Transient overvoltage evaluation model in GIS (Gas Insulated Switchgear) field same-frequency and same-phase voltage withstand test

Abstract

According to the transient overvoltage evaluation model in the GIS on-site same-frequency and same-phase voltage withstand test, in the model, a shell equivalent model is located between a test interval side and a transformer substation operation side and comprises a shell of which the grounding position is connected with a grounding bar; the circuit breaker closing model is located between a test interval side and a transformer substation operation side and comprises a lossless distribution parameter transmission line model equivalent circuit breaker, and the basin-type insulator equivalent model is located between the test interval side and the transformer substation operation side and comprises a frequency-variable capacitance equivalent basin-type insulator. The disconnecting switch fracture equivalent model is located between a test interval side and a transformer substation operation side and comprises a series static resistor and a dynamic resistor for simulating a dynamic arc channel resistor, and the coil equipment equivalent model is located between the test interval side and the transformer substation operation side and is a distributed parameter model.

Description

Technical Field

[0001] This invention relates to the field of high-voltage electrical insulation technology, and in particular to a transient overvoltage assessment model for GIS field same-frequency and same-phase withstand voltage tests. Background Technology

[0002] The application of gas-insulated switchgear (GIS) in substations is becoming increasingly widespread. Therefore, the operational status of GIS equipment is of paramount importance to the safe and stable operation of the entire power grid. After the expansion or maintenance of GIS bays, it is necessary to conduct AC withstand voltage tests on-site to detect and eliminate potential safety hazards such as internal insulation issues, ensuring the safe and reliable operation of the newly commissioned bays. To conduct transient overvoltage risk assessments for GIS in-situ in-phase withstand voltage tests, it is necessary to establish a rapid assessment model for transient overvoltages during GIS on-site in-situ in-phase withstand voltage tests.

[0003] Currently used GIS transient overvoltage models provide preliminary models for various equipment in substations. However, GIS in-phase and frequency withstand voltage tests, due to their high requirements and greater susceptibility to transient overvoltage transients (VFTO), place higher demands on the overall model and related equipment. The characteristics of VFTO require the simulation model to adapt not only to high-frequency conditions up to several megahertz but also to coexisting low-frequency conditions. Therefore, there is an urgent need for a simulation model that can better simulate in-situ GIS in-situ withstand voltage tests and provides rapid risk assessment of transient overvoltages.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of the present invention, and therefore may contain information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To address the shortcomings or defects of the existing technology, a transient overvoltage assessment model for on-site in-phase withstand voltage tests of GIS is provided.

[0006] The objective of this invention is achieved through the following technical solutions.

[0007] A transient overvoltage assessment model for GIS field in-phase and frequency withstand voltage tests includes,

[0008] Test bay side and substation operation side,

[0009] An equivalent model of the enclosure, located between the test bay side and the substation operation side, including the enclosure connected to the grounding busbar at the grounding location.

[0010] The circuit breaker closing model, located between the test bay side and the substation operating side, includes an equivalent circuit breaker model based on a lossless distributed parameter transmission line.

[0011] An equivalent model of a basin-type insulator is located between the test bay side and the substation operation side, and includes an equivalent basin-type insulator for a frequency-changing capacitor.

[0012] An equivalent model of the disconnector break is located between the test bay side and the substation operating side, and includes series static and dynamic resistances simulating dynamic arc resistance.

[0013] The equivalent model of coil-type equipment is located between the test interval side and the substation operation side and is a distributed parameter model.

[0014] In the transient overvoltage assessment model of the GIS field same-frequency and same-phase withstand voltage test, the risk assessment is carried out on the disconnecting switch, busbar, PT, excitation transformer, test side circuit breaker, each main line incoming node and each outgoing node.

[0015] Compared with the prior art, the beneficial effects of this invention are as follows:

[0016] The overall model structure of this invention considers the outer casing grounding busbar, allowing for a direct understanding of the transient ground potential rise during the same-frequency, same-phase withstand voltage test. Simultaneously, the various devices are optimized and refined to adapt to low-frequency and high-frequency operating conditions during breakdown discharge in the same-frequency, same-phase withstand voltage test. This also facilitates the simulation of real-world GIS field same-frequency, same-phase withstand voltage tests and enables rapid risk assessment. This model can modify the substation's operating mode to alter the location of the disconnecting switch for risk assessment, thus exploring the breakdown risk of the same-frequency, same-phase withstand voltage test under different operating modes. It can also use a three-capacitor equivalent model on the line to simulate grounding faults or test object breakdown to explore the breakdown risk of the same-frequency, same-phase withstand voltage test. This is of great significance for the safe conduct of the same-frequency, same-phase withstand voltage test. Furthermore, the overall model structure and equipment model are more suitable for the same-frequency, same-phase withstand voltage test.

[0017] The description provided is merely an overview of the technical solution of this invention. In order to make the technical means of this invention clearer and more understandable, so that those skilled in the art can implement it according to the contents of the specification, and to make the described and other objects, features and advantages of this invention more obvious and understandable, specific embodiments of this invention are described below. Attached Figure Description

[0018] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0019] In the attached diagram:

[0020] Figure 1 This is a schematic diagram of the structure of the present invention;

[0021] Figure 2 This is a graph showing the change in arc resistance at the disconnection point of the disconnector switch over time according to the present invention.

[0022] Figure 3 yes Figure 1 A partial structural diagram.

[0023] The present invention will be further explained below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0024] Specific embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0025] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0026] To facilitate understanding of the embodiments of the present invention, the following will provide further explanation and description with reference to the accompanying drawings and several specific embodiments, and the accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0027] To better understand, such as Figures 1 to 3 As shown in the diagram, in the blue markings, BSG represents bushing, PT represents voltage transformer, DS** represents disconnector, CB* represents circuit breaker, and LA represents surge arrester.

[0028] A transient overvoltage assessment model for GIS field in-phase and frequency withstand voltage tests includes,

[0029] Test bay side and substation operation side,

[0030] An equivalent model of the enclosure, located between the test bay side and the substation operation side, including the enclosure connected to the grounding busbar at the grounding location.

[0031] The circuit breaker closing model, located between the test bay side and the substation operating side, includes an equivalent circuit breaker model based on a lossless distributed parameter transmission line.

[0032] An equivalent model of a basin-type insulator is located between the test bay side and the substation operation side, and includes an equivalent basin-type insulator for a frequency-changing capacitor.

[0033] An equivalent model of the disconnector break is located between the test bay side and the substation operating side, and includes series static and dynamic resistances simulating dynamic arc resistance.

[0034] The equivalent model of coil-type equipment is located between the test interval side and the substation operation side and is a distributed parameter model.

[0035] In a preferred embodiment of the transient overvoltage assessment model for the on-site synchronous phase withstand voltage test of GIS, risk assessment is performed on the disconnecting switch, busbar, PT, excitation transformer, test side circuit breaker, each main line incoming node and each outgoing node.

[0036] In one embodiment, the breakdown of the disconnector switch is simulated using an arc resistance model or the breakdown of the test sample on the line is simulated using a three-capacitor partial discharge model to detect overvoltage at risk points, thereby assessing the breakdown risk. The grounding busbar is simulated by connecting a unit-length resistor and a unit-length inductor in series at the grounding location; therefore, the casing and busbar are also simulated using a lumped parameter model. The circuit breaker model should be located on both the test bay side and the substation operating side. When closed, it is equivalently represented using a lossless distributed parameter transmission line model, with an equivalent capacitance between each contact and ground connected to both ends. In the open state, both the inter-contact capacitance and the inter-contact capacitance are considered, represented by an equivalent capacitance between each contact and ground connected to both ends of the inter-contact equivalent capacitance. The basin-type insulator is located on both the test bay side and the substation operating side, and is only equivalent to one... The parameters of the frequency-varying capacitor are related to the equivalent capacitance of the basin insulator before and after the overvoltage. The disconnector break model is located on the test interval side and is equivalent to the series static resistance and dynamic resistance simulating the dynamic arc resistance. When an overvoltage occurs, it can simulate the reignition phenomenon of the break. The coil equipment is located on the test interval side and the substation operation side. A distributed parameter model is adopted, with the transformer turns as units. Each turn is regarded as a transmission line. According to the electrical connection sequence of the turns, the voltage on the transformer winding is obtained in terms of time and space. The frequency-varying effect of its parameters is considered, and the voltage response is calculated in the frequency domain.

[0037] In one embodiment, a three-capacitor partial discharge model is used to represent a bus grounding fault and a test interval side specimen breakdown. The three-capacitor partial discharge model consists of a charging / discharging capacitor connected in parallel with an ideal switch and a conduction impedance.

[0038] In one embodiment, in the equivalent model of the casing, to simulate the real situation of the GIS same-frequency and same-phase withstand voltage test, and at the same time to intuitively reflect the transient ground potential rise during breakdown discharge, a grounding busbar is connected at the grounding position. The grounding body can be equivalent to a grounding resistance and a grounding inductance connected in series, wherein the inductance per unit length... Resistance R = ρ d / S, where l is the shell length (m); r is the grounding electrode radius (m); β is taken as 1; ρ dWhere is the resistivity of the grounding electrode, Ω / m; S is the cross-sectional area of ​​the conductor; In the circuit breaker closing model, since the VFTO generated during breakdown discharge can often reach several megahertz, a lossless distributed parameter transmission line model that is more adaptable to high frequencies is used. The wave impedance and wave velocity of the equivalent circuit breaker transmission line model change with the voltage level of the substation; In the equivalent model of the basin insulator, since the experimental transient overvoltage involves both high and low frequencies, and the equivalent capacitance of the basin insulator is different under high and low frequency conditions, a frequency-varying capacitor is used to represent the basin insulator to ensure that the equivalent capacitance of the basin insulator can meet the actual requirements under both low and high frequency conditions; In the equivalent model of the disconnector break, since the arc resistance at the disconnector break changes greatly with time during breakdown discharge, such as Figure 2 As shown, a dynamic model of an arc-shaped resistor in series with a static resistor and a dynamic resistor is used for simulation. In the simulation calculation, the resistance value of the time-varying resistor is set using a MODEL module controller. In the equivalent model of coil-type equipment, since the electromagnetic fields in the windings are tightly coupled, using a lumped parameter model would disrupt the continuity of the electromagnetic field, easily leading to errors. Therefore, a distributed parameter model is used to simulate coil-type equipment. The distributed parameter model uses transformer turns as units, treating each turn as a transmission line. Based on the electrical connection sequence of the turns, the relationship between voltage and time and space on the transformer windings is obtained. Simultaneously, the frequency is not constant during the simulation; the effect of parameter variation needs to be considered, and the voltage response is calculated in the frequency domain. This model is more accurate in simulating the same-frequency and same-phase withstand voltage test in GIS field, and is more adaptable to the characteristics of VFTO. It can better reflect the overvoltage distribution law in the transformer winding under the action of VFTO. When conducting rapid assessment of transient overvoltage in the same-frequency and same-phase withstand voltage test of GIS field, risk assessment is carried out on the disconnecting switch, bus, PT, excitation transformer, test side circuit breaker, each main line incoming node and each outgoing node. Selecting the main weak points for risk assessment can improve the model assessment efficiency. Moreover, the weak points are the nodes that generate the largest overvoltage value in the actual test. If the simulation results of the weak points meet the conditions, it can serve as a guarantee for the safe operation of the same-frequency and same-phase withstand voltage test in GIS field.

[0039] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0040] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A transient overvoltage assessment model for on-site in-phase and frequency withstand voltage tests of GIS systems, characterized in that, It includes, Test bay side and substation operation side, An equivalent model of the enclosure, located between the test bay side and the substation operation side, including the enclosure connected to the grounding busbar at the grounding location. The circuit breaker closing model, located between the test bay side and the substation operating side, includes an equivalent circuit breaker model based on a lossless distributed parameter transmission line. An equivalent model of a basin-type insulator is located between the test bay side and the substation operation side, and includes an equivalent basin-type insulator for a frequency-changing capacitor. An equivalent model of the disconnector break is located between the test bay side and the substation operating side, and includes series static and dynamic resistances simulating dynamic arc resistance. The equivalent model of coil-type equipment is located between the test interval side and the substation operation side and is a distributed parameter model.

2. The transient overvoltage assessment model in the same-frequency and same-phase withstand voltage test of GIS field as described in claim 1, characterized in that, Preferably, risk assessments are conducted on disconnecting switch breaks, busbars, PTs, excitation transformers, test-side circuit breakers, incoming nodes of each main line, and outgoing nodes.

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