Design of solar central water heater control and management system for cluster applications

This paper proposes a technical solution using decentralized detection, centralized control and visual management, using embedded systems, wireless communication, computer software and Web technologies to realize the visual management and operation of the solar central water heater system, while providing convenient after-sales service for enterprises. Service management means and convenient statistics and release of energy-saving data are of great significance for promoting the promotion and application of solar central water heaters.

1 system design

The composition of the system is shown in Figure 1. It consists of three parts: the field terminal, the regional centralized control and management platform, and the enterprise centralized control and management center. The field terminal includes a main controller, a line controller, and a wireless data transmission module. The main controller implements automatic control of the solar water heater, and establishes a communication link with the regional centralized control and management platform through the wireless data transmission module, and realizes on-site setting and control of the system through the line controller. The regional centralized control and management platform consists of a computer and wireless data transmission module with control and management software. Its main tasks include: receiving data from the main controllers in the jurisdiction, and performing protocol analysis, data storage and update management. Interface information; responsible for sending control or setting commands to the designated master; data exchange with the enterprise centralized control and management center via the Internet or GSM/GPRS; synchronous transmission of relevant data to the enterprise centralized control and management center. The enterprise centralized control and management center consists of a data server, a management computer and necessary display and printing equipment. The center can conduct measurement and control of any solar central water heater through the regional centralized control and management platform and the main controller, and query any one of the water heaters. Real-time data and historical data, statistical heat production and energy saving data.

2 field terminal design

The structure of the field terminal is shown in Figure 2. The main control microprocessor, sensor module, system configuration and expansion module, output control module (including control of three subsystems of solar energy production, heating and auxiliary heating), communication module (including The line controller and the wireless data transmission module) and the power supply circuit are composed. The main control microprocessor LPC2368 compares the preset data stored in the extended memory (E2PROM) according to the field and system status and related parameters detected by the sensor module, obtains corresponding control logic, and outputs the control module to the solar energy. Central water heater

Control, realize the working mode of constant temperature water inlet, temperature difference cycle, antifreeze protection, pressurized water supply, constant temperature return water, water level over limit and variable capacity auxiliary heating; realize on-site and remote operation and measurement and control through communication module, apply for solar central water heater cluster Provides a communication link that controls and manages the data required.

3 Regional centralized control and management software design

The regional centralized control and management software includes regional control software and regional management software: the regional control software is responsible for sending instructions in the database to all the main controllers in the monitoring area, receiving, processing, and storing data from each main controller, and simultaneously calling The web service program synchronizes with the data of the enterprise centralized control and management center. The area management software consists of web browser, web server and data server management software, as shown in Figure 3.

3.1 Regional Control Software Design

The regional control software is written in .Net and is divided into a data communication module and a data synchronization module according to different communication objects. The modular design is used to realize the functions of receiving, transmitting, processing, storing, displaying and synchronizing data. The workflow of the regional control software is shown in Figure 4.

3.1.1 Data Communication Module

RS can be used between the regional control platform and all solar water heaters in the monitored area

485 and wireless data transmission two communication methods, according to the project site conditions to choose one. For the data communication module, once the data transmission communication protocol is determined, its task is to receive and transmit data. In order to ensure accurate and reliable data transmission, the module obtains the address field of the master controller that failed the last self-test through the self-test timer, and sends a self-test command to the master controller that fails the self-test in a polling manner. At the same time, the module judges the received instruction data, deletes the error and timeout instructions in the instruction list, and simultaneously merges the same instructions to eliminate redundant information.

The instructions sent by the data communication module to each of the main controllers further include instructions for querying real-time data, historical data, historical alarms, and historical parameter settings. The module processes the data returned by the main controller, decomposes and converts the data, and finally performs data storage and updates the data. The working flow chart of the data communication module is shown in FIG. 5.

3.1.2 Regional Central Control and Management Software Design

As a bridge between the connection area database and the enterprise management center database, the regional control platform synchronizes the two databases through the Web service. Regional and corporate data includes current and historical data. The synchronization area and enterprise data program flow are shown in Figure 6.

3.2 Regional Management Software Design

The area management software consists of a web browser, a web server, and data server management software. The web browsing interface of the system is designed with Flex technology. It is one of the most popular RIA (rich Internet application system) development technologies. The advantage is that the client can perform complete data processing, the interface interaction does not depend on the page, and the message can pass. Asynchronous request delivery reduces the frequency of remote interaction between the user and the system, and the interaction with the user is more friendly and rapid.

According to the actual needs, the system based on Flex technology design includes two functions: the parameter setting and data query function of the solar central water heater control system. When the client enters the Flex browsing interface, the browser sends a request (parameter setting instruction and data query instruction) to the web server, and the web server converts the request to access the database into a SQL statement and hands it to the data server. The data server processes the received data and returns it to the web server; the web server dynamically generates the HTML document and forwards it to the client, and the browser finally displays it in the form of a friendly web page to realize visual management of the solar water heating system.

In addition, through the Flex interface, you can add regional, provincial, and municipal geographic information, add a solar central water heater subsystem, and record installation information for all subsystems. At the same time, in order to facilitate the management of the system, the maintenance system administrator can be given different management rights.

4 Enterprise centralized control and management software design

The enterprise centralized control and management center is composed of a computer, a data server and necessary display and printing devices for installing enterprise centralized control and management software. The enterprise centralized control is different from the regional control and has exclusive control software, which cannot directly directly to the main controller. Send data, but the enterprise management software and the regional management software have the same architecture. They all adopt Flex design on the .Net platform, provide Web services, receive the control tasks of the Flex interface, enterprise centralized control and management center and regional centralized control and management platform. Data synchronization through web services. The main difference between it and the regional centralized control and management platform is also reflected in the management authority and the size of the database.

5 system functions and features

The system has been tested in the laboratory for 6 months, and all functions and indicators have met the design requirements. In addition to the control functions of the conventional solar central water heater, it also has the following characteristics:

(1) Implement distributed detection and centralized control of the system. The main controller of each solar water heater can exchange data with the regional centralized control and management platform through the RS 485 bus or wireless data transmission module, and upload the data to the enterprise centralized control and management center through the Internet.

(2) System configurability and control adaptability. The system can configure different components (including auxiliary heating equipment, number of heat collecting plates, combination of water storage tanks and connection mode of water pipes, etc.) according to different installation sites and user requirements. The main controller can adapt to different configurations of the system. Implement control.

(3) Intuitive display interface. The system can automatically generate an intuitive display interface according to different installation configurations. Figure 7 and Figure 8 show the system diagram of the field installation through the Flex interface. Different combinations of configurations can be seen from the figure, and the working status and main parameters of the system are clear at a glance.

6 Conclusion

This paper proposes a design scheme for solar central water heater control and management system for cluster applications, briefly introduces the principle block diagram and main functions of the field terminal, analyzes the design method of regional centralized control and management software in detail, and introduces the main features of the system. Laboratory tests show that the system has the characteristics of stable and reliable performance, intuitive and convenient operation, fast and accurate control, and accurate alarm. The system has been identified as an upgraded product by Fuzhou Zhongwangda Solar Technology Development Co., Ltd. and has been applied to the actual project of the company.

Note: Shenzhen Anpeilong Technology Co., Ltd. develops and produces various temperature sensors with stable performance and good reliability. Welcome to inquire! !