A Comparative Study on the Efficiency and Economic Performance of Distributed Photovoltaics in Buildings Using Low-Voltage AC and Low-Voltage DC Power Distribution Systems

As the main power supply system of the power supply network, low-voltage AC power distribution system has wide power grid coverage. Considering the safety of electrical equipment and personnel, the AC power system of the power grid is designed as a grounding system. At the same time, the power distribution line is designed with many fault detection and protection measures. The station-use AC system is an indispensable link to ensure the safe and reliable transmission of electric energy in the substation. The station-use electricity is mainly used to provide power for the primary and secondary equipment in the substation. Due to the several important devices in the substation, the power cannot be cut off at will. To ensure continuous power supply, protection measures of distribution lines are slightly weakened to enable continuous power supply. However, although power production improves the power supply quality, power production accidents caused by station-use AC system failures have attracted the attention of power production companies. In this context, this paper analyzes the insulation fault characteristics of station-use AC low-voltage power distribution system, summarizes the fault hazards, studies the methods for insulation fault detection, and proposes the idea of constructing an insulation fault monitoring system for the station-use AC power distribution system.

Low-voltage (LV) and high-voltage (HV) DC distribution systems are being investigated as alternatives due to the growth of DC distribution energy resources (DER), DC loads such as solar and wind power systems, and energy storage sources (ESSs). Furthermore, an HV/LV DC distribution system offers various advantages, including lower conversion losses, an easier connecting strategy for DC DERs, and less complex power management techniques. As renewable energy sources are increasingly incorporated into the electrical grid, it is important to create novel, effective approaches for connecting such sources and loads. It would hence be effective to merge DC distribution with AC distribution to fulfill the energy demands of both DC and AC consumers. To this end, this study proposes a multizone design with four buses: low-voltage direct current (LVDC), high-voltage direct current (HVDC), low-voltage alternating current (LVAC), and an electrical grid. A model of this system that covers crucial elements, including power systems, DER systems, and power electronic devices, to serve as a foundation for the analysis and design of this architecture is proposed. MATLAB/Simulink is used to conduct a simulation study to verify the performance of the proposed design. In this study, a hybrid electrical grid with an LVDC, HVDC, and LVAC distribution network test is used and implemented. Additionally, a transient and steady-state characteristic analysis of the test system is performed.

AC and DC hybrid power distribution has become the development trend of the distribution network. For enhancing the flexible operation capability of the AC and DC hybrid power distribution system, a flexible substation designed as an interface device is proposed in this paper. It consists of high /low voltage AC and DC ports. Except can achieve the voltage transformation and electrical isolation at the same time, it also can realize the power flow control between the grid side and the load side. The topology and basic operation principle of the flexible substation are analyzed. In addition, in order to ensure the effective and stable operation of the entire flexible substation system, the corresponding control strategy is also designed. Finally, the time-domain simulation studies in the MATLAB/SIMULINK software environment are conducted under different conditions. The results confirm the efficiency of the proposed flexible substation and control strategy.

The energy efficiency level of low voltage distribution network is strongly related with the consumption on electricity. With the rapid development of DC distribution power system and the integration of variety kinds of distributed resources, the quantitative evaluation and comparison of low voltage AC and DC distribution power system energy efficiency level is of great significance. However, there lacks the evaluation indices of energy efficiency for DC power distribution system, as well as the comparison of energy efficiency level between AC and DC system. According to the difference of topology structure of AC/DC distribution system, the energy efficiency evaluation indices and method is proposed. The power loss is mainly divided into line loss and device loss. The power loss and transmission efficiency of AC/DC distribution system are calculated by combining the load type and the characteristics of power electronic devices. By decomposes the loss and compares the loss composition and time sequence characteristics of AC and DC distribution system, the weak links affecting the efficiency of distribution system are explored. Furthermore, with the gradual increase of renewable energy access ratio and DC load ratio, the overall transmission efficiency of the AC/DC distribution network presents an upward trend within a certain range, indicating that the increase of dc components will be conducive to the improvement of distribution network efficiency to some extent.

This paper presents a multiobjective optimization technique for the submarine cables of high-power remotely operated vehicles (ROVs). A detailed design flowchart with integrated electrical and mechanical designs of the ROV submarine cables is provided to quantitatively compare AC and DC-based power distribution systems and identify the optimal design from multiple standpoints, prioritizing electrical loss and cable weight. The electromechanical cable design optimization plays a vital role in the ROV industry and in all those applications where the power distribution system is employed vertically from the support platform/vessel. The entire procedure is exemplified by carrying out a particular case study; for an ROV power hub with rated power of 5 MW and operational depth of 6000 m, the DC submarine cable design with distribution voltage of 33 kV results in an electrical loss reduction of 54.3% compared to the AC submarine cable design with distribution voltage of 22 kV at similar cable weights of 63 ton. Additionally, the proposed method can be widely applied to any type of AC-DC comparison to achieve the optimal ROV submarine cable design with a considerably short process time in comparison to the approaches with finite element analysis.

The recent emergence of power electronics equipment raises the possibility of implementation of DC shipboard electrical distribution systems. Several investigations on the effectiveness of DC shipboard electrical power distribution systems have proven that it is more profitable than AC distribution systems both in technical and economical aspect. However, known investigations are still limited to the system in ship with electric propulsion, which the consumption of electric power is enormous. The current study investigates the technical performance of both distribution systems in a non-electric propulsion ship, especially in the aspect of power losses. Both of the original AC distribution systems in a 17,500 DWT tanker ship and its equal DC distribution systems are modelled in a computer simulation program. The electric power flow simulation for both models are performed with the data of electric load during operating conditions, to compare the power losses in the distribution systems. The results show that the DC distribution systems has fewer drop voltage than its AC counterpart.

This manuscript presents the investigations on three different types of low voltage AC (LVAC) power distribution architectures of diesel-electric propulsion system for diving support vessel (DSV). It focuses on the qualitative analysis of three LVAC power distribution architectures employing: (1) the conventional 12-pulse converter and (2) active front end (AFE) converter and (3) the proposed 6-pulse converter with shunt active filter (SAF). The reliability evaluation of all the three power architectures has been performed to confirm the viability of the proposed architecture. Further a qualitative analysis of all the three different power architectures has also been furnished.

Efficiency is the factor that once wiped DC out of the power system at the birth of electricity, in nineteenth century. The battle of currents between AC and DC has reignited with the aggravating employment of DC in the sectors of generation, transmission, and utilization. This calls for cutting edge research in the field of comparative efficiency analysis of AC and DC, on distribution scale. The current research effort compares AC and DC distribution systems on efficiency grounds, for various topologies. The two systems are compared employing normal distribution technique for residential load profile. The varying efficiency of power electronic converters (PECs) with stochastic load profiles is modeled using MATLAB/SIMULINK, for each topology. DC takes the lead against AC with efficiency advantage for energy efficient load-based architectures. The architectures with variable speed drive-based loads, the efficiency advantage in favor of DC is between 1% and 2%, however, the efficiency advantage reaches to 12% with inherent DC loads. In contrast, AC takes the lead with conventional distribution, with an efficiency advantage between 4% and 5%. The findings of current research work can prove to be beneficial in making policy decisions for the adoption of DC at distribution scale.

We presently enjoy a predominantly AC electrical distribution system, the engineering basis for which was designed over 100 years ago. While AC distribution systems have served us well, we should periodically pause to assess what opportunities we have accepted or been denied by the overwhelming predominance of AC electrical power distribution systems. What opportunities could be obtained by engineering DC distribution into at least portions of our present system? What advantages of the present AC distribution system should be recognized and protected? This paper will focus on distribution within premise and low-voltage distribution systems. Specifically, we will address the conversion efficiency costs of adopting various premise AC and DC distribution system topologies. According to a simple predictive model formulated in this paper, premise residential DC distribution will incur unfavorable total conversion efficiency compared with existing AC premise distribution. However, if a residence is supplied by a fuel cell or another DC generator, the total conversion efficiency within a residential DC distribution system could be similar to, or even better than, that for AC distribution.

This paper describes the power flow control of a triple active bridge (TAB) DC-DC converter for a DC power distribution system. The proposed phase shift control utilized in power distribution is based on varying the phase shift angle among three ports of the converter. First the simulation system is a prototype 200-V TAB converter with double loads for low-voltage DC power distribution systems using the closed-loop phase shift control. In the experiment, an open-loop TAB converter rated at 500 W power was constructed and tested with double loads, using a three-winding transformer and Gallium Nitride (GaN) power devices. The smooth output waveforms indicate the good controllability of the power flow as well as functional performance in the low-voltage DC power distribution system.

Electrical energy is the most efficient and the cleanest form of energy at the moment that is being transmitted and distributed amongst end-users. From its earlier days, the AC system was preferred as an economical solution for transmission and distribution. However, the development in the power electronics technology and the evolution of highly efficient power electronic converters have established the resurgence of DC power system. Furthermore, the trend is shifting towards DC loads as various energy efficient appliances, such as DC inverter air conditioners, operate on DC nowadays. This further advocates the shift towards the DC power system. This research works is an effort to perform the comparative analysis of AC Distribution System (ACDS) and DC Distribution System (DCDS), with regards to power quality and harmonic distortion in particular. The comparison is performed considering load profile and load variation on daily basis. Simulations are performed in MATLAB. It has been concluded at the end that ACDS is better than DCDS in terms of power quality as total harmonic distortion of the DCDS under the same loading and same load variation during the whole day was significantly higher than that of ACDS.

Development of protective schemes for hybrid AC/DC low-voltage distribution system

In a low-voltage power distribution system, there are often disturbances that result in disruption of electricity distribution to customers, resulting in losses for customers and PLN. The problem that often occurs is the occurrence of voltage drops and power losses so that in planning the construction of a low-voltage electric power distribution network, it is necessary to anticipate the occurrence of these problems. This research is expected to be used as a lesson for the creation of a low-voltage electric power distribution network with suitable and environmentally friendly construction and with low investment costs. collected data by visiting the location to conduct a survey and obtain accurate data related to the state of the research location. The stages in planning the Low Voltage Electricity Distribution Network begin with a field survey to obtain the required data. The installed power for each unit is 1.300 VA, so the total installed power is 122,200 VA and the spare power is 5% of the installed power so that the total installed power is 128.310 VA. during peak load times it is estimated that power consumption will only absorb 80% or 97,760VA. The required substation is a Portal Type Pole with a transformator capacity is 160kVA. The total breakdown of the electricity distribution network budget at the Griya Arjuna Kejuden is IDR 382,333,141.

Data centers are multipurpose internet based centers which needs to perform different tasks without any perturbation of electric power. It is a very fast growing structures with significant contribution to the world’s energy consumption. For this paper, Bahirdar University data center is selected for reliability and efficiency evaluation of both AC and DC distribution system architecture. The study is based on the existing AC power distribution layout of the selected case area which gets supply from Ethiopian electric utility (EEU) with a nearby diesel generator as a backup power supply system in a case of power outage from the utility system as well as the proposed data center power distribution model with an off grid solar powered 380 V DC distribution system. Results show that an AC distribution system has an average efficiency of 72.96% while a proposed DC distribution system has an average efficiency of 82.63%. This demonstrated that a DC power distribution system is 9.67% efficient than AC power distribution architecture. The simulation analysis was done in MATLAB. KeywordsData centerDC distributionEfficiency analysis

The low-voltage multi-terminal DC power distribution system is an important form of distribution network in the future. However, the negative impedance characteristic of devices such as constant power load (CPL) will reduce the stability boundary of the whole system. In this paper, the analytical solution of the stable boundary of the low-voltage multi-terminal DC power distribution system is obtained by using the mixed potential function. Furthermore, an intelligent autonomous control method based on Lyapunov theory is proposed, and the feedback law and trigger time for each terminal are designed. Finally, the proposed method is tested and verified, and the results show that it can maintain the stable DC voltages when the system is subjected to large disturbances, and overstep the power limitation of the stable boundary only by local information.