TRƯỜNG ĐẠI HỌC ĐIỆN LỰC KHOA ĐIỀU KHIỂN TỰ & ĐỘNG ĐỘNG HÓA BÁO CÁO CHUYÊN ĐỀ NGÀNH CÔNG NGHỆ KTĐK&TĐH CHUYÊN NGÀNH TĐH&ĐKTBĐCN HỌC PHẦN Tiếng Anh chuyên ngành Giảng viên hướng dẫn TS Nguyễn Ngọc Khoát[.]
Applications
Inductors play a crucial role in analog circuits and signal processing, with applications ranging from large inductors in power supplies that, alongside filter capacitors, eliminate ripple associated with mains or switching frequencies, to smaller inductors like ferrite beads or toroids used to prevent radio frequency interference in cables In many switched-mode power supplies, inductors serve as energy storage devices, supplying energy to maintain current flow during off-switching periods and facilitating configurations that allow for output voltages exceeding input voltages.
A tuned circuit, made up of an inductor and a capacitor, serves as a resonator for oscillating currents These circuits are essential in radio frequency devices, including transmitters and receivers, where they function as narrow bandpass filters to isolate a specific frequency from a mixed signal Additionally, tuned circuits are utilized in electronic oscillators to produce sinusoidal signals.
Transformers, essential components of electric utility power grids, consist of two or more inductors with coupled magnetic flux, known as mutual inductance As frequency increases, transformer efficiency may decline due to eddy currents in the core and the skin effect on windings To counteract this, transformer core sizes can be reduced at higher frequencies, which is why aircraft utilize 400 hertz alternating current instead of the standard 50 or 60 hertz, resulting in significant weight savings from smaller transformers Additionally, transformers play a crucial role in enabling switched-mode power supplies, providing isolation between output and input.
Inductors, commonly known as reactors in electrical transmission systems, play a crucial role in limiting switching and fault currents.
Inductors exhibit parasitic effects that lead to deviations from their ideal performance, contributing to electromagnetic interference (EMI) Their physical dimensions hinder integration into semiconductor chips, resulting in a decline in their usage within modern electronic devices, especially in compact and portable gadgets.
7 inductors are increasingly being replaced by active circuits such as the gyrator which can synthesize inductance using capacitors.
Distinguish conductor and inductor
A conductor is a material that allows electrons to flow freely and efficiently in multiple directions, enabling the transmission of energy as heat or electric charge through the material with ease.
An inductor is a material that restricts the free flow of electrons, effectively trapping them within the molecules This characteristic prevents the unrestricted passage of energy, whether in the form of heat or electric current, through the material.
Work It resists changes in voltage and current, with the voltage in a conductor not changing immediately and the current in an inductor not responding promptly The unit of conductance is also a key aspect to consider.
The unit of inductance is Henry
Formula Voltage slacks current by /2� Current slacks voltage by �/2 Types of Current The conductor capacities as a short out for rotating current
Inductor capacities as a short out for direct current
Table 1.1: Distingust Inductor and Conductor
Electrical motors
A separately excited DC motor receives its main supply independently for both the armature and field windings, meaning the armature current does not flow through the field windings, as they are powered by a distinct external DC source This unique configuration is a key characteristic that differentiates it from other types of DC motors.
The torque in a separately excited DC motor can be adjusted by altering the field flux (φ), regardless of the armature current (Ia).
Figure 2 1 separately excited DC motor
In this type of motor, the field coil is energized by a separate DC voltage supply, while the armature coil receives power from another independent source The armature voltage can be variable, but a consistent fixed DC voltage is applied to the field coil, ensuring electrical separation between the two coils This distinct separation is a key characteristic of this motor design.
1.1, Definition of a Separately Excited DC Motor
Direct current motors have been utilized for adjustable speed controllers for more than a century, making them the most suitable choice for controlled electrical drives that require a wide range of speed variations.
The primary advantage of these motors lies in their outstanding performance and control capabilities However, a significant drawback is the mechanical commutator, which limits motor speed and power, increases inertia, and requires more frequent maintenance compared to other motor types In contrast, alternating current motors eliminate the need for a commutator, as they are powered by variable frequency static power converters, although this can lead to higher costs due to their complexity.
This is one of the main reasons why new AC controllers could not quickly supplant DC types, once the semiconductor technology had significantly improved.
The principle of a DC motor performing in steady-state is assumed to be known, but let us discuss some basic facts below.
1.2, Working Principle of a Separately Excited DC Motor
The schematic cross-section of a two-pole DC motor illustrates the fixed stator (S) and the cylindrical rotor, known as the armature (A) To minimize iron losses due to fluctuating magnetic flux, the rotor and pole shoes are consistently connected In larger machines, the remaining stator is laminated to enhance performance during rapid changes in torque and speed, especially when powered by a static power converter with significantly distorted currents and voltages.
The basic poles (M and P) are linked to the field windings, enabling the movement of field current that establishes the main flux across the rotor and stator An armature coil is situated within the axial slots of the rotor and is integrated with commutator bars, which, along with brushes, generate the armature current (ia) This process produces a distributed ampere-turn (mmf) wave that is fixed in space and rotates in alignment with the quadrature axis, perpendicular to the basic axis, thereby maximizing the output torque generated by the armature current.
When there is a significant distance in the quadrature direction, the armature flux becomes considerably weaker than the fundamental flux This can be further reduced by installing compensating coils in the axial slots of the pole shoes and connecting them in series with the armature These opposing ampere-turns counteract the quadrature field generated by the armature, effectively eliminating the unwanted armature reaction that can distort the uniform distribution of the main flux across the rotor's circumference.
Figure 2 2 Working Principle of a Separately Excited DC Motor
Compensating coils are primarily used in large machinery and converter-fed applications, particularly in heavy-duty environments like steel mills and traction drives Compensated DC motors can handle higher overloads compared to their uncompensated counterparts, allowing for a quicker rise in armature current and greater tolerance for current harmonics without negatively impacting commutation or causing brush sparking This capability is especially crucial when the motor operates with a static converter.
Commutating poles (C and P), positioned between the main poles and conducting the armature current, play a crucial role in adjusting the magnetic field in the neutral zone to ensure quick and spark-free commutation They achieve this by generating a suitable voltage in the armature coil, which is temporarily diminished by the brushes.
The principle of commutation in a two-pole DC motor involves the closed armature section, where the brush positions are adjusted at two consecutive time intervals As the brushes move to the next commutator bars, the feeding points of the winding are switched, leading to the immediate short-circuiting of the commutating winding and an inversion of the current.
The inductance of each winding, which is housed in iron-covered slots, leads to a continuous commutation process that requires a finite amount of time This limitation affects the operational speed of the device, preventing excessive sparking at the brushes.
2, Equations of Voltage, Current, and Power for a Separately Excited DC Motor
In a separately excited DC motor, field and armature windings are excited to form two various DC supply voltages In this motor, we have
Armature current I = Line current = I = Ia l
Back emf developed: where V is the main voltage and Ra is the armature resistance.
Power is drawn from the main source:
Mechanical power developed (Pm) = Power input to the armature – power wasted in the armature
3, Operating Characteristics of a Separately Excited DC Motor
Shunt-wound and separately excited DC motors both operate with a regulated voltage that maintains a fixed field current, resulting in similar characteristics for speed versus armature current and torque versus armature current In the case of separately excited DC motors, the magnetic flux is considered constant.
3.1,Speed – Armature Current (N – Ia) Characteristics
The speed of a motor is influenced by the relationship between back EMF and magnetic flux (Eb/φ) When the load on the motor increases, both back EMF and magnetic flux decrease due to the effects of armature resistance and armature reaction However, the reduction in back EMF is more significant than the decrease in flux, resulting in a slight drop in motor speed under increased load conditions.
3.2, Torque – Armature Current (Τ – Ia) Characteristics
Torque is directly linked to the armature current (Ia) while the flux remains constant, irrespective of armature reaction The T–Ia characteristic exhibits a linear relationship that begins at the origin, indicating that substantial current is necessary to initiate heavy loads Consequently, this type of motor is not suitable for starting under heavy load conditions.
4, Speed Control of a Separately Excited DC Motor
The speed of this type of DC motor is determined by the following methods:
PLC Siemens S7-300
PLC
A programmable logic controller (PLC) is a robust industrial computer designed for controlling manufacturing processes, including assembly lines and robotic devices It offers high reliability, user-friendly programming, and effective fault diagnosis, making it essential for various automated tasks in industrial settings.
Key features of a programmable logic controller include:
The CPU processes data while I/O modules connect the PLC to machinery, providing essential information and triggering specific outcomes These modules can be either analog or digital, and they can be mixed and matched to create the ideal configuration for various applications.
PLCs must connect with various system types beyond just input and output devices, enabling users to export application data to SCADA systems that monitor multiple connected devices To facilitate this communication, PLCs offer various communication protocols and ports.
A Human Machine Interface (HMI) is essential for users to effectively interact with a Programmable Logic Controller (PLC) These operator interfaces can range from large touchscreen panels to basic displays, enabling users to input and monitor PLC information in real-time.
In industrial automation, PLC performs a wide variety of manufacturing production, monitoring machine tool or equipment, building the system, and process control functions.
For the electrical power system analysis, PLC plays operation for maintenance and other main roles in the power plants and the smart grid system.
The rise of Programmable Logic Controllers (PLC) in commercial control applications highlights their ability to function efficiently with little to no manual labor By implementing PLC technology, businesses can streamline operations, significantly reducing the need for physical effort in various tasks.
For the domestic purpose, PLC act as a remote operating device or automatic sensing device We can automate some day-to-day activities with PLC.
Automation Industries where PLC is needed: Steel Industry, Glass Industry, Paper industry, Textile industry, Cement Industry, Chemical industry,
Automobile industry, Food Processing System, Oil and Gas Power Plant, Wind Turbine System, Robotic Automation System, Underground Coal Mine and many more industries…
When selecting a PLC for applications where speed is critical, it is essential to consider the total response time of the PLC, as it takes a specific amount of time to react to changes.
A Distributed Control System (DCS) is designed to manage and control entire processes within a plant, integrating multiple Programmable Logic Controllers (PLCs) with a Human-Machine Interface (HMI) This cohesive approach allows for simultaneous development of all system components, ensuring that the DCS is built holistically rather than in isolated stages, such as first creating the PLC, then the HMI, and subsequently adding alarms and historical data management.
Differences between PLC and relays
Programmable Logic Control (PLC) is a solid-state computerized industrial controller that performs software logic by using input
& output modules, CPU, memory, and others.
Relay is an electro-mechanical switching hardware device (Hardware Switching Device).
PLC plays a monitoring as well as controlling role in designing circuits.
Relay plays only a controlling role in the designing circuit. Monitoring is not so easy with a relay.
In the PLC, we can write the program using different types of programming languages.
In the Relay, we cannot write the program.
PLC consists of more programming functions like timer, counter, memory, etc.
Relay gives only one fault detection function And it does not have much-advanced functionalities.
Design You can easily modify the designing circuit.
Modification of the electronic circuit is more difficult as compared to PLC.
PLC has more capabilities of input and output modules.
The relay does not have more capabilities.
PLC provides more flexibility than the relay.
The relay provides less flexibility.
You can easily find the fault by using the software.
It is very hard to find fault in the Relay circuit.
PLC has a time response of nearly 50 msec and above.
Relays have less than 10 msec response time.
It consists of memory to store the program.
It does not consist of memory.
Introduce PLC S7-300 of Siemens
The Siemens Simatic S7-300 is a multi-block PLC featuring a basic processing unit that can be expanded with various standard modules These external expansion modules consist of functional units that can be tailored to meet specific engineering requirements, allowing for versatile automation solutions.
Figure 3 5 CPU front face shape
The PLC S7-300 features a modular design that is ideal for various applications, allowing for the creation of compact systems and facilitating easy system expansion Each application typically requires at least one CPU module, while additional modules, known as expansion modules, include signal transmission and reception modules, as well as specialized function modules.
The module expands the input/output (SM) port, including: DI, DO, DI/DO, AI, AO, AI/AO.
Separate control function module (FM).
To initiate a new project, begin by declaring the PLC workstation and configuring it thoroughly Next, proceed with PLC programming using OB1, followed by running the simulation program in PLC-SIM Finally, graph the program within PLC-SIM and execute the simulation to observe the results.
In fact, PLC S7-300 is used in a variety of applications, such as: Controlling industrial robots, clean water treatment lines, controlling servo motor systems or tool-making machines v.v
SCADA
Supervisory Control And Data Acquisition (SCADA)
Supervisory control and data acquisition (SCADA) is a system of software and hardware elements that allows industrial organizations to:
Control industrial processes locally or at remote locations Monitor, gather, and process real-time data
Directly interact with devices such as sensors, valves, pumps, motors, and more through human-machine interface (HMI) software
Record events into a log file
SCADA systems are crucial for industrial organizations since they help to maintain efficiency, process data for smarter decisions, and communicate system issues to help mitigate downtime.
The fundamental architecture of SCADA systems starts with programmable logic controllers (PLCs) and remote terminal units (RTUs), which are microcomputers that interact with various devices like factory machines, sensors, and HMIs These controllers collect data from connected objects and transmit it to computers running SCADA software The SCADA software then processes, distributes, and visualizes this data, enabling operators and staff to analyze information effectively and make informed decisions.
The SCADA system promptly alerts operators to batches with high error rates, allowing them to pause operations and investigate through the HMI Upon reviewing the data, the operator identifies a malfunction in Machine 4 This proactive notification from the SCADA system enables the operator to quickly address the issue, minimizing product loss.
Applications of SCADA
SCADA systems play a crucial role in industrial organizations and both public and private sectors by enhancing control, improving efficiency, and facilitating data distribution for informed decision-making while addressing system issues to minimize downtime Their versatility allows SCADA systems to be effectively implemented in various enterprises, accommodating everything from simple setups to extensive, intricate installations As a result, SCADA systems serve as the backbone of numerous modern industries.
In today's world, SCADA systems are integral to various industries, managing everything from refrigeration at supermarkets to production and safety in refineries They play a crucial role in maintaining quality at wastewater treatment plants and even monitoring energy consumption in homes.
Implementing effective SCADA systems can lead to substantial time and cost savings Many case studies demonstrate the advantages and financial benefits of utilizing contemporary SCADA software solutions like Ignition.
The structure of a SCADA system has the following basic components :
Central monitoring control station: is one or more central servers ( central host computer server ).
Intermediate data acquisition stations consist of blocks of remote I/O devices, such as Remote Terminal Units (RTUs) or Programmable Logic Controllers (PLCs), equipped with communication capabilities These stations interface with various actuators, including field-level sensors, switch control boxes, and actuator valves, facilitating efficient data management and control in industrial applications.
Communication system: includes industrial communication networks, telecommunications equipment and multiplexing converters that transmit field-level data to control units and servers.
Human-machine interface HMI ( Human-Machine I nterface ) : Are devices that display data processing for the operator to control the system's operations.
4 Systems using Scada 4.1 Water and Wastewater
Figure 4 4 Municipal water supply and sewage treatment
Water treatment plants and water usage facilities can enhance their operations by ensuring that their monitoring equipment is current and precise Although traditional SCADA (supervisory control and data acquisition) systems are widely used, the latest cloud-based SCADA systems offer a more reliable and effective solution for modern water management.
A cloud-based SCADA system empowers water management plants to monitor chemical and toxin levels while providing precise records that are accessible from any location This technology eliminates the limitation of fixed digital read-outs, allowing managers and operators to conveniently access data from their satellite or Wi-Fi-enabled devices.
In a recent study on contaminated water, the EPA aimed to address the issue promptly while developing stricter regulations Americans prioritize access to safe drinking water and are frustrated by the delays in the bureaucratic process of establishing these essential guidelines.
Congress requires the EPA to demonstrate a significant opportunity for public health improvement before implementing new regulations on water utilities This lengthy and complex process has hindered the successful regulation of any new contaminants for the past two decades.
Another benefit of a cloud-based SCADA system is that data collected in real- time from the contaminated areas can be studied, compared, and shared with
By utilizing digital tools, 25 researchers can efficiently compare data points to gain accurate insights, ultimately leading to quicker results and more timely actions.
Industrial advancements are rapidly altering the environment, often outpacing our understanding Nevertheless, technological progress enables us to leverage digital tools, such as cloud-based SCADA solutions, to effectively monitor, document, and enhance research efforts for environmental improvements.
4.2 Oil and Gas SCADA Efficiency Benefits
Figure 4 5 Oil and Gas systems
SCADA systems significantly enhance the efficiency of processes in the gas and oil industry by enabling close monitoring of performance By optimizing the supply chain, these systems reduce inefficiencies, minimize waste, and ensure proper equipment maintenance.
Oil and gas SCADA software empowers operators to effectively monitor pipeline operations and gas well production, ensuring any issues trigger automatic notifications and alerts This enhanced performance allows the oil and gas industry to stay competitive by optimizing resource management and operational processes.
The oil and gas industry poses significant environmental risks and safety concerns, as leaks and spills can lead to costly damages and severely impact ecosystems Implementing stringent environmental standards is essential for both the production and distribution processes Utilizing a SCADA monitoring system enhances safety by providing advanced alarm notifications and improving operational efficiency.
SCADA systems enhance issue resolution speed by integrating mobile device notifications with monitoring systems, allowing operators to promptly identify malfunctions This rapid deployment of solutions not only ensures public safety but also upholds environmental protection standards.
The Three Oil and Gas SCADA Applications
RTUs are effective for monitoring downstream conditions at a refinery This encompasses a significant footprint Time is required due to the complex nature and size of the sites
High temperatures in holding tanks can pose serious risks, making it crucial for maintenance workers to recognize the issue promptly This awareness enables first responders to arrive sooner and better equipped, ultimately saving both time and lives SCADA systems play a vital role in the oil and gas sector by preventing downtime, providing essential information to management, and mitigating risks.