Screw expander power generation system PT arrangement

Abstract

The utility model discloses a screw expander power generation system PT arrangement, a power generation system comprises a screw expander generator set, a PT cabinet, a grid-connected cabinet and a high-voltage contact cabinet, the PT cabinet is provided with a group of PTs, the grid-connected cabinet is provided with a group of PTs, the contact cabinet is not provided with PTs, a PT voltage signal at a synchronization device generator side is taken from the PT cabinet, and a PT voltage signal at a synchronization device generator side is taken from the high-voltage contact cabinet. A to-be-connected power grid side PT voltage signal of the synchronizing device is taken from a grid-connected cabinet, the PT cabinet and the grid-connected cabinet are both installed in an on-site power distribution room beside a screw expansion generator set, and the PT cabinet and the grid-connected cabinet are arranged in a cabinet splicing mode and spliced through copper bars at a time. According to the utility model, the PT arrangement completely eliminates the problems of voltage drop caused by cable distance and large impact current during synchronous grid connection; the PT adopts a V-shaped wiring method, the problem that the installation position of an original Y-shaped wiring method is limited by space is solved, the V-shaped wiring method can measure the line voltage, the synchronous detection requirement is met, and the purpose of utilizing resources to the maximum extent is achieved.

Description

Technical Field

[0001] This utility model relates to the technical field of screw expander power generation systems, and in particular to a PT arrangement for a screw expander power generation system. Background Technology

[0002] Screw expanders have evolved from initial development with actual generator power around 200kW to now reaching a maximum power of 3000kW. In the low-power range, low-voltage power generation technology is used. However, as power increases, so does the generating current. Firstly, low-voltage power generation is limited by the capacity of low-voltage transformers, and secondly, it is influenced by the economic factors of primary cable engineering costs. The disadvantages of low-voltage power generation are clearly insufficient to meet user needs. In the higher power range, generally above 800kW, high-voltage power generation technology is typically used. Currently, high-power screw expanders account for a large proportion of applications, and most practical projects utilize high-voltage power generation.

[0003] The following four requirements must be met for a screw expander to generate electricity and connect to the grid simultaneously: (1) The voltage of the generator must be equal to the voltage of the grid to be connected;

[0004] (2) The generator voltage phase is the same as the grid voltage phase;

[0005] (3) The generator voltage frequency is the same as the grid voltage frequency to be connected;

[0006] (4) The phase sequence of the generator is the same as that of the grid to be connected.

[0007] The existing screw expander generator system has one PT cabinet, but the grid connection cabinet and the high-voltage tie cabinet do not. The PT voltage signal on the generator side of the synchronizing device is taken from the PT cabinet, and the PT voltage signal on the grid side of the synchronizing device is taken from the original power grid system. The distance from the original power grid system to the distribution room next to the screw expander generator varies, generally ranging from 50M to 600M. The line voltage drop is shown in Table 1 below.

[0008] Table 1:

[0009]

[0010] In general engineering practice, a 2.5mm PT signal is selected. 2The cable has a voltage drop of 18.9 mV / m, meaning the voltage drop from 50m to 600m is 945mV to 11340mV (0.95V to 11.34V). The normal secondary voltage of the PT is 100V. Due to this voltage drop, assuming a distance of 600m, the voltage from the original power grid (100V) to the distribution room next to the screw expander generator is only 88.66V. The synchronizing device calculates and issues a synchronizing closing command based on the assumption that the voltage on the grid side and the generator side are completely equal. The synchronizing device displays two equal voltage readings, but the actual voltage deviation during closing is 11.34V. This voltage difference causes incomplete synchronization during grid connection, resulting in a large inrush current, noticeable abnormal generator noise, and a risk of generator burnout. Utility Model Content

[0011] The purpose of this invention is to provide an optimized PT arrangement for a screw expander.

[0012] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0013] A PT (Power Transmission Unit) arrangement for a screw expander generator system is disclosed. The generator system includes a screw expander generator set, a PT cabinet, a grid connection cabinet, and a high-voltage interconnection cabinet. The PT cabinet is equipped with one set of PTs, the grid connection cabinet is equipped with one set of PTs, and the interconnection cabinet is not equipped with a PT. The PT voltage signal of the generator side of the synchronizing device is taken from the PT cabinet, and the PT voltage signal of the grid side to be connected by the synchronizing device is taken from the grid connection cabinet. Both the PT cabinet and the grid connection cabinet are installed in the field distribution room next to the screw expander generator set. The PT cabinet and the grid connection cabinet are configured as a single unit and connected by copper busbars.

[0014] Furthermore, the distance between the PT secondary side output points of the PT cabinet and the grid-connected cabinet is set to be less than or equal to 0.5M. By controlling the distance between the PT secondary side output points of the two cabinets, the voltage drop can be controlled.

[0015] Furthermore, the PT wiring method adopts the V-type connection, which is for two PTs. The V-type connection can measure line voltage, meet the requirements for synchronous detection, and achieve the goal of maximizing resource utilization.

[0016] In summary, this utility model has the following beneficial effects:

[0017] 1. The PT arrangement of this utility model ensures that regardless of the distance between the installation of the synchronizing devices, the 100V voltage on both sides of the grid originates from the same point, the cable lengths are the same, and the voltage drop is the same. This PT arrangement completely eliminates the problem of voltage drop caused by cable distance and large inrush current during synchronous grid connection.

[0018] 2. The PT of this utility model adopts the V-type connection method, which overcomes the problem of space limitation of the original Y-type connection method. The V-type connection method can measure line voltage, meet the requirements of synchronous detection, and achieve the purpose of maximizing resource utilization. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the PT arrangement structure of the power generation system of this utility model;

[0020] Figure 2 This is a wiring diagram of the V-type connection of the PT of this utility model. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the accompanying drawings. The technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0022] A PT arrangement for a screw expander power generation system, such as Figure 1 As shown, the power generation system includes a screw expander generator set, a PT cabinet, a grid connection cabinet, and a high-voltage tie cabinet. The PT cabinet is equipped with one set of PTs, the grid connection cabinet is equipped with one set of PTs, and the tie cabinet is not equipped with a PT. The PT voltage signal of the generator side of the synchronizing device is taken from the PT cabinet, and the PT voltage signal of the grid side to be connected by the synchronizing device is taken from the grid connection cabinet. Both the PT cabinet and the grid connection cabinet are installed in the field distribution room next to the screw expander generator set. The PT cabinet and the grid connection cabinet are set up as a single unit and are connected by copper busbars.

[0023] Furthermore, the distance between the PT secondary side outgoing points of the PT cabinet and the grid-connected cabinet should be less than or equal to 0.5M. When the distance is 0.5M, the line voltage drop is shown in Table 2 below:

[0024] Table 2:

[0025]

[0026] In general engineering practice, a 2.5mm PT signal is selected. 2The voltage drop across the cable is 18.9 mV / m, meaning the voltage drop at 0.5m is 9.45 mV (0.0095 V). This voltage drop is extremely small and can be ignored. The 100 V voltage signal from the generator side of the synchronizing device and the 100 V voltage signal from the side to be connected to the grid are approximately equivalent to the same point of origin. Regardless of the installation distance between the synchronizing devices, the 100 V voltages on both sides originate from the same point, travel through the same cable length, and experience the same voltage drop. This PT device setup completely eliminates the voltage drop caused by cable distance and the problem of large inrush current during synchronizing.

[0027] Furthermore, the PT wiring method adopts a V-type connection, such as... Figure 2 As shown, the V-connection method uses 2 PTs, while the original Y-connection method used 3 PTs, each with a capacity of 30VA. Due to space constraints, it was impossible to install all 3 PTs simultaneously in the lower movable central switchgear. This invention uses a V-connection method to measure line voltage, meeting the requirements for synchronous testing and maximizing resource utilization without wasting or underutilizing any PTs. It also solves the PT installation problem of the original design. This design allows for the installation of circuit breakers in the middle layer and PTs in the lower layer within a single high-voltage central switchgear; otherwise, an additional cabinet would be needed to separately install PTs for testing the 100V voltage on the side to be connected to the grid.

[0028] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

Claims

1. A PT (Power Transmission Unit) arrangement for a screw expander power generation system, the power generation system comprising a screw expander generator set, a PT cabinet, a grid connection cabinet, and a high-voltage interconnection cabinet, characterized in that: The PT cabinet is equipped with one set of PTs, the grid-connected cabinet is equipped with one set of PTs, and the tie cabinet is not equipped with PTs. The PT voltage signal of the generator side of the synchronizing device is taken from the PT cabinet, and the PT voltage signal of the grid side of the synchronizing device is taken from the grid-connected cabinet. Both the PT cabinet and the grid-connected cabinet are installed in the field power distribution room next to the screw expansion generator set. The PT cabinet and the grid-connected cabinet are set up as a single unit and are spliced ​​together using copper busbars.

2. The PT arrangement of a screw expander power generation system according to claim 1, characterized in that: The distance between the PT secondary side output points of the PT cabinet and the grid-connected cabinet is less than or equal to 0.5M.

3. The PT arrangement of a screw expander power generation system according to claim 1, characterized in that: The PT wiring method uses a V-type connection.

Images