The resolution of two asynchronous three-phase power sources such that an optimal phase to phase matchup may be made between them. This is achieved with a logic system that receives a data point at the zero-voltage crossings of the three waveforms from each source. The data points create distinct "states" of the three-phase waveform for each power source. There are six data points for each power source per cycle. The states of the load and source, along with information pertaining to the connection configuration of the present source of power to the load, are used to determine the optimum configuration for connecting an alternate or new source to the load based on information obtained from a lookup table.
The method of interconnecting first and second synchronous polyphase AC networks is for regulating transfer of active power from one of the AC networks to the other. The method involves the steps of, for each phase line of the first AC network, connecting a first end of a first reactive element to the phase line of the first AC network; connecting a first end of a second reactive element to the phase line of the first AC network; applying to a second end of the first reactive element a first phase voltage derived from a second AC network; applying to a second end of the second reactive element a second phase voltage derived from the second AC network, the second phase voltage being phase shifted with respect to the first phase voltage. In a preferred method according to the invention, one of the reactive elements is inductive, and the other of the reactive elements is capacitive. In operation, a phase shift between the first and the second phase voltages forces a regulated transfer of active power from one of the AC networks to the other. Also provided is an interconnecting apparatus for the same purpose.
The present invention pertains to a device and method for determining the sign of a phase angle of a first and second, essentially identical, periodic electric signals on corresponding first and second electrical conductors L1, L2, in particular, to determine the phase sequence in a three-phase power system. The device according to the present invention has a sensing device for sensing of the first signal from the first conductor L1 and of the second signal from the second conductor L2; a trigger device 25 for receiving the sensed first signal and specifying a time reference point and/or a time reference window within the signal period of the first signal and outputting a corresponding trigger signal; and a determination device 31, 32, 33 for receiving the trigger signal and the sensed second signal and determining the sign of the phase angle under consideration of at least the value of the second signal at the time reference point and/or the waveform of the second signal within the time reference window.
