Capacitor impregnant used in low-temperature environment and preparation method thereof

Abstract

The invention discloses a capacitor impregnant used in a low-temperature environment. The capacitor impregnant is composed of the following components in percentage by weight: 59wt%-69wt% of benzyl toluene insulating oil; 30 wt% to 39 wt% of PEPE (polyethylene-polypropylene copolymer) which is subjected to suction filtration to remove impurities and moisture; and 0.75 wt% to 1.0 wt% of an ether epoxy stabilizer. The invention further discloses a corresponding preparation method. By implementing the capacitor impregnant, the partial discharge performance of the capacitor impregnant at low temperature can be improved, breakdown is avoided, and the safety of a capacitor is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric equipment, and in particular to the improvement of an impregnating agent for power capacitors. The invention aims to provide a capacitor impregnating agent for use in a low-temperature environment and a preparation process thereof, so as to solve the problems of increased viscosity and decreased partial discharge performance of the existing benzyltoluene (M / DBT) impregnating agent at low temperatures, thereby improving the reliability and service life of the capacitor. Background Art

[0002] As one of the important equipment in the power system, power capacitors play an important role in improving voltage distribution, increasing power factor, reducing line losses, etc. They are easy to install and maintain.

[0003] At present, most power capacitors are oil-immersed, and their internal structure is biaxially oriented polypropylene film (BOPP) impregnated with benzyltoluene (M / DBT). M / DBT is a mixture of monobenzyltoluene, dibenzyltoluene and their isomers, which has the advantages of low loss and good thermal conductivity and is widely used in oil-immersed capacitors.

[0004] However, the viscosity of the existing impregnating agent increases rapidly below 0°C, especially below -40°C, the partial discharge performance of the capacitor decreases rapidly, and the field strength has to be reduced, resulting in a larger volume and reduced reliability. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a capacitor impregnating agent for low temperature environment and a preparation method thereof. The impregnating agent can improve its partial discharge performance at low temperature, avoid breakdown, and improve the safety of the capacitor by mixing specific proportions of benzyltoluene insulating oil, PEPE (polyethylene-polypropylene copolymer) and ether epoxy stabilizer.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: As a first aspect of the present invention, a capacitor impregnating agent for low temperature environment is provided, which is composed of the following components and their weight percentages:

[0007] Benzyltoluene insulating oil: 59wt% to 69wt%;

[0008] PEPE (polyethylene-polypropylene copolymer) after filtration to remove impurities and water: 30wt% to 39wt%;

[0009] Ether epoxy stabilizer: 0.75wt% to 1.0wt%.

[0010] Optionally, the ether epoxy stabilizer is a mixture of polyethylene glycol glycidyl ether and diethylene glycol butyl ether, and the mixing ratio of the two is 1:7.

[0011] Optionally, the benzyltoluene insulating oil specifically comprises monobenzyltoluene, dibenzyltoluene and a mixture of isomers thereof.

[0012] Optionally, the impregnating agent consists of the following components and their weight percentages:

[0013] Benzyl toluene insulating oil: 60%;

[0014] PEPE: 39wt%;

[0015] Ether epoxy stabilizer: 1wt%.

[0016] Accordingly, as another aspect of the present invention, a method for preparing a capacitor impregnant for a low temperature environment is also provided, which comprises the following steps:

[0017] Step S1, performing adsorption purification, degassing and drying treatment on benzyl toluene oil;

[0018] Step S2, adding an ether epoxy stabilizer to the treated benzyl toluene oil in batches;

[0019] Step S3, subjecting PEPE to the same drying treatment as the benzyltoluene oil;

[0020] Step S4, slowly adding the treated PEPE into benzyltoluene oil containing a stabilizer, mixing evenly and then performing final treatment.

[0021] Optionally, in step S1:

[0022] The adsorption purification treatment is as follows: 2% to 5% of 100-200 mesh diatomaceous earth is added intermittently in batches, and stirred at a constant speed for 12 hours at room temperature each time, with a rest period of 2 hours, for a total of 3 times;

[0023] The drying and degassing treatment is as follows: the benzyltoluene oil purified by adsorption is placed in a suction filtration bottle and filtered at 60° C. for 36 hours.

[0024] Optionally, the ether epoxy stabilizer in step S2 is a mixture of polyethylene glycol glycidyl ether and diethylene glycol butyl ether, and the mixing ratio of the two is 1:7, which is added twice, each adding amount is 0.25wt% to 0.5wt%, and is added before adsorption purification and before filtration respectively.

[0025] Optionally, the PEPE in step S4 is slowly added at a rate of 2-3 wt% / h. After reaching a specified concentration, the entire mixture is filtered twice at 80°C, each time for 6 hours, to ensure sufficient mixing and remove possible impurities.

[0026] Optionally, the method further comprises the step of sealing and storing the impregnating agent after mixing and final treatment to ensure stable performance.

[0027] Optionally, the prepared capacitor impregnating agent consists of the following components and their weight percentages:

[0028] Benzyltoluene insulating oil: 59wt% to 69wt%;

[0029] PEPE (polyethylene-polypropylene copolymer) after filtration to remove impurities and water: 30wt% to 39wt%;

[0030] Ether epoxy stabilizer: 0.75wt% to 1.0wt%.

[0031] The implementation of the embodiments of the present invention has the following beneficial effects:

[0032] The present invention provides a capacitor impregnating agent for low temperature environment and a preparation method thereof. The capacitor impregnating agent obtained in the present invention adopts a new formula ratio, and compared with the traditional benzyltoluene impregnating agent, the partial discharge performance of the capacitor is significantly improved under low temperature conditions of -40°C, while maintaining the breakdown field strength and electrical performance similar to those at room temperature, thereby improving the safety of the capacitor.

[0033] The present invention obtains a high-performance capacitor impregnating agent suitable for low-temperature environments by optimizing the raw material ratio and the preparation process, which effectively solves the problem of capacitor performance degradation at low temperatures in the prior art, improves the reliability and stability of the capacitor, and is of great significance to the safe and efficient operation of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0035] Figure 1 is a graph showing the relationship between viscosity and temperature of two impregnating agents involved in the present invention;

[0036] Figure 2 It is a schematic flow chart of a method for preparing a capacitor impregnating agent for a low temperature environment provided by the present invention. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0038] One aspect of the present invention provides a capacitor impregnating agent for low temperature environment, which is composed of the following components and their weight percentages:

[0039] Benzyltoluene insulating oil: 59wt% to 69wt%;

[0040] PEPE (polyethylene-polypropylene copolymer) after filtration to remove impurities and water: 30wt% to 39wt%;

[0041] Ether epoxy stabilizer: 0.75wt% to 1.0wt%.

[0042] Optionally, the ether epoxy stabilizer is a mixture of polyethylene glycol glycidyl ether and diethylene glycol butyl ether, and the mixing ratio of the two is 1:7.

[0043] Optionally, the benzyltoluene insulating oil specifically comprises monobenzyltoluene, dibenzyltoluene and a mixture of isomers thereof.

[0044] It is understandable that the present invention uses an impregnating agent (PEPE) with a lower viscosity at low temperature to mix with the impregnating benzyltoluene M / DBT, although the performance at room temperature is partially reduced, but the low temperature performance is significantly improved. The relationship between the viscosity and temperature of the two impregnating agents can be seen in Figure 1 shown.

[0045] In a specific example, the capacitor impregnating agent has the following component formula:

[0046] Benzyl toluene insulating oil: 60%;

[0047] PEPE: 39wt%;

[0048] Ether epoxy stabilizer: 1wt%.

[0049] The data obtained from the partial discharge (PD) test of the capacitor between the poles and the shell (or "inter-pole") of the capacitor impregnating agent under specific test conditions, that is, the ambient temperature is -40°C and the applied voltage is 30 kilovolts (kV). At the same time, the partial discharge data comparison of the existing benzyl toluene impregnating agent under the same conditions is shown in Table 1:

[0050] Table 1

[0051]

[0052]

[0053] According to the data in Table 1, it can be known that the partial discharge amount of the power capacitor with the new formula of the present invention is lower than the partial discharge amount of the benzyltoluene capacitor in the prior art.

[0054] Accordingly, if Figure 2As shown, as another aspect of the present invention, a method for preparing a capacitor impregnating agent for a low temperature environment is also provided, which comprises the following steps:

[0055] Step S1, performing adsorption purification, degassing and drying treatment on benzyl toluene oil;

[0056] Step S2, adding an ether epoxy stabilizer to the treated benzyl toluene oil in batches;

[0057] Step S3, performing the same drying treatment on PEPE as that on benzyl toluene oil, that is, performing adsorption purification, degassing and drying treatment on PEPE, and then adding ether epoxy stabilizer to the treated PEPE in batches, and then performing sealing treatment;

[0058] Step S4, slowly adding the treated PEPE into benzyltoluene oil containing a stabilizer, mixing evenly and then performing final treatment.

[0059] In a specific example, in step S1:

[0060] The adsorption purification treatment is as follows: 2% to 5% of 100-200 mesh diatomaceous earth is added intermittently in batches, and stirred at a constant speed for 12 hours at room temperature each time, with a rest period of 2 hours, for a total of 3 times;

[0061] The drying and degassing treatment is as follows: the benzyltoluene oil purified by adsorption is placed in a suction filtration bottle, filtered at 60° C. for 36 hours, and sealed for storage.

[0062] In a specific example, the ether epoxy stabilizer in step S2 is a mixture of polyethylene glycol glycidyl ether and diethylene glycol butyl ether, and the mixing ratio of the two is 1:7. It is added twice, each adding amount is 0.25wt% to 0.5wt%, and is added before adsorption purification and before filtration respectively.

[0063] In a specific example, PEPE in step S4 is slowly added at a rate of 2 to 3 wt% / h. After reaching the specified concentration, the entire mixture is filtered twice at 80°C, each time for 6 hours to ensure sufficient mixing and remove possible impurities, and then sealed for storage.

[0064] In a specific example, the method further includes sealing and storing the impregnating agent after mixing and final treatment to ensure stable performance.

[0065] In the method provided by the present invention, the above preparation process must be strictly followed and the order cannot be changed arbitrarily.

[0066] The prepared capacitor impregnating agent is composed of the following components and their weight percentages:

[0067] Benzyltoluene insulating oil: 59wt% to 69wt%;

[0068] PEPE (polyethylene-polypropylene copolymer) after filtration to remove impurities and water: 30wt% to 39wt%;

[0069] Ether epoxy stabilizer: 0.75wt% to 1.0wt%.

[0070] More preferably, the prepared capacitor impregnating agent has the following component formula:

[0071] Benzyl toluene insulating oil: 60%;

[0072] PEPE: 39wt%;

[0073] Ether epoxy stabilizer: 1wt%.

[0074] For more details, please refer to and combine with the above description of the capacitor impregnant, which will not be repeated here.

[0075] The implementation of the embodiments of the present invention has the following beneficial effects:

[0076] The present invention provides a capacitor impregnating agent for low temperature environment and a preparation method thereof. The capacitor impregnating agent obtained in the present invention adopts a new formula ratio, and compared with the traditional benzyltoluene impregnating agent, the partial discharge performance of the capacitor is significantly improved under low temperature conditions of -40°C, while maintaining the breakdown field strength and electrical performance similar to those at room temperature, thereby improving the safety of the capacitor.

[0077] The present invention obtains a high-performance capacitor impregnating agent suitable for low-temperature environments by optimizing the raw material ratio and the preparation process, which effectively solves the problem of capacitor performance degradation at low temperatures in the prior art, improves the reliability and stability of the capacitor, and is of great significance to the safe and efficient operation of the power system.

[0078] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A capacitor impregnating agent for low temperature environment, characterized in that: It is composed of the following components and their weight percentages: Benzyltoluene insulating oil: 59wt% to 69wt%; PEPE (polyethylene-polypropylene copolymer) after filtration to remove impurities and water: 30wt% to 39wt%; Ether epoxy stabilizer: 0.75wt% to 1.0wt%.

2. The capacitor impregnating agent according to claim 1, characterized in that: The ether epoxy stabilizer is a mixture of polyethylene glycol glycidyl ether and diethylene glycol butyl ether, and the mixing ratio of the two is 1:

7.

3. The capacitor impregnating agent according to claim 1 or 2, characterized in that: The benzyltoluene insulating oil specifically comprises monobenzyltoluene, dibenzyltoluene and a mixture of isomers thereof.

4. The capacitor impregnating agent according to any one of claims 1 to 3, characterized in that The impregnating agent is composed of the following components and their weight percentages: Benzyl toluene insulating oil: 60%; PEPE: 39wt%; Ether epoxy stabilizer: 1wt%.

5. A method for preparing a capacitor impregnating agent for a low temperature environment, characterized in that: The following steps are involved: Step S1, performing adsorption purification, degassing and drying treatment on benzyl toluene oil; Step S2, adding an ether epoxy stabilizer to the treated benzyl toluene oil in batches; Step S3, subjecting PEPE to the same drying treatment as the benzyltoluene oil; Step S4, slowly adding the treated PEPE into benzyltoluene oil containing a stabilizer, mixing evenly and then performing final treatment.

6. The preparation method according to claim 5, characterized in that: In step S1: The adsorption purification treatment is as follows: 2% to 5% of 100-200 mesh diatomaceous earth is added intermittently in batches, and stirred at a constant speed for 12 hours at room temperature each time, with a rest period of 2 hours, for a total of 3 times; The drying and degassing treatment is as follows: the benzyltoluene oil purified by adsorption is placed in a suction filtration bottle and filtered at 60° C. for 36 hours.

7. The preparation method according to claim 6, characterized in that: The ether epoxy stabilizer in step S2 is a mixture of polyethylene glycol glycidyl ether and diethylene glycol butyl ether, and the mixing ratio of the two is 1:

7. It is added twice, each adding amount is 0.25wt% to 0.5wt%, and is added before adsorption purification and before filtration respectively.

8. The preparation method according to claim 6, characterized in that: The PEPE in step S4 is slowly added at a rate of 2-3 wt% / h. After reaching the specified concentration, the entire mixture is filtered twice at 80°C, each time for 6 hours, to ensure sufficient mixing and remove possible impurities.

9. The preparation method according to claim 8, characterized in that: The method also includes the step of sealing and storing the impregnating agent after mixing and final treatment to ensure its stable performance.

10. The preparation method according to any one of claims 5 to 9, characterized in that: The prepared capacitor impregnating agent is composed of the following components and their weight percentages: Benzyltoluene insulating oil: 59wt% to 69wt%; PEPE (polyethylene-polypropylene copolymer) after filtration to remove impurities and water: 30wt% to 39wt%; Ether epoxy stabilizer: 0.75wt% to 1.0wt%.

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