Distance protection setting method and system suitable for high-proportion new energy system

Abstract

The invention discloses a distance protection setting method and system suitable for a high-proportion new energy system. The high-proportion new energy system is an alternating current system with a conventional alternating current power supply on one side of a line and a high-proportion new energy on the other side. Firstly, the maximum short-circuit current ratio of short-circuit current provided by new energy to short-circuit current provided by a conventional alternating-current power supply is determined, and an initial constant value of a distance I section is obtained according to a setting method; and substituting the maximum short-circuit current ratio and the initial value of the distance I section constant value into an optimization setting calculation formula, and calculating the final value of the distance I section constant value. According to the technical scheme, the maximum short-circuit current ratio provided by the high-proportion new energy system and the conventional alternating-current power supply is introduced, and the setting value of the distance I section is adjusted, so that the steady-state override risk existing in the high-proportion new energy system adopting a conventional setting method is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of relay protection for power systems, and in particular relates to a distance protection setting method and system suitable for a high-proportion new energy system. Background Art

[0002] Distance protection measures impedance based on the voltage and current at the protection installation. The fault location is determined by comparing the measured impedance with the set impedance. Distance protection stage I operates without delay and should only respond to faults within the local line. It should reliably remain inoperative in the event of a short-circuit at the downstream line outlet. Therefore, the set impedance of the measuring element should be set to avoid the measured impedance when a short-circuit occurs at the end of the line, typically with a reliability factor of around 0.8.

[0003] When a fault occurs through a transition resistor on a two-terminal power supply line, the measured impedance on the leading side of the current is affected by the lagging current, potentially leading to steady-state overshoot. The greater the phase angle difference between the two currents, the more severe the overshoot problem. In conventional AC systems, properly setting the reliability factor for Distance Section I can prevent overshoot from causing malfunction of Distance Section I. In AC systems with a high proportion of renewable energy, when one side of the line is powered by conventional AC power and the other by renewable energy, the phase angle relationship between the two currents is affected by the renewable energy control. Therefore, the overshoot problem is more prominent than in conventional AC systems, and the traditional method of setting the reliability factor is no longer applicable.

[0004] Based on the above analysis, the applicant found that in a system with a high proportion of new energy, there is a risk of steady-state overshoot when the distance protection is adjusted using conventional adjustment methods. In view of this, this case arose. Summary of the Invention

[0005] The purpose of the present invention is to provide a distance protection setting method and system suitable for high-proportion renewable energy systems. The present invention introduces the maximum short-circuit current ratio provided by the high-proportion renewable energy system and the conventional AC power supply, adjusts the setting value of the distance I section, and thus avoids the steady-state overrun risk that exists in the conventional setting method in the high-proportion renewable energy system.

[0006] In order to achieve the above object, the solution of the present invention is:

[0007] A distance protection setting method applicable to a high-proportion renewable energy system, wherein the high-proportion renewable energy system is an AC system with a conventional AC power supply on one side of the line and a high-proportion renewable energy supply on the other side; the method comprises the following steps:

[0008] Step 1: Determine the maximum short-circuit current ratio of the short-circuit current provided by the renewable energy source to the short-circuit current provided by the conventional AC power source, and obtain the initial value of the distance I segment constant according to the setting method;

[0009] Step 2: Substitute the maximum short-circuit current ratio and the initial value of the distance I segment constant into the optimization setting calculation formula to calculate the final value of the distance I segment constant.

[0010] In the above step 1, the maximum short-circuit current ratio is obtained through simulation calculation.

[0011] In step 1 above, the initial value of the distance I segment constant is obtained according to the following setting formula:

[0012] Z set1 =k rel ×Z L

[0013] Where k rel is the reliability coefficient, Z L is the line impedance, Z set1 It is the initial value of distance I segment.

[0014] In step 2 above, the optimization setting calculation formula is:

[0015]

[0016] Where, is the line positive sequence impedance angle, m is the maximum short-circuit current ratio, p is the intermediate variable, k rel ′ is the additional reliability coefficient, Z set1 ′ is the final value of the fixed value of distance I segment.

[0017] The final value of the distance I stage setting calculated in step 2 above is used to implement the distance protection I stage setting for the high-proportion new energy system.

[0018] A distance protection setting system suitable for a high-proportion renewable energy system, wherein the high-proportion renewable energy system is an AC system with a conventional AC power supply on one side of the line and a high-proportion renewable energy supply on the other side; comprising:

[0019] A maximum short-circuit current ratio acquisition module is used to determine the maximum short-circuit current ratio of the short-circuit current provided by the renewable energy source to the short-circuit current provided by the conventional AC power source;

[0020] A distance I segment fixed value initial value acquisition module is used to obtain the distance I segment fixed value initial value according to the setting method; and

[0021] The distance I section fixed value final value calculation module is used to calculate the distance I section fixed value final value based on the maximum short-circuit current ratio and the distance I section fixed value initial value using the optimized setting calculation formula.

[0022] In the above step 1, the maximum short-circuit current ratio acquisition module is configured to determine the maximum short-circuit current ratio of the short-circuit current provided by the new energy source to the short-circuit current provided by the conventional AC power source through simulation calculation.

[0023] The above-mentioned distance I segment fixed value initial value acquisition module is configured to obtain the distance I segment fixed value initial value according to the following setting formula:

[0024] Z set1 =k rel ×Z L

[0025] Where k rel is the reliability coefficient, Z L is the line impedance, Z set1 It is the initial value of distance I segment.

[0026] The above-mentioned distance I segment fixed value final value calculation module is configured to obtain the distance I segment fixed value final value using the following optimized setting calculation formula:

[0027]

[0028] Where, is the line positive sequence impedance angle, m is the maximum short-circuit current ratio, p is the intermediate variable, k rel ′ is the additional reliability coefficient, Z set1 ′ is the final value of the fixed value of distance I segment.

[0029] The distance I section fixed value final value calculated by the above-mentioned distance I section fixed value final value calculation module is used to realize the distance protection I section setting for the high proportion of new energy systems.

[0030] After adopting the above scheme, compared with the existing technology, the beneficial effect of the present invention is: by introducing the maximum short-circuit current ratio provided by the high-proportion new energy system and the conventional AC power supply, the setting value of the distance I section is adjusted, thereby avoiding the steady-state overrun risk existing in the conventional setting method in the high-proportion new energy system, and is suitable for the setting of the distance protection I section in the high-proportion new energy system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0032] The technical solutions and beneficial effects of the present invention will be described in detail below with reference to the accompanying drawings.

[0033] The present invention provides a distance protection setting method applicable to a high-proportion new energy system, wherein the high-proportion new energy system is an AC system with a conventional AC power supply on one side of the line and a high-proportion new energy on the other side. The setting method of the present invention is applicable to the conventional AC power supply side; Figure 1 As shown, the setting method includes the following steps:

[0034] S101: Determine a maximum short-circuit current ratio between a short-circuit current provided by a new energy source and a short-circuit current provided by a conventional AC power source;

[0035] S102: Obtain the initial value of the distance I segment constant according to the conventional setting method;

[0036] The tuning formula of the conventional tuning method is:

[0037] Z set1 =k rel ×Z L

[0038] Where k rel is the reliability coefficient, Z L is the line impedance, Z set1 It is the initial value of distance I segment.

[0039] S103: Substitute the maximum short-circuit current ratio and the initial value of the distance I segment constant into the new optimization setting calculation formula to calculate the final value of the distance I segment constant;

[0040] The tuning formula of the optimization tuning method is:

[0041]

[0042] Where, is the line positive sequence impedance angle, m is the maximum short-circuit current ratio, p is the intermediate variable, k rel ′ is the additional reliability coefficient, Z set1 ′ is the final value of the fixed value of distance I segment.

[0043] The optimized setting calculation formula is applicable to the setting of stage I of distance protection in systems with a high proportion of new energy.

[0044] As a preferred embodiment of the present invention, in an AC system where one side of the line is a conventional AC power source and the other side of the line is a high-proportion renewable energy source, distance protection setting is performed on the conventional AC power source side according to the following steps:

[0045] First, a simulation model was built based on the actual AC system to be applied. The output of the high-proportion renewable energy source was adjusted to maximum, while the conventional AC power source on the other side operated at minimum power. The simulation was used to analyze the ratio of the short-circuit current provided by the renewable energy source to the short-circuit current provided by the conventional AC power source when a line fault occurred near the renewable energy source. This ratio was used as the maximum short-circuit current ratio, m.

[0046] On the other hand, according to the setting specification, the initial value of the distance I segment setting is calculated using the following formula;

[0047] Z set1 =k rel ×Z L

[0048] Among them, k rel is the reliability coefficient, Z Lis the line impedance, Z set1 The initial value of distance I segment;

[0049] Then, according to the maximum short-circuit current ratio m and the initial value Z of the distance I obtained above, set1 , calculate the final value of distance I segment fixed value according to the following optimization setting calculation formula;

[0050]

[0051] in, is the line positive sequence impedance angle, m is the maximum short-circuit current ratio, p is the intermediate variable, k rel ′ is the additional reliability coefficient, Z set1 ′ is the final value of the fixed value of distance I segment.

[0052] Thus, the calculated distance I segment fixed final value Z is used set1 'Realize the I-stage setting of distance protection for high-proportion new energy systems.

[0053] The present invention further provides a distance protection setting system applicable to a high-proportion renewable energy system. The high-proportion renewable energy system is an AC system with a conventional AC power supply on one side of the line and a high-proportion renewable energy supply on the other side. The setting system of the present invention is applicable to the conventional AC power supply side; the setting system comprises:

[0054] A maximum short-circuit current ratio acquisition module is used to determine the maximum short-circuit current ratio of the short-circuit current provided by the renewable energy source to the short-circuit current provided by the conventional AC power source;

[0055] A distance I segment fixed value initial value acquisition module is used to obtain the distance I segment fixed value initial value according to a conventional setting method; and

[0056] The distance I section fixed value final value calculation module is used to calculate the distance I section fixed value final value using the optimized setting calculation formula based on the maximum short-circuit current ratio and the distance I section fixed value initial value; the distance I section fixed value final value is used to realize the distance protection I section setting for a high proportion of new energy systems.

[0057] As a preferred embodiment of the present invention, in an AC system where one side of the line is a conventional AC power source and the other side of the line is a high-proportion renewable energy source, a system for performing distance protection setting on the conventional AC power source side includes:

[0058] The maximum short-circuit current ratio calculation module is configured to build a simulation model based on the actual AC system to be applied, and adjust the output of the high-proportion renewable energy side to the maximum, while the conventional AC power supply side on the other side operates at the minimum operating mode. Through simulation analysis, the ratio of the short-circuit current provided by the renewable energy side to the short-circuit current provided by the conventional AC power supply when a line fault occurs near the renewable energy side is calculated as the maximum short-circuit current ratio m;

[0059] The distance I segment fixed value initial value acquisition module is configured to calculate the distance I segment fixed value initial value using the following formula according to the setting specification;

[0060] Z set1 =k rel ×Z L

[0061] Among them, k rel is the reliability coefficient, Z L is the line impedance, Z set1 Set the initial value for distance I; and

[0062] The distance I segment fixed value final value calculation module is configured to calculate the distance I segment fixed value initial value Z obtained by the above-mentioned distance I segment fixed value initial value acquisition module based on the maximum short-circuit current ratio m obtained by the above-mentioned maximum short-circuit current ratio calculation module. set1 , calculate the final value of distance I segment fixed value according to the following optimization setting calculation formula;

[0063]

[0064] in, is the line positive sequence impedance angle, m is the maximum short-circuit current ratio, p is the intermediate variable, k rel ′ is the additional reliability coefficient, Z set1 ′ is the final value of the fixed value of distance I segment.

[0065] Thus, the calculated distance I segment fixed final value Z is used set1 'Realize the I-stage setting of distance protection for high-proportion new energy systems.

[0066] The above embodiments are only for illustrating the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A distance protection setting method applicable to a high-proportion new energy system, wherein the high-proportion new energy system is an AC system with a conventional AC power supply on one side of the line and a high-proportion new energy on the other side; characterized in that The steps include: Step 1, determining the maximum short-circuit current ratio of the short-circuit current provided by the new energy source to the short-circuit current provided by the conventional AC power source, and obtaining the initial value of the distance I segment constant according to the setting method; Step 2, substitute the maximum short-circuit current ratio and the initial value of the distance I section constant into the optimization setting calculation formula to calculate the final value of the distance I section constant.

2. The distance protection setting method applicable to a high proportion of new energy systems as claimed in claim 1, characterized in that: In the step 1, the maximum short-circuit current ratio is obtained through simulation calculation.

3. The distance protection setting method applicable to a high proportion of new energy systems as claimed in claim 1, characterized in that: In step 1, the initial value of the distance I segment constant is obtained according to the following setting formula: WITH set1 =k rel ×Z L In the formula, k rel is the reliability coefficient, Z L is the line impedance, Z set1 Set the initial value for distance segment I.

4. The distance protection setting method applicable to a high proportion of new energy systems according to claim 1, characterized in that: In step 2, the optimization setting calculation formula is: In the formula, is the line positive sequence impedance angle, m is the maximum short-circuit current ratio, p is the intermediate variable, k rel ′ is the additional reliability coefficient, Z set1 ′ is the final value of the fixed value of distance section I.

5. The distance protection setting method applicable to a high proportion of new energy systems as claimed in claim 1, characterized in that: The final value of the distance I segment constant calculated in step 2 is used to implement the distance protection I segment setting for a high proportion of new energy systems.

6. A distance protection setting system suitable for a high-proportion new energy system, wherein the high-proportion new energy system is an AC system with a conventional AC power supply on one side of the line and a high-proportion new energy on the other side; characterized in that: include: A maximum short-circuit current ratio acquisition module, used to determine the maximum short-circuit current ratio of the short-circuit current provided by the new energy source to the short-circuit current provided by the conventional AC power source; A distance I segment fixed value initial value acquisition module is used to obtain the distance I segment fixed value initial value according to the setting method; and The distance I section fixed value final value calculation module is used to calculate the distance I section fixed value final value according to the maximum short-circuit current ratio and the distance I section fixed value initial value using the optimized setting calculation formula.

7. The distance protection setting system applicable to a high proportion of new energy systems as claimed in claim 6, characterized in that: In the step 1, the maximum short-circuit current ratio acquisition module is configured to determine the maximum short-circuit current ratio of the short-circuit current provided by the new energy source to the short-circuit current provided by the conventional AC power source by using simulation calculation.

8. The distance protection setting system applicable to a high proportion of new energy systems as claimed in claim 6, characterized in that: The distance I segment fixed value initial value acquisition module is configured to obtain the distance I segment fixed value initial value according to the following setting formula: WITH set1 =k rel ×Z L In the formula, k rel is the reliability coefficient, Z L is the line impedance, Z set1 Set the initial value for distance segment I.

9. The distance protection setting system applicable to a high proportion of new energy systems as claimed in claim 6, characterized in that: The distance I segment fixed value final value calculation module is configured to obtain the distance I segment fixed value final value using the following optimization setting calculation formula: In the formula, is the line positive sequence impedance angle, m is the maximum short-circuit current ratio, p is the intermediate variable, k rel ′ is the additional reliability coefficient, Z set1 ′ is the final value of the fixed value of distance section I.

10. The distance protection setting system applicable to a high proportion of new energy systems as claimed in claim 6, characterized in that: The distance I section fixed value final value calculated by the distance I section fixed value final value calculation module is used to realize the distance protection I section setting for the high proportion of new energy system.

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