Current collection wire protection system based on electronic mutual inductor

Abstract

The invention discloses a current collection wire protection system based on an electronic mutual inductor, and belongs to the technical field of power system relay protection, and the system comprises an acquisition unit which is used for acquiring the current value of the electronic mutual inductor and the voltage value of a PT cabinet, the acquisition unit is connected with the electronic mutual inductor and the PT cabinet, and the PT cabinet is connected with a 10KV current collection bus; the merging unit is used for merging the current value im (t) and the voltage value um (t) acquired by the acquisition unit and formulating an equivalent potential circuit according to the current value im (t) and the voltage value um (t), and the merging unit is connected with the acquisition unit; the calculation unit is used for calculating the fault direction according to the equivalent potential circuit and is connected with the merging unit; and the signal receiving and transmitting unit is used for transmitting a calculation result of the calculation unit or receiving a control terminal signal, and is connected with the calculation unit. By means of the mode, large-scale off-network of new energy is effectively avoided, safe and stable operation of the new energy station is guaranteed, and safe, stable and reliable operation of a power system is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of relay protection of electric power systems, and in particular to a collector line protection system based on an electronic mutual inductor. Background Art

[0002] The fault characteristics of renewable energy power generation systems are determined by the control strategy during the fault period. The rapid regulation and fault current limiting characteristics of wind power, photovoltaic power, energy storage and other power sources affect the fault characteristics and features of the power grid. In a high-proportion renewable energy power system, the change in the fault characteristics of the power grid changes from "quantity" to "quality", which brings major challenges to relay protection.

[0003] If a fault occurs in the collection or transmission line of a new energy station and is not promptly detected and removed to restore the line to normal operation, it may cause failure of adjacent lines or even adjacent new energy power plants, leading to large-scale disconnection of new energy from the grid, which will have an adverse impact on the safe, stable and reliable operation of the power system.

[0004] Based on this, the present invention designs a collector line protection system based on an electronic transformer to solve the above problems. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a collector line protection system based on an electronic transformer.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] The collector line protection system based on electronic transformer includes:

[0008] Electronic transformers for sensing current on integrated circuits;

[0009] A collection unit for collecting the current value of the electronic transformer and the voltage value of the PT cabinet, the collection unit is connected to the electronic transformer and the PT cabinet, and the PT cabinet is connected to the 10KV collector bus;

[0010] The current value collected by the combined collection unit is i m (t) and voltage value u m (t), and according to the current value i m (t) and voltage value u m (t) formulating a merging unit of an equivalent potential circuit, wherein the merging unit is connected to the collecting unit;

[0011] A calculation unit for calculating the fault direction according to the equivalent potential circuit, the calculation unit being connected to the merging unit;

[0012] A signal transceiver unit is used to send the calculation result of the calculation unit or receive the control terminal signal, and the signal transceiver unit is connected to the calculation unit and the signal transceiver unit is connected to the control terminal signal through a wireless signal.

[0013] Furthermore, the equivalent potential circuit includes the M side potential E M 、N side potential E N , equivalent impedance Z S , Line impedance Z L And the system equivalent impedance Z W , M side potential E M and N-side potential E N Connection, M side potential E M With equivalent impedance Z S Connection, equivalent impedance Z S Connection and line impedance Z L Connection, line impedance Z L And the system equivalent impedance Z W Connection, system equivalent impedance Z W and N-side potential E N Connection, N side potential E M and the M side potential E M Connection, M side potential E M and N-side potential E N The voltage value is u m (t), through an equivalent impedance Z S The current value is i m (t).

[0014] Furthermore, the calculation method of the calculation unit is as follows:

[0015] Step 1: Calculate the equivalent impedance Z S Upper memory voltage drop u Sj (t);

[0016] Step 2: Calculate the line impedance Z L And the system equivalent impedance Z W Upper memory voltage drop u LWj (t);

[0017] Step 3: Calculate the equivalent impedance Z S Actual voltage drop u S (t);

[0018] Step 4: Calculate the line impedance Z L And the system equivalent impedance Z W Actual voltage drop u LW (t);

[0019] Step 5: According to the memory voltage drop u Sj (t) and actual voltage drop uS Substituting (t) into the time domain waveform number, we can get Then according to the memory voltage drop u LWj (t) and actual voltage drop u LW Substitute (t) into the time domain waveform number to calculate the time domain waveform number

[0020] Step 6: Convert the time domain waveform and time domain waveform number With r set To judge the size, if It is judged as a forward fault; if It is judged as a reverse fault.

[0021] Furthermore, the memory voltage drop u Sj (t) are as follows:

[0022]

[0023] u mj(t) =u m (t-nT);

[0024] i mj(t) =i m (t-nT);

[0025] L S is the equivalent impedance Z on the M side S The inductance, u mj (t) and i mj (t) is the memory voltage and memory current on the M side, t is the time point, R S is the equivalent impedance Z S resistance, T is 20ms, and n is a positive integer.

[0026] Furthermore, the memory voltage drop u LWj (t) The specific calculation is as follows:

[0027]

[0028] Among them, R W is the system equivalent impedance Z W Resistance, L W is the system equivalent impedance Z W The inductance, R L is the line impedance Z L Resistance, L L is the line impedance Z L inductance.

[0029] Furthermore, the actual voltage drop u S (t) The specific calculation is as follows:

[0030]

[0031] Furthermore, the actual voltage drop u LW (t) The specific calculation is as follows:

[0032]

[0033] Furthermore, the time domain waveform function is as follows:

[0034]

[0035] Among them, u x (i) is the time domain waveform u x (t) the sample value at time i; u y (i) is the time domain waveform u y (t) is the sample value at time i; N is the data window length; and is the time domain waveform u x (t) and u y (t) Average value within the data window.

[0036] Furthermore, set is 0.5.

[0037] The present invention has the following technical effects: the present invention utilizes the advantage of the wide bandwidth of the electronic mutual inductor measurement to accurately obtain the rich high-frequency current information generated when the collector line of the new energy station fails, and then collects the current information through the acquisition unit, and then timely detects and discovers the fault through the calculation unit, and the control terminal quickly and accurately cuts off the faulty line to restore the line to normal operation, avoiding causing failures in adjacent lines or even adjacent new energy electric fields, effectively avoiding large-scale disconnection of new energy from the grid, ensuring the safe and stable operation of new energy stations, and facilitating the safe, stable and reliable operation of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 It is a structural connection block diagram of the collector line protection system based on the electronic mutual inductor of the present invention;

[0040] Figure 2 It is the equivalent potential circuit diagram of the present invention. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0042] The present invention will be further described below in conjunction with the embodiments.

[0043] The terms “left”, “right”, “front”, “back”, “up” and “down” mentioned in the following description are oriented in the viewing direction of the front view.

[0044] Example 1: Please refer to Figure 1-Figure 2 , a collector line protection system based on electronic transformer, including:

[0045] Electronic transformers for sensing current on integrated circuits;

[0046] A collection unit for collecting the current value of the electronic transformer and the voltage value of the PT cabinet, the collection unit is connected to the electronic transformer and the PT cabinet, and the PT cabinet is connected to the 10KV collector bus;

[0047] The current value collected by the combined collection unit is i m (t) and voltage value u m (t), and according to the current value i m (t) and voltage value u m (t) formulating a merging unit of an equivalent potential circuit, wherein the merging unit is connected to the collecting unit;

[0048] The equivalent potential circuit includes the potential E on the M side M 、N side potential E N , equivalent impedance Z S , Line impedance Z L And the system equivalent impedance Z W , M side potential E M and N-side potential E N Connection, M side potential E M With equivalent impedance Z S Connection, equivalent impedance Z S Connection and line impedance Z L Connection, line impedance Z L And the system equivalent impedance Z W Connection, system equivalent impedance Z W and N-side potential E N Connection, N side potential E Mand the M side potential E M Connection, M side potential E M and N-side potential E N The voltage value is u m (t), through an equivalent impedance Z S The current value is i m (t);

[0049] A calculation unit for calculating the fault direction according to the equivalent potential circuit, the calculation unit being connected to the merging unit;

[0050] A signal transceiver unit is used to send the calculation result of the calculation unit or receive the control terminal signal, and the signal transceiver unit is connected to the calculation unit and the signal transceiver unit is connected to the control terminal signal through a wireless signal.

[0051] The calculation method of the calculation unit is as follows:

[0052] Step 1: Calculate the equivalent impedance Z S Upper memory voltage drop u Sj (t);

[0053] Step 2: Calculate the line impedance Z L And the system equivalent impedance Z W Upper memory voltage drop u LWj (t);

[0054] Step 3: Calculate the equivalent impedance Z S Actual voltage drop u S (t);

[0055] Step 4: Calculate the line impedance Z L And the system equivalent impedance Z W Actual voltage drop u LW (t);

[0056] Step 5: According to the memory voltage drop u Sj (t) and actual voltage drop u S Substituting (t) into the time domain waveform number, we can get Then according to the memory voltage drop u LWj (t) and actual voltage drop u LW Substitute (t) into the time domain waveform number to calculate the time domain waveform number

[0057] Step 6: Convert the time domain waveform and time domain waveform number With r set To judge the size, if It is judged as a forward fault; if It is judged as a reverse fault.

[0058] Memory voltage drop u Sj (t) are as follows:

[0059]

[0060] u mj(t) =u m (t-nT);

[0061] i mj(t) =i m (t-nT);

[0062] L S is the equivalent impedance Z on the M side S The inductance, u mj (t) and i mj (t) is the memory voltage and memory current on the M side, t is the time point, R S is the equivalent impedance Z S resistance, T is 20ms, and n is a positive integer.

[0063] Memory voltage drop u LWj (t) The specific calculation is as follows:

[0064]

[0065] Among them, R W is the system equivalent impedance Z W Resistance, L W is the system equivalent impedance Z W The inductance, R L is the line impedance Z L Resistance, L L is the line impedance Z L inductance.

[0066] Actual voltage drop u S (t) The specific calculation is as follows:

[0067]

[0068] Actual voltage drop u LW (t) The specific calculation is as follows:

[0069]

[0070] The time domain waveform function is as follows:

[0071]

[0072] Among them, u x (i) is the time domain waveform u x (t) the sample value at time i; u y (i) is the time domain waveform uy (t) is the sample value at time i; N is the data window length; and is the time domain waveform u x (t) and u y (t) Average value within the data window.

[0073] r set is 0.5.

[0074] The electronic transformer senses the current on the integrated circuit; the collection unit collects the current value of the electronic transformer and the voltage value of the PT cabinet, the collection unit is connected to the electronic transformer and the PT cabinet, and the PT cabinet is connected to the 10KV collector bus; the merging unit merges the current value collected by the collection unit to i m (t) and voltage value u m (t), and according to the current value i m (t) and voltage value u m (t) Formulate an equivalent potential circuit; the calculation unit calculates the fault direction according to the equivalent potential circuit. When a fault occurs in the forward direction, it indicates that the integrated circuit is faulty and needs to be removed. When a fault occurs in the reverse direction, it indicates that the integrated circuit is fault-free and can continue to be used. The signal transceiver unit sends the calculation result of the calculation unit or receives the control terminal signal. The simultaneous operation of multiple systems can accurately determine whether multiple integrated circuits are faulty and remove them when a fault occurs again.

[0075] The present application utilizes the advantage of the wide bandwidth of the electronic mutual inductor measurement to accurately obtain the rich high-frequency current information generated when the collector line of the new energy station fails, and then collects the current information through the acquisition unit, and then promptly detects and discovers the fault through the calculation unit. The control terminal quickly and accurately cuts off the faulty line to restore the line to normal operation, avoiding causing failures in adjacent lines or even adjacent new energy electric fields, effectively avoiding large-scale disconnection of new energy from the grid, ensuring the safe and stable operation of new energy stations, and facilitating the safe, stable and reliable operation of the power system.

[0076] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. The collector line protection system based on electronic transformer is characterized by: include: Electronic transformers for sensing current on integrated circuits; A collection unit for collecting the current value of the electronic transformer and the voltage value of the PT cabinet, the collection unit is connected to the electronic transformer and the PT cabinet, and the PT cabinet is connected to the 10KV collector bus; The current value collected by the combined acquisition unit is i m (t) and voltage value u m (t), and according to the current value i m (t) and voltage value u m (t) formulating a merging unit of an equivalent potential circuit, wherein the merging unit is connected to the collecting unit; A calculation unit for calculating the fault direction according to the equivalent potential circuit, the calculation unit being connected to the merging unit; A signal transceiver unit is used to send the calculation result of the calculation unit or receive the control terminal signal, and the signal transceiver unit is connected to the calculation unit and the signal transceiver unit is connected to the control terminal signal through a wireless signal.

2. The collector line protection system based on electronic mutual inductor according to claim 1 is characterized in that: The equivalent potential circuit includes the potential E on the M side M 、N side potential E N , equivalent impedance Z S , Line impedance Z L And the system equivalent impedance Z W , M side potential E M and N-side potential E N Connection, M side potential E M With equivalent impedance Z S Connection, equivalent impedance Z S Connection and line impedance Z L Connection, line impedance Z L And the system equivalent impedance Z W Connection, system equivalent impedance Z W and N-side potential E N Connection, N side potential E M and the M side potential E M Connection, M side potential E M and N-side potential E N The voltage value is u m (t), through an equivalent impedance Z S The current value is i m (t).

3. The collector line protection system based on electronic transformer according to claim 2 is characterized in that: The calculation method of the calculation unit is as follows: Step 1: Calculate the equivalent impedance Z S Upper memory voltage drop u Sj (t); Step 2: Calculate the line impedance Z L And the system equivalent impedance Z W Upper memory voltage drop u LWj (t); Step 3: Calculate the equivalent impedance Z S Actual voltage drop u S (t); Step 4: Calculate the line impedance Z L And the system equivalent impedance Z W Actual voltage drop u LW (t); Step 5: According to the memory voltage drop u Sj (t) and actual voltage drop u S Substituting (t) into the time domain waveform number, we can get Then according to the memory voltage drop u LWj (t) and actual voltage drop u LW Substitute (t) into the time domain waveform number to calculate the time domain waveform number Step 6: Convert the time domain waveform and time domain waveform number With r set To judge the size, if It is judged as a forward fault; if It is judged as a reverse fault.

4. The collector line protection system based on electronic transformer according to claim 3 is characterized in that: Memory voltage drop u Sj (t) are as follows: u mj (t)=u m (t-nT); i mj(t) =i m (t-nT); L S is the equivalent impedance Z on the M side S The inductance, u mj (t) and i mj (t) is the memory voltage and memory current on the M side, t is the time point, R S is the equivalent impedance Z S resistance, T is 20ms, and n is a positive integer.

5. The collector line protection system based on electronic transformer according to claim 4 is characterized in that: Memory voltage drop u LWj (t) The specific calculation is as follows: Among them, R W is the system equivalent impedance Z W Resistance, L W is the system equivalent impedance Z W The inductance, R L is the line impedance Z L Resistance, L L is the line impedance Z L inductance.

6. The collector line protection system based on electronic transformer according to claim 5, characterized in that: Actual voltage drop u S (t) The specific calculation is as follows:

7. The collector line protection system based on electronic transformer according to claim 6 is characterized in that: Actual voltage drop u LW (t) The specific calculation is as follows:

8. The collector line protection system based on electronic transformer according to claim 7, characterized in that: The time domain waveform function is as follows: Among them, u x (i) is the time domain waveform u x (t) the sample value at time i; u y (i) is the time domain waveform u y (t) is the sample value at time i; N is the data window length; and is the time domain waveform u x (t) and u y (t) Average value within the data window.

9. The collector line protection system based on electronic transformer according to claim 8, characterized in that: r set is 0.5.

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