A method including: mechanically driving a generator with an internal combustion engine, creating a generator rotary speed corresponding to a generator frequency, control of the internal combustion engine such that the generator frequency is in a tolerance range, wherein a grid frequency is within the tolerance range, detecting a phase angle difference between a current and/or a voltage generated by the generator and a grid current and/or a grid voltage, synchronizing the voltage and/or the current with the grid voltage and/or the grid current to reduce as phase angle difference (), and electrically connecting the generator to a power supply grid, wherein at least one temporary change in an ignition timing of at least one cylinder unit of the internal combustion engine is performed to reduce the phase angle difference ().

A method including: mechanically driving a generator with an internal combustion engine, creating a generator rotary speed corresponding to a generator frequency, control of the internal combustion engine such that the generator frequency is in a tolerance range, wherein a grid frequency is within the tolerance range, detecting a phase angle difference between a current and/or a voltage generated by the generator and a grid current and/or a grid voltage, synchronizing the voltage and/or the current with the grid voltage and/or the grid current to reduce as phase angle difference (), and electrically connecting the generator to a power supply grid, wherein at least one temporary change in an ignition timing of at least one cylinder unit of the internal combustion engine is performed to reduce the phase angle difference ().

The invention concerns a method for coupling to the grid a hydraulic unit having a synchronous generator, a runner, and wicket gates, the method comprises: a) a step of increasing the flow of water into the runner from a time t.sub.0 to a time t.sub.1 so that the rotation frequency of the rotor of the synchronous generator is, at time t.sub.1 equal to the frequency of the grid; b) a step of closing the circuit breaker at time t.sub.1, step a) further comprises a sub-step a1) executed from a time t.sub.2 to time t.sub.1, wherein the flow of water is adjusted so that, at time t.sub.1, the phase of the synchronous generator is aligned with the grid phase.

The invention concerns a method for coupling to the grid a hydraulic unit having a synchronous generator, a runner, and wicket gates, the method comprises: a) a step of increasing the flow of water into the runner from a time t.sub.0 to a time t.sub.1 so that the rotation frequency of the rotor of the synchronous generator is, at time t.sub.1 equal to the frequency of the grid; b) a step of closing the circuit breaker at time t.sub.1, step a) further comprises a sub-step a1) executed from a time t.sub.2 to time t.sub.1, wherein the flow of water is adjusted so that, at time t.sub.1, the phase of the synchronous generator is aligned with the grid phase.

An alternating current (AC) module system includes branch circuits and a main service panel to receive power from the branch circuits. A photovoltaic (PV) supervisor is located between the branch circuits and the panel. The PV supervisor aggregates the power from the branch circuits. The PV supervisor also performs a nonredundant operational function for one or more of the branch circuits. The PV supervisor includes a gateway device to permit control of the operational functions.

A method for generating electrical power comprising operating variable frequency generators using a common prime mover and controlling the variable frequency generators using a mechanical phase difference as follows: $MPD=\frac{360}{Gp}$
wherein MPD is the mechanical phase difference in degrees between rotors between a pair of variable frequency generators, G is a number of variable frequency generators, is a number of electrical phases in a variable frequency generator in the variable frequency generators, and p is a number of pole pairs in the variable frequency generator in the variable frequency generators, wherein the variable frequency generators are controlled such that each variable frequency generator in the variable frequency generators has a selected mechanical phase difference from another variable frequency generator in the variable frequency generators that is an integer multiple of the mechanical phase difference that is less than 360 degrees.

A method for generating electrical power comprising operating variable frequency generators using a common prime mover and controlling the variable frequency generators using a mechanical phase difference as follows: $MPD=\frac{360}{Gp}$
wherein MPD is the mechanical phase difference in degrees between rotors between a pair of variable frequency generators, G is a number of variable frequency generators, is a number of electrical phases in a variable frequency generator in the variable frequency generators, and p is a number of pole pairs in the variable frequency generator in the variable frequency generators, wherein the variable frequency generators are controlled such that each variable frequency generator in the variable frequency generators has a selected mechanical phase difference from another variable frequency generator in the variable frequency generators that is an integer multiple of the mechanical phase difference that is less than 360 degrees.

Disclosed are systems and methods to determine an overexcitation condition on electric power delivery system equipment that includes a magnetizing core. Overexcitation conditions are determined even during sub-synchronous resonance, ferro-resonance, and other complex events. Power system voltage is integrated and normalized to determine a flux on the magnetizing core. The flux is compared with a protection model to determine the overexcitation condition on the magnetizing core. Once an overexcitation condition is detected, a protective action may be taken to remove power from the effected power delivery system equipment.

Disclosed are systems and methods to determine an overexcitation condition on electric power delivery system equipment that includes a magnetizing core. Overexcitation conditions are determined even during sub-synchronous resonance, ferro-resonance, and other complex events. Power system voltage is integrated and normalized to determine a flux on the magnetizing core. The flux is compared with a protection model to determine the overexcitation condition on the magnetizing core. Once an overexcitation condition is detected, a protective action may be taken to remove power from the effected power delivery system equipment.

A method and a system sense at least one phase difference between at least two phases of a group of parallel connected three phase AC output terminals (e.g., a first phase AC output terminal, a second phase AC output terminal, or a third phase AC output terminal). The parallel connected AC output terminals may be three parallel connected DC to AC three phase inverters. Features of the parallel connected three phase AC output terminals enable wiring of conductors to one phase of an AC output terminal to be swapped with wiring of conductors of one phase of another phase AC output terminal. A sign of at least one phase difference is verified different from signs of other phase differences thereby the system determining the lateral position of the at least one three phase inverters relative to at least one other of the three phase inverters.