CN104297636B - Pole-mounted distribution substation traveling wave detection method - Google Patents

Abstract

The invention relates to a pole-mounted distribution substation traveling wave detection method. The pole-mounted distribution substation traveling wave detection method comprises the steps that the high-frequency band component amplitude of the current on a grounding line of a pole-mounted distribution substation is measured, and if the high-frequency band component amplitude is larger than a set value of the high-frequency band component amplitude, the high-frequency band component amplitude is judged to be a distribution network transient state jump signal; the energy value of a high-frequency band component and the energy value of a low-frequency band component of the current of the grounding wire after the transient state jump signal appears are calculated respectively, and if the energy value of the high-frequency band component is larger than a set value of the energy value of the high-frequency band component and the energy value of the low-frequency band component is smaller that a set value of the energy value of the low-frequency band component, it is detected that a fault of a distribution network on the high-voltage side of a transformer is generated, and a fault traveling wave signal is transmitted to the pole-mounted distribution substation; if the energy value of the high-frequency band component and the energy value of the low-frequency band component are larger than the respectively set values, it is detected that a fault of the distribution network on the low-voltage side of the transformer is generated, and a fault traveling wave signal is transmitted to the pole-mounted distribution substation. The pole-mounted distribution substation traveling wave detection method has the advantages that the traveling wave detection precision is high, the manufacturing cost is low, installation is easy and convenient, and application and popularization are easy. The pole-mounted distribution substation traveling wave detection method can be used for power grid fault traveling wave protecting and positioning.

Description

A traveling wave detection method for power distribution substation on pole

technical field

The invention relates to a traveling wave detection method of a power distribution substation on a pole.

Background technique

As a power network directly connected to the user end, the distribution network is responsible for the important task of supplying power to people's lives and industrial production. Once the distribution network fails, it will affect people's production and life, and even affect personal and equipment safety; If it is not cleared in time, it will lead to further expansion of the fault and cause a large-scale power outage. For this reason, grid operators must locate faults in the shortest possible time, determine the location of the fault point, find the line fault point, clear the fault, and restore the normal operation of the power grid as soon as possible.

Distribution network fault traveling wave location technology is the current development direction of distribution network fault detection technology. The accurate time difference of the fault traveling wave arriving at the distribution substation on the end column of the distribution network line is used to calculate the exact location of the distribution network fault point. Among them , the detection and identification of the traveling wave signal of the distribution substation on the pole is the key to realize the fault traveling wave location technology of the distribution network.

There have been in-depth studies on fault traveling wave detection technology of power lines and substations at home and abroad, which are divided into two research directions: current traveling wave detection technology and voltage traveling wave detection technology: current traveling wave detection technology has been widely used in domestic transmission networks, directly from The secondary side of the substation line or bus current transformer collects the current signal at high speed, and uses the wavelet analysis method to detect and identify the current traveling wave signal. However, according to the principle of traveling wave transmission, the current traveling wave will be totally reflected in the power distribution substation (only one high-voltage outgoing line) on the end column of the distribution network line. The wave method has blind spots in the detection of traveling waves in distribution substations on poles, so it cannot be applied to the detection of traveling waves in distribution substations on poles; voltage traveling wave detection technology is also widely used in domestic transmission networks, and usually requires the development of special traveling wave sensors, connected in series or set Connect to the CVT ground wire to extract the voltage traveling wave signal. Since the pole-mounted distribution substation at the end of the distribution network does not use a CVT device, the existing voltage traveling wave detection technology cannot be applied to the pole-mounted distribution substation traveling wave detection.

Contents of the invention

The technical problem to be solved by the present invention is to provide a traveling wave detection method for power distribution substations on poles, which can support the popularization and application of power grid fault traveling wave location technology in distribution networks, and effectively improve the online monitoring level of power distribution line faults .

To solve the problems of the technologies described above, the technical scheme adopted in the present invention is as follows:

A method for detecting traveling waves of distribution substations on poles, characterized by comprising the following steps:

S1 Install a current transformer on the grounding wire of the power distribution substation on the column;

S2 continuously measures the high-frequency component amplitude I ₁ of the secondary side output signal of the current transformer. If it is greater than the high-frequency component amplitude setting value I _1S , it is judged that I ₁ is a transient mutation signal of the distribution network;

S3 calculates the energy value E1 _of the high-frequency band component of the output signal of the secondary side of the current transformer within the delay time _t1 after the transient mutation signal of the distribution network appears and within the delay time _t2 after the transient mutation signal of the distribution network appears The energy value E ₂ of the low frequency band component of the secondary side output signal of the current transformer;

S4 If the high-frequency band energy value E ₁ is greater than its setting value E _1S and the low-frequency band energy E ₂ is less than its setting value E _2S , it is detected as a fault in the distribution network fault on the high-voltage side of the transformer and transmitted to the pole-mounted distribution substation. wave signal;

If the high-frequency band energy value E ₁ is greater than its setting value E _1S and the low-frequency band energy E ₂ is also greater than its setting value E _2S , it is detected as a fault in the low-voltage side distribution network of the transformer and transmitted to the pole-mounted distribution substation. wave signal.

The frequency band selection range of the high frequency band component in the step S2 is [f ₃ , f ₄ ], wherein the selection range of the lower limit frequency f ₃ is [5 kHz, 100 kHz], and the selection range of the upper limit frequency f ₄ is [1 MHz, 10 MHz].

The method for determining the amplitude setting value I _1S of the high-frequency band component in the step S2 is: respectively measure or calculate the 2A transient current discharge fault of the overhead line insulator under the breakdown fault condition of one insulator of the overhead line at the high-voltage side outlet of the transformer on the pole The amplitude of the mid-frequency band [f ₃ , f ₄ ] component of the secondary side output signal of the current transformer under the cable line 2A transient current partial discharge fault condition, the smallest one is the setting value of the high-frequency band component amplitude.

The frequency range of the low frequency band component in the step S3 is [f ₁ , f ₂ ], wherein the selection range of the lower limit frequency f ₁ is [0 Hz, 30 Hz], and the selection range of the upper limit frequency f ₂ is [100 Hz, 300 Hz].

The selection range of the delay time _t1 in the step S3 is [0.1ms, 5ms], and the selection range of the delay time _t2 is [10ms, 40ms].

The determination method of the high-frequency band component energy setting value _E1S in the step S4 is as follows: respectively measure or calculate the breakdown fault condition of one piece of insulator in the overhead line at the outlet of the high-voltage side of the transformer on the pole, and the fault condition of the 2A transient current discharge of the overhead line insulator Below, the energy value of the high-frequency band [f ₃ , f ₄ ] component of the output signal of the current transformer secondary side under the condition of 2A transient current partial discharge fault of the cable line, the smallest one is the energy setting value of the high-frequency band component.

The determination method of the low-frequency band component energy setting value E _2S in the step S4 is as follows: respectively measure or calculate the current mutual inductance under the condition of a 1,000-ohm high-resistance ground-to-ground fault at the low-voltage outlet of the substation on the column, and the phase-to-ground leakage current of 200mA. The energy value of the low-frequency band [f ₁ , f ₂ ] component of the output signal of the secondary side of the device, and the smallest one is the energy setting value of the low-frequency band component.

The demonstration of the method of the present invention is as follows: after a fault occurs in the distribution network, the fault point generates a fault traveling wave signal, including a wide-area frequency band signal component, which propagates along the power line to the entire power grid. interference. For this reason, the present invention sets three traveling wave signal detection criteria, one criterion is to detect the amplitude of the high-frequency band component, which is beneficial to quickly detect the transient mutation signal of the fault traveling wave head, and can be used to accurately determine the arrival time of the fault traveling wave Record; one criterion is to detect the energy value of the high-frequency band component. Because the high-frequency interference signal generally has a short duration and low energy, using the high-frequency band energy criterion can distinguish the fault traveling wave signal from electromagnetic interference, and does not cause the induction of line faults. Thunder and other pulse signals; another criterion is the detection of low-frequency component energy. Since the grounding wire is directly connected to the neutral point of the low-voltage side of the substation on the column, the ground fault of the low-voltage power grid will generate low-frequency (including power frequency) current on the grounding wire However, the power grid on the high-voltage side of the transformer and the grounding line are only coupled through distributed parameters, and the low-frequency signal generated on the grounding line by the fault of the distribution network on the high-voltage side of the transformer is small. wave signal and low-voltage side distribution network fault traveling wave signal.

The technical effect of the present invention is that it can meet the detection of various high-voltage distribution line faults such as breakdown faults of overhead line insulators in high-voltage distribution networks, pollution flashover and partial discharge faults of cable lines, and can identify faults in low-voltage power grids, with detection accuracy High, low cost, easy installation, easy to popularize and apply, it can be used for power grid fault traveling wave protection and location.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is the schematic diagram of traveling wave detection of power distribution substation on pole of the present invention;

Fig. 2 is the simulation model figure of distribution transformer on pole of the present invention;

Fig. 3 is the flow chart of detection of traveling waves in power distribution substation on pole of the present invention;

Figure 4 is the secondary signal waveform of the current transformer before and after the fault of the high-voltage distribution network;

Figure 5 is the high-frequency band [10kHz, 5MHz] component waveform of the secondary signal of the current transformer before and after the fault of the high-voltage distribution network;

Fig. 6 is the low-frequency band [0Hz, 280Hz] component waveform of the secondary signal of the current transformer before and after the high-voltage distribution network fault.

detailed description

The principle diagram of the traveling wave detection of the distribution substation on the pole of the present invention is shown in FIG. 1 . The high-voltage side outgoing line and low-voltage side outgoing line of the power distribution substation on the column pass through the lightning arrester and then connect to the grounding wire. The neutral point of the low-voltage side is directly connected to the grounding wire, and the transformer shell is also directly connected to the grounding wire. The amplitude and energy of the high-frequency component and the energy of the low-frequency component of the secondary side current signal of the transformer are used to identify the fault traveling wave signal of the distribution network.

Referring to Fig. 3, the embodiment of the traveling wave detection method of the distribution substation on the pole of the present invention includes the following steps:

S1 Install a current transformer on the grounding wire of the power distribution substation on the column;

S2 continuously measures the high-frequency component amplitude I ₁ of the secondary side output signal of the current transformer. If it is greater than the high-frequency component amplitude setting value I _1S , it is judged that I ₁ is a transient mutation signal of the distribution network;

The frequency band selection range of the high frequency band component is [f ₃ , f ₄ ], wherein the selection range of the lower limit frequency f ₃ is [5kHz, 100kHz], and the selection range of the upper limit frequency f ₄ is [1MHz, 10MHz].

The determination method of the amplitude setting value I _1S of the high-frequency band component is as follows: respectively measure or calculate the breakdown fault condition of one insulator of the overhead line at the outlet of the high-voltage side of the transformer on the column, the fault condition of the 2 ampere transient current discharge of the overhead line insulator, The amplitude of the mid-frequency band [f ₃ , f ₄ ] component of the output signal of the secondary side of the current transformer under the condition of a 2A transient current partial discharge fault on the cable line, the minimum of which is the setting value of the amplitude of the high-frequency band component.

S3 calculates the energy value E1 _of the high-frequency band component of the output signal of the secondary side of the current transformer within the delay time _t1 after the transient mutation signal of the distribution network appears and within the delay time _t2 after the transient mutation signal of the distribution network appears The energy value E ₂ of the low frequency band component of the secondary side output signal of the current transformer;

The frequency band selection range of the low frequency band component is [f ₁ , f ₂ ], wherein the selection range of the lower limit frequency f ₁ is [0Hz, 30Hz], and the selection range of the upper limit frequency f ₂ is [100Hz, 300Hz].

The selection range within the delay time _t1 is [0.1ms, 5ms], and the selection range within the delay time _t2 is [10ms, 40ms].

Calculating the energy value is an existing technology, which has been maturely applied.

S4 If the high-frequency band energy value E ₁ is greater than its setting value E _1S and the low-frequency band energy E ₂ is less than its setting value E _2S , it is detected as a fault in the distribution network fault on the high-voltage side of the transformer and transmitted to the pole-mounted distribution substation. wave signal;

If the high-frequency band energy value E ₁ is greater than its setting value E _1S and the low-frequency band energy E ₂ is also greater than its setting value E _2S , it is detected as a fault in the low-voltage side distribution network of the transformer and transmitted to the pole-mounted distribution substation. wave signal.

The determination method of high-frequency component energy setting value E _1S is as follows: respectively measure or calculate the breakdown fault condition of one piece of insulator in the overhead line at the outlet of the high voltage side of the transformer on the column, the fault condition of 2A transient current discharge of the overhead line insulator, the cable line The energy value of the high-frequency band [f ₃ , f ₄ ] component of the output signal of the secondary side of the current transformer under the condition of a 2A transient current partial discharge fault, and the smallest one is the energy setting value of the high-frequency band component.

The determination method of the low-frequency band component energy setting value E _2S is as follows: respectively measure or calculate the secondary side of the current transformer under the condition of a 1 kΩ high-resistance ground-to-ground fault at the low-voltage outlet of the substation on the column, and the phase-to-ground leakage current of 200mA The energy value of the [f ₁ , f ₂ ] component in the low frequency band of the output signal, and the smallest one is the energy setting value of the low frequency band component.

Simulation

The 10kV/380V pole-mounted distribution substation is selected as an example for simulation analysis. Figure 2 is the simulation model of the pole-mounted distribution transformer.

In the figure, R ₁ and R ₂ are the longitudinal distributed resistances of the 10kV high-voltage side and 380V low-voltage side coils respectively, C ₁ and C ₂ are the longitudinal distributed capacitances of the 10kV high-voltage side and 380V low-voltage side coils of the distribution substation on the column respectively, and C ₁₂ is The distributed capacitance between the high-voltage coil and the low-voltage coil, C ₁₀ is the distributed capacitance between the high-voltage coil and the shell, C ₃₀ is the distributed capacitance between the low-voltage coil and the iron core, L ₁ and L ₂ are the 10kV side and the 380V side respectively The distributed inductance of the coil (including self-inductance and inter-turn mutual inductance).

Firstly, the setting value is simulated and calculated, and the electromagnetic transient process of the distribution substation on the column in Fig. 1 is analyzed and calculated by using the electromagnetic transient simulation analysis software EMTP and the general calculation software MATLAB.

Simulate and calculate the fault electromagnetic transient process of the breakdown fault of one insulator of the overhead line at the outlet of the high-voltage side of the transformer on the column, the 2A transient current discharge fault of the overhead line insulator, and the partial discharge fault of the 2A transient current of the cable line;

Calculate the amplitude of the high-frequency band [10kHz, 5MHz] component of the secondary side output signal of the current transformer under the above three fault conditions, and use the formula E=∫I ² dt to calculate the high-frequency band within 1ms after the above three faults occur. For the energy of [10kHz, 5MHz] components, take the smallest high-frequency component amplitude as the amplitude setting value I _1S = 0.87A, and take the smallest high-frequency component energy value as the high-frequency component energy setting value E _1S =8.45×10 ^-5 J; and respectively simulate and analyze the electromagnetic transient process of the 1 kohm high-resistance ground-to-ground fault at the low-voltage outlet of the substation on the pole, and the phase-to-ground leakage sudden current 200mA;

Then use the formula E=∫I ² dt to calculate the energy value of the low-frequency band [0Hz, 280Hz] component of the output signal of the secondary side of the current transformer within 30ms after the occurrence of the above two kinds of faults, and take the smallest one as the low-frequency band [0Hz, 280Hz] ] Component energy setting value E _2S =6.86×10 ^-4 J.

The flow chart of the traveling wave detection of the distribution substation on the pole of the present invention is shown in FIG. 3 . Install a current transformer on the grounding wire of the distribution substation on the end column of the line, and continuously measure the amplitude I ₁ of the high-frequency band [10kHz, 5MHz] component of the output signal of the secondary side of the current transformer.

Simulation analysis of a high-voltage distribution network fault traveling wave identification process: Electromagnetic transient simulation obtains the secondary signal waveform of the current transformer 3ms before the high-voltage distribution network fault and 30ms after the fault as shown in Figure 4, and the current transformer secondary signal waveform is obtained by filtering. The high-frequency band [10kHz, 5MHz] component of the output signal on the secondary side, the waveforms of 0.1ms before the fault and 1ms after the fault are shown in Figure 5. The measured amplitude _I1 of the high-frequency band component is 34.1A, which is greater than the set The high-frequency component amplitude setting value I _1S (0.87A) is judged as a fault transient mutation signal; use the formula E=∫I ² dt to calculate the energy value E of the high-frequency component [10kHz, 5MHz] within 1ms after the fault occurs ₁ , the size is 0.126J, which is greater than the high frequency component energy setting value E _1S (8.45×10 ^-5 J); filter to obtain the low frequency [0Hz, 280Hz] component of the output signal of the secondary side of the current transformer, of which 3ms before the fault and the waveform 30ms after the fault are shown in Figure 6. Use the formula E=∫I ² dt to calculate the energy value E ₂ of the low frequency band [0Hz, 280Hz] component within 30ms after the fault occurs, and the magnitude is 2.25×10 ^-5 J, less than The low-frequency component energy setting value E _2S (6.86×10 ^-4 J); the high-frequency band energy value E ₁ is greater than its setting value E _1S and the low-frequency band energy E ₂ is less than its setting value E _2S . The fault traveling wave signal generated by the distribution network fault and transmitted to the distribution substation on the pole.

From the analysis of the above simulation experiments, it can be known that the traveling wave detection method of the power distribution substation on the pole of the present invention can be realized only by installing a current transformer on the ground wire of the power distribution substation on the pole. It has strong anti-interference ability, is economical and simple, and is easy to popularize Advantages of the application.

Claims (7)

1. A method for detecting traveling waves in a power distribution substation on a pole is characterized in that it comprises the following steps: S1 Install a current transformer on the grounding wire of the power distribution substation on the column; S2 continuously measures the high-frequency component amplitude I ₁ of the secondary side output signal of the current transformer. If it is greater than the high-frequency component amplitude setting value I _1S , it is judged that I ₁ is a transient mutation signal of the distribution network; S3 calculates the energy value E1 _of the high-frequency band component of the output signal of the secondary side of the current transformer within the delay time _t1 after the transient mutation signal of the distribution network appears and within the delay time _t2 after the transient mutation signal of the distribution network appears The energy value E ₂ of the low frequency band component of the secondary side output signal of the current transformer; S4 If the high-frequency component energy value E ₁ is greater than its setting value E _1S and the low-frequency component energy value E ₂ is less than its setting value E _2S , it will be detected as a fault in the distribution network on the high-voltage side of the transformer and transmitted to the pole-mounted distribution substation fault traveling wave signal; If the high-frequency component energy value E ₁ is greater than its setting value E _1S and the low-frequency component energy value E ₂ is also greater than its setting value E _2S , it is detected as a fault in the distribution network on the low-voltage side of the transformer and transmitted to the pole-mounted distribution substation fault traveling wave signal. 2. The method for detecting traveling waves in power distribution substations on poles according to claim 1, characterized in that: the frequency band selection range of the high frequency band component in the step S2 is [f ₅ , f ₆ ], wherein the lower limit frequency f ₅ is selected is [5kHz], and the upper limit frequency _f6 is selected as [10MHz]. 3. The traveling wave detection method of power distribution substation on pole according to claim 1, characterized in that: the determination method of high frequency band component amplitude setting value I _1S in step S2 is: respectively measure or calculate the high voltage of transformer on pole Under the condition of breakdown fault of one piece of insulator in the overhead line at the side exit, under the condition of 2A transient current discharge fault of the overhead line insulator, and under the condition of 2A transient current partial discharge fault _of the cable line , f ₄ ] component amplitude, whichever is the smallest one is the high frequency band component amplitude setting value. 4. The method for detecting traveling waves in power distribution substations on poles according to claim 1, characterized in that: the frequency band selection range of the low frequency band components in the step S3 is [f ₁ , f ₂ ], wherein the lower limit frequency f ₁ is selected is [0Hz], and the upper limit frequency f2 is selected as [ _300Hz ]. 5. The traveling wave detection method of power distribution substation on a pole according to claim ₁ , characterized in that: the delay time t in the step S3 is selected within the range of [0.1ms, 5ms], and the delay time t ₂ The selection range is [10ms, 40ms]. 6. The traveling wave detection method of power distribution substation on pole according to claim 1, characterized in that: the determination method of the high frequency band component energy setting value E _1S in step S4 is: respectively measure or calculate the high voltage side of transformer on pole Under the condition of breakdown fault of one piece of insulator in the overhead line at the exit, under the condition of 2A transient current discharge fault of the overhead line insulator, and under the condition of 2A transient current partial discharge fault of the cable line, the high frequency band of the output signal of the secondary side of the current transformer [f ₅ , f ₆ ] The energy value of the component, the smallest one is the energy setting value of the high frequency band component. 7. The traveling wave detection method of power distribution substation on pole according to claim 1, characterized in that: the determination method of the low-frequency component energy setting value E _2S in step S4 is: respectively measure or calculate the low-voltage outlet of substation on pole The energy value of the low-frequency band [f ₁ , f ₂ ] component of the output signal of the secondary side of the current transformer under the condition of a 1 kΩ high-resistance ground fault and a phase-line-to-ground leakage current of 200 mA, the minimum of which is the low frequency band Component energy setting.