Abstract: The invention provides a Saccharomyces cerevisiae strain for producing a human milk lipid substitute. By integrating a heterologous lysophosphatidic acid acyltransferase into Saccharomyces cerevisiae and knocking out its own natural lysophosphatidic acid acyltransferase, the content of palmitic acid (C16:0) at Sn-2 position of triacylglycerol produced by Saccharomyces cerevisiae is increased, to synthesize a human milk lipid substitute. On this basis, a metabolic pathway related gene is knocked out, to further increase the content of human milk lipid substitute in the product. In the present invention, a human milk lipid substitute is de novo synthesized by Saccharomyces cerevisiae for the first time, in which the total fatty acid is 15% or more, and the relative content of C16:0 at Sn-2 position reaches about 60%.

Abstract: It is a system for supplying power to at least one load. The system comprises at least one power source, load bank and control device coupled to the at least one load. The load bank is coupled to at least one power source and at least one load. The load bank comprises a controllable voltage source, at least three resistors coupled between an output side of the controllable voltage source and the at least one power source, and at least one storage element. The controllable voltage source comprises more than one switches. And the at least one storage element comprises one or more capacitors, batteries, or combinations thereof. The control device is configured for controlling the switches during a first condition such that, to the extent that an output power of the at least one power source exceeds a requisite power of the at least one load, any excess output power is either supplied to the at least one storage element or consumed by the at least three resistors.

Abstract: Methods for operating a wind turbine system are provided. In one embodiment, a method includes adjusting a threshold direct current (DC) bus voltage for a dynamic brake in a wind turbine power converter above a reference DC bus voltage based on at least one system condition. The method further includes gating the dynamic brake on when an experienced DC bus voltage is equal to or greater than the threshold DC bus voltage, and inputting a dynamic brake condition into a controller when the dynamic brake is gated on. The method further includes determining if a grid fault has occurred, reducing power generation of the wind turbine if no grid fault has occurred, and blocking the power converter if a grid fault has occurred. The method further includes gating the dynamic brake off when the experienced DC bus voltage is less than the threshold DC bus voltage.

Abstract: The present disclosure discloses a comb polymer or a salt thereof, wherein the structural formula of the comb polymer containing the following constitutional units. When the comb polymer provided in the present disclosure is used in a water-based drilling fluid as a filtration control agent, it can eliminate the defects of conventional filtration control agents which would be subject to ineffectiveness under high temperature and high salinity conditions. The comb polymer has high temperature and salt resistance, and can be produced through simple processes at comparatively low costs. When the comb polymer provided by the present disclosure is used as a filtration control agent, even being added into the drilling fluid at a comparatively low amount, it can still present rather good effects in lowering the amount of filter loss.

Abstract: It is a system for supplying power to at least one load. The system comprises at least one power source, load bank and control device coupled to the at least one load. The load bank is coupled to at least one power source and at least one load. The load bank comprises a controllable voltage source, at least three resistors coupled between an output side of the controllable voltage source and the at least one power source, and at least one storage element. The controllable voltage source comprises more than one switches. And the at least one storage element comprises one or more capacitors, batteries, or combinations thereof. The control device is configured for controlling the switches during a first condition such that, to the extent that an output power of the at least one power source exceeds a requisite power of the at least one load, any excess output power is either supplied to the at least one storage element or consumed by the at least three resistors.

Abstract: A power converter system includes a converter configured to be coupled to a power generation unit for receiving current from the power generation unit. A bus is coupled to the converter, and energy is stored within the bus when the current is conducted through the power converter system. A damping circuit is configured to be coupled to the bus and to the power generation unit, and a control system is coupled to the converter and to the damping circuit. The control system is configured to selectively discharge at least a portion of the energy stored within the bus through the damping circuit when the control system determines that a predetermined condition is met.

Abstract: Systems, power modules (108), and methods (200) for using in controlling a converter (110) coupled between a power generator (104) and an electric grid (102) are provided. One of the power modules (108) includes the converter (110) configured to supply an output from the power generator (104) to the electric grid (102), and a controller (112) coupled to the converter (110). The controller (112) includes a phase-lock-loop (PLL) module (123) and at least one regulator (128, 130). The at least one regulator (128, 130) is configured to at least partially control the converter (110) as a function of at least one parameter.

Abstract: Methods for operating a wind turbine system are provided. In one embodiment, a method includes adjusting a threshold direct current (DC) bus voltage for a dynamic brake in a wind turbine power converter above a reference DC bus voltage based on at least one system condition. The method further includes gating the dynamic brake on when an experienced DC bus voltage is equal to or greater than the threshold DC bus voltage, and inputting a dynamic brake condition into a controller when the dynamic brake is gated on. The method further includes determining if a grid fault has occurred, reducing power generation of the wind turbine if no grid fault has occurred, and blocking the power converter if a grid fault has occurred. The method further includes gating the dynamic brake off when the experienced DC bus voltage is less than the threshold DC bus voltage.

Abstract: In one aspect, a method for protecting one or more electrical machines during a grid fault on an electrical system connected with the one or more electrical machines is provided. The method includes detecting a grid fault on an electrical system; taking one or more first actions from a first set of actions based on detected grid fault on the electrical system; detecting at least one operating condition of the electrical system after taking one or more first actions from the first set of actions based on the detected grid fault on the electrical system; and taking one or more second actions from a second set of actions based on the detected at least one operating condition of the electrical system.

Abstract: A power conversion system is disclosed including a DC bus for receiving DC power, a power converter for converting the DC power to AC power, and a controller. The controller includes an active power regulator for generating a phase angle command signal, a reactive power regulator for generating a voltage magnitude command, and an active power (P) and reactive power (Q) decoupling unit for decoupling interaction between the active and reactive power regulators. The PQ decoupling unit includes an active power compensation element and a reactive power compensation element. The active power compensation element is used for generating a phase angle compensation signal based on a reactive power error signal, to compensate the phase angle command signal. The reactive power compensation element is used for generating a voltage magnitude compensation signal based on an active power error signal, to compensate the voltage magnitude command signal.

Abstract: In one aspect, a method for protecting one or more electrical machines during an islanding event is provided. The method includes connecting one or more electrical machines to an alternating current (AC) electric power system, wherein the AC electric power system is configured to transmit at least one phase of electrical power to the one or more electrical machines or to receive at least on phase of electrical power from the one or more electrical machines; electrically coupling at least a portion of a control system to at least a portion of the AC electric power system; coupling at least a portion of the control system in electronic data communication with at least a portion of the one or more electrical machines; and detecting an islanding of the one or more electrical machines based on one or more conditions monitored by the control system.

Abstract: The present disclosure discloses a comb polymer or a salt thereof, wherein the structural formula of the comb polymer containing the following constitutional units. When the comb polymer provided in the present disclosure is used in a water-based drilling fluid as a filtration control agent, it can eliminate the defects of conventional filtration control agents which would be subject to ineffectiveness under high temperature and high salinity conditions. The comb polymer has high temperature and salt resistance, and can be produced through simple processes at comparatively low costs. When the comb polymer provided by the present disclosure is used as a filtration control agent, even being added into the drilling fluid at a comparatively low amount, it can still present rather good effects in lowering the amount of filter loss.

Abstract: A power converter system includes a converter configured to be coupled to a power generation unit for receiving current from the power generation unit. A bus is coupled to the converter, and energy is stored within the bus when the current is conducted through the power converter system. A damping circuit is configured to be coupled to the bus and to the power generation unit, and a control system is coupled to the converter and to the damping circuit. The control system is configured to selectively discharge at least a portion of the energy stored within the bus through the damping circuit when the control system determines that a predetermined condition is met.

Abstract: An exemplary power conversion system comprises an MPPT unit, a DC bus, a power converter, and a converter controller. The MPPT unit receives a feedback current signal and a feedback voltage signal from a power source and generates an MPPT reference signal based at least in part on the feedback current and voltage signals. The DC bus receives DC power from the power source. The power converter converts the DC power on the DC bus to AC power. The converter controller receives the MPPT reference signal from the MPPT unit and an output power feedback signal measured at an output of the power converter; generates control signals for AC power regulation and maximum power extraction based at least in part on the MPPT reference signal and the output power feedback signal; and sends the control signals to the power converter.

Abstract: A power conversion system is disclosed including a DC bus for receiving DC power, a power converter for converting the DC power to AC power, and a controller. The controller includes an active power regulator for generating a phase angle command signal, a reactive power regulator for generating a voltage magnitude command, and an active power (P) and reactive power (Q) decoupling unit for decoupling interaction between the active and reactive power regulators. The PQ decoupling unit includes an active power compensation element and a reactive power compensation element. The active power compensation element is used for generating a phase angle compensation signal based on a reactive power error signal, to compensate the phase angle command signal. The reactive power compensation element is used for generating a voltage magnitude compensation signal based on an active power error signal, to compensate the voltage magnitude command signal.

Abstract: Systems, power modules (108), and methods (200) for using in controlling a converter (110) coupled between a power generator (104) and an electric grid (102) are provided. One of the power modules (108) includes the converter (110) configured to supply an output from the power generator (104) to the electric grid (102), and a controller (112) coupled to the converter (110). The controller (112) includes a phase-lock-loop (PLL) module (123) and at least one regulator (128, 130). The at least one regulator (128, 130) is configured to at least partially control the converter (110) as a function of at least one parameter.

Abstract: An exemplary power conversion system is disclosed including a DC bus for receiving DC power; a line side converter electrically coupled to the DC bus for converting the DC power to AC power; and a voltage source controller to provide control signals to enable the line side converter to regulate the AC power. The voltage source controller comprises a signal generator to generate the control signals based at least in part on a power command signal and a power feedback signal. The voltage source controller further comprises a current limiter to, during a transient event, limit the control signals based at least in part on an electrical current threshold. The voltage source controller further comprises a voltage limiter to, during the transient event, limit the control signals based at least in part on a DC bus voltage feedback signal and a DC boundary voltage threshold.

Abstract: Embodiments of the invention relate to a power system for converting direct current (“DC”) power on a DC bus into alternating current (“AC”) power with a regulated voltage output and for feeding the AC power to an electrical system which may include a power utility or an electric grid, for example. A power conversion control system is used for controlling the power conversion and for maintaining the DC bus voltage (“DC voltage”) at a certain level.