Tan (Tanek) Zhang, PhD, PE

A method for determination of the optimal deployment of battery energy storage systems for the purpose of deferral of feeder capacity upgrades is developed, together with determination of the economic consequences of such deferral. This work resulted in a practical software planning platform for utility engineers. Through this work it was learned that there may be an optimal deferral period for a given situation which yields the maximum benefit. This study also reveals that the annual rate of… Voir plus

A method for determination of the optimal deployment of battery energy storage systems for the purpose of deferral of feeder capacity upgrades is developed, together with determination of the economic consequences of such deferral. This work resulted in a practical software planning platform for utility engineers. Through this work it was learned that there may be an optimal deferral period for a given situation which yields the maximum benefit. This study also reveals that the annual rate of load increase and the cost per unit length for the feeder upgrade have critical impacts on the benefits. Under a low rate of load increase with a high cost of feeder upgrade, the deferral economic benefits may be substantial. Voir moins

This study extends previous work on the appropriate definition of reactive power in the presence of harmonic voltages and currents to the three-phase, unbalanced case. As in the single phase case, it is advocated that reactive power be defined in terms of the fundamental components (60/50 Hz) of the current and the phase angle separating them. It is demonstrated that common metering techniques for reactive power in the presence of harmonics yield inaccurate results, with errors as great as… Voir plus

This study extends previous work on the appropriate definition of reactive power in the presence of harmonic voltages and currents to the three-phase, unbalanced case. As in the single phase case, it is advocated that reactive power be defined in terms of the fundamental components (60/50 Hz) of the current and the phase angle separating them. It is demonstrated that common metering techniques for reactive power in the presence of harmonics yield inaccurate results, with errors as great as 200%. Modern digital instrumentation is able to conveniently calculate correct values so the time has arrived to start improvements in the design of a new generation of var meters through comprehensive implementation of these digital techniques. Voir moins

The scope of this study is two fold: first, it advocates the recognition of the 60/50 Hz, positive-sequence reactive power as the significant reactive power component of apparent power. This nonactive component must be monitored in the same way that the 60/50 Hz active power is monitored under nonsinusoidal conditions. Secondly, this paper documents the fact that instrumentation used today for reactive power measurement is marred by a significant difference between the indicated reactive power… Voir plus

The scope of this study is two fold: first, it advocates the recognition of the 60/50 Hz, positive-sequence reactive power as the significant reactive power component of apparent power. This nonactive component must be monitored in the same way that the 60/50 Hz active power is monitored under nonsinusoidal conditions. Secondly, this paper documents the fact that instrumentation used today for reactive power measurement is marred by a significant difference between the indicated reactive power and the correct 60/50 Hz reactive power. Regrettably, such instrumentation is still favored by many utilities, instrumentation manufacturers and supervisors of energy markets. This paper documents a wide spectrum of situations that shed light on the discrepancies between the correct value of the reactive power and the measured value. Voir moins

Planned and unplanned outages on distribution networks may cause major economic loss to the customers, and can result in substantial reparation payments by the utilities. This paper analyzes the use of a Battery Energy Storage System (BESS) to partially or completely avoid these outages. The analysis is conducted with a multi-day high demand scenario where the load demand at peak times exceeds the current capacity of the line. This would result in an outage unless the current from the… Voir plus

Planned and unplanned outages on distribution networks may cause major economic loss to the customers, and can result in substantial reparation payments by the utilities. This paper analyzes the use of a Battery Energy Storage System (BESS) to partially or completely avoid these outages. The analysis is conducted with a multi-day high demand scenario where the load demand at peak times exceeds the current capacity of the line. This would result in an outage unless the current from the substation can be reduced. Three basic scenarios representative of different degrees of sophistication of feeder automation were studied: A conventional feeder controlled by one or more reclosing breakers; a modern distribution feeder equipped with a limited number of remote controlled breakers that will disconnect non-vital loads belonging to residential, commercial and industrial customers and a modern distribution feeder equipped with numerous remote controlled breakers that will selectively disconnect commercial, industrial, and residential loads, based on their degree of criticality.
This study concluded that the total or partial avoidance of outages by way of BESS usage is feasible; however, the use of "smart grid" control technology can provide more benefit than BESSs in the scenarios studied. Voir moins

Implementing electric energy storage in distribution networks requires that the input and output of the storage units be controlled in a manner to achieve maximum economic benefit. This paper outlines an algorithm that ensures that the battery operate near or at its highest economic potential given predictions of Locational Marginal Pricing (LMP) and the time profile of demand. This is accomplished by using the application of the dynamic programming algorithm. This algorithm is increasingly… Voir plus

Implementing electric energy storage in distribution networks requires that the input and output of the storage units be controlled in a manner to achieve maximum economic benefit. This paper outlines an algorithm that ensures that the battery operate near or at its highest economic potential given predictions of Locational Marginal Pricing (LMP) and the time profile of demand. This is accomplished by using the application of the dynamic programming algorithm. This algorithm is increasingly accurate with complexity and is best coupled with computer simulation. Voir moins

This paper reports simulated results that detail the effects of the parameters that control the charge/discharge operation of a Battery Energy Storage System (BESS) located on a distribution feeder. The following BESS parameters were evaluated: energy capacity, maximum discharge current, and “round-trip” efficiency. Also, the following system parameters were studied: marginal cost (MC) of electric energy, and the 24 hour load profile of the feeder. The BESS performance was quantified as a… Voir plus

This paper reports simulated results that detail the effects of the parameters that control the charge/discharge operation of a Battery Energy Storage System (BESS) located on a distribution feeder. The following BESS parameters were evaluated: energy capacity, maximum discharge current, and “round-trip” efficiency. Also, the following system parameters were studied: marginal cost (MC) of electric energy, and the 24 hour load profile of the feeder. The BESS performance was quantified as a function of the differential cost of energy (DCE) representing the difference between the cost of energy purchased to charge the BESS and the cost of energy delivered, (sold). The obtained results prove that the use of BESS can be beneficial, yielding significant savings, if the battery size is sufficiently large and the battery efficiency is high enough. Voir moins

System planning for incorporation of electric energy storage systems into a distribution network requires consideration of a range of technical and economic variables. A modeling system with a graphical user interface has been developed to incorporate an accurate system model of a distribution feeder including distributed generation and energy storage located along the feeder, as well as economic parameters. Output of the model represents a time history of the simulated feeder with the given… Voir plus

System planning for incorporation of electric energy storage systems into a distribution network requires consideration of a range of technical and economic variables. A modeling system with a graphical user interface has been developed to incorporate an accurate system model of a distribution feeder including distributed generation and energy storage located along the feeder, as well as economic parameters. Output of the model represents a time history of the simulated feeder with the given parameters and time profiles of loads, generation, and storage systems. In addition to active power flows, the model also accounts for reactive power flows, with the capability of for reactive compensation from renewable generation and energy storage inverters. The cost of energy via Locational Marginal Pricing (LMP) and Renewable Energy Credits (RECs) is incorporated. This paper describes the modeling system and provides example results for an actual feeder in the Eastern Massachusetts LMP area. Voir moins

This paper studies a hybrid control strategy of induction motor. The strategy established loss model first, and in accordance with its magnetic flux to be near optimal, and determine the search range, at last using of "golden section" search method to search for the optimal flux values which makes the smallest input power. The simulation results show that the hybrid control strategy not only can reduce the search time effectively, and has good energy-saving effect.