CN105048507A - Automatic switching control device for photovoltaic micro-grid power generation system - Google Patents

Abstract

An automatic switching control device for a photovoltaic micro-grid power generation system, including a measurement control unit, a 4G wireless communication network, and a background decision-making system, wherein the measurement control unit is connected to the background decision-making system through a 4G wireless communication network, and through the 4G wireless communication network, The measurement control unit sends the grid information data to the background decision-making system, and/or the background decision-making system sends the background decision-making system instructions to the measurement control unit. Considering the whole network, the device of the present invention detects a plurality of power parameters, and combines with the background expert resource library to make a decision, selects the optimal combination of photovoltaic systems and puts them into grid-connected operation, avoids energy waste, and ensures power quality.

Description

Automatic switching control device for photovoltaic micro-grid power generation system

technical field

The invention relates to intelligent control of electric power systems, in particular to an automatic switching control device for a photovoltaic micro-grid power generation system.

Background technique

With the development of society and economy, energy and environment have become important issues facing the world. Energy shortages and environmental degradation are becoming more and more prominent. The development and utilization of green energy has become the most effective way for countries all over the world to solve the energy crisis and environmental degradation. Solar energy has become a renewable energy with good prospects for development and utilization due to its abundant resources, cleanness and pollution-free. As the main way of photovoltaic power generation, photovoltaic grid-connected power generation technology has been more and more recognized and concerned by people, and has gradually become the mainstream of photovoltaic power generation applications. Distributed generation (DG) has developed rapidly due to its many advantages such as less pollution, high energy utilization efficiency, and flexible installation locations. However, a large number of DGs connected to the grid also have some adverse effects.

Photovoltaic grid-connected needs to solve problems such as inverter, grid-connected, and harmonic control. At present, the commonly used method is to apply the maximum power tracking (MPPT) control to the charging circuit of the controller according to the working characteristics of the photovoltaic cell to realize the output of the maximum efficiency of the photovoltaic cell. ) generates SPWM pulses to drive the inverter circuit and connect to the grid. The controller realizes the utilization of the maximum efficiency of the photovoltaic cell and minimizes the harmonic distortion rate of the inverter part. But the existing problems are: (1) DSP chip processing capacity is limited, and precise control such as voltage and current monitoring, inverter drive, harmonic control, switching, etc. is completed at the same time. The technical requirements are high and the reliability is low, so it is necessary to study higher processing Performance chips, or large-scale increase in investment. (2) In the new energy power generation system with thermal power, hydropower, nuclear power and other traditional energy as the backbone, connected in a balanced manner, the photovoltaic micro-grid power generation system is a beneficial supplement to the distribution network, and its switching needs to be macroscopically controlled on the whole According to the load level and photovoltaic microgrid power generation capacity, select the most suitable photovoltaic microgrid system to put into the power grid, so as to achieve a reasonable allocation of resources and save costs. At present, this part of the content is still blank. (3) If it is necessary to achieve macro-control, each photovoltaic micro-grid system must be monitored and the data sent to the background to make an optimal judgment after decision-making by the expert system. The singleness of information and the development of background intelligent decision-making systems are also key issues in solving the effective grid connection of photovoltaic systems.

Patent document CN201410449595 provides an online switching method, device and system for photovoltaic power generation units. The disclosed method includes obtaining the bus voltage of the DC busbar and the output voltage of the DC-DC converter; calculating the bus voltage and the output voltage of the DC-DC converter The voltage difference of the output voltage; compare the amplitude of the voltage difference with the preset value; if the amplitude is less than the preset value, switch the photovoltaic power generation unit to the DC busbar through the buffer circuit; if the amplitude is greater than or equal to the preset value , the photovoltaic power generation unit enters the waiting state for switching. The disclosed embodiments can reduce the inrush current when the photovoltaic power generation unit is switched on and off, so that the photovoltaic power generation unit disconnected from the DC busbar can be smoothly put into the photovoltaic DC power supply system online, thereby improving the economic feasibility of the public DC busbar power supply system. Publicly expounded the online switching method and device of photovoltaic power generation units. From the perspective of voltage difference, the operation is simple and implementable, but it is not considered from the perspective of the whole network. If only from the perspective of voltage, after the photovoltaic system is connected to the grid, There will be a surplus of energy.

Patent document CN201110296814.0 discloses a plug-and-play photovoltaic power generation grid-connected system detection device, which includes a power supply circuit, a photovoltaic cell access circuit, a battery access circuit, a transformer access circuit, a load selector, and a photovoltaic cell detection Load circuit, inverter detection static load circuit, inverter dynamic load circuit and DSP processor, the advantages of the disclosed detection device include plug and play, by collecting data, determine the fault of the power generation system; realize photovoltaic panels, inverter The device can be detected under various load working conditions and can meet the switching between multiple photovoltaic cells to be tested at the same time, realize the comparison and detection of multiple photovoltaic cell power generation states, and greatly improve the efficiency and accuracy of photovoltaic cell detection ; The pulse generating device and the delay device can be set according to the actual load conditions corresponding to different power generating devices, so that the simulated load is closer to the real situation, and the detection accuracy is increased. The disclosed detection device detects multiple parameters, determines the fault, and can switch the battery of the photovoltaic system, but there is no description of the switching method of the photovoltaic system when it is put into the grid.

Contents of the invention

In view of the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide an automatic switching control device for a photovoltaic micro-grid power generation system, which detects multiple power parameters from the perspective of the entire network, and combines the background expert resource library to perform Decision-making, choose the optimal combination of photovoltaic systems to put into grid-connected operation, avoid energy waste, and ensure power quality.

In order to realize the foregoing invention object, the technical scheme that the present invention adopts is as follows:

An automatic switching control device for a photovoltaic micro-grid power generation system, including a measurement control unit, a 4G wireless communication network, and a background decision-making system, wherein the measurement control unit is connected to the background decision-making system through a 4G wireless communication network, and through the 4G wireless communication network, The measurement control unit sends the grid information data to the background decision-making system, and the background decision-making system sends the background decision-making system instructions to the measurement control unit;

The measurement control unit includes a digital signal processor, a display module, a key module, a data memory, a 4G interface module, a control output interface, a real-time clock circuit, an electric energy metering chip, an AD conversion circuit, a data acquisition module, a voltage transformer, and a current transformer. Among them, the display module, button module, data memory, 4G interface module, control output interface, real-time clock circuit, electric energy metering chip, and AD conversion circuit are respectively connected to the digital signal processor and controlled by the digital signal processor;

The measurement and control unit monitors power quality, analyzes harmonics, grid voltage levels, and three-phase unbalance, and performs load forecasting based on on-site measurement parameters and load statistics, and effectively matches the load forecast with the calculated value of photovoltaic micro-grid power generation. And complete the automatic switching of the photovoltaic micro-grid power generation system;

The background decision-making system includes a gateway server and the Internet. The background decision-making system receives and analyzes the real-time data collected by the measurement control unit through the gateway server, and intelligently sets and modifies the terminal strategy.

Further, the digital signal processor calculates the power generation amount of the photovoltaic matrix according to the data volume of solar radiation, environmental conditions, and matrix inclination angle collected by the data acquisition module.

Further, the AD conversion circuit converts the received temperature and humidity analog signals and photovoltaic array analog signals into temperature and humidity digital signals and photovoltaic array digital signals.

Further, the electric energy metering chip calculates the power generation information of the photovoltaic micro-grid power generation system.

Further, the display module enables the user to monitor the data on site.

Furthermore, the real-time clock circuit provides a clock signal for the digital signal processor in real time; the digital signal processor completes switching of the photovoltaic micro-grid power generation system through the control output interface.

Further, the button module completes the monitoring state conversion, parameter setting and fixed value modification, and completes the opening, closing and opening and closing locking operations of the local switching switch.

Furthermore, the background decision-making system publishes information to the Internet, and users manage, maintain, browse, and analyze the operating status of the photovoltaic microgrid system in different places.

The present invention also provides a method for controlling the automatic switching control device of the photovoltaic micro-grid power generation system, including the following steps:

Step 101, collecting photovoltaic array environmental information;

Step 102, calculating the power generation of the photovoltaic microgrid power generation system;

Step 103, performing load forecasting;

Step 104, making an intelligent decision;

Step 105, selecting the photovoltaic micro-grid power generation system with the optimal combination;

Step 108, complete automatic switching.

Further, the following steps are also included before step 108:

Step 106, collecting grid-connected voltage and grid-connected current information;

Step 107, judging whether there is a fault and analyzing the power quality.

The automatic switching control device of the photovoltaic micro-grid power generation system provided by the present invention performs macroscopic switching control on the whole, and selects the most suitable photovoltaic micro-grid system to be put into the power grid according to the load level and the photovoltaic micro-grid power generation capacity, so as to achieve resource utilization. Reasonable allocation and cost saving; on-site monitoring and automatic switching, reducing the number of failures, narrowing the scope of accidents, shortening the time of accidents, providing an effective basis for restoring power supply, quickly analyzing, diagnosing, and reporting the cause of accidents, reducing a lot of labor costs, and improving Power supply quality: after the completion of the new energy access system, through the local and remote monitoring of the wireless network, it is difficult to lay a special communication link due to the wide variety of new energy sources or the harsh geographical environment. The photovoltaic micro-grid power generation system of the present invention The automatic switching control device saves the cost of laying communication links. From the perspective of social and ecological benefits, corresponding to the construction of the country's smart grid renewable new energy access system, it provides a guarantee of reliability. It meets the needs of local social development, and at the same time realizes the goal of circular economy; moreover, technology research and development gathers a variety of knowledge in electronic information, computers, advanced control technology, advanced manufacturing and the environment, reflecting the importance of Internet of Things technology in power grids. application, has strong competitiveness, promotes the development of technology, and has broad market prospects. The industrialization investment is 300,000.

Description of drawings

Fig. 1 is the schematic diagram of the automatic switching control device of the photovoltaic microgrid power generation system of the present invention;

Fig. 2 is a program flow chart of the automatic switching control device of the photovoltaic micro-grid power generation system of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the embodiments and accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The automatic switching control device of the photovoltaic micro-grid power generation system provided by the present invention is mainly composed of three main parts: a measurement control unit 1 , a 4G wireless communication network 2 , and a background decision-making system 3 , as shown in FIG. 1 . Wherein the measurement control unit 1 is connected to the background decision-making system 3 through the 4G wireless communication network 2 .

Measurement control unit 1 includes DSP11, display module 12, button module 13, data memory 14, 4G interface module 15, control output interface 16, real-time clock circuit 17, electric energy metering chip 18, AD conversion circuit 19, data acquisition module (not shown Out), and PT (potential transformer) (not shown), CT (current transformer) (not shown). Among them, the display module 12, key module 13, data memory 14, 4G interface module 15, control output interface 16, real-time clock circuit 17, electric energy metering chip 18, and AD conversion circuit 19 are respectively connected to DSP11 and controlled by DSP11. The DSP11 of the present embodiment preferably adopts a programmable signal processor, such as a digital processor of a single-chip signal processor type, to quickly realize processing such as acquisition, transformation, filtering, evaluation, enhancement, compression, and identification of signals, and obtain a required signal form. The measurement control unit 1 can also use a single-chip microcomputer instead of the DSP11.

The data collection module of the measurement control unit 1 includes an environmental data collection sensor, a meter data collector, a voltage collection module and a current collection module. Environmental data acquisition sensors include: light intensity detection sensors, which are used to detect solar radiation; temperature and humidity sensors, which are used to detect environmental conditions; gravity acceleration sensors, which are used to measure the inclination angle of the photovoltaic matrix. The DSP11 of the measurement control unit 1 can calculate the power generation amount of the photovoltaic matrix according to the amount of solar radiation collected by the environmental data acquisition sensor, the environmental conditions, and the data amount of the inclination angle of the matrix.

The measurement control unit 1 uses the environmental data acquisition sensor of the data acquisition module, the meter data collector, the voltage acquisition module, and the current acquisition module to collect the environmental parameters of the photovoltaic array, the grid-connected voltage, and the grid-connected current, and simulate the obtained temperature and humidity Signals, photovoltaic (PV) array analog signals are transmitted to the AD conversion circuit 19, and the AD conversion circuit 19 converts the received temperature and humidity analog signals and photovoltaic array analog signals into temperature and humidity digital signals and photovoltaic array digital signals and transmits them to DSP11 to process.

The PT in the measurement control unit 1 is used to transform the voltage on the line, convert the high voltage into a low voltage in proportion, such as a standard secondary voltage of 100V or lower, and provide the voltage of the grid to the electric energy metering device 18 through the PT input information. Measure the CT in the control unit 1, convert the primary current with a large value in the line into a secondary current with a small value through a certain transformation ratio, and provide the current information of the power grid to the electric energy metering device 18 through the CT input. CT is preferably Use current transformers for measurement. In FIG. 1 , PT, CT inputs are schematically represented by reference numeral 4 . The measurement control unit 1 converts large current and large voltage into measurable voltage and current through PT, CT and voltage and current sensors (not shown), and transmits the converted measurable voltage and current to electric energy through PT and CT input 4 The metering chip 18 is then transmitted to the DSP 11 for collecting grid-connected voltage and grid-connected current. At the same time, the electric energy metering chip 18 calculates the power generation information of the photovoltaic microgrid power generation system through the chip function through the voltage information collected by the PT and CT.

The display module 12 of the measurement control unit 1 can adopt LCD display (liquid crystal display), and the display module 12 communicates with the DSP 11 to display the information of the DSP 11 in real time. The measurement control unit 1 uses the display module 12 to perform real-time tracking and display of grid waveforms, SOE (sequence of events) event recording, etc., so as to realize the user's on-site data monitoring.

The real-time clock circuit 17 of the measurement control unit 1 is used to provide a clock signal for the DSP 11 in real time, and the DSP 11 executes the program according to the time sequence driven by the clock to complete the operation of different instruction functions.

The key module 13 of the measurement control unit 1 is mainly used to complete the monitoring state conversion, parameter setting and fixed value modification, and complete the opening, closing and opening and closing locking operations of the local switching switch. The switching of the photovoltaic micro-grid power generation system can be automatically controlled by the DSP 11 through the key module 13 , or can be switched manually through the key module 13 according to the display of the display module 12 .

The control output interface 16 of the measurement control unit 1 is connected to a relay (not shown), and the DSP 11 realizes the control of the relay through the control output interface 16, thereby realizing the control of the switching switch and completing the switching of the photovoltaic microgrid power generation system .

The data memory 14 of the measurement control unit 1 can store information received and processed by the DSP 11 and can be accessed via the DSP 11 .

Measurement and control unit 1 monitors power quality through DSP11, analyzes harmonics, grid voltage level, three-phase unbalance, etc., and makes the photovoltaic micro-grid power generation system quickly withdraw from the distribution network when a fault or power quality does not meet the requirements; and according to the site Measure parameters and load statistics to carry out load forecasting, and effectively match the load forecasting with the calculated value of photovoltaic micro-grid power generation to ensure that the optimal combination of photovoltaic micro-grid power generation system is selected and put into operation, thereby ensuring the on-site optimum performance of the photovoltaic micro-grid power generation system. Excellent switching.

The measurement control unit 1 includes a wireless communication module (not shown), and the DSP11 is connected to the 4G wireless communication network 2 through the 4G interface module 15 of the wireless communication module, so the measurement control unit 1 can easily access the 4G wireless communication network of the communication operator 2. Through the 4G wireless communication network 2, the measurement control unit 1 sends the power grid information data to the background decision-making system 3, and the background decision-making system 3 sends the instructions of the background decision-making system 3 to the measurement control unit 1, and the DSP 11 of the measurement control unit 1 according to the background decision-making The command issued by system 3 executes the corresponding operation, and completes the automatic switching of the photovoltaic micro-grid power generation system.

The background decision-making system 3 includes a gateway server 31 and an Internet (Internet) 32 . The background decision-making system 3 receives and analyzes the real-time data collected by the measurement control unit 1 through the gateway server 31, and can intelligently set and modify terminal policies based on long-term operation experience according to local power grid conditions and user requirements. The background decision-making system 3 mainly adopts an artificial neural network or an expert system program. In this embodiment, the background decision-making system 3 adopts an expert system program to provide a recommended strategy execution plan and perform artificial experience-assisted monitoring and decision-making to compensate for automatic switching. fail.

The background decision-making system 3 publishes information to the Internet 32 through the Web (web page). Through the off-site monitoring system 5, such as a browser, users can manage, maintain, browse, and analyze the operating status of the photovoltaic microgrid system in off-site.

The switching index of the automatic switching control device of the photovoltaic micro-grid power generation system of the present invention is the grid connection requirement, which is shown in Table 1-4. When grid-connected, the normal range of the grid voltage is 88% to 110% of the standard voltage. When the phase voltage of the grid exceeds the normal range, the automatic switching control device of the photovoltaic micro-grid power generation system of the present invention should detect the abnormality immediately and respond within the specified time. The abnormal voltage response time of the grid-connected system is shown in Table 1.

Table 1

Voltage range (standard voltage percentage%) Response time (Ms) V<50% 160 50%≤V<88% 2000 110%<V<120% 1000 V≥120% 160

The grid-connected synchronization requirements of the automatic switching control device of the photovoltaic micro-grid power generation system of the present invention are shown in Table 2.

Form 2

Capacity (KVA) Frequency (ΔF,HZ) Voltage difference (ΔV,%) Phase difference (ΔU,;°) 0～500 0.3 10 20 >500～1500 0.2 5 15 >1500～10000 0.1 3 10

The grid-connected voltage harmonic technical indicators of the automatic switching control device of the photovoltaic micro-grid power generation system of the present invention are shown in Table 3.

Form 3

Odd harmonic H H<11 11≤H<17 17≤H<23 23≤H<35 35≤H Total harmonics (THD) (%) 4.0 2.0 1.5 0.6 0.3 5.0

The grid-connected current harmonic technical index of the automatic switching control device of the photovoltaic micro-grid power generation system of the present invention is shown in Table 4.

Form 4

Odd harmonic H H<11 11≤H<17 17≤H<23 23≤H<35 35≤H Total harmonics (THD) (%) 4.0 2.0 1.5 0.6 0.3 5.0

The program flow chart of the automatic switching control device of the photovoltaic micro-grid power generation system of the present invention is shown in Figure 2, including the following steps: Step 101, the environmental data acquisition sensor of the measurement control unit 1 and the meter data collector collect the photovoltaic array Environmental information; after step 101, in step 102, utilize the power metering unit 18 of control unit 1 to calculate the power generation of the photovoltaic microgrid power generation system; Perform load forecasting with load statistics, and effectively match the load forecast with the calculated value of photovoltaic micro-grid power generation; after step 103, in step 104, DSP11 matches the load forecast with the calculated value of photovoltaic micro-grid power generation through 4G wireless The communication network 2 transmits to the background decision-making system 3, and the background decision-making system 3 makes intelligent decisions through the expert system program; after step 104, in step 105, the background decision-making system 3 selects the photovoltaic microgrid power generation system with the optimal combination, and switches The command is sent to DSP11; after step 105, in step 108, DSP11 completes automatic switching.

Simultaneously in step 106, the voltage acquisition module of measurement control unit 1, the current acquisition module gathers grid-connected voltage, grid-connected current information; After step 106, in step 107, DSP11 judges whether there is fault and power quality analysis; After step 107 , in step 108, DSP11 completes automatic switching according to the judgment result of step 107.

The measurement control unit 1 of the automatic switching control device of the photovoltaic micro-grid power generation system of the present invention collects the environmental parameters of the photovoltaic column, the grid-connected voltage, and the current collected by the environmental data acquisition sensor, the meter data collector, the voltage acquisition module, and the current acquisition module. , passed to DSP11 for processing. The 4G interface module 15 of the measurement control unit 1 ensures that the data is effectively and quickly transmitted through the 4G communication network 2 to the background decision-making system 3 for decision-making; the automatic switching control device of the photovoltaic micro-grid power generation system of the present invention can monitor power quality and perform Harmonic analysis, when faults and power quality do not meet the requirements, the photovoltaic micro-grid power generation system will be withdrawn from the distribution network quickly. At the same time, the on-site measurement parameters are effectively matched with the calculated value of the micro-grid power generation to ensure that the photovoltaic micro-grid power generation system with the optimal combination is put into operation; the background decision-making system of the automatic switching control device of the photovoltaic micro-grid power generation system of the present invention 3 It can also integrate local power grid conditions and user requirements to intelligently set and modify terminal strategies based on long-term operating experience.

The above-mentioned embodiments only express the implementation manner of the present invention, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention.

Claims (10)

1. the automatic switching control device of a photovoltaic micro-grid power generation system, it is characterized in that, comprise measure-controlling unit, 4G cordless communication network, backstage decision system, wherein, described measure-controlling unit is connected to described backstage decision system by described 4G cordless communication network, by described 4G cordless communication network, electric network information data are sent to described backstage decision system by described measure-controlling unit, and/or the decision system instruction of described backstage is issued to described measure-controlling unit by described backstage decision system;

Described measure-controlling unit comprises digital signal processor, display module, key-press module, data storage, 4G interface module, controls output interface, real time clock circuit, electric energy computation chip, A/D convertor circuit, data acquisition module and voltage transformer, current transformer, and wherein said display module, key-press module, data storage, 4G interface module, control output interface, real time clock circuit, electric energy computation chip, A/D convertor circuit are communicatively connected to described digital signal processor respectively and are subject to described DSP CONTROL;

Described measure-controlling unit carries out electric energy quality monitoring, analyze harmonic wave, voltage level of power grid, tri-phase unbalance factor, and carry out load prediction according to in-site measurement parameter and load statistics, the calculated value of load prediction with photovoltaic microgrid energy output is effectively mated, and completes the automatic switching of photovoltaic micro-grid power generation system;

Described backstage decision system comprises gateway server, the Internet, and described backstage decision system is received by described gateway server and analyzes the real time data that described measure-controlling unit collects, and intelligent setting and modifying terminal strategy.

2. the automatic switching control device of photovoltaic micro-grid power generation system according to claim 1, it is characterized in that, described digital signal processor, according to the data volume at the solar radiation quantity of described data collecting module collected, environmental aspect, matrix inclination angle, calculates photovoltaic matrix energy output.

3. the automatic switching control device of photovoltaic micro-grid power generation system according to claim 1, is characterized in that, described A/D convertor circuit converts the warm and humid analog signal received, Photovoltaic array analog signal to humiture digital signal, Photovoltaic array digital signal.

4. the automatic switching control device of photovoltaic micro-grid power generation system according to claim 1, is characterized in that, described electric energy computation chip calculates the energy output information of photovoltaic micro-grid power generation system.

5. the automatic switching control device of photovoltaic micro-grid power generation system according to claim 1, is characterized in that, described display module realizes user scene and monitors data.

6. the automatic switching control device of photovoltaic micro-grid power generation system according to claim 1, is characterized in that, described real time clock circuit is in real time for digital signal processor provides clock signal; Described digital signal processor completes the switching of photovoltaic micro-grid power generation system by described control output interface.

7. the automatic switching control device of photovoltaic micro-grid power generation system according to claim 1, it is characterized in that, described key-press module completes monitor state conversion, optimum configurations and fixed value modification, complete local fling-cut switch point, close a floodgate and divide-shut brake lock operation.

8. the automatic switching control device of photovoltaic micro-grid power generation system according to claim 1, it is characterized in that, described backstage decision system by Information issued to described the Internet, the operation such as the operation conditions of user strange land to photovoltaic microgrid system manages, safeguard, browse, analysis.

9. control a method for the automatic switching control device of photovoltaic micro-grid power generation system according to claim 1, comprise the steps:

Step 101, gathers Photovoltaic array environmental information;

Step 102, calculates the energy output of photovoltaic micro-grid power generation system;

Step 103, carries out load prediction;

Step 104, carries out intelligent decision;

Step 105, selects the photovoltaic micro-grid power generation system of optimum combination;

Step 108, completes automatic switching.

10. method according to claim 9, is characterized in that, simultaneously further comprising the steps of before described step 108:

Step 106, gathers grid-connected voltage, grid-connected current information;

Step 107, has judged whether fault and power quality analysis.