1, characterized in that: The S300 further includes: The total resistive residual current is split into phases, and the specific formula is: Idr=Idra+Idrb+Idrc; Where, Idra, Idrb, and Idrc are the resistive residual current values ​​of phase A, phase B, and phase C respectively; idr=idra+idrb+idrc; Where, idr is the total resistive residual current of the line under test, idra, idrb, idrc are the instantaneous values ​​of the residual currents of phase A, phase B, and phase C respectively; The total capacitive residual current is split into phases, and the specific formula is: Idc=Idca+Idcb+Idcc; Where, Idca, Idcb, and Idcc are the compatibility residual currents of phase A, phase B, and phase C respectively; The relationship between the parameters is obtained as follows: idr*ua=ua*ua / Ra+ub*ua / Rb+uc*ua / Rc; Where ua, ub, uc are the instantaneous values ​​of the three-phase voltages, idr is the resistive component of the total residual current in the three-phase circuit, Ra, Rb, Rc are the insulation resistances of the three phases to ground, respectively; Perform full-frequency domain ZH network transformation on the above formula to establish the resistive residual current signal split-phase network function and the capacitive residual current signal split-phase network function.

6. A three-phase power supply line fire prevention and control method according to claim 5, characterized in that: The function for establishing the resistive residual current signal split phase network is: The resistive current value of each phase to ground is obtained according to the resistive residual current signal split phase network function.

7. A computer storage medium, characterized in that: The computer storage medium stores a computer program, and when the computer program is executed by the processor, the steps of a three-phase power supply line fire prevention and control method as described in any one of claims 1 to 6 are implemented.

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