Objectives of Control
To follow the command
To reduce the time of response
To reduce the overshoot
PID
Proportional
Simple Multiplication with a constant Kp
Increase proportional to reduce steady state time
Increase overshoot
Integral
Integrate the input and multiply with a constant Ki
Increase Integral to reduce steady state error (Follow the command)
Introduce oscillations
Derivative
Differentiate the input and multiple with a constant Kd
Increase derivative to reduce overshoot
Slow down the system
Active and Reactive Power
AC source ke sath agr aik resistor lgayein, to voltage or current ki direction same hogi.
o Resistor bs active power use kre ga.
AC source ke sath agr aik inductor lgayein, to Voltage, current ko lead kre ga (aik angle hoga
voltage or current mein)
o Inductor active or reactive dono power use kre ga.
Power factor:
Pa Pr
o p . f =cos ( θ ) is called power factor, cos (θ )= ∨tan ( θ )=
√P +P
2
a
2
r
Pa
o Why power factor is important:
Reactive power is of no use, because reactive power don’t do any real work in
the real world.
So we try to minimize the reactive power in a system.
For that we need to minimize the angle θ . That leads to low reactive power.
o Why a p.f of 1 is considered good:
SCADA
Ignition software se SCADA ki development ki hai
Ignition mein SCADA system ke liye GUI bna skte hain (Using interactive environment)
Python mein backend hota hai
MySQL database mein data store hota hai
PLC
Siemens, TIA Portal
HMI
Human Machine Interface
HMI is a device used to interact with the systems including PLC, SCADA and/or DCS
(Distributed Control Systems)
HMI and PLC are two different devices and can work standalone.
HMI and PLC both needs to be programmed separately.
HMI usually contains GUI (Graphical User Interface), have buttons, slides, display icons, status
of devices, sensor readings etc.
Components of HMI:
o Display Screen: Touch screen or display with mouse/keyboard
o Processor and Memory: Handles data processing
o Communication Interface: Allows to connection with PLCs, sensors, Industrial
Controllers via protocols like Modbus, Ethernet/IP, and PROFIBUS.
o Software: Used for designing GUI and managing control logic.
o Power Supply: Typically 24V DC for industrial applications.
Types of HMI:
o Push-button replacer HMI: Replaces over traditional mechanical push buttons.
o Graphical HMI Panel: Offers Advanced visualization with touch screen or something to
display.
o PC-Based HMI: Runs on computer.
o Web-Based HMI: Runs remotely on internet.
o Mobile HMI: Running on tablets or something to carry with.
Common Communication Protocols in HMI:
o Modbus (RTU, TCP/IP): A widely used protocol for industrial communication.
o PROFIBUS & PROFINET: Used for high-speed industrial automation.
o Ethernet/IP: Provides real-time data exchange over industrial Ethernet.
o BACnet: Common in building automation systems.
o CAN Bus: Used in automotive and industrial control applications.
Modbus
Modbus is a communication protocol that allows communication between multiple devices
connected to the same network, such as PLCs, sensors, HMIs, and SCADA systems. It is widely
used due to its simplicity, reliability, and open-source nature.
Types of Modbus:
o Modbus RTU (Serial communication over RS-232, RS-485)
o Modbus ASCII (Similar to RTU but uses ASCII encoding)
o Modbus TCP/IP (Modbus over Ethernet)
o Modbus Plus (Proprietary high-speed version)
Working:
o Modbus uses a master-slave (or client-server) architecture where the master initiates a
request, and the slave responds. The master can read/write data to/from the slave using
function codes. Communication occurs through serial (RTU/ASCII) or Ethernet (TCP/IP)
protocols.
Modbus use function codes to handle its features, commonly used codes include 01 (read coils),
02 (read discrete inputs), 03 (Read holding registers), 04(read input registers), 05 (write single
coil), 06 (write single register), 16 (Write multiple registers).
Modbus data addressing and register mapping:
o Each Modbus device has a unique slave ID.
o Data is stored in registers that have specific addresses.
o The master uses function codes to read/write data from these registers.
Types of Modbus registers:
o Coils (0xxxx): Read/Write single-bit (1-bit) values (ON/OFF).
o Discrete Inputs (1xxxx): Read-only single-bit (1-bit) values.
o Input Registers (3xxxx): Read-only 16-bit values.
o Holding Registers (4xxxx): Read/Write 16-bit values.
Software for Modbus:
o ModScan
o Modbus Poll
o Modbus Slave
o QModMaster
o Wireshark
IEC61850
IEC 61850 is an international standard for substation automation systems (SAS).
It defines communication protocols and configuration language to ensure interoperability among
different vendors/devices.
It is used to improve efficiency, reliability, and flexibility in power systems.
Objectives:
o Interoperability between different manufacturers' devices.
o High-speed and reliable communication.
o Efficient substation automation.
o Standardized data modeling.
o Support for real-time and event-driven communication.
Why IEC61850 when we already have Modbus
o Unlike Modbus, which are register-based and slow.
o IEC 61850 uses object-oriented data models.
o It supports high-speed peer-to-peer communication (GOOSE)
o Uses Ethernet instead of serial communication.
Components of IEC61850
o Communication protocols (GOOSE, MMS, Sampled Values).
o Data modeling using Logical Nodes.
o Substation Configuration Language (SCL).
o Communication network architecture (Station Bus, Process Bus).
Types of Communication protocols in IEC61850
o Station Bus: Used for communication between control and protection devices.
o Process Bus: Used for communication between IEDs and field devices like CTs and PTs.
An IED (Intelligent Electronic Device) is a smart device that performs protection, monitoring,
and control functions in a substation. It communicates using IEC 61850 protocols.
Advantages of IEC61850
o Faster protection response time.
o Standardized communication reduces integration complexity.
o Reduces wiring and installation costs.
o Supports future expansion and remote monitoring.
Solar System
Types:
o On-grid
o Off-grid
o Hybrid
Components:
o On-grid
Photovoltaic Cells
Inverter
MPPT
Energy in and out tracker for On-grid systems
o Off-grid
Photovoltaic Cells
Inverter
MPPT
Batteries
Charge controller
o Hybrid
Photovoltaic Cells
Inverter
MPPT
Energy in and out tracker for On-grid systems
Batteries
Charge controller
Purpose of MPPT
o Maximum Power Point Tracker
o In solar panels when current is increased voltage will decrease.
o Temperature will also have an effect on the voltage and current or power output of the
solar cell.
o MPPT finds a point where P=VI is maximum that is maximum power, thus called
maximum power point tracker.
o It uses an incremental control logic to do this.
Choosing and series and parallel connections of panels:
o Based on maximum voltage of inverter.
o Some panels and connected in series as the voltage rating the inverter.
o Likewise series panels and connected in parallel to make a grid to increase the current
instead of voltage.
Deciding MPPT:
o MPPT is decided based on the power rating of the system let say if there is a system of
10kW, then an MPPT that can handle enough current will be used.
o Voltage rating of MPPT should also align with the voltage rating of the inverter or panels
connected in series/parallel.
Deciding Batteries:
o Typically 24V or 48V batteries are used.
o Energy consumption is calculated for the load in one hour.
o Battery energy is calculated to deliver that energy for a given time.
o The batteries should not drain below Depth of Discharge (DoD) limit or Cut-off Voltage.
Depth of Discharge (DoD) Limit: This is the percentage of the battery's total
capacity that can be safely used before recharging. For example:
Lead-Acid Batteries: Recommended DoD is 50% (should not go below
12V for a 12V battery).
Lithium-Ion Batteries: Can handle 80-90% DoD (should not go below
2.5V per cell).
Cutoff Voltage: The minimum voltage level before the battery is considered
discharged and should not be drained further to prevent damage.
