As China's national economy rapidly develops, the supply of electricity is becoming increasingly tight, and electricity consumption is also on the rise. Coal mining enterprises, as both major producers and consumers of energy, urgently need to tap into internal potential, reduce production costs, and conserve energy and electricity.
Traditional coal mine power management is relatively extensive, with equipment such as belt conveyors, scraper conveyors, pumping stations, and submersible pumps often running at no load during peak hours, resulting in significant waste. As an example, a certain coal mine has greatly improved the peak load factor and achieved effective energy saving by constructing a data transmission network for the power management system, including data collection, analysis, and the establishment of a management platform, resulting in better outcomes.
1. The main issues previously existing in the coal mine.
A coal mine company faces complex underground geological conditions with significant water inflow, leading to high electricity consumption for drainage. The main transportation system has not reached full capacity, with numerous large power-consuming equipment such as compressed air, ventilation, mining, and water source heat pumps. On the ground, there are severe electricity waste phenomena in key areas such as the 110kV substation, hoisting house, compressor room, laundry room, coal washing plant, employee building, comprehensive office building, machine harvesting workshop, and the central power distribution rooms at -500 and -690 meters underground, as well as the main conveyer belt transportation system.
To effectively reduce energy consumption and enhance equipment operation efficiency, a coal mine has implemented an energy management system to automatically monitor and analyze the entire company's production and living electricity usage. It has adopted a strengthened management of electricity quotas, rationally scheduling electricity, and conducting load shifting to avoid peak usage. This promotes the optimal allocation of energy resources, increasing load factor, peak-to-valley ratio, and power factor, while reducing various losses and electricity costs.
Design of Coal Mine Power Management System
2.1 Overall Architecture
The Mine Power Management System utilizes a hierarchical distributed network architecture, offering excellent reliability and real-time performance. It is composed of three main parts: the field equipment layer (power metering terminals), the communication management layer (data collection terminals), and the master control layer (power management platform), as shown in Figure 1.
Figure 1: Power Management System Architecture of a Certain Mine
2.2 Original Data Collection
Data collection is achieved through the installation of 100 intelligent electricity metering terminals across the entire mine, which collect real-time electricity consumption data from major electrical equipment. The electricity quality monitoring terminals have a metering accuracy controlled at the factory of 0.2S class. They are equipped with RS-485 fieldbus communication, input/output functions, and can realize remote signaling, measurement, and control, along with remote power-off functionality through the output function. They also offer electricity quality statistical analysis and support the Modbus-RTU protocol. The main areas, including the 35kV substation -500 Central Substation and the -690 Central Substation, have all been retrofitted with electricity quality monitoring terminals.
2.3 Data Transmission
Each electricity metering terminal is connected to the electricity substation locally. The substation can utilize the industrial Ethernet ring network to connect to the industrial Ethernet locally via the Ethernet port and transmit data to the energy control center.
All power quality monitoring terminals installed in areas with 35kV substation, -500 central transformer, and -690 central transformer power supply have been successfully connected via RS-485 communication to either general or explosion-proof and intrinsic safety type power monitoring stations (electrical parameter metering stations). By connecting to the existing fiber optic ring network, the power data is transmitted to the ground power monitoring center, enabling remote monitoring of the power quality at the substation.
The electrical parameter metering substation primarily facilitates data exchange between the underground high and low voltage power supply system's power quality monitoring terminal and the ground energy management monitoring system, enabling local monitoring functions. It automatically reads and stores electricity data from intelligent instruments, quality monitoring terminals, collection modules, and various carrier communication terminals via the downstream channel, as well as collects external RS-485 meter data through its RS-485 serial communication channel. Additionally, it exchanges data with the master station or handheld devices via the upstream channel, which uses the public communication network to support client-server communication modes. With modular design, the communication method can be directly changed by replacing the communication module, in compliance with IEC international standards and also with the communication protocol, technical conditions, and type specifications for the power consumption information collection system's master station and concentrator.
Power Management System
3.1 Comprehensive Management and Control
As shown in Figure 2, the production electricity management follows the actual requirements for electricity management of a certain coal mine. The electricity management system achieves real-time collection and network transmission of electricity parameters, and provides comprehensive management and control of electricity resources.
Achieve the following functionalities
1) Achieve energy management across peak, peak, flat, and valley segments, regulating and adjusting power distribution for each segment.
2) Features automatic meter reading and billing, time-of-use rate management, and load curve control.
3) Event logging and query functionality, data collection and query analysis, real-time monitoring and alerting, long-term high-load monitoring, power dispatch monitoring, archive management, statistical analysis, report management, storage, printing capabilities, and a power consumption comparison chart that directly displays the electricity consumption of different billing units and the proportion of electricity consumed by certain billing units within the total consumption. Additionally, an electricity expense comparison chart is provided to directly display the electricity expense situation of different billing units over a specific period and the proportion of electricity expenses paid by certain billing units within the total expenses.
Figure 2: Production Electricity Management Diagram
3.2 Implement Early Warning Management
Set range values for various energy indicators; issue early warnings for trend curves within the range; handle alarms for values exceeding the range; provide graded early warnings for system equipment operation failures, along with troubleshooting plans, as shown in Figure 3.
Figure 3: Early Warning Management Diagram
By periodically concentrating and reporting on actual energy consumption data (including both statistical and forecasted data) and comparing it with the expected energy consumption calculated based on actual production parameters, the reliability of energy data measurement and calculation can be improved. Energy management authorities can use this to plan, observe, and control, and to make arrangements for the implementation of energy-saving technology projects. Coordination of energy supply and control based on production plans and energy forecasts can ensure that both the energy needs of the production process are met and load peaks are reasonably avoided.
The Energy Center utilizes real-time and historical energy databases to calculate energy forecasts for various energy accounting units, adopting data mining models or multivariate statistical methods based on different production and operational states, and proposes trends in energy consumption.
3.3 Utilizing Big Data for Energy Consumption Equipment Management
Figure 4 illustrates the energy control and dispatch diagram. It primarily involves predicting and warning about the operational status and service life of equipment, providing a basis for scheduled maintenance. Additionally, it performs intelligent analysis on equipment utilization rate, operation rate, running records, and fault records.
Figure 4: Energy Management and Scheduling Diagram
Ankore Acrel-3000WEB Energy Management Solution
4.1 Overview
Consumers account for 80% of the electricity consumed in the entire power grid. Intelligent electricity management at the consumer end is of great significance for ensuring reliability, safety, and energy savings. Constructing an intelligent electricity service system and promoting solutions for electricity management using smart meters and intelligent electricity management terminals will achieve a positive, two-way interaction between the power grid and consumers. The urgent research topics at the consumer end primarily include: metering, intelligent buildings, smart appliances, value-added services, customer electricity management systems, and demand-side management.
The Acrel-3000WEB Energy Management Solution by Ankeai meticulously analyzes and tallies power consumption at the user end, presenting detailed usage and consumption data through intuitive charts and graphs to management or decision-makers. This facilitates the identification of high-energy consumption areas or inefficient habits, effectively conserving electricity. It also provides accurate data support for users' further energy-saving renovations or equipment upgrades.
4.2 Application Scenarios
(1) Office Buildings (business offices, large public buildings, etc.)
(2) Commercial Buildings (shopping malls, financial institution buildings, etc.)
(3) Hospitality Architecture (hotels, restaurants, etc.)
(4) Educational, cultural, scientific, research, health, and sports architecture;
(5) Telecommunications Infrastructure (postal, telecommunications, broadcasting, television, data centers, etc.)
(6) Transportation Infrastructure Construction (airport, station, port buildings, etc.)
4.3 System Structure
4.4 System Function
4.4.1 Real-time Monitoring
The system features a user-friendly human-machine interface, displaying the operation status of the power distribution lines in the form of a single distribution diagram. It real-time monitors electrical parameters such as voltage, current, power, power factor, and energy, dynamically supervising the switching states of circuit breakers, disconnect switches, and ground switches in each distribution loop, as well as related fault and alarm signals.
4.4.2 Electric Power Statistics Report
The system supports the integrity of the metering system with rich reports. It features a time-scheduled meter reading and summary statistics function, allowing users to freely query the power consumption of each distribution node at any time period since the system's normal operation. This includes the statistical analysis report of the power consumption at the incoming line of the node and the power consumption of each branch circuit. This function makes power consumption visible and transparent, and can analyze and trace back in cases of significant power consumption errors, ensuring the correctness of the metering system.
4.4.3 Detailed Electrical Parameter Inquiry
In the primary distribution diagram, when the mouse cursor hovers near each loop, it changes to a hand icon. A single click on the loop allows you to view detailed electrical parameters, including three-phase current, three-phase voltage, total active power, total reactive power, total power factor, forward active energy, and also displays 24-hour phase current trend curves and 24-hour voltage trend curves.
4.4.4 Operational Report
The system features real-time and historical power parameter storage and management capabilities. All real-time collected data and sequential event records can be saved in the database. Users can customize the parameters, time, or select updated records for querying in the search interface, and the results are displayed through reports. Users can tailor daily and monthly reports as needed, support exporting in Excel format, and can also export in PDF format upon request.
4.4.5 Transformer Operation Monitoring
The system performs real-time online monitoring of the operating status of the main incoming line of the distribution system, the main transformer, and the important load output lines. It displays trends such as current, transformer operating temperature, active power demand, active power, apparent power, and transformer load rate with curves, analyzes transformer load rate and losses, facilitating operation and maintenance personnel to promptly grasp the operating level and power demand, ensuring safe and reliable power supply.
4.4.6 Real-time Alarm
The system features real-time alerting capabilities, capable of monitoring remote signals for changes in distribution circuit circuit breakers, disconnect switches, grounding knives, and their opening and closing actions. It also protects against protective actions, accident tripping, and events like voltage, current, power, and power factor limits. The system issues alerts based on the severity of the events. Upon alerting, a real-time alert window automatically pops up, accompanied by audio or voice reminders.
4.4.7 Historical Event Inquiry
The system is capable of storing and managing records of events such as remote signal changes, protective actions, accident tripping, and over-limit conditions of voltage, current, power, and power factor, facilitating users in tracing historical system events and alarms, as well as conducting query statistics and accident analysis.
4.4.8 Power Quality Monitoring
The system continuously monitors the power quality within the entire distribution system. Operation and maintenance personnel can utilize harmonic analysis bar graphs and reports to grasp the voltage, current harmonic distortion rates, harmonic content, and voltage unbalance levels of incoming lines, transformers, and critical circuits. This enables timely implementation of appropriate measures to reduce harmonic losses and minimize abnormal conditions and accidents caused by harmonics. (This feature requires an optional power meter with harmonic monitoring capabilities; it can be deleted if not needed.)
4.4.9 Remote Operation
The system supports remote control operations for disconnectors, isolators, and grounding switches. It features strict password protection and operational permission management. For each remote operation, the system automatically generates operation records, which include the operator, operation time, and operation type. To achieve this functionality, the circuit breaker itself must have an electric operating mechanism, and the protective and control devices must have remote control capabilities, requiring support from specific hardware equipment.
4.4.10 User Permission Management
The system has set up user permission management to ensure the secure and stable operation. User permission management can prevent unauthorized operations (such as modifying distribution circuit names). Different levels of user login names, passwords, and operation permissions can be defined, providing reliable security for the system's operation, maintenance, and management.
4.4.11 Communication Status Diagram
The system supports real-time monitoring of communication statuses of all devices connected to the system, fully displaying the entire network structure of the system. It allows for online diagnosis of device communication statuses, and can automatically display faulty devices or components, along with their malfunctioning parts, on the interface when network anomalies occur. This facilitates operation and maintenance personnel in real-time monitoring of the communication statuses of all devices on-site, enabling timely maintenance of devices with anomalies, and ensuring the stable operation of the system.
4.4.12 Video Surveillance
Video surveillance displays the live feed (video streaming). Select a specific substation transformer, and you can view the video information within that substation.
4.4.13 User Report
The User Report Page is primarily used for automatically compiling a monthly operation data summary of selected transformer substations. It conducts statistical analysis on transformer loads, distribution circuit power consumption, power factor, and alarm events.
4.4.14 APP Support
The Power Operation and Maintenance mobile app supports five major modules: "Monitoring System," "Equipment Records," "To-Do List," "Inspection Records," and "Defect Records." It offers features such as one-image display, demand, electricity consumption, video, curve, temperature and humidity, year-on-year and month-on-month comparisons, power quality, and various event alarm inquiries. It also includes equipment records search, to-do event management, and inspection record checks.
4.5 System Hardware Configuration List
5. Summary
A coal mine has implemented an energy management system, which has enhanced the timeliness, accuracy, and efficiency of energy usage management. By monitoring energy consumption and unit energy data through the network, the system has scientifically improved the peak-to-valley ratio. Currently, the peak-to-valley ratio of electricity usage at the mine has increased from 1:1:1 before the system's application to 1:1:5, resulting in an average monthly savings of over 500,000 yuan in electricity costs.
