Power Distribution and Utilization Lecture # 4

Impact of dispersed storage and generation Due to the oil Embargo and the rising prices of Oil, the efforts toward the development of alternative energy sources ( preferably renewable resources) for generating electric energy have been increased. A small power production facility is one which produces electric energy solely by the use of the primary fuels if biomass, waste, renewable resources or any combination thereof. Furthermore, the capacity of such production sources together with other facilities located at the same site must not exceed 80 MW A cogeneration facility is one which produces electricity and steam or forms of useful energy for industrial, commercial, heating or cooling applications.

A qualified facility is any small power production or cogeneration facility which conforms to the previous definition and is owned by an entity not primarily engaged in generation or sale of electric power.

In general, these generators are small ( typically ranging in size from 100KW to 10MW and connectable to either side of the meter) and can be economically connected only to the distribution system. They are defined as Dispersed Storage and Generation (DSG) devices. If properly planned and operated, DSG may provide benefits to Distribution systems by reducing capacity requirements, improving reliability and reducing loses. Example of DSG technologies includes Hydro-electric Diesel generators Wind electric systems Solar electric systems Batteries Storage space and water heaters And fuel cells

DSG Devices Biomass Geothermal Pumped hydro Compressed air storage Solar thermal Photovoltaic's Wind Fuel cells Storage battery Loow-head hydro

Cogeneration devices Gas turbine Burning refuse Landfill gas

Distribution automation will be indispensable for maintaining a reliable electric supply and for cutting down operating costs. In distribution systems with DSG, the feeder or feeders will no longer be radial. Consequently a more complex set of operating conditions will prevail for both steady state and fault conditions. If the dispersed generator capacity is large relative to the feeder supply capacity, then it might be considered as backup for normal supply. If so this could improve service security in instances of loss of supply. In a given fault, a more complex distribution of higher magnitude fault currents will occur because of multiple supply sources. Such system require more sophisticated detection and isolated techniques than those adequate for radial feeders. Therefore, distribution automation, with its multiple point monitoring and control capability, is well suited to the complex of a distribution system with DSG.

Name of Energy Management System Functions Automatic generation control Economic dispatch Voltage control Protection State estimation Online load flow Security monitoring

Distribution System Automation The Main purpose of an electric power system is to efficiently generate, transmit and distribute electric energy. The operation involved dictate geographically dispersed and functionally complex monitoring and control systems as show in figure As noted in the figure, the EMS exercise overall control over the total system. The supervisory control and data acquisition (SCADA) system involves the distribution system, including connected load. Automatic monitoring and control features have long been a part of SCADA system. More automation has become a part of the overall energy management, including the distribution system. The monitoring objectives of the DAC system are [25] 1.Improved overall system efficiency in the use of both capital and energy 2.Increased market penetration of coal, nuclear and renewable domestic energy sources. 3.Reduced reserve requirements in both transmission and generation 4.Increased reliability of service to essential loads.

Recently, inexpensive minicomputers and powerful microprocessors ( computer on a chip) have provided distribution system engineers with new tools that are making any distribution automation of today. The term distribution automation has a very broad meaning and additional applications are added every day. To some people, it may mean a communication system at the distribution level that can control customer load and can reduce peak load generation through load management. To others, the distribution automation may mean an unattended distribution substation that could be considered attended through the use of an on site microprocessor. The microprocessor, located at a distribution substation can continuously monitor the system, make operating decision, issue commands and report any change in status to the distribution dispatch centre DDC, store it on-site for later use, or forget it, depending on the need of utility.

Distribution Automation and Control Functions Table 1.4 gives some of the automated distribution function which can be categorized as the load management functions, real-time operational management function and remote meter reading functions. Discretionary Load Switching, This function is also called the cutromer load management. It involves direct control of loads at individual customer sites from a remote central location. Peak Load Pricing. This function allows the implementation of peak load pricing programs by remote switching of meter registers automatically for the purpose of time-of-day metering. Load Shedding. This function is corollary tow the Load-shedding function. It entails the controlled pick-up of dropped load. Here, cold load pick-up describes the load that causes a high magnitude, shot duration in-rush current, followed by the undiversified demand experienced when re- energizing a circuit following an extended, that is, 20 min or more, interruption.

Load Reconfiguration. This function involves remote control of switches and breakers to permit routine daily, weekly, or seasonal reconfiguration of feeders or feeder segment for the purpose of taking advantage if load diversity among feeders. It enables the system to effectively serve Larger loads without requiring feeder reinforcement or new construction. Voltage Regulation. This function allows the remote control of selected voltage regulators within the distribution network, together with network capacitor switching, to effect coordinated system voltage control from a central facility. Transformer Load Management TLM. This function enables the monitoring and continuous reporting of transformer loading data and core temperature to prevent overloads, burnouts, or abnormal operation by timely reinforcement, replacement, or reconfiguration. Feeder Load Management FLLM. This function is similar to TLM, but the loads are monitored and measured on feeders and feeder segments ( known as the line section) instead, This function permits loads to be equalized over several feeders. Capacitor Control. This function permits selective and remote-controlled switching of distribution capacitors. Fault detection, location and isolation. Sensors located throughout the distribution network can be used to detect and report abnormal conditions. This information, in turn, can be used to automatically locate faults, isolate the faulted segment, and initiate proper sectionalisation and circuit reconfiguration. Load Studies. This function involves the automatic on-line gathering and recording of load data for special off-line analysis. The data may be stored at the collection point, at the substation or transmitted to a dispatch centre. This function provides accurate and timely information for planning and engineering of the power system. Condition and State Monitoring. This function involves real-time data gathering and status reporting from which the minute by minute status of the power system can be determined.

Load Management Discretionary load switching Peak load pricing Load shedding Cold load pick-up Operational Management Load Reconfiguration Voltage regulation Transformer load management Feeder load management Capacitor control Dispersed storage and generation Load studies Condition and stat monitoring Remote Meter reading Automatic customer meter reading

Thankyou.