Extra-Long-Distance-Transmission

In a preliminary study and evaluation of ELD transmission, it is desirable to have available a general but relatively simple method of estimating the magnitudes and interrelationships of the principal factors and variables. More detailed planning or design would, of course, require refinements and closer examination of operating and equipment limitations. The method incorporated in this paper involves the following assumptions and constraints: 1. Series and shunt compensating elements are applied in the pi configuration, and conmplete shunt compensation of the line sections is assumed. 2. Line loading or capability is based on a displacement angle of 30 degrees between the high-side terminal voltages. 3. Terminal power factors at the two ends are held at equal values, leading at the receiving end and lagging at the sending end. 4. Sending and receiving end terminal voltage magnitudes are restricted so that their geometric mean is equal to the nominal line voltage. The following general conclusions arise from the results of applying these restrictions to the studies reported herein, and these, in turn, prompt some comments and conjecture on the problems and prospects of ELD transmission in the range of 600 miles and beyond. 1. When unit transmission costs are considered in mills per kwhr, ELD transmission inherently calls for the utilization of EHV. 2. In ELD transmission, shunt compensation is required to control voltage conditions, and economic considerations dictate the use of relatively heavy series compensation, up to 80% and above. 3.