Methods and systems for redundant power detection, including forward power and reverse power, utilize sensors separate from microwave power sensors. The redundant power detection can be compared to measurements of the microwave power sensors to ensure that the sensors are operating correctly.

A method and an arrangement are provided in connection with a photovoltaic power generator composed of series-connected photovoltaic modules. The method includes determining a maximum power point voltage (U.sub.MPP) and a maximum power point current (I.sub.MPP). The method also includes determining the ambient temperature (T.sub.amb), calculating an estimated maximum power point voltage (U.sub.est) by using maximum power point current (I.sub.MPP) and the determined ambient temperature (T.sub.amb), comparing the estimated maximum power point voltage with the determined maximum power point (U.sub.MPP), and determining on the basis of the comparison whether the generator is operating under uniform conditions or in conditions with two maximum power points.

A method and an arrangement are provided in connection with a photovoltaic power generator composed of series-connected photovoltaic modules. The method includes determining a maximum power point voltage (U.sub.MPP) and a maximum power point current (I.sub.MPP). The method also includes determining the ambient temperature (T.sub.amb), calculating an estimated maximum power point voltage (U.sub.est) by using maximum power point current (I.sub.MPP) and the determined ambient temperature (T.sub.amb), comparing the estimated maximum power point voltage with the determined maximum power point (U.sub.MPP), and determining on the basis of the comparison whether the generator is operating under uniform conditions or in conditions with two maximum power points.

The present disclosure provides a power control system for motor preheating including a current sensor, a power calculation module, a power error calculation module, a power control module, a current control module and a voltage control module. The current sensor senses a motor current output by the motor. The power calculation module calculates an output power of the motor according to the voltage command and the motor current. The power error calculation module calculates a power error according to a power command and the output power. The power control module outputs a current braking command according to the power error. The current control module calculates a voltage command according to the current braking command and the motor current. The voltage control module outputs a three-phase voltage according to the voltage command, and the motor is operated in a stationary state, and the stator of the motor is preheated.

The present disclosure provides a power control system for motor preheating including a current sensor, a power calculation module, a power error calculation module, a power control module, a current control module and a voltage control module. The current sensor senses a motor current output by the motor. The power calculation module calculates an output power of the motor according to the voltage command and the motor current. The power error calculation module calculates a power error according to a power command and the output power. The power control module outputs a current braking command according to the power error. The current control module calculates a voltage command according to the current braking command and the motor current. The voltage control module outputs a three-phase voltage according to the voltage command, and the motor is operated in a stationary state, and the stator of the motor is preheated.

A power load prediction method includes determining a relationship between power load and temperature during a selected time. A decomposition of the determined relationship is determined. The decomposition indicates a plurality of contributors to the determined power load. A predicted power load is estimated based on the plurality of contributors and a regression model.

Disclosed is a radio frequency (RF) calorimeter having National Metrology Institute (NMI) traceable measurement accuracy with uncertainty of less than about +0.25%, including the incorporation of a low-frequency reference source integral to the calorimeter for the purpose of self-calibration, a load with very high thermal efficiency, a temperature-controlled load enclosure, a vacuum relay high-power RF switch, an integrated low-frequency reference source, a non-reactive coolant liquid, a liquid-to-liquid heat exchanger, a self-calibration routine that can be performed on demand, and machine learning algorithms to create more accurate data models.

Disclosed is a radio frequency (RF) calorimeter having National Metrology Institute (NMI) traceable measurement accuracy with uncertainty of less than about +0.25%, including the incorporation of a low-frequency reference source integral to the calorimeter for the purpose of self-calibration, a load with very high thermal efficiency, a temperature-controlled load enclosure, a vacuum relay high-power RF switch, an integrated low-frequency reference source, a non-reactive coolant liquid, a liquid-to-liquid heat exchanger, a self-calibration routine that can be performed on demand, and machine learning algorithms to create more accurate data models.

Disclosed is a liquid-cooled termination for calorimic RF power measurement having an RF transmission line, a coolant flowpath having a coolant input and a coolant output, and an RF load. The RF transmission line being electrical communication with said RF load having a resistor and a heat sink. The RF load is in the coolant flowpath, such that said heat generated by the RF power being applied to the RF load through said RF transmission line is convected to the coolant while said coolant flows past said RF load.

Disclosed is a liquid-cooled termination for calorimic RF power measurement having an RF transmission line, a coolant flowpath having a coolant input and a coolant output, and an RF load. The RF transmission line being electrical communication with said RF load having a resistor and a heat sink. The RF load is in the coolant flowpath, such that said heat generated by the RF power being applied to the RF load through said RF transmission line is convected to the coolant while said coolant flows past said RF load.