35kV single-core cable metal sleeve grounding structure of photovoltaic power station
By directly grounding at the end of each phase of the 35kV single-core cable and grounding through the cable sheath voltage limiter, combined with the use of insulation and through connectors, the problem of complex grounding structure of the single-core 35kV cable is solved, and the effect of reducing construction costs and construction period is achieved.
Patent Information
- Application Number
- CN202420607271.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-26
- Publication Date
- 2025-03-07
- Estimated Expiration
- 2034-03-26
AI Technical Summary
In large and medium-sized photovoltaic power stations, the long-line grounding structure of single-core 35kV cables is complex, resulting in high construction costs, long construction periods and low cost performance.
Each phase cable terminal of a 35kV single-core cable is directly grounded and grounded through a cable sheath voltage limiter. Insulated connectors are used at the first and last connectors, and a straight through intermediate connectors are used in the middle section.
It effectively reduces the cost of cable grounding, reduces the cost and construction period of the project, and improves the cost-effectiveness of cable grounding.
Smart Images
Figure CN222581513U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of new energy power generation, in particular to a 35kV single-core cable metal sheath grounding structure of a photovoltaic power station. Background Art
[0002] More and more large and medium-sized photovoltaic power stations and photovoltaic bases are springing up at home and abroad. As their scale increases, their occupied area and the collector cables entering the booster station are getting longer and longer. In order to meet the current carrying capacity requirements and control cable losses, the cross-sections used are getting larger and larger. For domestic projects, some three-core medium-voltage cables cannot meet the above requirements. It is necessary to use single-core cables as medium-voltage collector cables to increase the cable cross-section; for foreign projects, due to different standards, most countries using IEEE are currently accustomed to using single-core cables as collector cables for conventional projects, and there is a lack of three-core cable manufacturers in the local area.
[0003] Single-core cables are cables that need special treatment. Unlike three-core cables, the way to ground the metal sheath of the cable needs to be determined according to the specific project conditions. Considering the acceptability of the induced potential in the metal sheath and trying to avoid faults caused by circulating currents caused by multi-point grounding, the following methods are currently commonly used in national standards and project applications:
[0004] When the line is not long, the metal sheath at one end of the line is directly grounded, and the other end is not grounded or grounded through a sheath voltage protector. Figure 1 .
[0005] When the line is long, the metal sheath at the midpoint of the line is directly grounded, and both ends are grounded through the sheath voltage protector. Figure 2 .
[0006] When the line is very long (about 1500m or more), the cable metal sheath adopts cross-connection grounding method, see Figure 3 .
[0007] The collector cables of large and medium-sized photovoltaic power stations mostly use a voltage level of 35kV. The lines from the terminal box transformer to the booster station or switch station are generally very long, especially for mountain photovoltaic projects, where the cable length of the station section may even be more than 6km. If a single-core cable is used, the conventional practice should adopt the above-mentioned solution 3 according to the specifications. However, this solution requires that the cable line be divided into 3 (or multiples of 3) equal-length small sections during the design and construction phase to achieve the desired effect. Due to related factors such as construction errors, it is often difficult to be very accurate, so this solution also has defects. In addition, this solution requires the use of more cable insulation joints and cable sheath protection boxes, with high equipment and construction economic costs, more complex procedures and longer construction periods, so it is not cost-effective. Utility Model Content
[0008] In order to solve the above problems, the utility model aims to propose a 35kV single-core cable metal sheath grounding structure for a photovoltaic power station, which is achieved by directly grounding the two cable terminals of each phase of the 35kV single-core cable and grounding them through a cable sheath voltage limiter. The first joint position and the last joint position of the 35kV single-core cable both use insulating joints, and the middle section joints use straight-through middle joints; the insulating joints at the first joint position and the last joint position are both grounded through a cable sheath voltage limiter and directly grounded, respectively, so that the induced potential of the metal sheath at the farthest point of the cable can be within a safe range, thereby reducing the cable grounding cost, reducing the project cost, saving construction period, and improving the cost performance of the cable grounding project.
[0009] In order to achieve the above object, the technical solution of the utility model is implemented as follows:
[0010] A 35kV single-core cable metal sheath grounding structure for a photovoltaic power station comprises a 35kV single-core cable, wherein two cable terminals of each phase of the 35kV single-core cable are respectively directly grounded and grounded through a cable sheath voltage limiter, the first joint position and the last joint position of the 35kV single-core cable are respectively insulated joints, and a straight-through middle joint is used for the middle section joint; the insulated joints at the first joint position and the last joint position are respectively grounded through the cable sheath voltage limiter and directly grounded.
[0011] Furthermore, the distance between the first joint position and the last joint position of the 35kV single-core cable and the corresponding terminal of each phase cable is between 1.4-1.6km.
[0012] Furthermore, the length of the 35kV single-core cable is not more than 4.5km.
[0013] In order to achieve the above-mentioned purpose, the utility model also provides a 35kV single-core cable metal sheath grounding structure for a photovoltaic power station, including a 35kV single-core cable, wherein the two cable terminals of each phase of the 35kV single-core cable are directly grounded, the first joint position and the last joint position of the 35kV single-core cable respectively adopt insulating joints, and the middle section joint adopts a straight-through middle joint; the two ends of the insulating joint at the first joint position and the last joint position are respectively grounded through a cable sheath voltage limiter, directly grounded, and grounded through two cable sheath voltage limiters.
[0014] Furthermore, the distance between the first joint position and the last joint position of the 35kV single-core cable and the corresponding terminal of each phase cable is between 1.4-1.6km.
[0015] Furthermore, the length of the 35kV single-core cable is not more than 4.5km.
[0016] Beneficial effects: The utility model directly grounds the two cable terminals of each phase of the 35kV single-core cable and grounds them through a cable sheath voltage limiter. The first joint position and the last joint position of the 35kV single-core cable both use insulating joints, and the middle section joints use straight-through middle joints. The insulating joints at the first joint position and the last joint position are grounded through a cable sheath voltage limiter and directly grounded, respectively, which can make the induced potential of the metal sheath at the farthest point of the cable within a safe range, thereby reducing the cable grounding cost, reducing the project cost, saving construction time, and improving the cost performance of the cable grounding project. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the accompanying drawings:
[0018] Figure 1 It is a schematic diagram of one-end grounding method in the background technology of the utility model;
[0019] Figure 2 This is a schematic diagram of a grounding method at a point in the middle of a circuit in the background technology of the present utility model;
[0020] Figure 3 It is a schematic diagram of the cross-connection grounding method in the background technology of the present utility model;
[0021] Figure 4 This is a schematic diagram of the structure of the 35kV single-core cable metal sheath grounding structure of the photovoltaic power station described in the embodiment of the utility model Figure 1 ;
[0022] Figure 5 This is a schematic diagram of the structure of the 35kV single-core cable metal sheath grounding structure of the photovoltaic power station described in the embodiment of the utility model Figure 2 . DETAILED DESCRIPTION
[0023] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.
[0024] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.
[0025] Example 1
[0026] See also Figure 4: A 35kV single-core cable metal sheath grounding structure for a photovoltaic power station, comprising a 35kV single-core cable 1, wherein two cable terminals 101 of each phase of the 35kV single-core cable 1 are respectively directly grounded 102 and grounded 103 through a cable sheath voltage limiter, the first joint position and the last joint position of the 35kV single-core cable 1 are respectively equipped with an insulating joint 104, and a straight-through intermediate joint 105 is adopted for the middle section joint; the insulating joints 104 at the first joint position and the last joint position are respectively grounded 103 and directly grounded 102 through a cable sheath voltage limiter.
[0027] This embodiment uses the above-mentioned grounding structure to ensure that the induced potential of the farthest metal sheath of the cable is within a safe range, thereby reducing the cable grounding cost, lowering the project cost, saving construction time, and improving the cost-effectiveness of the cable grounding project.
[0028] In a specific example, the distance between the first joint position and the last joint position of the 35 kV single-core cable 1 and the corresponding cable terminal 101 of each phase is between 1.4 and 1.6 km.
[0029] It should be noted that in the section where the collector cable enters the photovoltaic power station, the transformer end and the switch station end are often operated and maintained, and there are many personnel activities. The length of the 35kV single-core cable coil of common specifications is generally between 1.4-1.6km. After the above segmentation, the length of the first and last cable sections is within this length range. The normal induced potential of any non-direct grounding point calculated in this section does not exceed 50V. Even if no effective safety measures are taken to prevent personnel from arbitrarily contacting the metal sleeve, the regulatory requirements for the maximum value of the induced potential can be met, effectively improving the safety of operators such as operation and maintenance.
[0030] In a specific example, the length of the 35 kV single-core cable 1 is not more than 4.5 km.
[0031] It should be noted that in the traditional method, the cable joints in the middle section are connected by a straight-through intermediate joint. This section of cable is also directly grounded at one end, and the other end is grounded through a cable sheath voltage protector. According to calculations, when the overall length of this section of the line is not more than 4.5km, the normal induced potential of any non-direct grounding point in this section does not exceed 300V. Since this cable section has less contact with people, after taking effective safety measures to prevent people from arbitrarily contacting the metal sheath, the regulatory requirements for the maximum value of the induced potential can be met. Compared with the cross-connection method, this embodiment replaces the insulating joint of this section with an intermediate joint that does not require grounding, eliminating the work of cross-connection grounding boxes and evenly dividing cables, greatly reducing the project cost and construction period.
[0032] Example 2
[0033] See also Figure 5 A 35kV single-core cable metal sheath grounding structure for a photovoltaic power station comprises a 35kV single-core cable 1, wherein two cable terminals 101 of each phase of the 35kV single-core cable 1 are directly grounded 102, an insulating joint 104 is respectively used at the first joint position and the last joint position of the 35kV single-core cable 1, and a straight-through intermediate joint 105 is used at the middle joint; both ends of the insulating joint 104 at the first joint position and the last joint position are respectively grounded 103 through a cable sheath voltage limiter, directly grounded 102 and two cable sheath voltage limiter groundings 103.
[0034] This embodiment uses the above-mentioned grounding structure to ensure that the induced potential of the farthest metal sheath of the cable is within a safe range, thereby reducing the cable grounding cost, lowering the project cost, saving construction time, and improving the cost-effectiveness of the cable grounding project.
[0035] In a specific example, the distance between the first joint position and the last joint position of the 35 kV single-core cable 1 and the corresponding cable terminal 101 of each phase is between 1.4 and 1.6 km.
[0036] It should be noted that in the section where the collector cable enters the photovoltaic power station, the transformer end and the switch station end are often operated and maintained, and there are many personnel activities. The length of the 35kV single-core cable coil of common specifications is generally between 1.4-1.6km. After the above segmentation, the length of the first and last cable sections is within this length range. The normal induced potential of any non-direct grounding point calculated in this section does not exceed 50V. Even if no effective safety measures are taken to prevent personnel from arbitrarily contacting the metal sleeve, the regulatory requirements for the maximum value of the induced potential can be met, effectively improving the safety of operators such as operation and maintenance.
[0037] In a specific example, the length of the 35 kV single-core cable 1 is not more than 4.5 km.
[0038] It should be noted that in the traditional method, the cable joints in the middle section are connected by a straight-through intermediate joint. This section of cable is also directly grounded at one end, and the other end is grounded through a cable sheath voltage protector. According to calculations, when the overall length of this section of the line is not more than 4.5km, the normal induced potential of any non-direct grounding point in this section does not exceed 300V. Since this cable section has less contact with people, after taking effective safety measures to prevent people from arbitrarily contacting the metal sheath, the regulatory requirements for the maximum value of the induced potential can be met. Compared with the cross-connection method, this embodiment replaces the insulating joint of this section with an intermediate joint that does not require grounding, eliminating the work of cross-connection grounding boxes and evenly dividing cables, greatly reducing the project cost and construction period.
[0039] In summary, according to Figure 4 , Figure 5 As shown in the figure, when the 35kV single-core cable line is very long, the entire line will inevitably be divided into several sections and connected with cable joints or cable junction boxes due to the limitation of the cable reel length. Insulated joints are used at the first and last joint positions of the line, and straight-through intermediate joints are used for the remaining joints. The metal sheath of the entire line can be divided into 3 sections. According to the two different grounding methods in the figure above, one end of the metal sheath of each section can be directly grounded, and the other end can be grounded through the cable sheath voltage protector; through the above two grounding structure methods, the induced potential of the metal sheath at the farthest point of the cable can be within a safe range, thereby reducing the cable grounding cost, reducing the project cost, saving construction time, and improving the cost performance of the cable grounding project.
[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A 35kV single-core cable metal sheath grounding structure for a photovoltaic power station, characterized in that: The invention comprises a 35 kV single-core cable (1), wherein two cable terminals (101) of each phase of the 35 kV single-core cable (1) are respectively directly grounded (102) and grounded via a cable sheath voltage limiter (103); the first joint position and the last joint position of the 35 kV single-core cable (1) are respectively provided with insulating joints (104), and the middle joint is provided with a straight middle joint (105); the insulating joints (104) at the first joint position and the last joint position are respectively grounded via a cable sheath voltage limiter (103) and directly grounded (102).
2. The 35kV single-core cable metal sheath grounding structure of the photovoltaic power station according to claim 1 is characterized in that: The first joint position and the last joint position of the 35 kV single-core cable (1) are located at a distance of 1.4-1.6 km from the corresponding cable terminal (101) of each phase.
3. The 35kV single-core cable metal sheath grounding structure of the photovoltaic power station according to claim 1, characterized in that: The length of the 35 kV single-core cable (1) is no more than 4.5 km.
4. A 35kV single-core cable metal sheath grounding structure for a photovoltaic power station, characterized in that: The invention comprises a 35 kV single-core cable (1), wherein two cable terminals (101) of each phase of the 35 kV single-core cable (1) are directly grounded (102), the first joint position and the last joint position of the 35 kV single-core cable (1) respectively use insulating joints (104), and the middle joint uses a straight middle joint (105); the two ends of the insulating joint (104) at the first joint position and the last joint position are respectively grounded (103) through a cable sheath voltage limiter, directly grounded (102), and grounded (103) through two cable sheath voltage limiters.
5. The 35kV single-core cable metal sheath grounding structure of the photovoltaic power station according to claim 4, characterized in that: The first joint position and the last joint position of the 35 kV single-core cable (1) are located at a distance of 1.4-1.6 km from the corresponding cable terminal (101) of each phase.
6. The 35kV single-core cable metal sheath grounding structure of the photovoltaic power station according to claim 4, characterized in that: The length of the 35 kV single-core cable (1) is no more than 4.5 km.