CN106229946A - A kind of ferromagnetic resonance harmonic elimination apparatus and method - Google Patents

Abstract

The present invention relates to a ferromagnetic resonance resonance elimination device and method, wherein the device is electrically connected to an electromagnetic voltage transformer in a distribution network, including: a power supply module, a resonance judgment module, a resonance elimination module and a current transformer , wherein, the power supply module is electrically connected to the resonance judgment module and the resonance elimination module; the current transformer is electrically connected to the connection wire between the neutral point of the electromagnetic voltage transformer and the ground, and the current mutual inductance The device is electrically connected to the resonance judgment module; the resonance elimination module includes a resonance elimination resistance and a first control switch, and the two ends of the resonance elimination resistance are connected in series to the two ends of the open triangle circuit of the electromagnetic voltage transformer , the first control switch is connected in series between the resonance elimination resistor and the open triangle circuit; the resonance judging module is electrically connected to the first control switch. The device provided by this embodiment can accurately and rapidly eliminate ferromagnetic resonance, and improve the efficiency of ferromagnetic resonance elimination.

Description

A ferromagnetic resonance resonance elimination device and method

technical field

The invention relates to the technical field of power system safety prevention and control, in particular to a ferromagnetic resonance resonance elimination device and method.

Background technique

In the distribution network below 66kV and below 66kV, a non-effective grounding system is usually adopted in which the neutral point of the system is not grounded and the neutral point is grounded through a small resistance or an arc suppression coil. The system bus is connected with an electromagnetic voltage for monitoring insulation to ground. Transformer (Potential Transformer, PT). Transient impacts caused by lightning strikes on the line, single-phase grounding, combined-air bus operation, drastic load changes, and secondary voltage-load switching may excite ferromagnetic resonance between the excitation reactance of the electromagnetic voltage transformer and the ground capacitance of the system . In recent years, frequent damage to electromagnetic voltage transformers and frequent blown fuses caused by ferromagnetic resonance still plague equipment operation and maintenance units. This type of neutral point ungrounded system or non- The effective grounding system (the part accidentally disconnected from the grounding of the small resistance or the arc suppression coil) is likely to cause frequent damage to the equipment and increase the cost of operation and maintenance.

At present, the protection methods for ferromagnetic resonance in related technologies are mainly: installing a resonance eliminator at the primary neutral point of the electromagnetic voltage transformer, or installing damping in the zero-sequence voltage circuit of the electromagnetic voltage transformer Resistor, by adding a microcomputer secondary harmonic elimination device and detecting zero-sequence voltage and voltage waveform of each phase, etc. Among them, a resonance eliminator is installed at the primary neutral point of the electromagnetic voltage transformer, that is, the resonance eliminator is connected to the neutral point of the electromagnetic voltage transformer in turn, and the generated ferromagnetic resonance is eliminated through the resonance eliminator.

However, the method of installing a resonance eliminator at the primary center point of the electromagnetic voltage transformer can prevent the ferromagnetic resonance between the three-phase voltage and the ground that is easily generated in the system, but for the power frequency resonance caused by disconnection The effect is poor, and it is easy to cause the voltage increase of the neutral point of the electromagnetic voltage transformer, the insulation breakdown of the end of the electromagnetic voltage transformer and other undesirable phenomena, causing the resonance eliminator to lose its function; adding a damping resistor will cause heat due to the damping resistor Affect the effect of harmonic elimination; using a microcomputer secondary resonance eliminator device, it is difficult to distinguish power frequency resonance due to the method of detecting zero-sequence voltage and three-phase voltage waveform, and there is a problem that the detection circuit and harmonic elimination circuit share or need to detect three-phase voltage.

Therefore, adopting the above-mentioned existing harmonic elimination method will not only prolong the harmonic elimination time and increase the harmonic elimination cost, but also greatly affect the harmonic elimination efficiency, cause frequent damage to equipment, and pose a serious threat to the safe and stable operation of the power grid and equipment .

Contents of the invention

In order to overcome the problems existing in the related art, the present invention provides a ferromagnetic resonance resonance elimination device and method.

According to the first aspect of the embodiments of the present invention, a ferromagnetic resonance elimination device is provided, which is used to eliminate the ferromagnetic resonance of the electromagnetic voltage transformer in the distribution network, including: a power supply module, a resonance judgment module, a resonance elimination module and current transformers, where,

The power supply module is electrically connected to the resonance judgment module and the resonance elimination module;

The current transformer is electrically connected to the connection wire between the neutral point of the electromagnetic voltage transformer and the ground, and the current transformer is electrically connected to the resonance judgment module;

The harmonic elimination module includes a resonance elimination resistor and a first control switch, the two ends of the resonance elimination resistor are connected in series to the two ends of the open triangle circuit of the electromagnetic voltage transformer, and the first control switch is connected in series to the between the resonance elimination resistor and the open triangle circuit; the resonance judging module is electrically connected to the first control switch.

Optionally, the harmonic elimination module further includes a second control switch, wherein,

The second control switch is connected in parallel with the harmonic elimination resistor and the first control switch, and the second control switch is electrically connected to two ends of the open triangle circuit respectively.

Optionally, the device further includes a timer, and the timer is electrically connected to the resonance judgment module and the resonance elimination module, respectively.

Optionally, the resistance range of the harmonic elimination resistor is 0.5-10Ω.

Optionally, the resistance value of the harmonic elimination resistor is 1Ω.

In the second aspect of the embodiments of the present invention, a ferromagnetic resonance resonance elimination method is also provided, including:

Judging whether the current transformer detects the zero-sequence current between the neutral point of the electromagnetic voltage transformer and the ground;

When it is detected that the zero-sequence current reaches the preset zero-sequence current, calculate the pulse number and pulse width of the zero-sequence current that reaches the preset pulse amplitude within the first preset time length, wherein the preset pulse width The value is greater than the pulse amplitude of the preset zero-sequence current;

According to the number of pulses and the pulse width, it is judged whether ferromagnetic resonance occurs in the electromagnetic voltage transformer;

When ferromagnetic resonance occurs in the electromagnetic voltage transformer, the first control switch connected in series with the resonance elimination resistor is controlled to close, and the resonance elimination process is performed on the electromagnetic voltage transformer.

Optionally, the calculation of the pulse number and pulse width of the zero-sequence current reaching the preset pulse amplitude within the first preset duration includes:

When it is detected that the zero-sequence current reaches the preset zero-sequence current, start the first timer and start timing;

Collecting the zero-sequence current within the first preset duration of the timing through a current transformer;

Find the zero-sequence current whose pulse amplitude is greater than or equal to the preset pulse amplitude;

Calculate the pulse number and pulse width of the zero-sequence current whose pulse amplitude is greater than or equal to the preset pulse amplitude.

Optionally, judging whether ferromagnetic resonance occurs in the electromagnetic voltage transformer includes:

judging whether the number of pulses of the zero-sequence current is greater than 6, and whether the pulse width is greater than 3ms;

When the number of zero-sequence current pulses is greater than 6 and the pulse width is greater than 3 ms, it is determined that ferromagnetic resonance occurs in the electromagnetic voltage transformer.

Optionally, when the first control switch connected in series with the resonance elimination resistor is controlled to be closed, the method further includes:

Start the second timer and start counting;

judging whether the pulse amplitude of the zero-sequence current falls below the preset pulse amplitude of the zero-sequence current within a second preset duration;

When the zero-sequence current does not drop below the pulse amplitude of the preset zero-sequence current, control the first control switch to turn off, and control the open delta circuit electrically connected to the electromagnetic voltage transformer The second control switch is closed to short-circuit the open delta circuit of the electromagnetic voltage transformer and eliminate the ferromagnetic resonance of the electromagnetic voltage transformer.

Optionally, when controlling the closing of the second control switch electrically connected to the open delta circuit of the electromagnetic voltage transformer, the method further includes:

Start the third timer and start counting;

judging in real time whether the pulse amplitude of the zero-sequence current is lower than the pulse amplitude of the preset zero-sequence current;

When the pulse amplitude of the zero-sequence current does not drop below the preset zero-sequence current pulse amplitude and the third duration of the timing reaches a third preset duration, control the second control switch to turn off open;

When controlling the off time of the second control switch to reach the fourth preset time length, re-control the second control switch

Close and close until the pulse amplitude of the zero-sequence current drops below the pulse amplitude of the preset zero-sequence current.

The technical solutions provided by the embodiments of the present invention may include the following beneficial effects:

An embodiment of the present invention provides a ferromagnetic resonance resonance elimination device, the device is electrically connected to the electromagnetic voltage transformer in the distribution network, specifically, the device includes a power supply module, a resonance judgment module, a resonance elimination module and a current A transformer, wherein the power supply module is electrically connected to the resonance judgment module and the resonance elimination module; the current transformer is electrically connected to the connection wire between the neutral point of the electromagnetic voltage transformer and ground; the The harmonic elimination module includes a resonance elimination resistor and a first control switch, the two ends of the resonance elimination resistor are connected in series to the two ends of the open triangle circuit of the electromagnetic voltage transformer, and the first control switch is connected in series to the between the resonant resistor and the open triangle circuit; the resonant judging module is electrically connected to the first control switch.

In the embodiment of the present invention, the power supply module provides the power supply voltage for the resonance judgment module and the resonance elimination module, and the current transformer detects the zero-sequence current of the open delta circuit (that is, the zero-sequence voltage circuit) of the electromagnetic voltage transformer, and converts the zero-sequence The sequence current is sent to the resonance judging module, and the resonance judging module can judge whether ferromagnetic resonance occurs in the electromagnetic voltage transformer according to the magnitude of the zero-sequence current, and if ferromagnetic resonance occurs, it can control the first control switch to close, The harmonic elimination resistor and the open triangle circuit form a series circuit, and the resonance elimination resistor increases the damping of the primary circuit of the electromagnetic voltage transformer, thereby quickly eliminating the ferromagnetic resonance of the electromagnetic voltage transformer. Since the resonance elimination resistor is directly connected to the open triangle circuit , can accurately and quickly eliminate ferromagnetic resonance, thereby effectively improving the efficiency of ferromagnetic resonance resonance elimination, and the structure is simple, effectively reducing the cost of complex microcomputer secondary resonance elimination devices used in power grids in the prior art.

In addition, in the implementation of the present invention, by connecting a second control switch in parallel with the resonance elimination resistor and the first control switch, once passing through the resonance elimination resistor, the ferromagnetic resonance generated by the electromagnetic voltage transformer cannot be quickly When the resonance is eliminated, the second control switch can be controlled to close by the resonance judging module, so that the open triangle circuit of the electromagnetic voltage transformer forms a short circuit, which is equivalent to short-circuiting the excitation circuit of the electromagnetic voltage transformer of the resonant circuit. The rapid elimination of the ferromagnetic resonance generated by the electromagnetic voltage transformer can further improve the elimination efficiency of the ferromagnetic resonance, and greatly shorten the time for eliminating the ferromagnetic resonance in the prior art.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description serve to explain the principles of the invention.

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, In other words, other drawings can also be obtained from these drawings without paying creative labor.

Fig. 1 is a schematic structural diagram of a ferromagnetic resonance resonance elimination device provided by an embodiment of the present invention;

Fig. 2 is a schematic diagram of an application scenario of a ferromagnetic resonance resonance elimination device provided by an embodiment of the present invention;

FIG. 3 is a schematic flow chart of a ferromagnetic resonance resonance elimination method provided by an embodiment of the present invention;

FIG. 4 is a detailed flowchart of step S102 of a ferromagnetic resonance resonance elimination method provided by an embodiment of the present invention;

FIG. 5 is a detailed flowchart of step S103 of a ferromagnetic resonance resonance elimination method provided by an embodiment of the present invention;

FIG. 6 is a schematic flowchart of another ferromagnetic resonance harmonic elimination method provided by an embodiment of the present invention;

FIG. 7 is a schematic flowchart of another ferromagnetic resonance harmonic elimination method provided by an embodiment of the present invention.

detailed description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numerals in different drawings refer to the same or similar elements unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with aspects of the invention as recited in the appended claims.

Fig. 1 is a schematic structural diagram of a ferromagnetic resonance resonance elimination device according to an exemplary embodiment. As shown in 1, the device may include a power supply module 11, a resonance judgment module 12, a resonance elimination module and a current transformer 16 (CT, Current Transformer).

In the disclosed embodiment of the present invention, the power supply module 11 is electrically connected to the resonance judgment module 12 and the resonance elimination module respectively, so as to provide power for the resonance judgment module 12 and the resonance elimination module, and the power supply module 11 can provide the resonance The judging module 12 and the harmonic elimination module provide the power supply of the corresponding supply voltage, and the power module 11 can be directly connected to the mains, and the resonance judging module 12 can be a CPU (Central Processing Unit, central processing unit) or a PLC (ProgrammableLogic Controller, programmable logic controller), the resonance judgment module 12 is electrically connected to the resonance elimination module, and is used to control the resonance elimination module to eliminate resonance; the current transformer 16 is used to be electrically connected to the electromagnetic voltage transformer 17 The connection wire between the neutral point and the ground, so that the current transformer 16 measures the zero-sequence current (that is, the sum of the three-phase excitation current of the electromagnetic voltage transformer).

In order to realize the ferromagnetic resonance of the electromagnetic voltage transformer 17 in the distribution network, the resonance elimination module at least includes a resonance elimination resistor 13 and a first control switch 14, and the two ends of the resonance elimination resistor 13 are connected in series to the The two ends of the open delta loop of the electromagnetic voltage transformer 17, the first control switch 14 is connected in series between the harmonic elimination resistor 13 and the open triangle loop, namely the open triangle loop, the resonance elimination resistor 13 and the first control switch 14 forms a series loop, and the open triangle loop, the harmonic elimination resistor 13 and the first control switch 14 form a closed or disconnected series loop by turning on and off the first control switch 14 . And in the disclosed embodiment of the present invention, the resonance judging module 12 is electrically connected to the first control switch 14 , so that the resonance judging module 12 controls the on-off of the first control switch 14 .

Wherein, in the disclosed embodiment of the present invention, the resistance range of the harmonic elimination resistor 13 is 0.5-10Ω, preferably 1Ω, and the two sides of the open triangle circuit of the electromagnetic voltage transformer 17 are connected through the harmonic elimination resistor 13 end, so that the resistance of the resonance elimination resistor 13 increases the loop damping of the electromagnetic voltage transformer in turn, thereby eliminating the ferromagnetic resonance generated by the electromagnetic voltage transformer. Moreover, the first control switch 14 generally adopts a power electronic switch or a relay switch, and the power supply module 11 is electrically connected to the first control switch 14 and the second control switch 15 respectively, so that the resonance judgment module 12 controls the first control switch 14 to make The harmonic elimination resistor 13 is directly connected in series with the open triangle circuit, so that it can quickly eliminate the resonance of the electromagnetic voltage transformer. In the specific implementation process, the smaller the resistance value of the harmonic elimination resistor 13, the better. For example, when the resistance value of the harmonic elimination resistor 13 is 0.5Ω, the primary loop damping of the electromagnetic voltage transformer 17 can be increased to the greatest extent, so that the electromagnetic The ferromagnetic resonance of the type voltage transformer 17 is quickly eliminated.

In the ferromagnetic resonance resonance elimination device provided by the embodiment of the present invention, when the resonance elimination resistor 13 cannot be used to quickly eliminate the ferromagnetic resonance of the electromagnetic voltage transformer 17, the ferromagnetic resonance resonance elimination device provided by the embodiment of the present invention The harmonic elimination module also includes a second control switch 15, the second control switch 15 is provided in parallel with the harmonic elimination resistor 13 and the first control switch 14, and the second control switch 15 is electrically connected to the open triangle circuit respectively. At both ends, the open triangle circuit and the second control switch 15 form a series circuit by controlling the on-off of the second control switch 15 . Thereby, when the ferromagnetic resonance produced by the electromagnetic voltage transformer cannot be quickly eliminated by the resonance elimination resistor 13, the second control switch 15 can be put into use, so that the open triangle circuit is connected in series with the second control switch 15 to form a short circuit, and then the electromagnetic voltage transformer The ferromagnetic resonance of the voltage transformer is eliminated.

In addition, in the disclosed embodiment of the present invention, the device can also include a timer (not shown in the figure), and the timer is electrically connected to the resonance judgment module 12 and the resonance elimination module respectively, and the power supply module 11 is used for timing The resonant judgment module 12 precisely controls the closure of the first control switch 14 and the second control switch 15 according to the timing of the timer, so as to achieve the purpose of precisely eliminating the ferromagnetic resonance of the electromagnetic voltage transformer 17 , effectively improve the efficiency of harmonic elimination. At the same time, in the disclosed embodiments of the present invention, one timer can be used to time different periods of time, and the number of the timers can be set in multiples as required, and multiple timers can time different periods of time in segments, so that Effectively improve the precise control of time.

Fig. 2 shows a schematic diagram of the application scene of the ferromagnetic resonance resonance elimination device provided by the embodiment of the present invention in the distribution network. As shown in Fig. 2, the ferromagnetic resonance resonance elimination device provided by the embodiment of the present invention includes a power module 11, a resonance Judgment module 12, resonance elimination resistance 13, first control switch 14, second control switch 15 and current transformer 16, described power module 11 is electrically connected to described resonance judgment module 12 and resonance elimination module respectively, and described current mutual inductance The transformer 16 is also electrically connected to the resonance judging module 12, and the current transformer 16 is used to send the collected zero-sequence current to the resonance judging module 12.

Wherein, in the distribution network, the three-phase voltages (E1, E2, E3) are respectively electrically connected to the electromagnetic voltage transformer 17, and the electromagnetic voltage transformer 17 is connected in parallel with a three-phase capacitor (C1, C2, C3), The three-phase capacitors are respectively electrically connected to the three-phase voltages. The electromagnetic voltage transformer 17 includes an open delta circuit, and the current transformer 16 is electrically connected to the connection wire between the neutral point of the electromagnetic voltage transformer 17 and the ground, so as to collect the electromagnetic voltage transformer 17 zero-sequence current; the harmonic elimination resistor 13 and the first control switch 14 are connected in series, and connected in series at both ends of the open triangle circuit, and the second control switch 15 is connected in parallel with the harmonic elimination resistor 13 and the first control switch 14 set, and the second control switch 15 is connected in series to both ends of the open triangle circuit.

In the specific implementation process, when the electromagnetic voltage transformer 17 does not have electromagnetic resonance, the first control switch 14 and the second control switch 15 are all in the state when the electromagnetic voltage transformer 17 has electromagnetic resonance, and the resonance is judged The module 12 controls the first control switch 14 to close, so that the open triangle loop and the resonance elimination resistor 13 form a series loop, and the primary loop damping of the electromagnetic voltage transformer 17 is increased through the resonance elimination resistor 13, thereby eliminating ferromagnetic resonance; when the first control If the ferromagnetic resonance has not been eliminated after the switch 14 is closed for a preset time (such as 50 ms), the resonance judgment module 12 controls the second control switch 15 to close, and simultaneously opens the first control switch 14 to make the open triangle circuit and the second control switch 15 A series circuit is formed. After the second control switch 15 is connected in series with the open delta circuit, the second control switch 15 forms the same wire, that is, the open delta circuit is directly short-circuited, thereby eliminating the ferromagnetic resonance of the electromagnetic voltage transformer 17.

Using the ferromagnetic resonance resonance elimination device provided by the embodiment of the present invention, the power supply module provides the power supply voltage for the resonance judgment module and the resonance elimination module, and the current transformer detects the zero-sequence current of the open triangle circuit of the electromagnetic voltage transformer, and The zero-sequence current is sent to the resonance judging module, and the resonance judging module can judge whether ferromagnetic resonance occurs in the electromagnetic voltage transformer according to the magnitude of the zero-sequence current, and if ferromagnetic resonance occurs, it can control the first control The switch is closed, so that the resonance elimination resistor and the open triangle circuit form a series circuit, and the resonance elimination resistor increases the damping of the primary circuit of the electromagnetic voltage transformer, thereby quickly eliminating the ferromagnetic resonance of the electromagnetic voltage transformer. Since the resonance elimination resistor is directly connected to the opening On the triangular circuit, the ferromagnetic resonance can be quickly eliminated, thereby effectively improving the efficiency of ferromagnetic resonance elimination, and the structure is simple, which effectively reduces the cost of complex devices used by enterprises in the prior art.

In addition, in the implementation of the present invention, by connecting a second control switch in parallel with the resonance elimination resistor and the first control switch, once passing through the resonance elimination resistor, the ferromagnetic resonance generated by the electromagnetic voltage transformer cannot be quickly When the resonance is eliminated, the second control switch can be controlled to close through the resonance judging module, so that the open triangle circuit of the electromagnetic voltage transformer forms a short circuit, thereby quickly eliminating the ferromagnetic resonance generated by the electromagnetic voltage transformer, which can further improve the ferromagnetic resonance. The elimination efficiency of the magnetic resonance greatly shortens the time for eliminating the ferromagnetic resonance in the prior art.

The above is a detailed description of the embodiment of the device provided by the present invention. In the disclosed embodiment of the present invention, an embodiment of the resonance elimination method for ferromagnetic resonance is also provided. For details, refer to the following detailed implementation Example description.

Fig. 3 shows a schematic flowchart of a ferromagnetic resonance resonance elimination method provided by an embodiment of the present invention. The ferromagnetic resonance resonance elimination method disclosed in the present invention is applied to the resonance judgment module 12 in the ferromagnetic resonance resonance elimination device, and the resonance judgment module 12 judges whether the electromagnetic voltage transformer 17 occurs according to the zero-sequence current collected by the current transformer 16 Ferromagnetic resonance, and by controlling the on-off of the first control switch 14 and the second control switch 15, the ferromagnetic resonance generated by the electromagnetic voltage transformer 17 is eliminated. As shown in Fig. 3, the method may include the following steps.

In step S101, it is judged whether the current transformer detects the zero-sequence current between the neutral point of the electromagnetic voltage transformer and the ground. Otherwise, end.

When the electromagnetic voltage transformer does not have ferromagnetic resonance, the open triangle circuit of the electromagnetic voltage transformer will not generate induced current, so the current transformer can be used to detect the neutral point of the electromagnetic voltage transformer and the ground. The magnitude of the zero-sequence current is enough.

When it is detected that the zero-sequence current reaches the preset zero-sequence current, in step S102, the pulse number and pulse width of the zero-sequence current reaching the preset pulse amplitude within the first preset duration are calculated.

In the disclosed embodiments of the present invention, under normal circumstances, when the electromagnetic voltage transformer does not generate ferromagnetic resonance, there will still be zero-sequence current, but at this time the pulse amplitude of the zero-sequence current is relatively low, about 0-0.2 mA. When detecting the zero-sequence current, it is necessary to judge whether the zero-sequence current exceeds the preset pulse amplitude zero-sequence current (that is, the starting zero-sequence current of the ferromagnetic resonance resonance elimination device), and the pulse amplitude of the preset zero-sequence current is 10 -100mA, and the pulse amplitude of the preset zero-sequence current is preferably 60mA. And the preset pulse amplitude is greater than the preset zero-sequence current pulse amplitude, only the pulse number and pulse width of the zero-sequence current within a certain period of time can determine whether the electromagnetic voltage transformer has ferromagnetic resonance. Wherein, when the zero-sequence current is detected, the timer can be started, and the pulse number and pulse width of the zero-sequence current reaching the preset pulse amplitude within the first preset duration can be calculated. In the specific implementation process, the first preset duration can be set to 20ms, the preset pulse amplitude is the amplitude of the start-up of the ferromagnetic resonance resonance elimination device, and the preset pulse amplitude can be set to 100-500mA, The preferred setting is 200mA, so that ferromagnetic resonance can be found and eliminated in time. In the implementation process, the first preset duration and preset pulse amplitude are not limited to the values proposed in the above embodiments, and can be determined according to the resistance value of the electromagnetic voltage transformer and the resonance elimination resistor, which will not be repeated here Elaborate.

Refer to FIG. 4 for a detailed flowchart of step S102 provided in the embodiment of the present invention. As shown in Figure 4, step S102 specifically includes the following steps:

When it is detected that the zero-sequence current reaches the preset zero-sequence current, in step S1021, start a first timer to start timing.

In the disclosed embodiments of the present invention, it is necessary to determine whether the electromagnetic resonance occurs in the electromagnetic current transformer by judging the number of pulses and pulse width of the zero-sequence current within a certain period of time, and when the zero-sequence current is greater than 10-100mA, it starts That is to count the pulse number and pulse width of the zero-sequence current. Therefore, when the zero-sequence current is detected, the first timer is started to count the first preset duration. During the implementation process, the timing can be counted down .

In step S1022, the current transformer is used to collect the zero-sequence current within the first preset period of time.

When the timing starts, the current transformer collects all zero-sequence currents within the first preset time length, and calculates the pulse width of each zero-sequence current according to the recorded pulse number of all zero-sequence currents, which facilitates step S1023 deal with. Wherein, the first preset duration is 20ms, and the first preset duration is not necessarily set to 20ms, it can also be calculated according to the period of the ferromagnetic resonance pulse current generated by the electromagnetic voltage transformer, which can be The multiple of the period of the pulsed current for ferroresonance.

When all the zero-sequence currents within the first preset time period are collected, in step S1023, the zero-sequence current whose pulse amplitude is greater than or equal to the preset pulse amplitude is searched.

In the disclosed embodiment of the present invention, the preset pulse amplitude is a preset value. In the specific implementation process, the preset pulse amplitude is 100-500mA, that is, only the pulse amplitude of the zero-sequence current Only when it is greater than or equal to the preset pulse amplitude can it be regarded as the zero-sequence current under the occurrence of ferromagnetic resonance. Therefore, it is only necessary to search for the zero-sequence current greater than or equal to the preset pulse amplitude in step S1022.

When the zero-sequence current whose pulse amplitude is greater than or equal to the preset pulse amplitude is found, in step S1024, the pulse number and pulse width of the zero-sequence current whose pulse amplitude is greater than or equal to the preset pulse amplitude are calculated .

According to the zero-sequence current determined in step S1023, the number of pulses of the zero-sequence current in step S1023 and the corresponding pulse width are calculated.

In the disclosed embodiments of the present invention, the detailed flow of step S102 is not limited to the sequence of the steps shown in the above-mentioned embodiments. The pulse number and pulse width of all zero-sequence currents can be calculated first, and then according to the zero-sequence current The zero-sequence pulse current that meets the requirements is screened out based on the pulse amplitude of the sequence current.

By adopting the method of the above-mentioned embodiment, the amount of data processing can be reduced to the greatest extent, thereby speeding up the screening of suitable zero-sequence current, thereby reducing the processing time, quickly judging whether electromagnetic resonance occurs in the electromagnetic voltage transformer, and passing through the resonance elimination resistor Harmonic elimination is carried out to further improve the efficiency of harmonic elimination.

When the pulse number and pulse width of the zero-sequence current reaching the preset pulse amplitude within the first preset duration are obtained, in step S103, it is judged whether ferromagnetic resonance occurs in the electromagnetic voltage transformer. Otherwise, continue to execute step S101.

In the embodiment of the present invention, it is judged whether ferromagnetic resonance occurs in the electromagnetic voltage transformer by obtaining the pulse number and pulse width of the zero-sequence current reaching the preset pulse amplitude in step S102, wherein, specifically, when the step When the number of pulses and the pulse width of the zero-sequence current obtained in S102 reach the preset number of pulses and the preset pulse width, it is determined that ferromagnetic resonance occurs in the electromagnetic voltage transformer.

In the embodiment of the present invention, refer to FIG. 5 for a detailed flowchart of step S103. As shown in Figure 5, the step S103 may include the following steps:

In step S1031, it is judged whether the number of pulses of the zero-sequence current is greater than 6, and whether the pulse width is greater than 3ms. Otherwise, execute step S101.

When the number of pulses and the pulse width of the zero-sequence current reaching the preset pulse amplitude within the first preset time length are calculated in step S102, it is necessary to determine whether the electromagnetic voltage transformer is ferromagnetic according to the number of pulses and the pulse width resonance. When the number of pulses and the pulse width of the zero-sequence current in step S102 reach a preset value, it is determined that the electromagnetic voltage transformer has ferromagnetic resonance. In the specific implementation process, the above preset values are: the number of zero-sequence current pulses is 6, and the pulse width is 3ms. Therefore, by judging whether the number of zero-sequence current pulses is greater than 6, and whether the pulse width is greater than 3ms, then It can be determined whether the electromagnetic voltage transformer has ferromagnetic resonance.

When the number of zero-sequence current pulses is greater than 6 and the pulse width is greater than 3 ms, it is determined that ferromagnetic resonance occurs in the electromagnetic voltage transformer.

When ferromagnetic resonance occurs in the electromagnetic voltage transformer, in step S104, the first control switch connected in series with the resonance elimination resistor is controlled to be closed, and the resonance elimination process is performed on the electromagnetic voltage transformer.

In the embodiment of the present invention, when it is determined in step S103 that ferromagnetic resonance occurs in the electromagnetic voltage transformer, the first control switch is controlled to be closed, so that the open triangle circuit of the electromagnetic voltage transformer, the resonance elimination resistor and the first control switch form a A series circuit, so that the primary loop damping of the electromagnetic voltage transformer is increased by the harmonic elimination resistor, thereby eliminating the ferromagnetic resonance generated by the electromagnetic voltage transformer.

Using the method provided by the embodiment of the present invention, the electromagnetic voltage mutual inductance can be determined according to the pulse number and pulse width of the zero-sequence current exceeding the preset pulse amplitude (that is, the current threshold started by the ferromagnetic resonance resonance elimination device) within a certain period of 20ms Whether the transformer produces ferromagnetic resonance, and then controls the action of the first control switch, so that the resonance elimination resistor increases the primary loop damping of the electromagnetic voltage transformer, thereby quickly eliminating the ferromagnetic resonance generated by the electromagnetic voltage transformer, thereby effectively improving the ferromagnetic The harmonic elimination efficiency of resonance avoids frequent damage to equipment and poses a serious threat to the safe and stable operation of the power grid and equipment.

FIG. 6 shows a schematic flowchart of another ferromagnetic resonance resonance elimination method provided by an embodiment of the present invention. As shown in Fig. 6, the method may include the following steps.

In step S101, it is judged whether the current transformer detects the zero-sequence current between the neutral point of the electromagnetic voltage transformer and the ground.

When it is detected that the zero-sequence current reaches the preset zero-sequence current, in step S102, the pulse number and pulse width of the zero-sequence current reaching the preset pulse amplitude within the first preset duration are calculated.

When the number of pulses and the pulse width of the zero-sequence current are calculated, in step S103, it is judged whether ferromagnetic resonance occurs in the electromagnetic voltage transformer.

When ferromagnetic resonance occurs in the electromagnetic voltage transformer, in step S104, the first control switch connected in series with the resonance elimination resistor is controlled to be closed, and the resonance elimination process is performed on the electromagnetic voltage transformer.

When the first control switch connected in series with the resonance elimination resistor is controlled to be closed, in step S105, the second timer is started to start timing.

In the disclosed embodiment of the present invention, the second timer can be preset to distinguish it from the first timer in step S1021. Since the first control switch is controlled to be closed, the resonance elimination resistor will react to the ferromagnetism generated by the electromagnetic voltage transformer. When the resonance is used to eliminate the resonance, it is not allowed to connect the resonance elimination resistor and the open triangle circuit of the electromagnetic voltage transformer in series for a long time, otherwise the resonance elimination resistor will be burned. Therefore, the second timer needs to be used to count again. When the second preset duration is reached, the first control switch is turned off to protect the resonance elimination resistor. Of course, in this step, the first timer can also be used to re-time.

Wherein, in the implementation process, the second preset duration is a preset duration, that is, the resonance elimination is performed by the resonance elimination resistor within the second preset duration, and if the resonance elimination by the resonance elimination resistor is successful within the second preset duration, then The resonance judging module immediately disconnects the first control switch, so that the electromagnetic voltage transformer is put into use again. The timing method of the second preset duration can be counted down.

In step S106, it is determined whether the pulse amplitude of the zero-sequence current falls below the preset pulse amplitude of the zero-sequence current within a second preset time period. Otherwise, the first switch is controlled to be turned off.

In the embodiment of the present invention, when step S105 starts timing, read the zero-sequence current collected by the current transformer, and judge whether the pulse amplitude of the zero-sequence current reaches the preset pulse according to the pulse amplitude of the zero-sequence current below the magnitude. If within the second preset time period, the pulse amplitude of the zero-sequence current drops below the preset zero-sequence current pulse amplitude, it ends, and at the same time, the first control switch is controlled to be turned off, and the electromagnetic voltage transformer Ferroresonance cancellation. If the pulse amplitude of the zero-sequence current does not drop below the preset pulse amplitude of the zero-sequence current when the counted time reaches the second preset time, step S107 is executed. Wherein, in the specific implementation process, the second preset duration is 50ms, that is, if the resonance elimination resistor is input for 50ms and the resonance elimination is still performed, the resonance elimination resistor may be burned, which will affect the next resonance elimination process, and it needs to be controlled Closing of the second control switch further implements harmonic elimination, however, the second preset duration is not limited to 50ms.

When the zero-sequence current does not drop below the pulse amplitude of the preset zero-sequence current, in step S107, the first control switch is controlled to be turned off, and the opening of the electromagnetic voltage transformer is controlled. The second control switch electrically connected to the delta circuit is closed.

In the embodiment of the present invention, when the timed duration reaches the second preset duration, and the pulse amplitude of the zero-sequence current has not decreased to below the preset zero-sequence current pulse amplitude of 10-100mA, firstly control the first The first control switch is disconnected, that is, the series circuit between the harmonic elimination resistor and the open triangle circuit of the electromagnetic voltage transformer is disconnected, and the second control switch is controlled to be closed at the same time, that is, the open triangle circuit of the electromagnetic voltage transformer and the second control The switches form a series loop. Because the second control switch has no resistance value and no other electrical components in this loop, the open triangle loop is like a short circuit, thereby eliminating the ferromagnetic resonance of the electromagnetic voltage transformer.

In the implementation process of the embodiment of the present invention, when the ferromagnetic resonance generated by the electromagnetic voltage transformer is relatively large, and the second control switch is controlled to close for a certain period of time, and the ferromagnetic resonance cannot be eliminated, if the electromagnetic voltage transformer is consistently maintained If the open delta circuit of the open circuit is short-circuited, the electromagnetic voltage transformer may be burned. Therefore, the embodiment of the present invention provides another implementation manner on the basis of the foregoing FIG. 6 . See Figure 7 for details.

As shown in FIG. 7 , the detailed flowchart of the ferromagnetic resonance harmonic elimination method is provided. Step S107 of the method may also include the following steps.

When the second control switch electrically connected to the open delta circuit of the electromagnetic voltage transformer is controlled to be closed, in step S1071, the third timer is started to start timing.

In the disclosed embodiment of the present invention, a third timer can be preset, and the third timer is different from the first timer and the second timer, so that when the second control switch is closed, the third timer starts timing. In the specific implementation process, the third timer can also be the second timer or the first timer, or the first timer, the second timer and the third timer are the same timer, but they are timed separately, and Independent timing in each timing process.

In step S1072, it is judged in real time whether the pulse amplitude of the zero-sequence current is lower than the preset pulse amplitude of the zero-sequence current. Otherwise, turn off the second control switch.

When the third timer starts counting, by receiving the zero-sequence current collected by the current transformer, the magnitude of the pulse amplitude of the zero-sequence current is judged, and according to the magnitude of the pulse amplitude of the zero-sequence current, it is judged whether it is less than the preset zero-sequence current The pulse amplitude of the preset zero-sequence current is 10-100mA. When the pulse amplitude of the zero-sequence current is reduced below the preset zero-sequence current pulse amplitude, that is, the harmonic elimination is successful, and the first control switch can be turned off; when the pulse amplitude of the zero-sequence current does not decrease When the pulse amplitude of the preset zero-sequence current is below, step S1073 is executed.

In step S1073, when the pulse amplitude of the zero-sequence current does not drop below the preset zero-sequence current pulse amplitude and the third duration of the timing reaches a third preset duration, control the The second control switch is turned off.

When the pulse amplitude of the zero-sequence current does not drop below the pulse amplitude of the preset zero-sequence current, and the timing time does not reach the third preset duration, the harmonic elimination will continue to be performed by shorting the open triangle circuit; when the zero-sequence When the pulse amplitude of the current does not decrease below the pulse amplitude of the preset zero-sequence current, and the timing time reaches the third preset duration, the ferromagnetic resonance of the electromagnetic voltage transformer has not been eliminated. Therefore, the first The second control switch is disconnected to prevent the open triangle circuit of the electromagnetic voltage transformer from being short-circuited for a long time to burn the electromagnetic voltage transformer. Wherein, the third preset time length is set to 200ms, so as to avoid the electromagnetic voltage transformer from burning out. However, the third preset duration is not limited to 200 ms, it can be set according to the open delta circuit of the electromagnetic voltage transformer, and will not be described in detail here.

When the second control switch is controlled to be turned off, in step S1074, when the second control switch is controlled to be turned off for a fourth preset duration, the second control switch is re-controlled to be closed until the zero-sequence current falls below the pulse amplitude of the zero-sequence current.

In the disclosed embodiment of the present invention, the fourth preset duration can be set to 20-60ms, and the preferred fourth preset duration can be set to 40ms. There can be a third timer to re-time, or, the fourth timer is preset, and the fourth timer starts to count. When the timing reaches 20-60ms, the second control switch is re-controlled to close, so that the electromagnetic voltage mutual induction The open delta circuit of the transformer is short-circuited to eliminate the ferromagnetic resonance of the electromagnetic voltage transformer. And repeat the above step S1071 to step S1073 until the pulse amplitude of the zero-sequence current is lower than the preset pulse amplitude of the zero-sequence current.

Using the above method provided by the embodiment of the present invention, when the resonance elimination resistor cannot quickly eliminate the ferromagnetic resonance generated by the electromagnetic voltage transformer, the resonance judgment module can control the second control switch to be closed, so that The open triangle circuit of the electromagnetic voltage transformer forms a short circuit, thereby quickly eliminating the ferromagnetic resonance generated by the electromagnetic voltage transformer, which can further improve the elimination efficiency of the ferromagnetic resonance, and greatly shorten the time for eliminating the ferromagnetic resonance in the prior art. At the same time, avoid frequent damage to equipment, which poses a serious threat to the safe and stable operation of the power grid and equipment.

Other embodiments of the invention will be readily apparent to those skilled in the art from consideration of the specification and practice of the invention disclosure herein. This application is intended to cover any modification, use or adaptation of the present invention, these modifications, uses or adaptations follow the general principles of the present invention and include common knowledge or conventional technical means in the technical field not disclosed in the present invention . The specification and examples are to be considered exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

It should be understood that the present invention is not limited to the precise constructions which have been described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.

Claims (10)

1. A ferromagnetic resonance resonance elimination device, used to eliminate the ferromagnetic resonance of the electromagnetic voltage transformer in the distribution network, is characterized in that, comprising: a power supply module, a resonance judgment module, a resonance elimination module and a current transformer, wherein , The power supply module is electrically connected to the resonance judgment module and the resonance elimination module; The current transformer is electrically connected to the connection wire between the neutral point of the electromagnetic voltage transformer and the ground, and the current transformer is electrically connected to the resonance judgment module; The harmonic elimination module includes a resonance elimination resistor and a first control switch, the two ends of the resonance elimination resistor are connected in series to the two ends of the open triangle circuit of the electromagnetic voltage transformer, and the first control switch is connected in series to the between the resonance elimination resistor and the open triangle circuit; the resonance judging module is electrically connected to the first control switch. 2. The device according to claim 1, wherein the harmonic elimination module further comprises a second control switch, wherein, The second control switch is connected in parallel with the harmonic elimination resistor and the first control switch, and the second control switch is electrically connected to two ends of the open triangle circuit respectively. 3 . The device according to claim 1 , further comprising a timer, and the timer is electrically connected to the resonance judgment module and the resonance elimination module, respectively. 4 . 4. The device according to claim 2, characterized in that, the resistance range of the harmonic elimination resistor is 0.5-10Ω. 5. The device according to claim 4, characterized in that, the resistance value of the harmonic elimination resistor is 1Ω. 6. A ferromagnetic resonance harmonic elimination method, characterized in that, comprising: Judging whether the current transformer detects the zero-sequence current between the neutral point of the electromagnetic voltage transformer and the ground; When it is detected that the zero-sequence current reaches the preset zero-sequence current, calculate the pulse number and pulse width of the zero-sequence current that reaches the preset pulse amplitude within the first preset time length, wherein the preset pulse width The value is greater than the pulse amplitude of the preset zero-sequence current; According to the number of pulses and the pulse width, it is judged whether ferromagnetic resonance occurs in the electromagnetic voltage transformer; When ferromagnetic resonance occurs in the electromagnetic voltage transformer, the first control switch connected in series with the resonance elimination resistor is controlled to close, and the resonance elimination process is performed on the electromagnetic voltage transformer. 7. The method according to claim 6, wherein the calculation of the number of pulses and the pulse width of the zero-sequence current reaching the preset pulse amplitude within the first preset duration includes: When it is detected that the zero-sequence current reaches the preset zero-sequence current, start the first timer and start timing; Collecting the zero-sequence current within the first preset duration of the timing through a current transformer; Find the zero-sequence current whose pulse amplitude is greater than or equal to the preset pulse amplitude; Calculate the pulse number and pulse width of the zero-sequence current whose pulse amplitude is greater than or equal to the preset pulse amplitude. 8. The method according to claim 6, wherein judging whether ferromagnetic resonance occurs in the electromagnetic voltage transformer comprises: judging whether the number of pulses of the zero-sequence current is greater than 6, and whether the pulse width is greater than 3ms; When the number of zero-sequence current pulses is greater than 6 and the pulse width is greater than 3 ms, it is determined that ferromagnetic resonance occurs in the electromagnetic voltage transformer. 9. The method according to claim 8, characterized in that, when the first control switch connected in series with the resonance elimination resistor is controlled to be closed, the method further comprises: Start the second timer and start counting; judging whether the pulse amplitude of the zero-sequence current falls below the preset pulse amplitude of the zero-sequence current within a second preset duration; When the zero-sequence current does not drop below the pulse amplitude of the preset zero-sequence current, control the first control switch to turn off, and control the open delta circuit electrically connected to the electromagnetic voltage transformer The second control switch is closed to short-circuit the open delta circuit of the electromagnetic voltage transformer and eliminate the ferromagnetic resonance of the electromagnetic voltage transformer. 10. The method according to claim 9, characterized in that, when the second control switch electrically connected to the open delta circuit of the electromagnetic voltage transformer is controlled to be closed, the method further comprises: Start the third timer and start counting; judging in real time whether the pulse amplitude of the zero-sequence current is lower than the pulse amplitude of the preset zero-sequence current; When the pulse amplitude of the zero-sequence current does not drop below the preset zero-sequence current pulse amplitude and the third duration of the timing reaches a third preset duration, control the second control switch to turn off open; When controlling the opening time of the second control switch to reach the fourth preset duration, re-control the closing of the second control switch until the pulse amplitude of the zero-sequence current drops to the pulse amplitude of the preset zero-sequence current the following.