Dispersed Storage And Generation Research Articles

Advanced voltage regulation method of power distribution systems interconnected with dispersed storage and generation systems

This paper deals with an issue of voltage regulation for power distribution systems interconnected with dispersed storage and generation (DSG) systems. Since DSGs within power distribution systems impact on the conventional voltage regulation method, there is a possibility that customers' voltages violate the permissible limits. A multiple line drop compensation (MLDC) voltage regulation method that determines tap positions of under-load tap changer (ULTC) transformers is proposed to maintain the customers' voltages within the permissible limits. Several case studies indicate that the proposed MLDC voltage regulation method can be applied well to practical power distribution systems having DSGs and/or severely unbalanced load diversity on different feeders.

Advanced voltage regulation method at the power distribution systems interconnected with dispersed storage and generation systems

DSGs (dispersed storage and generation systems) in power distribution systems impact on the conventional voltage regulation method. Therefore, there is a possibility that the customers' voltage will violate the permissible limits. In this paper, we propose the MLDC (multiple line drop compensation) voltage regulation method considering the unbalanced load diversity among feeders, the operations of DSGs, and the hysterical tap changing mechanism of ULTC (under load tap changer). The result from a case study shows that the proposed MLDC method can be practically applied to the voltage regulation method at the power distribution system interconnected with DSGs and severely unbalanced load diversity among feeders.

A new microprocessor based islanding protection algorithm for dispersed storage and generation units

The ability to detect when dispersed storage and generation (DSG) units become islanded from the main source of generation enables the DSG to be quickly disconnected from the utility network and for that network to be rebuilt in a safe and orderly manner. The new islanding protection algorithm described in the paper has been developed to be part of an integrated protection package to cover all the protection requirements of a DSG. A selection of the results obtained from extensive laboratory and field tests are presented and show that the algorithm reliably trips for islanding conditions within 120 milliseconds, trips for load fluctuations should the DSG be operating independent of the main source of supply and restrains for single phase faults close to the DSG. >

A new pole slipping protection algorithm for dispersed storage and generation using the equal area criterion

The probability of pole slipping of dispersed storage and generation (DSG) synchronous machines is being viewed with concern, since this can damage the machine as well as promote power system instability. This is particularly the case for small and medium sized machines because their low inertia and high resistance make them inherently more unstable. Research has therefore been directed into new techniques for detecting pole slipping and the formulation of protection algorithms which can be included into an integrated microcomputer based protection scheme for these generators. This paper describes a method for detecting pole slipping using power measurements taken at the generator's terminals. This technique has been shown to correctly detect pole slipping using both computer simulation and a laboratory model power system. The algorithm remains stable for recoverable swing conditions and power system faults. >

Static power converters of 500 kW or less serving as the relay interface package for nonconventional generators

The special publication was prepared by the Power System Relaying Committee of the IEEE to assist people involved in the installation application, and operation of utility-interconnected dispersed storage and generation (DSG) systems of 500 kW or less. The energy sources considered are batteries, fuel cells, windmills, and photovoltaic arrays. In most cases, the electrical energy produced is direct current, which must be converted to alternating current, for connection to the electric utility network. The interface between the DC source and the utility AC is often a static power converter (SPC). The purpose of the publication is to illustrate those SPC characteristics that can obviate the need for the interface relay protection package normally required by a utility. A qualifying SPC can detect utility system disturbances or other conditions that would require generator separation in addition to its normal function of protection and control of the DSG. >

Intertie protection of consumer-owned sources of generation, 3 MVA or less: summary report of an IEEE working group report

A summary is presented of a special publication, 'Intertie Protection of Consumer-Owned Sources of Generation 3 MVA or Less', which has been recently prepared by the IEEE PES Power System Relaying Committee to assist people involved in the installation, application, and operation of interconnected dispersed storage and generation (DSG) systems. The purpose of the present summary is to highlight protection considerations, other than surge protection, associated with the connection of small, dispersed sources of generation to utility distribution lines. Primary emphasis is given to detection of system disturbances or conditions that would require generator separation. Background information on the various types of utility distribution systems and small generators is provided to facilitate communication between utility engineers and owners of small generation sources.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A Decision Analysis Model to Determine the Appropriate Level of Protection for the Small Power Producer/Utility Interconnection

This paper formulates a methodology to aid in deciding on the appropriate quality and quantity of protection equipment required for a small electric power producing device, known in the industry as dispersed storage and generation (DSG). In this methodology, a discrete state-space model of the response of both the utility's and DSG's protection equipment to shunt and series faults on an electric distribution feeder is developed. The parameters of the model are linked to the component reliabilities of the protection schemes and the specific characteristics of the distribution system. The mathematics of semi-Markov theory are used in the methodology to calculate the expected annual damage costs for various protection schemes. The total costs are calculated for alternative protection schemes by considering equipment damaqe, repair time, lost revenue, outage costs, and time spent in different operating states during the hazardous conditions. This methodology is useful to electric utilities, small power producers, and regulatory bodies who must make decisions regarding the adequacy as well as the cost-effectiveness of protection requirements for DSG installations.

A Decision Analysis Model to Determine the Appropriate Level of Protection for the Small Power Producer/Utility Interconnection

This paper formulates a methodology to aid in deciding on the appropriate quality and quantity of protection equipment required for a small electric power producing device, known in the industry as dispersed storage and generation (DSG). In this methodology, a discrete state-space model of the response of both the utility's and DSG's protection equipment to shunt and series faults on an electric distribution feeder is developed. The parameters of the model are linked to the component reliabilities of the protection schemes and the specific characteristics of the distribution system. The mathematics of semi-Markov theory are used in the methodology to calculate the expected annual damage costs for various protection schemes. The total costs are calculated for alternative protection schemes by considering equipment damaqe, repair time, lost revenue, outage costs, and time spent in different operating states during the hazardous conditions. This methodology is useful to electric utilities, small power producers, and regulatory bodies who must make decisions regarding the adequacy as well as the cost-effectiveness of protection requirements for DSG installations.

Operational and Design Considerations for Electric Distribution Systems with Dispersed Storage and Generation (DSG)

Three studies have examined the operational and planning problems associated with connecting small power sources to an electric distribution system. In one study [ 6], the harmonic distortion produced by a subdivision of PV arrays connected through line-commutated inverters was simulated. A second study [1,2,3] exami ned the protection and safety problems associated with the operation of small ac generators and dc-to-ac inverters. A third study [11] assessed the the effects of dispersed sources on distribution planning and design. The purpose of the studies was to determine the adequacy of the electric utility industryl traditional practices, hardware, and design for the operation of dispersed power sources on electric distribution systems. The purpose of this paper is to summarize the important results of these studies and related studies, give recommendations for accommodating this new technology, and identify areas needing further research.

Operational and Design Considerations for Electric Distribution Systems with Dispersed Storage and Generation (DSG)

Operational and Design Considerations for Electric Distribution Systems with Dispersed Storage and Generation (DSG)

Electric Distribution Protection Problems Associated with the Interconnection of Small Dispersed Generation Devices

This paper discusses the results of simulating three potential protection problems associated with the interconnection of rotating-type, small dispersed storage and generation (DSG) devices to the electric distribution system. These simulations were performed as part of a study to address the-adequacy of the electric utility industry's present protection practices and hardware for distribution systems with DSG. The simulations considered phenomena such as the effect of dispersed generati, on infeed on the coordination of fuses, resonance of an isolated section of feeder with a three-phase DSG device, and the islanding of a DSG device on an isolated feeder. The phenomena were simulated for a 12. 47 kV feeder with DSG. A digital computer program was used to calculate the transient currents and voltages produced on the feeder for the three types of phehomena. Results of the simulations indicate that these are concerns which should be considered by electric utilities in the connection of dispersed generation sources to the electric distribution system.

Integrating Dispersed Storage and Generation(DSG) with an Automated Distribution System

Dispersed storage and generation (DSG) devices connected to an electric distribution system can cause operational problems-reenergization of distribution feeders under repair by utility personnel production of harmonics by DSG power inverters, and voltage regulation because of fluctuating DSG generation - on an electric utility system. Many of these problems can be overcome by carefully applied automated control schemes. This paper discusses both emergency-and normal-state operations for distribution systems with DSG devices and presents concepts for improving these operations by applying automated control schemes.

Electric Distribution Protection Problems Associated with the Interconnection of small, disperesed Generation Devices

This paper discusses the results of simulating three potential protection problems associated with the interconnection of rotating-type, small dispersed storage and generation (DSG) devices to the electric distribution system. These simulations were performed as part of a study to address the-adequacy of the electric utility industry's present protection practices and hardware for distribution systems with DSG. The simulations considered phenomena such as the effect of dispersed generati, on infeed on the coordination of fuses, resonance of an isolated section of feeder with a three-phase DSG device, and the islanding of a DSG device on an isolated feeder. The phenomena were simulated for a 12. 47 kV feeder with DSG. A digital computer program was used to calculate the transient currents and voltages produced on the feeder for the three types of phehomena. Results of the simulations indicate that these are concerns which should be considered by electric utilities in the connection of dispersed generation sources to the electric distribution system.

Impact of Dispersed Supply Management on Electric Distribution Planning and Operations

Small-scale Dispersed Storage and Generation (DSG) technologies connected to the electric distribution system may offer many of the advantages of central supply management options such as pumped-hydro storage and interconnections. In addition, they may provide benefits to the distribution systems by reducing capacity requirements, improving reliability, and lowering losses.