stalled and operational, is the centered activity in the process of assessing the efficacy of distribution ... as a current-limiting reactor. The standard ... of economy interchange and operating benefits versus tie-line capacities as well as versus the ...
Distribution System The distribution sub-system to be automated comprises two, 27.6/16 kV, 4 wire distribution feeders supplied from Ontario Hydro's Agin¬ court Transformer Station. These will supply (by the end of the demon¬ stration) about 40 MV.A of mixed residential and commercial loads, representing a load density of 20 kV.A per hectare (5 MV.A per square mile). The sum of the total feeder lengths is approximately 26 km (16 miles) and is roughly 57% overhead construction, 43% direct buried un¬ derground construction. The feeders and load area are located in the north end of the Borough of Scarborough, in the northeast part of Metropolitan Toronto. Distribution Automation System The distribution automation system will consist of a master station with the necessary executive, monitoring, storage and analytical capa¬ bility provided by appropriate software and hardware, and 180 remote stations. 150 remote stations will be located at customers' services for load management and meter reading. The remainder will be located on the feeders for feeder automation and control.
The distribution of the impulse voltage in a multiple-package air core power reactor has an important effect on the design of high voltage reWhen seeking the transient voltage of the air core reactor, the equiva¬ lent network of the multiple-package reactor winding was replaced by a system of capacitances. A method for calculating these capacitances was proposed. The reactor surge voltage was then calculated. A test re¬ actor was jHiilt for the purpose of comparing the experimental findings with the calculated impulse voltage distribution. The calculated impulse voltage distribution. The calculated voltage distribution agrees reason¬ ably well with the measured value, Figure 2. The steady-state voltage distribution of the multiple-package air core power reactor, determines the design limitation. The steady-state voltage distribution was calculated, based on the as¬ sumption that only the self and the mutual inductances of the windings were considered. A test reactor was built and tested as Trench Electric Ltd. power laboratory, Toronto, Canada. The test data along with the calculated results are shown in Figure 3. It is evident from Figure 3, that the proposed method, calculates very accurately the steady state voltage distribution of the air core power reactor.
Analysis of Distribution System and Automation System Behavior A thorough investigation into the behaviour of the distribution auto¬ mation system under normal and abnormal conditions, when it is in¬ stalled and operational, is the centered activity in the process of assessing the efficacy of distribution automation. This will be facilitated by having the ability to monitor events, system and element status and operating parameters, and then to analyse this information extensively and thoroughly, using a computer provided for the purpose. It is important to note that information gathered by the system will relate to the be¬ haviour of both the automation system, and the distribution system. Analysis of all of the information will yield useful knowledge of both
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Spacer
systems.
Conclusion The distribution automation system described in this paper is being installed to evaluate the capabilities and cost effectiveness of distribu¬ tion automation thoroughly and in a real and typical situation, to allow for intelligent decisions to be made on future courses of action. It will have a very extensive array of capabilities so that the worth of each, as well as the worth of the system can be determined.
April 1981, p. 1752
A Calculation Method for Voltage Distribution in a Large Air Core Power Reactor M. M. A. Salama Electrical Engineering
University, Cairo, Egypt
Department,
Fig.
1.
Typical Air Core Power Reactor.
Ain Shams
In the later 1950's the main application of an air core inductance was current-limiting reactor. The standard method of construction, used by all major electrical equipment manufactures, comprised a cable winding supported in cast concrete form. In the early 1960's, a break¬ through in coil manufacturing was achieved by innovating the use of new materials, such as continuous filament glass fibers in an epoxy resin matrix to provide the physical strength of the air core reactor. The cable winding was replaced by aluminum conductor insulated by poly¬ ester film. With the increasing demand of high rating power reactor, the winding was divided to a large number of parallel concentric layers of conductors. The concept of fractional turns in each layer was introduced to balance the current flow. Two to five layers are completely encapsu¬ lated in the epoxy-fiberglass composite material, to form a winding package. Each package is separated from adjacent ones by axial cooling ducts. This resulted in further improvements in strength, and protection from contamination, Figure 1. Research work on the air core power reactor is very limited in the literature. A method for the calculation of the voltage distribution of the multiple-package air core reactor is developed.
#
Measured
^Calculated
as a
46
0
10
% age of the
20 30 winding length
Fig. 2. Impulse Voltage Distribution 0.5 m sec.
Along the Winding Length at T
=
PER APRIL 1981
Measured Calculated
0 20 40 60 80 100 %age of the winding length
Fig. 3. Steady State voltage Distribution for a Multiple Package Air Core Reactor.
April 1981, p. 1759
Estimation of Power-Pooling Benefits From Production Simulations
the transfer capacity of a company. These are further divided into im¬ port and export curves. The three output variables are cumulative time, cumulative energy and cumulative operating benefits. The second cate¬ gory shows the same output variables versus the bX for each company. These are useful for discounting some of the operating benefits by eliminating those associated with a OX less than the incremental cost of transmission losses. Furthermore, by looking at the existing transfer capacity of a company, one can estimate the operating benefits that are already utilized by existing interconnected operation. And, the additional benefits of increased interconnection can be assessed. The application of the POLCA model was demonstrated by applying it to a sample power pool with four member companies. The pool con¬ sisted of 62,916 MW of generating capacity and 51,331 MW peak pod The generation mix of the pool included 15% hydro, 22% nuclear, 12% coal and 51% other types of generation. The POLCA model produced a number of tabular reports and plots to facilitate a better and broader understanding of power pooling benefits. Two key figures are shown below. The authors have presented a simple, more practical and feasible pro¬ cedure to assess the power-pooling benefits. Indirectly, the procedure considered forced outages of generating units, transmission capacity limits and losses. It could be applied to a power pool with any number of member companies. The model is implemented in a computer pro¬ gram.POLCA.which is extremely fast computationally and is well suited for power pooling studies.
Salim U. Khan, Member, IEEE
Systems Control, Inc. Stephen T. Lee, Senior Member, IEEE Energy Management Associates, Inc. This paper presents a computationally feasible and practical procedure for calculating operating benefits of power pooling by using a number of production simulations. The procedure is implemented in a computer program called POLCA, and application of the program to a realistic power pool with four member utilities is described in the paper. Techniques for evaluating the reliability benefits of power pooling are reasonably well developed. They are usually based on LOLP calcu¬ lation and parametric studies varying the degree of interconnection. Using these methods, it is possible to estimate the generation capacity benefits (reduction in reserve requirement) for increased transfer ca¬ pacity. It is, however, not possible to estimate the operating-cost bene¬ fits which are due to economy interchange. For this problem, a differ¬ ent approach is needed. One has to model the relative incremental op¬ erating costs of all generating units in the interconnected system and their economic dispatch under transmission capacity limitations and transmission losses. Because the effect of random forced outages on system operating costs is significant, it must also be included. The ef¬ fect of forced outages is perhaps the most difficult phenomenon to consider in this problem. A brute-force technique would be to apply Monte Carlo simulation for the forced outages and solve an optimum power flow for each system configuration. This is unfortunately al¬ most infeasible from the computational viewpoint. Recognizing the complexity of the problem and the need for a tech¬ nique that captures most of these factors and yet remains computa¬ tionally practical, we developed a relatively simple procedure for esti¬ mating the operating benefits due to power pooling. This method requires the use of a production simulation, model, pre¬ ferably a probabilistic production costing model that treats random forced outages of generating units. A production simulation is made for each individual area operated in isolation. Then one is made for all areas combined into a single area simulating pool dispatch without transmission limitations. The results of these simulations are input to the POLCA (Pooling Cost Analysis) model which estimates the amount of economy interchange and operating benefits versus tie-line capacities as well as versus the difference between the area's and the pool's incre¬ mental costs. The POLCA model requires as inputs the company and area ID, gen¬ erating unit capacities, forced outage and maintenance outage rates, capacity factors before and after pooling, and average production cost (mills/kWh) before and after pooling. The procedure and model de¬ scribed in the paper is sufficient to produce three types of curves under two categories. One category shows the three output variables versus
PER APRIL 1981
COMPANY B
Fig.
1.
Energy Transfer Among Companies.
8000r
3000:
2000
lOOOh 3500
Fig. 2. Export Tie-Capacity Requirement for Economy Interchange.
47
