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Series of commissioning tests are needed before UHV transmission system putting into operation. In this paper, with the characteristics of Huainan-Shanghai 1000kV transmission system, electromagnetic transient simulation results and experimental data portion commissioning tests were compared and analyzed. Three typical experiments were studied, including the switching capacitor of low-voltage side...
This paper presents a new type of cascaded PWM ac-ac converter with phase-shift PWM control. It can reach high output voltage by cascading single-phase units of low voltage rating devices. The proposed converter does not sense current/voltage polarity, and does not require current/voltage sensors and lossy snubbers for commutation, thereby the control complexity can be decreased. It has no shoot-through...
In this paper, a modulation strategy based on zero-sequence voltage injection is proposed for module multilevel converter (MMC). By the proposed method, the remaining capacitor voltages not vary and the line-to-line voltages are balanced. This method is easy to be implemented by adjusting the voltage injection coefficient when SM fault occurs. The coefficient of injected zero-sequence voltage is designed...
The concept of HVDC taps drawing small amount of power from HVDC lines to the rural places has been considered for several decades. Most of the earlier tap converters were limited by its loss, cost, reliability, and control difficulties. However, in this paper, the emerging modular multilevel converter (MMC) is adopted as the series HVDC tap, which reveals significantly improved performance and feasibility...
A new galvanically isolated DC-DC converter has been presented in this paper. The proposed topology is based on the quasi-switched-boost impedance network. It not only includes all positive characteristics of previous converters including continuous input current, high boost ability and high efficiency, but also has the prominent features of less passive elements utilization, small size and light...
This paper presents high-power-density inverter with pulse current injection power decoupling method. In order to reduce the dc-link capacitor significantly, dc-link current is fully analyzed with double Fourier method in theory. Compared with the traditional 2nd harmonic power decoupling method, the pulse current injection method considers not only 2nd order harmonic but also the higher order harmonics...
A low power switching method for SAR ADC is proposed in this paper. With this switching method the comparator first compares the sampled input voltage with Vref/2 to generate the MSB and determine whether to use Vref/2 or Vref as the comparator reference voltage in the following conversation steps, and the DAC with a split capacitor array uses Vref/2 as the reference voltage to generate the remaining...
The paper aims at various techniques to approximate fractional capacitor using passive elements. The fractional capacitors have been used to implement an astable multivibrator, sinusoidal oscillator, function generator and filters. PSPICE simulation results have been shown for the circuits both with and without using the fractional capacitors. By comparing the simulation results, it can be shown that...
In most substation protection studies, capacitor bank parameters are derived from manufacturer nameplate values. However, the actual parameters could be different from the nominal rating as a result of manufacturing variance, assembling, material aging, and temperature dependencies. Wide manufacturing tolerance could lead to non-negligible calculation inaccuracy that affecting successive studies....
This paper develops an integrated multi-domain simulation tool for distribution systems designed specifically for applications in wind power analysis. The proposed tool consists of steady-state, electromechanical transient, and electromagnetic transient models of voltage sources, transmission lines, transformers, capacitor banks, fixed-speed wind turbines (FSWTs), and wide-slip wind turbines (WSWTs)...
A new high-voltage-tolerant level shifter is proposed and verified in a 0.18-µm CMOS process with 1.8-V/3.3-V devices, whereas the operation voltage can be up to 12V. The output signal of high-voltage-tolerant level shifter has an offset of 3 times the normal supply voltage (VDD) of the used technology with respect to the input signal. The converting speed of level shifter is improved by using the...
A power management control method is proposed for the three-phase-to-single-phase matrix converter (MC)-based solid state transformer (SST) linking two grids. The MC-SST presents low weight and high controllability with respect to a conventional line-frequency transformer. Moreover, the single-stage ac-ac power conversion and compact volume are achieved compared to a three-stage SST, owing to the...
Digital discrete-time implementations of non-Foster circuit elements offer an alternative approach to the design of devices such as negative capacitors and negative inductors. However, practical implementations of high-speed digital non-Foster circuits are affected by latency and noise, where latency can arise from analog-to-digital conversion time and computation time. Thus, the present work explores...
A novel aperture error reduction technique for subrange successive approximation register analog-to-digital converter (SAR ADC) is presented in this paper. By reusing capacitors of flash ADC during fine conversion phase, thermometer coarse capacitors belonging to CDAC can be removed from the circuit. Compared with the conventional subrange SAR ADC without front-end T/H, this technique can minimize...
A novel direct ac-ac converter based on the switched-capacitor and series resonant principle, featuring with soft switching characteristic and bidirectional power flow, is proposed in this paper. The converter consists of a LC resonant tank, switched-capacitors and reverse blocking IGBTs (RB-IGBT), resulting in small size and light weight; high efficiency is achieved by adopting soft switching technology...
In this paper, a new active-only integrator which can be used to realize low frequency filters with small chip area is presented. The circuit can be effectively implemented using transconductance elements and its integration frequency is electronically controllable. In order to illustrate its usefulness, a second-order multifunction filter with low cut-off frequency, yet which occupy a small chip...
This paper presents a comparable study of the locking characteristics of phase-locked loops (PLLs) with an integrating bang-bang phase detector with that of PLLs with an Alexander full-rate bang-bang phase detector. Both periodic and single-event data transients are used to investigate the lock performance of two PLLs with identical configuration and components but different phase detectors. Simulation...
In this paper, a multilevel capacitor clamped buck converter is investigated for AC-AC applications. The proposed topology significantly improves the flexibility of distribution systems in applications such as data centers and residential / industrial power distribution in urban settings. This paper discusses the operation and control of the proposed topology for a load of 50 kVA and 0.9 power factor,...
The paper proposes an original DC-AC inverter that is based on combination of buck converter with standard three-level H-bridge inverter. This inverter uses simple feed-forward control in order to obtain almost sinusoidal output currents and voltages.
Factory acceptance tests performed on High Voltage Direct Current (HVDC) transmission apparatus usually involve the application of high direct voltage and switching impulse voltage in separate withstand tests used to qualify the insulation system. However, the actual stress subjected to the equipment insulation system while in-service on the HVDC transmission system, is a switching surge transient...
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