Mingda Jiang¹, Yanbo Che¹, Hongfeng Li^1,*, Muhammad Ishaq¹, Chao Xing^1,2

Energy Engineering, Vol.119, No.2, pp. 699-721, 2022, DOI:10.32604/ee.2022.017556

Abstract The full-bridge converters usually use transformer leakage inductance and parallel resonant capacitors to achieve smooth current commutation and soft switching functions, which can easily cause problems such as energy leakage and significant duty cycle loss. This paper designs a novel full-bridge zero-current (FB-ZCS) converter with series resonant capacitors and proposes a frequency and phase-shift synthesis modulation (FPSSM) control strategy based on this topology. Compared with the traditional parallel resonant capacitor circuit, the passive components used are significantly reduced, the structure is simple, and there is only a slight energy loss. By controlling the charging time of the capacitor, it can… More >

Jianfeng Yang^*, Rende Qi^*, Yang Liu, Yu Ding

Energy Engineering, Vol.119, No.2, pp. 609-620, 2022, DOI:10.32604/ee.2022.016969

Abstract In order to minimize the harmonic distortion rate of the current at the common coupling point, this paper proposes a coordinated allocation strategy of harmonic compensation capacity considering the performance of active power filters (APF). On the premise of proportional distribution of harmonic compensation capacity, the harmonic compensation rate of each APF is considered, and the harmonic current value of each APF to be compensated is obtained. At the same time, the communication topology is introduced. Each APF takes into account the compensation ability of other APFs. Finally, three APFs with different capacity and performance are configured at the harmonic… More >

Lei Huang^*, Qian Zhang, Wenlei Liu, Ruixue Liu

Energy Engineering, Vol.119, No.2, pp. 621-636, 2022, DOI:10.32604/ee.2022.016769

Abstract Due to the low impedance characteristic of the high voltage direct current (HVDC) grid, the fault current rises extremely fast after a DC-side fault occurs, and this phenomenon seriously endangers the safety of the HVDC grid. In order to suppress the rising speed of the fault current and reduce the current interruption requirements of the main breaker (MB), a fault current limiting hybrid DC circuit breaker (FCL-HCB) has been proposed in this paper, and it has the capability of bidirectional fault current limiting and fault current interruption. After the occurrence of the overcurrent in the HVDC grid, the current limiting… More >

Zhihao Zheng¹, Yanbo Che^1,*, Hailian Bi¹, Dan Wu¹, Wei He²

Energy Engineering, Vol.119, No.2, pp. 637-651, 2022, DOI:10.32604/ee.2022.016661

Abstract With the implementation of electric energy alternatives, the large-scale application of electric energy substitution represented by air-source heat pumps has replaced traditional coal-fired heating, which is beneficial for the environment and alleviates air pollution. However, the large-scale application of air-source heat pumps has brought power quality problems such as voltage sags, harmonic pollution, and three-phase imbalance to the distribution network. This paper studies the fixed-frequency and variable-frequency air-source heat pump, introduces its working principle, analyzes the mechanism of its power quality problem. Moreover, the paper establishes a simulation model for the fixed-frequency heat pump and variable-frequency heat pump to connect… More >

Min Liu^*

Energy Engineering, Vol.119, No.2, pp. 781-800, 2022, DOI:10.32604/ee.2022.016657

Abstract With the application of phasor measurement units (PMU) in the distribution system, it is expected that the performance of the distribution system state estimation can be improved obviously with the PMU measurements into consideration. How to appropriately place the PMUs in the distribution is therefore become an important issue due to the economical consideration. According to the concept of efficient frontier, a value-at-risk based approach is proposed to make optimal placement of PMU taking account of the uncertainty of measure errors, statistical characteristics of the pseudo measurements, and reliability of the measurement instrument. The reasonability and feasibility of the proposed… More >

Mingwan Mei¹, Ping Wang¹, Yanbo Che^1,*, Zihan Lv¹, Zmarrak Wali Khanand¹, Chao Xing^1,2

Energy Engineering, Vol.119, No.2, pp. 591-607, 2022, DOI:10.32604/ee.2022.016585

Abstract

In the medium voltage direct current (MVDC) transmission system, a small number of MMC sub modules will reduce the power quality. In this paper, based on the research background of Photovoltaic Medium Voltage Direct Current (PV-MVDC) system, a Hybrid Modulation Strategy based on the Decoupled Double Synchronous Reference Frame (DDSRF) control strategy is proposed. The dual arm complementary hybrid modulation combining nearest-level-SPWM (NL-SPWM) can keep the number of SMs in the ON state constant. Then, the corresponding voltage sharing control algorithm of sub module (SM) is introduced. Through theoretical calculation, the modulation strategy can be found to stabilize the DC… More >

Junaid Khan, Rashid Ali, Muzammil Zubair, Syed Mohd Yahya^*

Energy Engineering, Vol.119, No.2, pp. 827-846, 2022, DOI:10.32604/ee.2022.016344

Abstract Cooling the PV surface in a Photovoltaic Thermal system is a pivotal operational aspect to be taken into account to achieve optimized values of performance parameters in a Photovoltaic Thermal System. The experimental design used in this study facilitates the flow of varying concentrations of Zn-water nanofluid in serpentine copper tubing installed at the rear of the PV panel thereby preventing the PV surface temperature from increasing beyond the threshold value at which a decrease in electrical efficiency starts to occur. This fusion of solar thermal with PV devices leads to better electrical and thermal efficiency values resulting in decreased… More >

Bin Yang^1,*, Xingchen Zhu¹, Jie Deng¹, Xiaoxu Guo¹, Jinke Han², Xiaowei Liu²

Energy Engineering, Vol.119, No.2, pp. 511-522, 2022, DOI:10.32604/ee.2022.016079

Abstract Aiming at the problem of soot concentration measurement under ultra-low emission conditions, a forward small angle soot concentration measurement method is proposed. Taking a typical boiler emission of 0.1 μm–3.0 μm bimodal distribution soot as an object, the particle scatter simulation calculation under different parameters is carried out, and the influence of detection angle and particle size on the angular scattering measurement of ultra-low emission soot is analyzed. The influence of detection angle and particle size on the angular scattering measurement of ultra-low emission soot is analyzed. Preferably, the wavelength of incident light is 650 nm, and the forward detection… More >

Xueqin Tian¹, Jinfei Sun², Tong Xu¹, Mengran Cui², Xinlei Wang¹, Jianxiang Guo², De-gejirifu^1,*, Na Wang¹

Energy Engineering, Vol.119, No.2, pp. 723-737, 2022, DOI:10.32604/ee.2022.015982

Abstract Although the Combined Cooing, Heating and Power System (hereinafter referred to as “CCHP”) improves the capacity utilization rate and energy utilization efficiency, single use of CCHP system cannot realize dynamic matching between supply and demand loads due to the unbalance features of the user’s cooling and heating loads. On the basis of user convenience and wide applicability of clean air energy, this paper tries to put forward a coupled CCHP system with combustion gas turbine and ASHP ordered power by heat, analyze trends of such parameters as gas consumption and power consumption of heat pump in line with adjustment of… More >

Hongchun Shu^1,2, Yaqi Deng^1,2,*, Pulin Cao², Jun Dong², Hongjiang Rao², Zhiqian Bo²

Energy Engineering, Vol.119, No.2, pp. 523-538, 2022, DOI:10.32604/ee.2022.015570

Abstract The arc-suppression coil (ASC) in parallel low resistance (LR) multi-mode grounding is adopted in the mountain wind farm to cope with the phenomenon that is misoperation or refusal of zero-sequence protection in LR grounding wind farm. If the fault disappears before LR is put into the system, it is judged as an instantaneous fault; while the fault does not disappear after LR is put into the system, it is judged as a permanent fault; the single-phase grounding fault (SLG) protection criterion based on zero-sequence power variation is proposed to identify the instantaneous-permanent fault. Firstly, the distribution characteristic of zero-sequence voltage… More >