One of the most important concerns in generators is their launch. The performance characteristic of synchronous machines is determined by the amount of output voltage terminal of the generator in the overload state, this voltage value depends on the current of the magnetic field (startup current), and if this current changes, the characteristic of the generator's performance also changes.
The synchronous rotor to create an excitation field requires a direct controlled flow. The source of this current is an excitation system that sends the stimulus to a synchronous machine (generator). This system consists of a set of feeders, regulators, controls and protection devices.
The excitation system of synchronous machines has two main parts:
A) The power system, which includes equipment required to generate the required magnetic field of the synchronous motor rotor coil.
B) the control system, which has the task of controlling the amount of magnetic field current under normal operation conditions and in the event of an error occurring.

The excitation system is divided into three main types based on the source of magnetic field flux production:

1. Direct current stimulation systems
In this type of excitation system, direct current generators are used as a source of flow generation, which provide stimulation through brushes. The stimulus may be rotated either by an independent motor or by the generator axis or by self-stimulating or stimulating. In an independent stimulation state, the stimulation current of the excitation system is provided through an auxiliary stimulation system that has a permanent magnetic field. Of course, these kind of systems are old and nowadays static and alternating current systems are used. Some of these systems utilize amplifier voltage regulators.

2. Alternating current propulsion systems
In this type of excitation system, alternating current generators are used to create the required stimulation current in the main generator rotor coil. In this case, the oxidizer (stimulator) is usually located on the same main axis of the turbogenerator. Then the output of the diverging flow of the oxidizers is recirculated and the direct current generated is transmitted to the main generator's actuator coil. The rectifier system can either be stationary or rotary.

2.1. Systems with resident rectifier
If the rectifier system is stationary, the output of their direct current must be transmitted through brushes to the main generator's actuator coil. In the case of uncontrolled diode rectifiers, the alternating current controls the excitation excitation regulator, which, in turn, is responsible for controlling the output voltage of the oxide.

2.2. Systems with rotating rectifier
In these types of systems, due to the turning of the rectifiers, the use of brushes or charcoal is removed and the output of the direct current of the oxide directly to the generator is applied. The design of these kind of systems is known as the brushless excitation system.
Primary alternating current propulsion systems used a combination of magnetic and rotary amplifier systems as regulators, but most other systems use electronic amplifiers.

3. Static flow stimulation systems
In this method, the generator excitation current is supplied from an external source, usually an independent source of battery. For proper use and prolong battery life, after the generator is launched, the source is extracted from the circuit and the generator's own power Using electronic devices, it replaces power.

The purpose of this excitation system is to create an intelligent system with standard components in a form that offers superb reliability and perfect performance.

The actuator control control system is designed to be installed on steam generators and gas generators. The AVR control and control system, regardless of the type of stimulation, can be installed on a variety of static and dynamic propulsion systems. Due to the needs of the employer, it is also possible to customize this system for different units.

After nearly two decades of experience in the manufacture of various electronic cards, the Ahar Power Company has been able to acquire specialized knowledge and experience by producing various excitation and designing systems, such as making Tabriz, Kish, Petrochemicals, Bandar Abbas and others. In this field, for the first time in the country, it will know the design and construction of generator control and protection systems for steam and gas power plants. Designing and implementing all of the power and control systems of the system and its implementation as a DCS system are part of the company's technical capabilities in this regard. The hardware and topology of these systems are largely based on the Siemens DCS technology in Germany.

The most important features of this system include:

Configuration of the Siemens hardware and control unit based on PLCs of class 300 and 400
Using Siemens PCS7 software and CFC programming
The processing speed of the control loops is less than 2 ms
Possibility to implement the system through hot redundancy in control, power and cooling systems
Reducing generator losses by placing its operating point at the work point and hence increasing the generator efficiency
Possibility to communicate with the proxy bus network and industrial Ethernet network
Possibility to change the power of the excitation system from the dynamic to static mode and the removal of the middle and middle power generators
Full control over the generator by various control modes
Voltage controller in automatic mode (automatic voltage regulator) AVR
FCR (Field Current Regulator) Flow Control
Reactive power control and generator power factor in PF (power factor), VAR
Transition without muting between control modes
Reactive flow heater and the ability to determine the line drupe or reactive power drill
The soft start function of the generator's voltage to prevent sudden spurts when triggered
UEL (under excitation limiter), OEL (over excitation limiter) limiting stator current limiter (STOR current limiter) and limiting volts per Hz (V / Hz)
Show the generator's work point in the generator's power generation curve on the HMI
Design of the power sector as a two-part system for increasing the speed of the De-excitation
Monitoring the position of the rotating diodes in the dynamic stimulation system and the state of the thyristors in the static excitation system

The following table describes the features, features and hardware features of the Ahar Corporation excitation system:


Hardware Specification

Yes- modular

Selectable Control System Redundancy

Yes- Up to 5

Selectable Converter Redundancy


Selectable Cooling Fan Redundancy

Yes- modular

Selectable I/O Redundancy


Selectable communication Redundancy

Yes- Optional

Selectable Auxiliary power


Power Supply Redundancy

950 V

Max AC Voltage

2200 A

Max Output DC Current

Yes- Optional

Fibr Optic Communication

< 0.2 % Nominal Voltage

Voltage Regulation Accuracy


Response Time in Static Excitation System

with a typical cycle time of 1 ms

Fast analog and digital process I/Os

with a typical cycle time of 5 ms

Low-speed I/Os

from 50 to 420 Hz

Rated supply frequency

12-19 inch

Touch Screen



Ethernet and fieldbus protocols communication


Field suppression (discharge resistor and crowbar for fast de-excitation)


Field flashing


Technical support

IP42 as a standard, IP>51 upon request

Cubicle protection degree


And in the following table, the characteristics, features and software features of this excitation system are expressed:


Software Specification


Easy system operation, monitoring and maintenance


AUTO operating mode


MAN operating mode


Voltage regulator with PID filter


Field current regulator with PI filter


Reactive current droop compensation


Line droop compensation


Limiter Maximum and minimum field current


Limiter Maximum stator current


Limiter Volt / Hertz


Underexcitation (UEL) and overexcitation (OEL)


Power factor / reactive load control


Generator Voltage Softstart

Yes- Optional

Power system stabilizer (PSS)


Overcurrent protection (instantaneous / inverse time)


Volt / Hertz protection

Yes- Optional

Loss of field protection


Thyristor conduction monitoring


Actual value monitoring


Field flashing time limit


Capability curve of the machine


Setting characteristics of all limiters

Up to 16 selectable signals

(2.5 ms - 1 s sampling rate)



Automatic follow-up of all non-active control modes


Reference value setting


Start-stop sequence for any configurable application


PT and/or CT signals supervision


Rotating diodes (rectifier) branch faults

Up to 4000 events

internal event recorder


Up to 64 signals

data recorder


Free Coding and HMI Flexibility


Advantages of the designed system:

Use the simple interface and touch LCD display for easy operation
Ability to create a specific list of arbitrary parameters in the system for error detection and maintenance
Ability to define different access levels for operator, user and repairer
Modular design for quick repair and replacement of parts
Use the datagram to record important events in the system

Advantages of using a shaving stimulus system:

Enhance the flexibility of the system to achieve a specific work point
Reduce repair time
Enhance process reliability
Increase system access
Protective system for monitoring the system and responding to an error
Uninterrupted recording of system events

The modular design of this system has made it possible to accommodate different needs of this system and, for any conditions and requirements, it is possible to install and implement a steam agitation system. This system has the ability to adapt and function alongside the old systems, which makes it possible to replace the system with parts of the old system to meet the demands of modernization and upgrading the old systems.
In addition, it is possible to upgrade this excitation system at any time, without any major changes in the structure, will be updated by installing new system modules, which will also increase the flexibility of the system.

Significant performance indicators in Sanyar's system make it a system that is effective:

Short delivery time: In general, the installation and testing process of this equipment is possible over a short period of time and is ready for delivery in a short time.

Flexible settings: The high-level configuration of the system allows the preparation to be implemented in a completely customized format for each unit and adapted to the day's parameters of that unit.

Simple operation: The existence of an HMI in the system body provides easy access to stored events, accessible settings, and monitoring of the system and its components.

Optimal Dimensions: The small size of the cabin system makes it possible for the panel to be placed in small environments.

Tracking Changes: Any activity performed by the user of the system or changes made in the parameter settings will be stored in the form of recording the history of events in the system memory.

Due to the use of parallel structure (redundant) in the design of Ahar's agitation system, the reliability of this system increases significantly and in the event of a random error in active units, with an uninterrupted replacement of the part, the overall performance of the unit will not stop. Became

The parallel structure is observed in the following sections and the following modules can be easily and in the shortest possible time:

Full throttling in the controller and processors section
Full throttle in the power converters section
Perfect thinning in a fiber-optic network between processors
Perfect thinning in PROFINET network and PROFIBUS network
Full level readout at the level of I / O modules
Full scalding in the nutrition section
Full throttling in transducer modules
Reading in the reading of generator voltage feedback
Rejection in power supply converters

Using this system will reduce the cost of operation and repairs and because of the services of a domestic company, will provide reliable and long-term after-sales service.

Advantages of the AHAR Excitation system

The benefits

Parallel structure with separate function

High flexibility to set the system

Perform repairs during active system operation

Enhance access and reliability of the process

Simple replacement of parts

Time and cost of repairs



The executive generator team consists of eight senior engineers with advanced education in electrical engineering, electrical engineering control, electrical engineering, mechanical engineering and computer engineering, as well as a background in the field of generator control and how it works. Their performance has led to the creation of an excitation system for Alstom and Steam units, and has been stepping up the process of localization of this knowledge.
This unit is managed directly by the company's manager.
The organizational chart of this unit is as follows:


1. Design, construction and installation of Kish Power Plant's F5 Turbine Excitation System Cards


Project Designing and Replacing Excitation System Cards for Kish Power Plant's Generator
Employer Kish Power Plant
Unit name GE gas
Used Technology Electronic card production
Estimated time 7 Month
Unit capacity 25 Mega Watt


2. Design, construction and installation of Tabriz Power Plant's fiat Turbine Excitation System Cards


Project Designing and Replacing Excitation System Cards for Tabriz Power Plant's Generator
Employer Tabriz Power Plant
Unit name Fiat
Used Technology Electronic card production
Estimated time 6Month
Unit capacity Mega Watt


3. Design, construction and installation of Excitation series of cards for the Westinghouse unit of Shahid Hasheminejad gas refinery (Khangiryan)


Project Designing and Replacing Excitation System Cards for Shahid Hasheminejad Refinery's Generator
Employer Shahid hashemi nejad refinery (khangiran)
Unit name Westinghouse
Used Technology Electronic card production
Estimated time 6 Month
Unit capacity 4 Mega Watt


4. Design, construction and installation of Afghanistan (Harat) Power Plant Turbine Excitation System Cards


Project Designing and Replacing Excitation System Cards for Afghanistan Power Plant's Generator
Employer Harat Power Plant
Unit name  AEG
Used Technology Electronic card production
Estimated time 3 Month
Unit capacity 25 Mega Watt


5. Design, construction and installation of Fuji synchronous motor Excitation system cards of Bandar Abbas refinery


Project Designing and Replacing Excitation System Cards for Bandar Abbas Refinery's Generator
Employer Bandar Abbas Refinery
Unit name Fuji
Used Technology Electronic card production
Estimated time 5 Month
Unit capacity 3 Mega Watt


7.Design, construction and installation of the Alstom Generator's Excitation System at Shams Sarakhs Power Plant


Project Designing and Replacing Excitation System for Shams Sarakhs Power Plant
Employer Shams Sarakhs Power Plant
Unit name Alstom Gas
Used Technology DCS SIEMENS PCS7
Estimated time  8 Month
Unit capacity 25 Mega Watt


8. Design and construction of the GE steam unit generator for Besat Power Plant


Project Designing and Replacing steam unit Excitation System for Besat Power Plant's Generator
Employer Besat Power Plant
Unit name GE steam
Used Technology DCS SIEMENS PCS7
Estimated time 6 Month
Unit capacity 100 Mega Watt




1.Design, construction and installation of the Skoda Generator's Excitation System at Mashhad Power Plant


Project Designing and Replacing Excitation System for Mashhad Power Plant
Employer Mashhad Power production management
Unit name Skoda Gas
Used Technology DCS SIEMENS PCS7
Estimated time 5 Month
Unit capacity 60 Mega Watt





Sarakhs Power Plant
Besat Power Plant
Kish Power Plant
Tabriz Power Plant
Afghanistan Herat Power Plant

Shahid Hasheminejad Refinery
Bandar Abbas refinery