13-06-2012, 01:59 PM
INTELLIGENT AUTOMATION SYSTEM FOR ELECTRICAL ENERGY DISTRIBUTION TO DIFFERENT CUSTOMER CATEGORIES
INTELLIGENT AUTOMATION SYSTEM FOR ELECTRICAL ENERGY DISTRIBUTION TO DIFFERENT ........doc (Size: 625.5 KB / Downloads: 67)
ABSTRACT
Electric power distribution is an important part of electrical power systems in delivery of electricity to consumers. Electric power utilities worldwide are increasingly adopting the consumer aided monitoring, control and management of electric power distribution system to provide better service to electric consumers. Therefore, research and development activities worldwide are being carried out to automate the electric power distribution system utilizing recent development in the area of information technology (IT) and data communication system. This paper (PART-1- ) deals with six demand sectors geographically distributed throughout the city of Baghdad were selected and used as test sample. These are Al-SADER CITY, Al- MUHANDESSEN CITY, Al-MANSUR CITY, Al-KADRAA CITY, Al- ADHAMIYA CITY, and Al-KADHMIYA CITY. Each sample consists of record all information about the consumers such as Automatic supply restoration, Automatic network re-configuration, Automatic load shedding and restoration, Demand management, intelligent voltage regulator, etc. So, this paper has completed into three steps:-
1- Transmit, Receive and Transfer the Information.
2- Automated Meter Reading Prepaid.
3- Prepaid Metering with card.
These three steps are satisfied by:-
• Communication and networking technology using wired and wireless media,
• micro-controller based remote terminal unit (RTU),
• Remotely operable switch for 11kV and 415V feeders,
• Application Specific Integrated Circuit (ASIC) for electrical instrumentation,
• DA software to enable remote monitoring, alarm generation and remote control, and
• Distribution network simulator (scaled down model of a real-life distribution network) to provide a test bed for a comprehensive testing of the developed technology, components and software.
In this paper, the functions that can be automated in distribution systems can be classified into two categories, namely, monitoring functions and control functions. Monitoring functions are those needed to record meter readings at different locations in the system, the system status at different locations in the system, and events of abnormal conditions. The data monitored at the system level are not only useful for day-to-day operations but also for system planning. Distribution supervisory control and data acquisition (DSCADA) systems perform some of these monitoring functions. Control functions are related to switching operations, such as switching a capacitor. The function that is the most popular among the utilities is fault location and service restoration or outage management. This function directly impacts the customers as well as the system reliability. This research work to be aimed at developing indigenous know-how of full scale Distribution Automation system, which can cover from secondary sub- stations to consumer level intelligent automation, the power distribution automation is expected into following broad areas. The Distribution Automation system starting from development of various components till the integration of the complete distribution automation systems. Therefore at present, power utilities have to need full scale distribution automation to achieve real time system information and remote control system.
This paper explains the Methods of the Communication Media in the Distribution System, also get gross Intelligent Electronic Device used in this simulation.
The paper was explaining the communicant’s volume (approximately) to test the residential loads from using prepaid card to the consumers during two months. So, becouse the electrical power deficit in the country is clearly, reduction in distribution losses can reduce this deficit significantly. It is possible to bring down the distribution losses to a minimum level in Iraq with the help of newer technological options (including information technology) in the electrical power distribution sector which will enable better monitoring and control. So, Automation is , in its largest meaning, the control and the management of automatic systems carried out through particular techniques and devices, and remain the important question, what you need from apply automation system to your electrical power system?
INTRODUCTION
The idea of distribution automation began in 1970s.
The motivation at that time was to use the evolving computer and communications technology to improve operating performance of distribution systems. Since then, the growth of distribution automation has been dictated by the level of sophistication of existing monitoring, control, and communication technologies, and performance and cost of available equipment.
Although distribution systems are a significant part of power systems, advances in distribution control technology have lagged considerably behind advances in generation and transmission control. Small pilot projects were implemented by a few utilities to test the concept of distribution automation in the
1970s. In the 1980s, there were several major pilot projects. By the
1990s, the distribution automation technology had matured and that resulted in several large and many small projects at various utilities. Some people expected that most of the utilities would come forward for large-scale distribution automation. However, many utilities found it difficult to justify distribution automation based on hard cost-benefit numbers. Business uncertainties due to deregulation and restructuring of the power industry slowed wide scale implementation of distribution automation. Thus, it is justified to re- examine the overall philosophy of distribution automation. It is time to think small. Instead of a top-down approach, it is perhaps better for the utilities to opt for the bottom-up approach. Moreover, selection of distribution automation functions for implementation should always be need-based. Improvements of system reliability and voltage profile on the feeders are two examples of the needs for utilities. Need-based automation would be easier to justify and win approval of the management.
Distribution automation also provides many intangible benefits, which should be given consideration while deciding for implementation of distribution automation. After the deregulation and restructuring issues are settled, distribution automation activities should increase.
PHILOSOPHY OF DISTRIBUTION AUTOMATION
Distribution automation refers to a system that enables an electric utility to remotely monitor, coordinate and operate distribution components in a real-time mode. Automation allows utilities to implement flexible control of distribution systems, which can be used to enhance efficiency, reliability, and quality of electric service. Flexible control also results in more effective utilization and life- extension of the existing distribution system infrastructure.
Another goal for a utility should be improvement in system efficiency by reducing system losses. The functions that can be automated in distribution systems can be classified into two categories, namely, monitoring functions and control functions.
Monitoring functions are those needed to record meter readings at different locations in the system, the system status at different locations in the system, and events of abnormal conditions. The data monitored at the system level are not only useful for day-to-day operations but also for system planning. Distribution supervisory control and data acquisition (DSCADA) systems perform some of these monitoring functions.
Control functions are related to switching operations, such as switching a capacitor. The function that is the most popular among the utilities is fault location and service restoration or outage management. This function directly impacts the customers as well as the system reliability.
DISTRIBUTION SYSTEM IN BAGHDAD CITY
Electric power is normally generated at 11-25kV in a power station. To transmit over long distances, it is then stepped-up to400kV, 220kV or 132kV as necessary. Power is carried through a transmission network of high voltage lines. Usually, these lines run into hundreds of kilometers and deliver the power into a common power pool called the grid. The grid is connected to load centers (cities) through a sub-transmission network of normally 33kV (or sometimes 66kV) lines. These lines terminate into a 33kV (or 66kV) substation, where the voltage is stepped-down to 11kV for power distribution to load points through a distribution network of lines at 11kV and lower. The power network, which generally concerns the common man, is the distribution network of 11kV lines or feeders downstream of the 33kV substation. Each 11kV feeder which emanates from the 33kV substation branches further into several subsidiary 11kV feeders to carry power close to the load points (localities, industrial areas, villages, etc.,). At these load points, a transformer further reduces the voltage from 11kV to 415V to provide the last-mile connection through 415V feeders (also called as Low Tension (LT) feeders) to individual customers, either at 240V (as single-phase supply) or at 415V (as three-phase supply). A feeder could be either an overhead line or an underground cable. In urban areas, owing to the density of customers, the length of an 11kV feeder is generally up to 3 km. On the other hand, in rural areas, the feeder length is much larger (up to 20 km). A 415V feeder should normally be restricted to about 0.5-1.0 km. unduly long feeder’s lead to low voltage at the consumer end. So, the power supply to the city of Baghdad is provided basically from two main substations 400/132 kV (Baghdad east and Baghdad west), which in turn supply many substations 132/33 kV distributed geographically throughout the city. These substations provide the power supply to large number of 33/11 kV substations, mostly equipped with two transformers of 31.5 MVA each. The 11 kV distribution feeders are supplied from the low voltage bus bars of these substations using underground cable/or overhead line systems. Each 11 kV feeder provide supply to a large number of 11/0.4 kV transformers installed using one of the following systems.
1-Pole-mounted transformer supplied directly from 11kV overhead feeders, the transformer size in this system is mostly 250 kVA. In few cases in areas with low load density the 100 kVA size is used.
2- Compact type unit substations installed usually at street pavements. These substations are provided with three components, high voltage, transformer, and low voltage components. Transformers used with this system are usually 630 kVA in size (sometimes the 400 kVA size is also used). The low voltage compartment is provided with several outgoing 400 V feeders. Each low voltage feeder Provide the power supply to a various numbers of consumers.
3-Privately owned substations installed at the consumer’s premises in building basements or in conventional brick-wall rooms. Transformer sizes used in this case vary from 100 to 1000 kVA and in accordance with the load size.
POWER DISTRIBUTION S CENARIO
Lack of information at the base station (33kV sub-station) on the loading and health status of the 11kV/415V transformer and associated feeders is one primary cause of inefficient power distribution. Due to absence of monitoring, overloading occurs, which results in low voltage at the customer end and increases the risk of frequent breakdowns of transformers and feeders. In the absence of switches at different points in the distribution network, it is not possible to isolate certain loads for load shedding as and when required. The only option available in the present distribution network is the circuit breaker (one each for every main 11kV feeder) at the 33kV substation. However, these circuit breakers are actually provided as a means of protection to completely isolate the downstream network in the event of a fault. Using this as a tool for load management is not desirable, as it disconnects the power supply to a very large segment of consumers. Clearly, there is a need to put in place a system that can achieve a finer resolution in load management.
In the event of a fault on any feeder section downstream, the circuit breaker at the 33kV substation trips (opens). As a result, there is a blackout over a large section of the distribution network. If the faulty feeder segment could be precisely identified, it would be possible to substantially reduce the blackout area, by re-routing the power to the healthy feeder segments through the operation of switches (of the same type as those for load management) placed at strategic locations in various feeder segments. Figures 1, 2, observe the main components of distribution system with distribution automation respectively.
In a distribution automation (DA) system, the various quantities (e.g., voltage, current, and switch status, temperature, and oil level) are recorded in the field at the distribution transformers and feeders, using a data acquisition device called Remote Terminal Units (RTU). These system quantities are transmitted on-line to the base station (33kV substation) through a variety of communication media. The media could be either wireless (e.g., microwave, satellite, and radio) or wired (e.g., telephone line, fiber optic cable, power line carrier). The measured field data are processed at the base station for display of any operator selected system quantity through Graphic User Interface (GUI). In the event of a system quantity crossing a pre- defined threshold, an alarm is automatically generated for operator intervention. Any control action (for opening or closing of the switch or circuit breaker) is initiated by the operator and transmitted from the 33kV base station through the communication channel to the remote terminal unit associated with the corresponding switch or circuit breaker. The desired switching action then takes place and the action is acknowledged back to operator for information.
DISTRIBUTION SYSTEM AUTOMATION COMPONENT
Communication and Networking Technology
This enables distributed data acquisition, monitoring and control system functions. Unlike traditional communication solutions, the approach here is to have a core communication controller in the base station that can support diverse choices of communication media (fiber optical cable, Ethernet, microwave, power line carrier, and radio). This open approach facilitates cost effective implementation. The base station communication controller has cross-platform portability, supports functions for communications network management, and permits LAN, Internet, and Intranet connectivity through Ethernet. All command communication functions are invoked through GUI of automation software. Data transfer from/to RTUs supports industry standard data links.
Remote Terminal Unit
The micro-controller based pole-top RTU has 32 analog and 16 digital channels, and affords RS232 full duplex asynchronous communication. The acquired data (voltage and current) is processed for rms and power factor calculations. Some design goals focus at low cost, flexibility and expandability, modularity at signal conditioning level, and communication interface.
Application Specific Integrated Circuit (ASIC)
ASIC supports up to four-phase analog inputs (four voltages and four currents) for applications such as tri-vectormetre, RTU, and single- phase meter. It has an option for frequency selection (50/60 Hz) and is of 0.2 class accuracy with 16 bit A/D converter. Sampling rate is 5000 samples per second per channel. It calculates quantities like rms values of voltage and current (both actual and fundamental), power, power factor, total harmonic distortion, frequency, and energy