Reactance Compensation Research Articles

Actively compensated parametric amplifiers — some further results

This letter details further results obtained with active reactance compensation of parametric amplifiers; in particular, a useful measure of gain independence of pump power is described.

500 KV Series Capacitor Installations in California

Construction of the Pacific Intertie transmission system, and other related EHV lines has included unprecedented installations of 500 kV series capacitors. Twenty series capacitor banks, totaling 4,465 mvar, and providing 70% reactance compensation, have been installed in California by Southern California Edison Company and Pacific Gas and Electric Company.

Parallel Operation of Load Ratio Control Transformers Using Reverse Reactance Compensation [includes discussion

When transformers with automatic load ratio control are operated in parallel, a miethod of preventing excessive circulating current is required. Some of the methods used are extremely complex, requiring additional equipment and control connections between units. The combination of resistance compensation to produce constant voltage at the load center as well as reverse reactance compensation to limit the circulating current between units is applicable to many circuits where more complicated means of parallel operation are now used. This system has the advantage of requiring no additional equipment and no control connections between units. The relations developed show that satisfactory performance in limiting circulating current between units and maintaining voltage can be secured in many cases. The best performance is obtained when the power factor of the circuit is high and substantially constant, and when the power factor of the circulating current is low. However, variations in load power at light loads have little effect on the performance. Equations for calculating the performance of this control on paralleled circuits are derived.

A 24,000-Kilovar Series Capacitor in a 230-Kv Transmission Line

The necessity for long distance transmission of electric power has grown rapidly during recent years. Line reactance becomes a problem of increasing importance when transmission distances continue to increase. Long lines cannot be loaded sufficiently for maximum over-all economy because of limitations imposed by transient stability an kilovar requirements. The most important alternative to reduction in equivalent line impedance by further increase in transmission voltage, is the use of line reactance compensation. Such compensation can best be obtained through the use of capacitors operating in series with the line conductors. To permit the use of series capacitors rated on the basis of normal load conditions, it is necessary to protect them effectively during line fault conditions. To make maximum use of line reactance compensation with capacitors it is necessary to by-pass and protect them only during line fault condition and reinsert them with minimum delay after the line fault is cleared. Lack of means for accomplishing the latter has prevented the use of capacitors for line reactance compensation where the primary objective is increasing power transmission. While protective devices have been developed which are adequate for use with series capacitors when used to improve voltage regulation, they are by far too slow in operation to meet the requirements when series capacitors are used to increase power transmission.

Wide-band folded-slot aerials

Among the possible applications of Babinet's principle proposed by C.E.G. Bailey and H.G. Booker was the “folded slot,” the slot analogue of the well-known folded dipole. The paper describes modified forms of folded slot designed to exhibit reactance compensation, so that the variation of impedance over a wide band of frequencies is small. Calculation of the input impedance is facilitated by considering an equivalent circuit which applies to certain types of 3-terminal network. The bandwidth of an aerial for multi-channel f.m. broadcasting has been improved by the use of folded slots.

Short-circuit characteristics and load performance of inductor-type alternators

The paper develops a graphical method of determining the short-circuit current of an inductor alternator, taking into account the effect of a damping circuit which prevents oscillations of the total flux. It is shown that the short-circuit current depends mainly on the important ratio of maximum to minimum flux and on the leakage. The equivalent circuit for the inductor alternator is determined from the open-circuit voltage and short-circuit current. The ratio of these values varies owing to saturation effects, but can be taken as constant for a given excitation and independent of the load circuit. Compensation of the internal inductive reactance by series condensers for an alternator with constant and variable speed is considered, and the transient- and steady-voltage changes are investigated. The reason for the voltage drop of the fully compensated machine being many times greater than the resistive drop is given. The effect on the speed/torque characteristic of series-condenser compensation is shown. The paper explains that the damping winding increases the effective excitation for a load circuit having a lagging power factor and reduces for a leading power factor. An unusual type of instability arising when paralleling series-compensated alternators is investigated, and a remedy for this phenomenon is given.

Steady-state and transient-stability analysis of series capacitors in long transmission lines

IN long-distance large-block power transmission, where is reactance compensation applicable? The complete answer to this question involves the weighing of compensated line performance against its costs, tempered with engineering judgment. This paper presents the results of an analysis made to determine basic performance data of compensated lines under steady-state and transient conditions. The data presented therefore allow the question to be partly answered and, it is believed, to a sufficient degree to permit certain general conclusions to be drawn. The system designer is thus provided with the fundamentally necessary data permitting him to proceed with an economic analysis for his particular case, where the cost factors are available. It is felt that in this field lies the value of these data. The costs of the various factors for a particular case can be weighed with the performance obtained by the same factors. The best design must necessarily be one where per cent line compensation, number of parallel circuits, generator short-circuit ratio, and number of intermediate switching stations are all used to their optimum degree for a given reliability of service. The number of factors which may be varied obviously depends upon whether compensation is to be used for increasing the power limits of a system already in operation or to be used as a factor in the design of a projected system.

Steady-State and Transient-Stability Analysis of Series Capacitors in Long Transmission Lines

IN long-distance large-block power transmission, where is reactance compensation applicable? The complete answer to this question involves the weighing of compensated line performance against its costs, tempered with engineering judgment. This paper presents the results of an analysis made to determine basic performance data of compensated lines under steady-state and transient conditions. The data presented therefore allow the question to be partly answered and, it is believed, to a sufficient degree to permit certain general conclusions to be drawn. The system designer is thus provided with the fundamentally necessary data permitting him to proceed with an economic analysis for his particular case, where the cost factors are available. It is felt that in this field lies the value of these data. The costs of the various factors for a particular case can be weighed with the performance obtained by the same factors. The best design must necessarily be one where per cent line compensation, number of parallel circuits, generator short-circuit ratio, and number of intermediate switching stations are all used to their optimum degree for a given reliability of service. The number of factors which may be varied obviously depends upon whether compensation is to be used for increasing the power limits of a system already in operation or to be used as a factor in the design of a projected system.

Stability Limitations of Long-Distance A-C Power-Transmission Systems

Conventional methods of transmission are analyzed and discussed both for existing transmission distances up to about 300 miles and for greater distances up to a full wave length; also eight different methods that have been proposed for increasing the loading per circuit or distance to which a-c power can be transmitted are discussed. Of these methods, series compensation of the line reactance appears to be the most favorable for straightaway distances up to about 600 to 700 miles at 60 cycles. The problem is analyzed mathematically and with the aid of an a-c network analyzer. Curves are included which give the power limits and reactive kilovoltampere requirements for a large number of parameters, including the effect of distance, voltage, conductor size, series and shunt compensation, terminal impedances, and stability margin. This analysis indicates that the limitation of the transmission of a-c power greater straightaway distances than has been accomplished heretofore is primarily that of the cost of the line, the stability limitation can be overcome by a comparatively small increase in cost.