Networking system for improving power factor under distributed photovoltaic grid-connected power generation

Abstract

The utility model discloses a networking system for improving a power factor under distributed photovoltaic grid-connected power generation, and effectively solves the problem that the power factor of a power utilization enterprise is reduced after distributed photovoltaic grid connection. A distributed photovoltaic grid-connected power generation system is characterized in that a solution for improving a power factor in the distributed grid-connected power generation system comprises a power grid power supply module, a distributed photovoltaic power generation module, an enterprise load module, a reactive compensation module and a 380V direct current bus module, the power grid power supply module and the distributed photovoltaic power generation module are respectively connected with the 380V direct current bus module; the device is ingenious in structure and convenient to use, and can more accurately measure the current and reactive compensation capacity at a grid-connected point through the arrangement of the photovoltaic special four-quadrant capacitance compensation controller in a'self-generation and self-use 'grid-connected mode. At the moment, the capacitor reactive compensation control cabinet can supplement capacitive reactive power to an electricity load of an enterprise according to a measured value, and has the advantages of low cost and high replaceability.

Description

Technical Field

[0001] The utility model relates to the technical field of distributed photovoltaic power generation, in particular to a networking system for improving power factor under distributed photovoltaic grid-connected power generation. Background Art

[0002] Distributed photovoltaic power generation refers specifically to photovoltaic power generation facilities that are built near user sites, operate in a way that users generate electricity for their own use, and connect excess electricity to the grid, and are balanced and regulated in the distribution system. Distributed photovoltaic power generation follows the principles of adapting measures to local conditions, being clean and efficient, decentralized, and using nearby resources, making full use of local solar energy resources to replace and reduce fossil energy consumption.

[0003] After distributed photovoltaics are connected to the grid, the power factor of electricity users decreases, which is assessed by the power grid and affects the enthusiasm of electricity users to use photovoltaic power generation. At present, how to solve the problem of reduced power factor after distributed photovoltaics are connected to the grid, meet the power factor requirements of the power grid relative to enterprises, and increase the enthusiasm of electricity users to build and use photovoltaics. Utility Model Content

[0004] In view of the above situation, in order to overcome the defects of the prior art, the purpose of the utility model is to provide a networking system for improving the power factor in distributed photovoltaic grid-connected power generation, which effectively solves the problems mentioned in the background technology.

[0005] The technical solution is that the utility model includes a power grid power supply module, a distributed photovoltaic power generation module, an enterprise load module, a reactive power compensation module and a 380V DC bus module;

[0006] The grid power supply module and the distributed photovoltaic power generation module are respectively connected to the 380V DC bus module;

[0007] The 380V DC bus module is connected to the reactive power compensation module, and the reactive power compensation module is connected to the enterprise load module.

[0008] Preferably, the grid power supply module includes a current transformer and a 10 / 0.4kV power transformer, and the grid power supply module is connected to the distributed photovoltaic power generation module via the 10 / 0.4kv power transformer.

[0009] Preferably, the reactive power compensation module includes a photovoltaic-specific four-quadrant capacitor compensation controller and an active reactive power compensation filter, and the reactive power compensation module is connected to the enterprise load module via a capacitor reactive power compensation control cabinet.

[0010] Preferably, the distributed photovoltaic power generation module includes a solar power generation device and a photovoltaic inverter, and the distributed photovoltaic power generation module is connected to a 380V DC bus module via the photovoltaic inverter.

[0011] Preferably, the power factor calculation formula of the enterprise's gateway metering meter is:

[0012]

[0013] The P 电网 The enterprise load module uses the active power of the grid power supply module, the Q 电网 is the reactive power provided by the grid power supply module, the Q 上网 It is the reactive power provided by the distributed photovoltaic power generation module to the grid power supply module.

[0014] Preferably, a grid-connected cabinet is provided in the 380V DC bus module.

[0015] Compared with the prior art, the beneficial effects of the utility model are:

[0016] 1. In the "self-generation and self-use" grid-connected mode, the current and reactive power compensation capacity at the grid-connected point can be measured more accurately through the setting of the photovoltaic special four-quadrant capacitor compensation controller. At this time, the capacitor reactive power compensation control cabinet can supplement the capacitive reactive power to the enterprise power load according to the measured value, which has the advantages of low cost, convenient wiring and strong replaceability.

[0017] 2. In the grid-connected mode of "self-generation for self-use and surplus power to the grid", on the basis of the "self-generation for self-use" grid-connected mode, when the electricity produced by the photovoltaic power generation equipment cannot be fully absorbed by the load, an active reactive power compensation filter is set to replace the capacitor reactive power compensation control cabinet, which can follow the reactive power changes of the enterprise's power load and realize dynamic compensation of reactive power. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the principle of the utility model.

[0019] Figure 2 It is a schematic diagram of the distributed photovoltaic power generation access to the user side in two modes in the utility model. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0021] Depend on Figure 1 and Figure 2It includes power grid power supply module, distributed photovoltaic power generation module, enterprise load module, reactive power compensation module and 380V DC bus module;

[0022] The grid power supply module and the distributed photovoltaic power generation module are respectively connected to the 380V DC bus module;

[0023] The 380V DC bus module is connected to the reactive power compensation module, and the reactive power compensation module is connected to the enterprise load module.

[0024] Furthermore, the power factor calculation formula of the enterprise's two-way gateway electric energy meter is:

[0025]

[0026] P 电网 It is the active power of the enterprise load module using the grid power supply module, Q 电网 is the reactive power provided by the grid power supply module, Q 上网 It is the reactive power provided by the distributed photovoltaic power generation module to the grid power supply module.

[0027] Furthermore, the grid power supply module includes a current transformer and a 10 / 0.4kV power transformer, and the grid power supply module is connected to the distributed photovoltaic power generation module through the 10 / 0.4kv power transformer.

[0028] Furthermore, the distributed photovoltaic power generation module includes a solar power generation device and a photovoltaic inverter, and the distributed photovoltaic power generation module is connected to the 380V DC bus module through the photovoltaic inverter.

[0029] Furthermore, a grid-connected cabinet is provided in the 380V DC bus module.

[0030] Due to the existence of photovoltaic power generation equipment, the power consumption of enterprise factories is preferentially used by photovoltaic power generation equipment. When the distributed photovoltaic power generation is large and the power consumption of enterprise power load is small, the power factor of the gateway meter is low, and even when the photovoltaic power generation cannot be fully absorbed by the load, the photovoltaic power generation will send active power back to the grid, that is, generate grid power. At this time, the grid power consumption P 电网 If it is very small, the power factor of the gateway meter will decrease, and the power factor will not meet the standard. The user will need to bear part of the power factor adjustment fee every month.

[0031] Before improving the power factor, we first analyze the grid-connected mode of photovoltaic power generation. Its typical grid-connected modes include "self-generation for own use, surplus power to the grid", "self-generation for own use" and "full grid-connected". In the "self-generation for own use, surplus power to the grid" and "full self-use" modes, the distributed photovoltaic power generation modules are connected to the enterprise load module through the photovoltaic inverter to the 380V DC bus module, and the power grid is used to provide electricity when the enterprise is short of electricity. In the "full grid-connected" mode, the distributed photovoltaic power generation modules are connected to the nearest grid power supply module through the photovoltaic inverter. This mode has nothing to do with user electricity consumption, that is, it is only necessary to analyze the changes in power factor under the two modes of "self-generation for own use, surplus power to the grid" and "self-generation for own use".

[0032] When the distributed photovoltaic power generation module is connected to the enterprise load module, a bidirectional gateway electric energy meter is set in the 380V DC bus module for the enterprise's online access and grid power consumption electricity fee settlement.

[0033] Secondly, in order to improve the power factor, reactive power compensation is required. First, the type of reactive power generated by the enterprise's load module should be analyzed.

[0034] There are three types of reactive power: inductive reactive power, capacitive reactive power, fundamental reactive power and harmonic reactive power. In electrical equipment, any equipment composed of windings and magnets that generates electrical and magnetic alternation in AC circuits, during the energy conversion process, part of the magnetic energy is still restored to electrical energy. This part of the current does not consume active power and is called inductive reactive power. Capacitive reactive power refers to the charging and discharging between the two plates of a capacitor. The capacitive current does not consume active power. The power caused by this current is called capacitive reactive power, and capacitive reactive power can offset inductive reactive power and improve the power factor. Since most of the power loads in enterprises, such as motors and transformers, are inductive loads, a certain amount of reactive power will be generated during the operation of the equipment, which is inductive reactive power.

[0035] The reactive power compensation module includes a capacitor reactive power compensation control cabinet and an active reactive power compensation filter. The reactive power compensation module is connected to the enterprise load module through the capacitor reactive power compensation control cabinet. It should be noted that the active reactive power compensation filter is not required in all cases. It is only added in the mode of "self-generation for self-use and surfing the surplus power to the grid".

[0036] Finally, based on the photovoltaic power generation grid-connected mode mentioned above, two networking systems for improving the power factor under the grid-connected types of "self-generation for self-use" and "self-generation for self-use and surplus power to the grid" are proposed:

[0037] In the "self-generation and self-use" grid-connected mode, the reactive power compensation device in the traditional capacitor reactive power compensation control cabinet is replaced with a photovoltaic-specific four-quadrant capacitor compensation controller, which can more accurately measure the current at the grid-connected point, obtain the positive and negative directions of the active power and reactive power at the point, and determine the reactive power compensation capacity. At this time, the reactive power at the load is inductive reactive power, and the capacitive reactive power is supplemented to the load through the capacitor reactive power compensation control cabinet, so that the two are offset. The networking system in this solution has low cost, convenient wiring, strong replaceability, and good results;

[0038] In the grid-connected mode of "self-generation for self-use and surplus power to the grid", when the electricity produced by the photovoltaic power generation equipment can be fully absorbed by the enterprise's power load, its processing solution is consistent with the above-mentioned "self-generation for self-use" processing solution. When the electricity produced by the photovoltaic power generation equipment cannot be fully absorbed by the load, when the surplus power is connected to the grid, since the current direction is in the second quadrant of the photovoltaic special four-quadrant capacitor compensation controller, the reactive power type generated by the enterprise's power load is converted to capacitive reactive power, making it impossible for the capacitor reactive power compensation control cabinet to compensate and offset it. Therefore, on the basis of the above solution, an active reactive power compensation filter (SVG device) is installed to replace the capacitor reactive power compensation control cabinet, which can not only output capacitive reactive power to the enterprise's power load, but also output inductive reactive power to the enterprise's power load when the enterprise's power load is capacitive reactive power, so that the two can offset each other and improve the power factor. The advantage of this solution is that it can follow the reactive power changes of the enterprise's power load and realize dynamic compensation of reactive power.

[0039] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A networking system for improving power factor in distributed photovoltaic grid-connected power generation, characterized in that: Including grid power supply module, distributed photovoltaic power generation module, enterprise load module, reactive power compensation module and 380V DC bus module; The grid power supply module and the distributed photovoltaic power generation module are respectively connected to the 380V DC bus module; The 380V DC bus module is connected to the reactive power compensation module, and the reactive power compensation module is connected to the enterprise load module; The reactive power compensation module comprises a photovoltaic-specific four-quadrant capacitor compensation controller and an active reactive power compensation filter. The reactive power compensation module is connected to the enterprise load module via the photovoltaic-specific four-quadrant capacitor compensation controller.

2. A networking system for improving power factor in distributed photovoltaic grid-connected power generation according to claim 1, characterized in that: The grid power supply module includes a current transformer and a 10 / 0.4kV power transformer, and the grid power supply module is connected to the distributed photovoltaic power generation module through the 10 / 0.4kv power transformer.

3. A networking system for improving power factor in distributed photovoltaic grid-connected power generation according to claim 1, characterized in that: The distributed photovoltaic power generation module includes a solar power generation device and a photovoltaic inverter. The distributed photovoltaic power generation module is connected to a 380V DC bus module via the photovoltaic inverter.

4. A networking system for improving power factor in distributed photovoltaic grid-connected power generation according to claim 1, characterized in that: A grid-connected cabinet is arranged in the 380V DC bus module.

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