| Accurate electricity computation has important meanings to the calculation of electricity generating and supply, the integrated balance and examination of economic technical index of system of electricity, energy saving and reasonable collection of electricity fee, etc.The synthesis errors in the electric power measuring equipment include these of the ammeter, the transformer and these caused by the secondary circuit voltage drop of the transformer. All these errors are mainly caused by a far distance between the outdoor voltage transformer and indoor ammeter, which is connected by such units as the secondary contact wires, switch ,fuse and terminal block.Their uncertain contact resistance can cause a voltage drop in the secondary circuit which is a dynamic variable. This problem cannot be solved by making the transformer and the measuring ammeter accurate but an necessary compensation.The traditional ones are fixed value compensation and current following compensation, which belong to static compensation. That is to compensate for the current drop caused by load changes without changing the resistance of the secondary circuit. This method may be less or over compensated, which can not reach the purpose of measuring the electirc power exactly.This paper puts forward dynamic compensating equipment. It makes use of intellectual controlling way of single chip microprocessor, following the chages of the secondary circuit voltage drop of voltage transformer at real time, and adjusting the gains in the system, to meet the parameter changes caused by that of resistance. Its purpose is that the amplitude of input can be well followed by that of output to realize dynamic compensate and impedance matching.Through this way we can solve the problems existing in the compensating equipment, and reach the standard by which the electric power can be calculated exactly to make the secondary circuit voltage drop compensated far below the standard of courtry. The results of both analog and on-the-spot experiments, which prove the vast vistas for application and spead value of this equipment. |
