Operating Aspects of Reactive Power

This paper is written to present the point of view of the practical operating engineer to whom ``reactive power'' is something that he has to generate and deliver to his customers much as he does ordinary or real power. It happens that this kind of reactive power is the kind which causes the current to lag behind the voltage when it happens to be flowing in the same direction in the circuit as the ``active'' power. However, when it happens to be flowing in the direction opposite to that of the active power (which, in a transmission system is just about as likely to happen), it makes the total current in the circuit appear to lead the voltage and deceives the technician who observes this phenomenon into thinking that a different kind of reactive power (viz., leading reactive power) is flowing in the same direction as the active power. The paper presents an interpretation of such observations in terms of the one kind of reactive power with which the practical operation and control of power systems has to deal and points out the parallelism between active and reactive power in their operating aspects. It also presents an unorthodox metering technique for keeping track of the flow of reactive power in a complicated power transmission network which greatly clarifies and simplifies the problem of dispatching reactive power in such a system; such dispatching being necessary to obtain maximum transmission system capacity and efficiency as well as for system voltage control.