TECHNOVATIONS OF ELECTRICAL ENGINEERING IN GREEN ENERGY SYSTEM
Year:2026 | Volume:5 | Issue:2|Papers Count:6

Considering the huge amount of transmitted power in high voltage direct current networks, protection of these networks against internal and external faults of the network is of particular importance. For the correct operation of protection equipment and prevention of DC pole block in AC faults, first the internal fault must be distinguished from the external fault of the network and then, according to the position of the fault, the appropriate protective function should be applied. Also, to increase reliability, backup protection is essential when the primary protection fails. In this paper, the current symmetrical components inside the converters are analyzed under various fault conditions in a high voltage direct current network and according to that, a new protection method is proposed, which can discriminate the internal fault from the external fault in the network by checking the negative component of the fault current on the rectifier or inverter side and comparing of the average value of the negative and zero components of the fault current. This single-ended method with low sampling rate doesn’t need a communication line and along with differential protection can increase the reliability and speed of the backup protection system. The data of this paper are obtained by simulating a bipolar high voltage direct current transmission system with 12-pulse current source converter in PSCAD software based on the frequency-dependent line model. The simulation results confirm the effectiveness of the proposed method.

This study introduces a novel system for energy exchange management in a two-layer network of microgrids. In this framework, the first layer facilitates energy exchange among multiple microgrids, while the second layer enables energy sharing among users within each microgrid. The proposed model employs a multi-objective optimization framework based on the Hiking Optimization Algorithm and ensures transaction security and transparency using a multi-blockchain architecture. Simulation results, utilizing real-world data from five microgrids in Guizhou Province, China, reveal significant performance improvements compared to traditional methods. Specifically, the average utility values of users increased from 17.3 to 31.4 (a 96.2% improvement), while those of microgrid operators rose from 28.2 to 38.98 (a 34.58% enhancement). Moreover, the average energy transaction price dropped by up to 45% with increased distributed energy resources. These findings demonstrate the superior performance of the proposed HOA and blockchain-based method in competitive scenarios, offering greater flexibility in pricing and energy distribution. This work establishes an effective approach to sustainable energy management.

In modern power distribution networks, traditional methods of allocating losses among participants are becoming inadequate due to the rise of distributed generation and the need for fair loss allocation. This paper investigates the τ-value method for allocating losses resulting from the connection of new consumers and producers in radial and weakly meshed networks. The results show that this method, with its low computational volume and high efficiency, is a suitable tool for loss allocation in restructured networks. It was also found that placing consumers in weakly meshed networks and producers in radial networks is economically and technically preferable. However, the τ-value method imposes stricter loss allocation on consumers, which is due to the initial allocation of losses among consumers. Despite this limitation, this method can be used as an efficient tool in competitive electricity markets. This study demonstrates that the network structure has a significant impact on how losses are allocated, and that the appropriate placement of producers and consumers can lead to reduced losses and improved network efficiency. Furthermore, the use of game theory-based methods such as the τ-value can contribute to fairer loss allocation and create healthy competition in the electricity market.

This paper presents a novel algorithm for load control of a hydraulic turbine connected to an infinite bus with transient droop compensator. The proposed method utilizes PID control and a hybrid particle swarm optimization algorithm. The considered PID controller can tolerate a wide range of variations in system parameters and stabilize the system without significant overshoots and oscillations. The optimized PID controller has lower overshoot and settling time compared to the non-optimized PID controller. The PID controller also reduces ripple and fluctuations in output power, making it a valuable tool for frequency and power control of hydraulic turbine systems. Overall, the results show that the optimized PID controller can effectively control the frequency and power of hydraulic turbine systems, but in some cases, more advanced control methods may be required. The network under study is modeled in the Simulink environment of MATLAB software. The results obtained from the implementation of various scenarios confirm the correct performance of the proposed algorithm. The optimized PID controller can tolerate a wider range of variations in system parameters. While the non-optimized PID controller may operate without overshoot at Tw=3 (hydraulic turbine time constant), the optimized controller stabilizes the system without overshoot up to Tw=5.

In recent years, peer to peer energy trading have become an important component of local and decentralized electricity markets. One of the remarkable challenges in implementing these trades between users is keeping the technical constraints of distribution networks within the permitted limits and utilizing the maximum capacity of prosumers during energy transactions. Usually, power demand at points in the grid that do not have generations varies over time, which makes it very difficult for prosumers to determine their operating range. In this paper, a structure based on dynamic operation envelopes is presented to dynamically calculate network constraints, which, in addition to maintaining the technical constraints of the network within the permitted range, allows the maximum use of the capacity of prosumers to participate in the market. The proposed structure is presented for P2P trades of energy communities consisting of solar and wind generation, fixed and flexible loads, and batteries in an active distribution network. Also, in this structure, dynamic operation envelopes are calculated from the agreement between the energy communities and the distribution system operator. The proposed method has been implemented on standard IEEE 33 bus system with the presence of several energy communities. The optimization of the equations is performed using the alternating direction method of multipliers (ADMM) and is completely decentralized. The simulations in this paper are accomplished using GAMS software version 24. 8. 1., and the obtained results show that the presented method increases the trades of energy communities and maintains the technical constraints of the network within the safe range.

Non-isolated step-up converters have wide applications such as photovoltaics, fuel cells, hybrid vehicle, etc. In many applications, it is very important to stabilize the output voltage despite changes in load or input voltage, so a suitable control circuit for the converter should be designed so that its dynamic response to load changes is fast. To reduce losses and increase efficiency, soft switching techniques are also provided. In this paper, a new high boost converter with an innovative sliding mode control circuit is presented. The converter has high voltage gain, low stress and zero current switching. Also, the energy of the leakage inductor is well absorbed by the clamp capacitor and the voltage spike at both ends of the switch is not observed. All diodes are switched at zero current, so they don't have reverse recovery problem. The converter has been fully analyzed and a 130 W sample has been simulated and built to confirm the circuit analysis.