<title>Abstract</title> The strength of magnetic field modulation effect coaxial gears is a key factor to measure the transmission performance gears. Although dual with double modulating rings can effectively enhance effect, there are still problems low torque density and serious leakage loss. In order address above problems, this paper proposes three-rotor single-regulating ring dual-modulated gear that simultaneously adopts “sum effect” “differential effect”, analyzes its working principle...

Against to the problems of low utilization rate DC-side voltage Cascaded H-bridge (CHB) multi-level inverter Carrier Disposition (CD) modulation strategy and unbalanced output power each cascaded units, a balanced based In-Phase Trapezoidal Pulse Width Modulation (IPD-TPWM) is proposed in this article. By selecting an appropriate trapezoidal wave triangulation δ, can greatly increase amplitude CHB fundamental while ensuring waveform quality phase voltage, realize power-balance units within...

Abstract A virtual water flow meter is developed that uses the chilled control valve on an air-handling unit as a measurement device. The rate of through calculated using differential pressure (DP) across and its associated coil, command, empirically determined characteristic curve. Thus, uncertainty in measurements could be significantly greater than for conventional hardware meters. In this article, mathematical models are used to conduct analyses meter, results from compared made with...

Compared with the traditional cascaded H-bridge multi-level inverters, hybrid inverters have been receiving attention because they can generate more levels same number of power cells. However, general pulse width modulation (PWM), output distribution between high-voltage and low-voltage cells is extremely uneven in low amplitude modulation, it may appear that cell feeds into some ratio intervals causing capacitor voltage boost. To avoid this problem, a method modified PWM strategy balance...

This article proposes an innovative DC line protection utilizing current correlation coefficient for hybrid cascaded high-voltage direct-current (HVDC) system. First, the equivalent discharge circuit after fault is inferred, and then characteristic analysis on superimposed network reveals that transmission lines connecting commutated converter (LCC) modular multilevel converters (MMCs), high-frequency currents of faulty non-fault are negatively correlated, their theoretically −1. Whereas,...

High penetration rates of renewable energy will bring stability problems for the future power grid. One critical issues is lack inertia. In this paper, a synchronous motor-generator pair (MGP) system proposed as possible solution integration to enhance inertia and improve grid stability. First, feasibility studies MGP on inertia, damping, efficiency, cost are presented. Second, an analytical model established based its rotor angle relation. An active control scheme voltage phase difference...

Large yellow croaker (Pseudosciaena crocea) is the main coastal economic fish in China. After harvesting, rarely traded as fresh product, but usually held cold storage. Therefore, it important to understand quality changes occurring during preservation. In this study, freshly collected fishes were frozen by cryogenic (cabinet liquid nitrogen freezer at -40, -60 and -80 °C) forced convection (ultra-low temperature -40 freezing stored -18 °C for 6 months. Drip loss, relative moisture loss...

On August 9, 2019, a blackout event with significant impacts occurred in the British power grid (BPG). The technical report submitted by BPG points out that accident originated from multiple independent and concurrent events, resulting sudden shortage, which exceeded fortification requirements of relevant standards. This incident has led us to reflect on some bottlenecks exist high-proportion renewable energy system, such as frequency oscillations, security defense large grid,...

This paper proposes a novel pilot protection scheme for LCC-HVDC transmission lines based on the measured surge impedance at tuning frequency. On basis of amplitude-frequency characteristic DC filter, it is found that voltage forward traveling wave and reverse frequency approximately satisfy total reflection line boundary after internal fault. Then, combined with propagating processes faults external faults, two terminals line, impedances are both close to 0 Ω, whereas near faulty terminal...

Abstract The virtual flow meter introduced in this article is developed by calculating water rates through two measurable inputs (differential pressure measurements and pump speed measurements) a calibrated curve. However, due to the fact that are achieved indirect calculations based on multiple input variable measurements, possibility of error significantly increased compared with direct measurements. This first introduces mechanism analyzes typical errors can result incorrect readings,...

With the occurrence of major blackouts in "Australia 9·28" and "U.K. 8·9," technical bottlenecks power generation system with a high proportion renewable energy have attracted more attention. Based on this background, article studies control method that is suitable for AC microgrid strong current-limiting ability. First, outer loop controller adopts power-state equation based PI to achieve accurate tracking reference power. Furthermore, order make fault current having lower asymmetry degree...

In this paper, a novel low voltage ride-through (LVRT) technique for three-phase grid-connected inverters is proposed. The proposed consists of two parts: nonlinear phase locked loop based on complex-coefficient filters (NLCCF-PLL) and an LVRT control scheme. Generally, the synchronization process performed via PLL with relatively bandwidth, which delays detection sag recovery during process. To accelerate process, NLCCF-PLL adaptive controller gains to improve both filtering capability...

Photovoltaic power generation system (PV system) is a device which changes the solar into electricity by cells and principle of use semiconductor materials electronics characteristics P-V conversion. PV its application profound research project, facing 21st century, gathers utilization green renewable energy, improve ecological environment, ameliorate people's living conditions as integral whole will be great benefits to economy, politics, coupled with society, also contains rich academic...

While automated fault detection and diagnosis (AFDD) in residential heating, ventilation, air-conditioning (HVAC) using smart thermostat data is gaining increasing attention recent times, it still requires in-depth investigation for market adoption, especially with real-life data. This paper proposes an Internet of Things (IoT) - based approach that adds a sensor to the carry out AFDD. The uses model which predicts enthalpy change across evaporator compares prediction measured change....

Offsets between the primary and secondary coils of loosely coupled transformers (LCT) are attributable to efficiency decline wireless power transfer (WPT) system. To improve misalignment tolerance in WPT system, this paper presents a LCT system with movable intermediate coil adjustable frequency, which can promote under condition. First, influences position compensation parameter on during migration summarized. The optimal selection method proposed. Then, influence frequency is studied,...

Currently there is no reliable and accurate method available for building pressure control due to the difficulties of airflow measurement. Recently, a fan station was developed that measures using head, speed, curve. Both speed head can be measured accurately existing sensors transducers. Therefore, accuracy depends on An experimental has been determine in situ curve without interrupting normal system operations. This paper presents theoretical background, methodology, implementation...