ELECTRICAL, INSTRUMENTATION & CONTROL SYSTEMS Presentation by: RANA NASIR ALI General Manager, Power Plants Projects, at PITCO November 02, 2017
ELECTRICAL PLANT CONCEPT The electrical equipment, depending on the power plant / unit size and grid interconnection arrangement will mainly comprise the following: Generator & Excitation System 11 &132 kv Switchgears (Medium Voltage / High Voltage Systems) 400 V Switchgear / LV Power Distribution Automatic and Manual Synchronizing System DC System including batteries, battery chargers and DC distribution Uninterruptable Power Supply System Generator Step-up and Station Service / Auxiliary Transformers Motors LV / MV & Control Cables Electrical Control & Protection System Lighting and Small Power Services & Earthing and Lightning Protection System
ELECTRICAL PLANT CONCEPT For dimensioning, design and layout of the various plant components and installations, the following features and aspects will be considered: Ratings to safely cope with normal and fault conditions, the prevailing site conditions, avoiding any over-stressing of material and equipment Equipment to be of standard design, providing highest degree of safety, reliability, availability, redundancy and ease in operation Equipment arrangements to consider adequate space and access for transportation, installation, commissioning, operation and maintenance The layout, design and manufacturing of all electrical equipment shall comply with the latest edition of the relevant international standards
ELECTRICAL PLANT CONCEPT Pre-requisites for the selection of the main connections and station auxiliary power supply system are: the reliability of power supply to the consumer, simplicity in the design, operational flexibility, ease in maintenance and low capital and operation costs. GCB shall be in accordance with IEEE Std C37.013a
GENERATOR Three phase synchronous machines complying with IEC 60034 Equipped with state-of-the-art static or brushless excitation system with a digital Automatic Voltage Regulator (AVR) Designed for both interconnected and isolated load operation Closed air circuit water (CACW) cooling system with ducting and coolers. The power generated will be dispersed through appropriate voltage level transmission / sub-transmission lines Generator Main Parameters
MAIN DESIGN PARAMETERS OF 11 kv & 132 kv SWITCHGEARS
MAIN DESIGN PARAMETERS OF GENERATOR STEP-UP TRANSFORMER Parameters Unit Value Quantity 1 Type - Oil-filled Rating at IEC Conditions Rated Voltage Ratio MVA 25 kv / kv 11 / 132 Vector Group - Dyn11 Cooling - ONAN Tap Changer - NLTC Dimensions L x W x H mm x mm x mm 3700 x 2350 x 3900
MAIN DESIGN PARAMETERS OF STATION SERVICE TRANSFORMERS Parameters Unit Value No. of Auxiliary Transformers Qty 2 Type - Dry AN Rating at IEC Conditions kva 250 Rated Voltage Ratio kv / kv 11 /.4 Vector Group - Dyn11 Tap Changer - NLTC Impedance Voltage % 6.0 Frequency Hz 50 Dimensions (L x W x H) Mm 1350 x 740 x 1065 Total Weight Kg 990
Generator Protection Scheme
CONTROL SYSTEM DESIGN In order to take full advantage of the powerful features of the present day state-of-the art control systems, it is advisable that the control, protective and supervisory functions required for central operation of all the power plant facilities shall be implemented in a single Distributed Control System (DCS). The system typically performs the functions of data acquisition, signal conditioning, closed loop control, open loop control, alarm processing and annunciation, event recording, reporting, historical and real-time trend recording and communication with foreign devices/ systems Only well proven, state-of-art, with modern reliable design and commercially supported systems and equipment with established operating history in thermal power plants are to be deployed
CONTROL SYSTEM DESIGN Safety, Redundancy and Availability Requirements Safety and availability are of utmost importance for achieving the intended trouble-free plant operation. This can in general be achieved by pursuing two different strategies: Distribution of the system into several functional areas: i.e. in the event of outage of one system component only the appertaining section would be affected with the rest of the system remaining fully functional. Redundancy of system components lessening the probability of outage of essential functions. There shall be no potential for single points of failure in the DCS system. Failure of any single device shall not affect the ability of the system to communicate with other devices in the system. Redundant equipment, hardware and software, shall be continuously monitored for errors The DCS shall utilize redundancy of hardware and facilities at the supervisory and Human Machine Interface (HMI) levels and must be unitized at the automation level to match the mechanical/ process plant redundancy. Redundancy shall be ensured for all main (common) components like CPU, communication modules, power supplies etc
CONTROL SYSTEM DESIGN
Human Machine Interface (HMI) The Human Machine Interface (HMI) being the user interface for operator interaction with the DCS and the process provides a graphics-based visualization of the power generation process with the corresponding control and monitoring functions. It typically resides in a windows based workstation with a graphic Visual Display Unit (VDU) that communicates with data servers and process stations. The HMI shall be used for different functions: Operation, monitoring, and alarm handling of the process controlled by the DCS system. Diagnostic functions for fault analysis. Information management for business relevant data. Asset management for maintenance related tasks. Engineering functions for program and configuration changes. General management functions related to the IT infrastructure. The HMI shall follow an ergonomic, intuitive, and easy design and support the operator in his familiar way to operate the process.
Other Important DCS Features Engineering Workstation (EWS) The EWS shall support all the up-to-date standards in respect to structuring, configuring, programming, and commissioning. It shall communicate with the entire DCS system in order to execute all necessary work on the entire user-software package. Fault Diagnostics All failures and anomalies in the DCS shall be automatically detected and alarmed identifying the kind of failure and the malfunctioning module. Sequence of Events Recording, Post Trip Reports and Printed Logs Sequence of event recording shall be provided as integral part of the DCS to record and print trips and causes of trips for quick diagnostics of fault and remedial action. Post trip reports shall include a compilation of analogue and binary signals which are relevant and specific for a given trip event. Process Controllers, I/O Modules & Field Bus Redundant Process Controllers are must. The Process Controllers execute the control tasks in the system. Measuring devices, I/O devices, drives, and actuators shall be connected to the process stations by cables carrying analogue or binary values, or by standard fieldbuses.
Other Important DCS Features Workstation Hardware, Data Servers and Printers Workstations consisting of PC like computer with sufficient computing power and RAM memory, a standard, and a function key keyboard, a pointing device and reasonable sized flat screen displays shall be located in the Central Control Room (CCR). All workstations shall be equipped with double monitors. The data servers shall provide the necessary functions for an undisturbed operation even when two hard disc drives fail simultaneously A sufficient number of high reliable, low noise, industrial duty monochrome, and color laser printers shall be used to execute all the different printing tasks. Power Supply Modules Power supply modules in the DCS cabinets shall be redundant and shall be fed from two independent sources Master Clock A GPS Master Clock System with appropriate slave clocks shall be used for time synchronization of DCS and the connected computer systems.
TYPICAL DCS CONFIGURATION
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