CN111355217A - Automatic tracking and adjusting method for resonance elimination resistor - Google Patents

Automatic tracking and adjusting method for resonance elimination resistor Download PDF

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Publication number
CN111355217A
CN111355217A CN202010243741.8A CN202010243741A CN111355217A CN 111355217 A CN111355217 A CN 111355217A CN 202010243741 A CN202010243741 A CN 202010243741A CN 111355217 A CN111355217 A CN 111355217A
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Prior art keywords
phase
voltage
phases
automatic tracking
harmonic elimination
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李绍孔
段军鹏
沈寅辰
陈寅
刘勇
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Chuxiong Power Supply Bureau of Yunnan Power Grid Co Ltd
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Chuxiong Power Supply Bureau of Yunnan Power Grid Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
    • H02H7/05—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers for capacitive voltage transformers, e.g. against resonant conditions
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/005—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection avoiding undesired transient conditions
    • H02H9/007—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection avoiding undesired transient conditions avoiding or damping oscillations, e.g. fenoresonance or travelling waves

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

The invention discloses an automatic tracking and adjusting method for a harmonic elimination resistor, which comprises the automatic tracking and adjusting for the harmonic elimination resistor under the condition of single-phase grounding, the automatic tracking and adjusting for the harmonic elimination resistor under the condition of three-phase unbalance and the automatic tracking and adjusting for the harmonic elimination resistor under the condition of interphase short circuit.

Description

Automatic tracking and adjusting method for resonance elimination resistor
Technical Field
The invention relates to the technical field of automatic tracking adjustment of harmonic elimination resistors, in particular to an automatic tracking adjustment method of a harmonic elimination resistor.
Background
The method that the resistors are put into the open triangles of the voltage transformer to eliminate the resonance of the voltage transformer is a known reason, the smaller the harmonic elimination resistor is, the better the harmonic elimination capability is, but the more the overload of the winding of the voltage transformer is easily caused, and the overload causes the iron core to be saturated to cause new resonance until the voltage transformer is damaged. On one hand, the prior art harmonic eliminator takes measures after resonance, namely a passive protection mode; on the other hand, in actual operation, whether the voltage transformer is single-phase grounding or the resonance of the voltage transformer is difficult to judge under some conditions, and when the resonance or the single-phase grounding fault cannot be accurately judged, the voltage transformer harmonic elimination resistor is not put into use in order to prevent burning out, namely, the open triangle is not short-circuited. When the single-phase grounding is carried out, the harmonic elimination resistor is put into the open triangle, so that the iron core is saturated to generate new voltage transformer resonance, and a plurality of error zone dead zones can not be eliminated.
Disclosure of Invention
The invention aims to provide an automatic tracking and adjusting method for a harmonic elimination resistor, which aims to solve the problems in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme: a method for automatically tracking and adjusting a resonance elimination resistor comprises the steps of automatically tracking and adjusting the resonance elimination resistor under the condition of single-phase grounding, automatically tracking and adjusting the resonance elimination resistor under the condition of three-phase unbalance and automatically tracking and adjusting the resonance elimination resistor under the condition of inter-phase short circuit.
Preferably, the automatic tracking adjustment for the resonance elimination resistance in the case of single-phase grounding is specifically: when the phase B is in single-phase grounding, Uam, Ubm and Ucm are phase voltages of three phases of an open triangle, Ua, Ub and Uc are secondary voltages of the three phases of the open triangle relative to the ground when the phase B is in grounding, and Uo is neutral point-to-ground voltage and is open triangle voltage U△Theta is an included angle between the zero-sequence voltage Uo and the phase B voltage Ubm, the phase B grounding phase A has the largest relative ground voltage Ua, the apparent power of the phase A is the largest, and the open delta voltage U cannot be overloaded as long as the phase A winding in the open delta is not overloaded by the other two phases△As monitored, in right triangle △ OBG:
Figure BDA0002433401090000021
when θ < 60 °, in triangle △ OAG, OA and OG are known, the angle between OA and OG is 120 ° + θ, and Ua, characterized by the length of AG according to the cosine law, is:
Figure BDA0002433401090000022
when theta is more than 60 degrees, OA and OG are known in triangle △ OAG, the included angle between OA and OG is 240-theta, the cosine value of 240-theta is equal to the cosine value of 120-theta, Ua represented by the length of AG is the same as the formula (2) according to the cosine law, Ua represented by the length of AG is 50V when theta is 60 degrees, the calculation result is the same as the calculation result of the formula (2), R is harmonic elimination resistance, U is equal to harmonic elimination resistance, and△is open delta voltage, I is open delta current, I ═ U△The voltage of the phase of the open delta three-phase voltage is the rated power of the open delta three-phase winding; the maximum value Um of the A-phase voltage when the B-phase is grounded in a single phase is equal to Ua, and the maximum value Um of the A-phase voltage is as follows:
UmI≤KS (3)
Figure BDA0002433401090000023
let Umx be the maximum phase voltage of the three-phase secondary voltage of the system, i.e. the voltage of the three-phase secondary side of the voltage transformer, then there are:
Figure BDA0002433401090000024
belt-in (4) having:
Figure BDA0002433401090000025
therefore it has the advantages of
Figure BDA0002433401090000026
Thus, U△Resistance R at 100V100Comprises the following steps:
Figure BDA0002433401090000031
the same can be said for A, C phase single phase grounding.
Preferably, the automatic tracking adjustment of the resonance elimination resistor under the condition of three-phase imbalance is specifically as follows: when three phases are unbalanced, a neutral point of the system can drift, and the open triangle can have power frequency voltage; when the open delta voltage is less than U△At ≦ 15V, the phase voltage corresponding to the phase up to the maximum is
Figure BDA0002433401090000032
Thus, the resonance elimination resistance RO put into the fault-free state is minimized
Figure BDA0002433401090000033
Preferably, the automatic tracking adjustment of the resonance elimination resistor under the condition of the interphase short circuit is specifically as follows: two-phase short circuit and three-phase short circuit can be rapidly removed within 700ms by the microcomputer protection device, and the voltage transformer cannot be burnt out due to overload within 700ms no matter what resistance value of the resistor is set by the opening triangle; the worst two phases are grounded and shorted through a large resistor in different places, and the characteristics are that the voltage of one phase is reduced by the two phases and is unchanged, and no phase is increased, so that the harmonic elimination resistors are adjusted according to the condition that the voltage of the two phases is larger than that of the two phases in the formulas (7), (8) and (10), and the adjustment of the resistance value of the automatic tracking and adjusting harmonic elimination resistor cannot be influenced by the fault of the interphase short circuit.
Compared with the prior art, the invention has the beneficial effects that: the automatic tracking and adjusting method for the harmonic elimination resistor does not overload the voltage transformer, and the voltage transformer is effectively protected.
Drawings
Fig. 1 is a schematic diagram of the single-phase grounding theta of the invention being less than 60 degrees;
FIG. 2 is a schematic diagram of single-phase ground θ > 60 according to the present invention;
fig. 3 is a schematic diagram of the single-phase grounding of the present invention, where θ is 60 °.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a technical scheme that: a method for automatically tracking and adjusting a resonance elimination resistor comprises the steps of automatically tracking and adjusting the resonance elimination resistor under the condition of single-phase grounding, automatically tracking and adjusting the resonance elimination resistor under the condition of three-phase unbalance and automatically tracking and adjusting the resonance elimination resistor under the condition of inter-phase short circuit.
The automatic tracking adjustment of the harmonic elimination resistor under the condition of single-phase grounding specifically comprises the following steps: when the phase B is in single-phase grounding, Uam, Ubm and Ucm are phase voltages of three phases of an open triangle, Ua, Ub and Uc are secondary voltages of the three phases of the open triangle relative to the ground when the phase B is in grounding, and Uo is neutral point-to-ground voltage and is open triangle voltage U△Theta is an included angle between the zero-sequence voltage Uo and the phase B voltage Ubm, the phase B grounding phase A has the largest relative ground voltage Ua, the apparent power of the phase A is the largest, and the open delta voltage U cannot be overloaded as long as the phase A winding in the open delta is not overloaded by the other two phases△As monitored, in right triangle △ OBG:
Figure BDA0002433401090000041
when θ < 60 °, as shown in fig. 1, in triangle △ OAG, OA and OG are known, the angle between OA and OG is 120 ° + θ, and Ua, which is characterized by the length of AG according to the cosine law, is:
Figure BDA0002433401090000042
when theta > 60 DEG, as shown in FIG. 2In triangle △ OAG, OA and OG are known, the angle between OA and OG is 240 ° - θ and the cosine of 240 ° + θ equals the cosine of 120 ° + θ, Ua, according to the cosine law, characterized by the length of AG, is the same as in equation (2), when θ is 60 °, Ua is 50V, as shown in fig. 3, and the result calculated by equation (2), let R be the detuning resistance and U be the detuning resistance△Is open delta voltage, I is open delta current, I ═ U△The voltage of the phase of the open delta three-phase voltage is the rated power of the open delta three-phase winding;
because the excitation characteristic of the conventional voltage transformer is designed according to 1.9 times of the rated voltage of a phase, and 1.9 of the excitation characteristic is called as a voltage transformer excitation characteristic voltage multiple K, the overload capacity can be very strong, the rated apparent power can reach 1.9 times, the iron core saturation caused by overload can not be caused, the multiple is higher for the voltage transformer resisting saturation resonance, for example, K is 2.5, and for the maximum value Um of the phase voltage of A when the phase of B is grounded in a single phase, Ua is provided, and the voltage transformer excitation characteristic comprises:
UmI≤KS (3)
Figure BDA0002433401090000051
let Umx be the maximum phase voltage of the three-phase secondary voltage of the system, i.e. the voltage of the three-phase secondary side of the voltage transformer, then there are:
Figure BDA0002433401090000052
belt-in (4) having:
Figure BDA0002433401090000053
therefore it has the advantages of
Figure BDA0002433401090000054
Thus, U△Resistance R at 100V100Comprises the following steps:
Figure BDA0002433401090000055
the same can be said for A, C phase single phase grounding.
In the invention, the automatic tracking adjustment of the harmonic elimination resistor under the condition of three-phase unbalance is specifically as follows: when three phases are unbalanced, a neutral point of the system can drift, and the open triangle can have power frequency voltage; when the open delta voltage is less than U△At ≦ 15V, the phase voltage corresponding to the phase up to the maximum is
Figure BDA0002433401090000056
Thus, the resonance elimination resistance RO put into the fault-free state is minimized
Figure BDA0002433401090000057
In addition, in the invention, the automatic tracking adjustment of the resonance elimination resistor under the condition of interphase short circuit is specifically as follows: two-phase short circuit and three-phase short circuit can be rapidly removed within 700ms by the microcomputer protection device, and the voltage transformer cannot be burnt out due to overload within 700ms no matter what resistance value of the resistor is set by the opening triangle; the worst two phases are grounded and shorted through a large resistor in different places, and the characteristics are that the voltage of one phase is reduced by the two phases and is unchanged, and no phase is increased, so that the harmonic elimination resistors are adjusted according to the condition that the voltage of the two phases is larger than that of the two phases in the formulas (7), (8) and (10), and the adjustment of the resistance value of the automatic tracking and adjusting harmonic elimination resistor cannot be influenced by the fault of the interphase short circuit.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (4)

1. A method for automatically tracking and adjusting a resonance elimination resistor is characterized by comprising the following steps: the method comprises the automatic tracking adjustment of the resonance elimination resistor under the condition of single-phase grounding, the automatic tracking adjustment of the resonance elimination resistor under the condition of three-phase unbalance and the automatic tracking adjustment of the resonance elimination resistor under the condition of inter-phase short circuit.
2. The method for automatically tracking and adjusting the harmonic elimination resistor according to claim 1, wherein: the automatic tracking adjustment of the harmonic elimination resistor under the condition of single-phase grounding specifically comprises the following steps: when the phase B is in single-phase grounding, Uam, Ubm and Ucm are phase voltages of three phases of an open triangle, Ua, Ub and Uc are secondary voltages of the three phases of the open triangle relative to the ground when the phase B is in grounding, and Uo is neutral point-to-ground voltage and is open triangle voltage U△Theta is an included angle between the zero-sequence voltage Uo and the phase B voltage Ubm, the phase B grounding phase A has the largest relative ground voltage Ua, the apparent power of the phase A is the largest, and the open delta voltage U cannot be overloaded as long as the phase A winding in the open delta is not overloaded by the other two phases△As monitored, in right triangle △ OBG:
Figure FDA0002433401080000011
when θ < 60 °, in triangle △ OAG, OA and OG are known, the angle between OA and OG is 120 ° + θ, and Ua, characterized by the length of AG according to the cosine law, is:
Figure FDA0002433401080000012
when theta is more than 60 degrees, OA and OG are known in triangle △ OAG, the included angle between OA and OG is 240-theta, the cosine value of 240-theta is equal to the cosine value of 120-theta, Ua represented by the length of AG is the same as the formula (2) according to the cosine law, Ua represented by the length of AG is 50V when theta is 60 degrees, the calculation result is the same as the calculation result of the formula (2), R is harmonic elimination resistance, U is equal to harmonic elimination resistance, and△is open delta voltage, I is open delta current, I ═ U△The voltage of the phase of the open delta three-phase voltage is the rated power of the open delta three-phase winding; the maximum value Um of the A-phase voltage when the B-phase is grounded in a single phase is equal to Ua, and the maximum value Um of the A-phase voltage is as follows:
UmI≤KS (3)
Figure FDA0002433401080000013
let Umx be the maximum phase voltage of the three-phase secondary voltage of the system, i.e. the voltage of the three-phase secondary side of the voltage transformer, then there are:
Figure FDA0002433401080000014
belt-in (4) having:
Figure FDA0002433401080000021
therefore it has the advantages of
Figure FDA0002433401080000022
Thus, U△Resistance R at 100V100Comprises the following steps:
Figure FDA0002433401080000023
the same can be said for A, C phase single phase grounding.
3. The method for automatically tracking and adjusting the harmonic elimination resistor according to claim 1, wherein: the automatic tracking adjustment of the harmonic elimination resistor under the condition of three-phase unbalance specifically comprises the following steps: when three phases are unbalanced, a neutral point of the system can drift, and the open triangle can have power frequency voltage; when the open delta voltage is less than U△At ≦ 15V, the phase voltage corresponding to the phase up to the maximum is
Figure FDA0002433401080000024
Thus, the resonance elimination resistance RO put into the fault-free state is minimized
Figure FDA0002433401080000025
4. The method for automatically tracking and adjusting the harmonic elimination resistor according to claim 1, wherein: the automatic tracking adjustment of the harmonic elimination resistor under the condition of interphase short circuit specifically comprises the following steps: two-phase short circuit and three-phase short circuit can be rapidly removed within 700ms by the microcomputer protection device, and the voltage transformer cannot be burnt out due to overload within 700ms no matter what resistance value of the resistor is set by the opening triangle; the worst two phases are grounded and shorted through a large resistor in different places, and the characteristics are that the voltage of one phase is reduced by the two phases and is unchanged, and no phase is increased, so that the harmonic elimination resistors are adjusted according to the condition that the voltage of the two phases is larger than that of the two phases in the formulas (7), (8) and (10), and the adjustment of the resistance value of the automatic tracking and adjusting harmonic elimination resistor cannot be influenced by the fault of the interphase short circuit.
CN202010243741.8A 2020-03-31 2020-03-31 Automatic tracking and adjusting method for resonance elimination resistor Withdrawn CN111355217A (en)

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