摘要:
The present disclosure relates to power system sensitivities as computed from power flow parameters and control parameters of a Power Flow Control Device (PFC). To this end, control parameter variations are applied to or generated by a PFC, and comprise variations in a control input u, a control effort e (injected series voltage, inserted series reactance), or a control effect q (power flow, active power transfer, phase-shift, current). A power flow response measuring unit measures a variation of a power flow response such as current, active or apparent power, in a way sufficiently synchronized with the control parameter variation to allow establishing an unambiguous causal relationship or correspondence in the form of a power system sensitivity. The latter may be on-line adapted to continuously reflect an updated aspect of the power system behaviour, and thus enable an improved, fast and reliable power flow control in power systems comprising a meshed power network with two parallel flow paths or corridors connecting two areas or sub-systems.
摘要:
A sample preparation method for characterization of nanoparticles embedded in the supports of heterogeneous catalysts, with improved particle dispersion, is introduced. The supported catalyst is first ground or milled into fine powder. Then, the powder is mixed into an organic solvent, and an etchant is added to the solvent to digest the supports and release metallic nanoparticles. The resulting solution is then placed in an ultrasonic bath where ultrasonic waves are generated and applied to the solution. The ultrasonic waves suppress agglomeration of the particles and also break up those particle clusters resulting from agglomeration during the prior steps. Subsequently, a sample is extracted from the solution and prepared for analysis.
摘要:
A telescopic fork leg incorporates mutually displaceable inner and outer tube parts and a damping arrangement for damping the relative movements of the tube parts. The damping arrangement comprises tubular and coaxially disposed units. A piston belonging to a first outer tube part operates in a chamber within the interior of the tubular units in a medium present in the chamber, which medium, at a piston speed above a chosen value, is transferred between the top and bottom sides of the piston via passage(s) disposed in, on or by the piston and adjustable damping-influencing members. The passage(s) is/are closed by the damping-influencing member(s) at piston speeds below the chosen value and the medium is conducted only via one or more leak flow paths extending from the chamber on one side of the piston, via a gap between the outside of the inner tubular unit and within a second tubular unit disposed outside the inner unit, one or more leak-flow-size-determining members, and back to the chamber on the other side of the piston. Independently adustable compression and the return leak flows can be easily arranged around the piston and an important component in the leg can provide a strength function and a leak-flow-conducting function.
摘要:
In a method, computer program and system for determining an operational limit of a power transmission line, time-stamped current phasor information and voltage phasor information for a first end and a second end of the line are determined, an ohmic resistance of the line is computed from the phasor information, and an average line temperature is computed from the ohmic resistance. This allows to determine the average line temperature without dedicated temperature sensors. The average line temperature represents the actual average temperature and is largely independent of assumptions regarding line parameters.
摘要:
The invention concerns an improved segregation-resistant and dust-resistant metallurgical composition for making compacted parts, comprising at least about 80 percent by weight of an iron or iron-based powder; at least one alloying powder; and (c) about 0.05 to about 2 percent by weight of a binding/lubricating combination of polyethylene wax and ethylene bis-stearamide, the polyethylene wax having a weight average molecular weight below about 1000 and a melting point below that of ethylene bis-stearamide, and being present in amount between 10 and 90% by weight of the binding/lubricating combination.
摘要:
Inductor core including: a base core portion having a first surface and an opposite second surface; an inner core portion extending from the first surface in a direction transverse to the first surface; an outer core portion extending, in the direction transverse to the first surface, from the first surface to an end surface of the outer core portion, the outer core portion at least partly surrounding the inner core portion, thereby forming a space around the inner core portion for accommodating a winding; wherein the first surface includes a recess for accommodating a connection portion of the winding, said recess extending at least a part of a distance between the inner core portion and the outer core portion, and wherein the outer core portion presents a slit extending from said end surface towards the recess, and wherein the second surface comprises a first protrusion oppositely arranged to the recess.
摘要:
The invention relates to a method for determining angle of incidence for a projectile in the path of the projectile from launcher to target, which projectile is guidable and substantially or partially roll-stable and comprises a control system and at least two actuators with associated control members, in which the following steps are included: determination of applied force for pitch control by evaluation of the moment upon the actuators of the projectile, determination of applied force for yaw control by evaluation of the moment upon the actuators of the projectile, calculation of the pitch component α of the angle of incidence and of the yaw component β of the angle of incidence, based on comparison between the evaluated moments and reference data for moments. The invention also relates to a GNC system.
摘要:
Time synchronization of two clocks is disclosed herein, such as two stationary clocks. A global time signal from a global time reference or common time source can be used to calculate a common view based clock offset between the two clocks. In parallel, a network based clock offset between the two clocks can be calculated based on messages exchanged over a communication network interconnecting the two clocks, without reverting to the global time reference. Two recent values (e.g., the two most recent values) of the common view clock offset and the network based clock offset can be combined or superposed in a seamless way to produce a final time offset estimate. The combination of independently calculated common view and network based clock offsets can be a weighted average of the two values, involving respective weights based on quality estimates of the latter. The time synchronization schemes based on a Global Positioning System (GPS) and a wide area communication network can be combined to synchronize the stationary clocks of phasor measurement units (PMUs) of a wide area monitoring system to a central server clock at a Network Control Center (NCC) of the system.
摘要:
Exemplary embodiments of the present disclosure provide a method and controller for damping multimode electromagnetic oscillations in electric power systems which interconnect a plurality of generators and consumers. The controller for damping such oscillations includes a phasor measurement unit (PMU) and a power oscillation damper (POD) controller. Each oscillating mode signal is damped and then superposed to derive a control signal. A feedback controller is used to feedback the control signal to a power flow control device in the power system.
摘要:
A relationship between a temperature TI of a power line or power transmission conductor, an electrical quantity of the power line such as a current I or power flow P through the power line, as well as meteorological quantities or ambient conditions of the power line such as wind speed W, wind direction, humidity, solar radiation S and ambient temperature Ta, is established in the form of a thermal model of the power line. Values of the aforementioned quantities or variables are continuously measured, and the collected values of the quantities are evaluated in order to update model parameters of the thermal model during operation of the power line. In one example, an average temperature representative of the entire line is determined via two Phasor Measurement Units (PMU) 11, 11′ providing synchronized phasor values from two ends of the power line. An ohmic resistance of the power line is computed from the phasor values, from which in turn the average line temperature can be derived.