Collecting system and method suitable for photovoltaic station
By adopting a combination system of overhead lines and collecting lines in photovoltaic stations, the problem of traditional collection systems being not flexible enough and costly in complex terrain areas is solved, efficient collection and transmission of electricity is achieved, and power loss and construction costs are reduced.
Patent Information
- Application Number
- CN202311272398.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-27
- Publication Date
- 2025-03-28
AI Technical Summary
The 35kV convergence system of traditional photovoltaic stations is not flexible enough in complex terrain areas, resulting in increased cable laying costs and extended construction periods. At the same time, the investment costs are high and lean control cannot be achieved, resulting in waste of electricity.
A combined system of overhead lines and collecting lines is adopted. By setting up multiple nodes on the overhead lines and setting up sub-array units and boost integration units in parallel on each collecting line, the gathering and transport of electricity is realized, reducing the dependence on traditional collecting stations.
It improves the efficiency of power transmission, reduces the power loss, reduces the cost and construction period of cable laying, and improves the flexibility and safety of the system.
Smart Images
Figure CN119726882A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of photovoltaic power station power transmission, and in particular relates to a collection system and method suitable for photovoltaic stations. Background Art
[0002] As the energy industry has entered a stage of high-quality and rapid development. Accelerating the construction of a new power system that adapts to the increasing proportion of new energy, promoting high-quality development of new energy in the new era, and promoting the green and low-carbon transformation of energy are important directions for the transformation and upgrading of the power system. With the growing development of the photovoltaic power generation industry, by the end of 2022, the national photovoltaic installed capacity will be about 390 million kilowatts, a year-on-year increase of 28.1%. However, the geological resources for the construction of photovoltaic power stations in most regions are uneven, which has caused certain difficulties for the cable laying and construction in the site and the transmission of electricity. At the same time, the traditional sub-array side power system architecture is relatively rigid and less flexible.
[0003] In addition, the 35kV collection system of the traditional photovoltaic field station is: 5 to 6 photovoltaic sub-arrays are connected to form a 35kV collection line through the high-voltage side of the booster box transformer, and connected to the 35kV collection station. According to the actual working conditions, after 3 to 4 35kV collection lines are connected to a section of the busbar of the 35kV collection station, the collection station leads an outgoing line to the incoming line cabinet of the opposite booster station, and the same type of optical fiber differential protection is configured on both sides of the line. The disadvantages are:
[0004] 1. Inflexible collection method. In some areas with complex terrain, the installation location of the 35kV collection station is often restricted, resulting in increased cable laying costs and delayed construction period;
[0005] 2. High cost. The investment cost of 35kV collection station is high, and each collection station needs to be equipped with a set of secondary monitoring equipment, which is not economical.
[0006] 3. Unable to achieve lean control. In the traditional solution, only one set of optical fiber differential protection device is installed in the outgoing line cabinet of the aggregation station. When the differential current exceeds the limit, the protection action causes the outgoing line circuit breaker of the aggregation station to trip, and all the incoming line cabinets connected to the bus corresponding to the outgoing line cabinet are disconnected from the grid side. The control level is rough, resulting in energy waste. Summary of the invention
[0007] In order to solve at least one problem in the background technology, the present invention provides a collection system suitable for a photovoltaic station.
[0008] In order to achieve the above object, the present invention adopts the following technical solutions:
[0009] A collection system suitable for a photovoltaic station, comprising:
[0010] The overhead line is provided with n nodes, where n is greater than or equal to 1;
[0011] n collector lines are respectively connected to n nodes on the overhead line, and each collector line is provided with m nodes, where m is greater than or equal to 1;
[0012] m-1 sub-array units are provided corresponding to one of the collector lines, and the m-1 sub-array units are respectively connected to the 1st to (m-1)th nodes on the collector line;
[0013] The boost integrated unit is connected to the mth node on the collector circuit.
[0014] Preferably, the mth node on the collector circuit is the node closest to the overhead line.
[0015] Preferably, the subarray unit comprises a transformer and a fuse, the transformer and the fuse are connected in series in sequence, and one end of the fuse is connected to a node on the collector circuit.
[0016] Preferably, the boost integrated unit comprises a transformer, a fuse and a circuit breaker, the transformer and the fuse are connected in series in sequence, one end of the fuse is connected to a node on the collector circuit, and the circuit breaker is arranged in series on the collector circuit and is located between the mth node and the overhead line.
[0017] Preferably, the boost integrated unit includes a transformer, a fuse, a circuit breaker, an inverter and an energy storage device, the transformer and the fuse are connected in series in sequence, one end of the fuse is connected to a node on the collector circuit, the circuit breaker is arranged in series on the collector circuit and is located between the mth node and the overhead line, the inverter and the energy storage device are arranged in parallel and one end of each is connected to the transformer.
[0018] Preferably, the energy storage device is a lithium-ion battery.
[0019] Preferably, the transformer is a sub-array 10kV transformer or a sub-array 35kV transformer.
[0020] Preferably, the overhead line is connected to a booster station incoming cabinet.
[0021] Preferably, it also includes n+1 multi-port optical differential protection devices;
[0022] The n+1 multi-port optical differential protection devices are respectively installed in the incoming line cabinet of the booster station and the n booster integrated units.
[0023] Preferably, the multi-port optical differential protection devices in the n booster integrated units are arranged in parallel, and are all connected to the multi-port optical differential protection device in the booster station incoming cabinet via optical fibers.
[0024] A collection method applicable to a photovoltaic station, used in the above-mentioned collection system applicable to a photovoltaic station, comprises the following steps:
[0025] The total power of a single collector line is obtained by first accumulating the power through the integrated boost unit and m-1 sub-array units;
[0026] The power is accumulated for the second time through n parallel collector lines to obtain the total power of a single overhead line;
[0027] A single overhead line transmits electrical energy corresponding to the total power to the incoming cabinet of the booster station.
[0028] Beneficial effects of the present invention:
[0029] 1. The present invention sets an overhead line and then connects a plurality of collector lines to the overhead line. A plurality of sub-array units and a booster integrated unit are set in parallel in each collector line. The electric energy generated by each sub-array unit is collected in the booster integrated unit and then reaches the booster station incoming cabinet through the overhead line. There is no need to set up a collection station. The system uses the overhead line as the "busbar and outgoing line of the collection station" to reduce the power loss, which is beneficial to improving the power transmission efficiency. At the same time, it has the functional status of power collection and power transmission.
[0030] 2. The present invention sets a multi-port differential protection device. Each differential protection device can detect the voltage of the subarray unit and the booster station incoming cabinet under the working incoming line. If an abnormal situation occurs, the power can be cut off in time to prevent accidents and improve safety.
[0031] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0033] Figure 1 A schematic structural diagram of a collection system applicable to a photovoltaic station of the present invention is shown;
[0034] Figure 2 An optimized structural diagram of a collection system suitable for a photovoltaic station of the present invention is shown;
[0035] Figure 3 The structure diagram of the multi-port differential protection device of the present invention in the system is shown. DETAILED DESCRIPTION
[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0037] A collection system suitable for photovoltaic stations, such as Figure 1 As shown, it includes overhead lines, integrated lines, sub-array units and booster integrated units. There are n nodes set on the overhead line, n is greater than or equal to 1, and the booster station incoming line cabinet is connected at one end of the overhead line; there are n collector lines, which are respectively connected to the n nodes on the overhead line, and each collector line is set with m nodes, m is greater than or equal to 1; corresponding to a collector line, there are m-1 sub-array units, and the m-1 sub-array units are respectively connected to the 1st to (m-1)th nodes on the collector line; the booster integrated unit is connected to the mth node on the collector line. In addition, the mth node on the collector line is the node closest to the overhead line.
[0038] It should be noted that in Figure 1 The electric energy of each sub-array unit will first be collected by the booster integrated unit, and then collected by the booster integrated unit to the booster station incoming cabinet.
[0039] Furthermore, if Figure 1 As shown, the subarray unit includes a transformer and a fuse, the transformer and the fuse are connected in series, and one end of the fuse is connected to a node on the collector circuit. Figure 1 In the embodiment, three collector lines are arranged, and four nodes are arranged on each collector line, wherein three nodes correspond to three sub-array units, and the fourth node corresponds to an integrated boost unit.
[0040] It should be noted that the transformer plays the role of boosting the voltage to a value that matches the grid-side access conditions, and by raising the voltage, reduces transmission losses; the fuse is a safety device for the system. When the system has a short circuit or other fault and the current exceeds the set value, the fuse itself will generate heat, causing the fuse in the device to melt, disconnecting the circuit and achieving current protection.
[0041] Furthermore, the step-up integrated unit includes a transformer, a fuse and a circuit breaker, the transformer and the fuse are connected in series in sequence, one end of the fuse is connected to a node on the collector line, and the circuit breaker is arranged in series on the collector line and is located between the mth node and the overhead line. Figure 1 In the embodiment, the step-up integrated unit generally also includes a cabinet structure, in which the transformer (generally a sub-array 10kV transformer or a sub-array 35kV transformer), fuses and circuit breakers are all installed.
[0042] It should be noted that in the integrated boost unit, the role of the transformer and fuse is the same as that of the sub-array unit. The circuit breaker realizes the disconnection of the line, realizes the disconnection and connection of the line, cuts off the fault circuit, prevents the spread of the accident, and ensures the safe and stable operation of the line.
[0043] Furthermore, if Figure 2 As shown, the boost integrated unit can also be Figure 1 It is optimized on the basis of, including transformers, fuses, circuit breakers, inverters and energy storage equipment. The transformers and fuses are connected in series in sequence, one end of the fuse is connected to the node on the collector line, the circuit breaker is set in series on the collector line and is located between the mth node and the overhead line, the inverter and energy storage equipment (generally lithium-ion batteries) are set in parallel and one end of each is connected to the transformer.
[0044] It should be noted that after optimization, the inverter, as the core power generation equipment, realizes the inversion of direct current generated by photovoltaic modules and converts it into alternating current for access to the power grid; the energy storage device (generally a lithium-ion battery) is coupled with the AC side of the inverter to realize the storage and release of electric energy on the AC side. It can store electric energy when the inverter output is too high and release electric energy when the inverter output is insufficient. It can also be used as a factory power supply to power protection devices, measurement and control devices, fans and other equipment.
[0045] Furthermore, the photovoltaic station collection system also includes n+1 multi-port optical differential protection devices; the n+1 multi-port optical differential protection devices are respectively installed in the booster station incoming cabinet and the n booster integrated units. In addition, the multi-port optical differential protection devices in the n booster integrated units are arranged in parallel, and are all connected to the multi-port optical differential protection device in the booster station incoming cabinet through optical fibers.
[0046] It should be noted that the optical differential protection device is a fiber-optic phase-splitting current differential protection, which transmits sampled data to the opposite side in real time through the line optical fiber channel, and receives sampled data from the opposite side at the same time. The protection on each side uses the local and opposite current data to calculate the differential current by phase to determine whether the protection device is actuated. The incoming cabinet and the booster integrated unit will be equipped with a special set of protection-level CTs (CT is a current transformer), which are connected to the fiber-optic differential protection device and connect the current signal to their respective fiber-optic differential protection devices.
[0047] It should be further explained that a small box can be installed on the upper end of the cabinet of the integrated booster unit, and then the multi-port differential protection device can be installed in the small box to achieve precise control of the integrated booster unit. Figure 3 As shown, there are four integrated booster units, each of which corresponds to a multi-port optical differential protection device, and then there is a multi-port differential protection device in the booster station incoming cabinet. The multi-port differential protection device in the integrated booster unit is connected to the multi-port differential protection device in the booster station incoming cabinet through optical fiber. In the working state, if a single sub-array unit fails, it will not affect other sub-array units. The multi-port differential protection device can cut off the sub-array unit with the failure; for example: the differential protection devices on both sides (sub-array unit and booster station cabinet) respectively take the current signals of the protection-level current transformers on both sides, and calculate the current difference on both sides. If there is no fault, the current difference on both sides is 0, and the protection devices on both sides do not operate; if there is an internal fault, there is a difference in the current on both sides. When the difference exceeds the allowable value (the allowable value is the protection setting value, which is set by the equipment manufacturer and the owner during the construction and commissioning period based on the power company policy), the devices on both sides send trip signals to their own side, and the switches on both sides of the corresponding sub-array unit line trip at the same time.
[0048] A collection method suitable for photovoltaic stations, used for the above-mentioned collection system suitable for photovoltaic stations, comprising the following steps: S1: performing a first power accumulation through an integrated boost unit and m-1 sub-array units to obtain the total power of a single collection line; S2: performing a second power accumulation through n parallel collection lines to obtain the total power of a single overhead line; S3: the single overhead line transmits electric energy corresponding to the total power to the boost station incoming cabinet.
[0049] It should be noted that the power of m-1 sub-array units and integrated booster units on a collector line is P1-Pm (integrated booster unit to Pm). The high-voltage side of the sub-array box transformer is connected in π to achieve parallel connection of the high-voltage sides of adjacent sub-array box transformers on the collector line, that is, to ensure that the voltage remains unchanged (35kV / 10kV), and the power accumulation is achieved. The calculation formula is as follows:
[0050] P∑1# collector line=P1+P2+...+Pm
[0051] Then the power of n collector lines on an overhead line is P∑1#collector line-P∑n#collector line. Several collector lines T are connected to an overhead line, that is, different collector lines are regarded as parallel, and the overhead line is regarded as a busbar. Under the premise of ensuring that the voltage remains unchanged (35kV / 10kV), the power accumulation is achieved. The calculation formula is as follows:
[0052] P∑1# overhead line = P∑1# collector line + P∑2# collector line + ... + P∑n# collector line
[0053] Finally, a single overhead line transmits the power to the 35kV (10kV) booster station incoming line cabinet at the opposite side to realize the transmission of electric energy.
[0054] The 35kV collection station is no longer set up. According to the actual line capacity, several circuit breakers of the first terminal arrays of several collection lines are respectively connected to the overhead lines, and the overhead lines are connected to the incoming line cabinet of the opposite side substation. The overhead lines are used as "busbar + outgoing line of the collection station", and have the functions of both collecting and transmitting electric energy.
[0055] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A collection system suitable for photovoltaic stations, characterized in that: include: The overhead line is provided with n nodes, where n is greater than or equal to 1; n collector lines are respectively connected to n nodes on the overhead line, and each collector line is provided with m nodes, where m is greater than or equal to 1; m-1 sub-array units are provided corresponding to one of the collector lines, and the m-1 sub-array units are respectively connected to the 1st to (m-1)th nodes on the collector line; The boost integrated unit is connected to the mth node on the collector circuit.
2. A collection system suitable for a photovoltaic station according to claim 1, characterized in that: The mth node on the collector circuit is the node closest to the overhead line.
3. A collection system suitable for a photovoltaic station according to claim 1, characterized in that: The subarray unit comprises a transformer and a fuse, wherein the transformer and the fuse are connected in series in sequence, and one end of the fuse is connected to a node on the collector circuit.
4. A collection system suitable for a photovoltaic station according to claim 3, characterized in that: The step-up integrated unit comprises a transformer, a fuse and a circuit breaker, wherein the transformer and the fuse are connected in series in sequence, one end of the fuse is connected to a node on the collector line, and the circuit breaker is arranged in series on the collector line and is located between the mth node and the overhead line.
5. The collection system applicable to a photovoltaic station according to claim 3, characterized in that: The boost integrated unit includes a transformer, a fuse, a circuit breaker, an inverter and an energy storage device. The transformer and the fuse are connected in series in sequence. One end of the fuse is connected to a node on the collector circuit. The circuit breaker is arranged in series on the collector circuit and is located between the mth node and the overhead line. The inverter and the energy storage device are arranged in parallel and one end of each is connected to the transformer.
6. A collection system suitable for a photovoltaic station according to claim 5, characterized in that: The energy storage device is a lithium-ion battery.
7. A collection system suitable for a photovoltaic station according to any one of claims 3 to 5, characterized in that: The transformer is a sub-array 10kV transformer or a sub-array 35kV transformer.
8. A collection system suitable for a photovoltaic station according to any one of claims 1 to 6, characterized in that: The overhead line is connected to a booster station incoming cabinet.
9. A collection system suitable for a photovoltaic station according to claim 8, characterized in that: Also included are n+1 multi-port optical differential protection devices; The n+1 multi-port optical differential protection devices are respectively installed in the incoming line cabinet of the booster station and the n booster integrated units.
10. A collection system suitable for a photovoltaic station according to claim 9, characterized in that: The multi-port optical differential protection devices in the n booster integrated units are arranged in parallel, and are all connected to the multi-port optical differential protection device in the booster station incoming cabinet through optical fibers.
11. A collection method applicable to a photovoltaic station, used in the collection system applicable to a photovoltaic station as claimed in any one of claims 1 to 10, characterized in that: The following steps are involved: The total power of a single collector line is obtained by first accumulating the power through the integrated boost unit and m-1 sub-array units; The power is accumulated for the second time through n parallel collector lines to obtain the total power of a single overhead line; A single overhead line transmits electric energy corresponding to the total power to the incoming cabinet of the booster station.