The installed capacity of distributed generation (DG) based on renewable energy sources has increased continuously in power systems, and its market-oriented transaction is imperative. However, traditional transaction management based on centralized organizations has many disadvantages, such as high operation cost, low transparency, and potential risk of transaction data modification. Therefore, a decentralized electricity transaction mode for microgrids is proposed in this study based on blockchain and continuous double auction (CDA) mechanism. A buyer and seller initially complete the transaction matching in the CDA market. In view of the frequent price fluctuation in the CDA market, an adaptive aggressiveness strategy is used to adjust the quotation timely according to market changes. DG and consumer exchange digital certificate of power and expenditure on the blockchain system and the interests of consumers are then guaranteed by multi-signature when DG cannot generate power due to failure or other reasons. The digital certification of electricity assets is replaced by the sequence number with specific tags in the transaction script, and the size of digital certification can be adjusted according to transaction energy quantity. Finally, the feasibility of market mechanism through specific microgrid case and settlement process is also provided.

Soft open points (SOPs) can transfer active power between feeders and compensate reactive power. These features help increase the integration capacity of distributed generation (DG), but the installation location and capacity of SOPs will affect DG planning. In addition, the distribution networks are usually unbalanced due to asymmetric line parameters, unbalanced loads, and DG. Converter-based DG units and SOPs have individual phase active and reactive power regulating ability and provide unbalance compensation. The objective of this paper is to develop a coordinated planning model of converter-based DG units and SOPs in an unbalanced distribution network (UDN) to incorporate their individual phase power control abilities. The individual phase power control characteristics of DG converters and SOPs are first analyzed. A bi-level optimization model of converter-based DG units and SOP planning is then established, in which the upper-level problem minimizes the total cost of the UDN and the lower-level problem minimizes the power loss and voltage unbalance. The bi-level model is transformed into a single-level mixed integer second-order cone programming problem that can be efficiently solved by widely used commercial solvers. Finally, the proposed model is verified on IEEE 33-node and Taiwan Power Company systems.

This paper proposes an electric load demand model of the 5th generation (5G) base station (BS) in a distribution system based on data flow analysis. First, the electric load model of a 5G BS is developed according to its components and their characteristics. Second, critical factors of the power consumption of 5G BS, including area, data flow with uncertainty number of activated terminals and data usage of the terminal, are discussed. A statistical model of the number of activated terminals and data usage of the terminal are established using a probability distribution, and Monte Carlo sampling is used to handle the uncertainties. Then, the model is extended for multiple terminal connections. A case study is conducted to analyze the impact of the critical factors on the load of 5G BS and the influence of 5G BSs load on the other loads in three typical areas. Numerical results demonstrate that the proposed model is effective and can be employed as an accurate representation of the 5G BS load profile for the analysis of load characteristics. Case studies also show that the 5G BS loads have diverse impact on different typical areas in a distribution system.

In this paper, a method is proposed to mitigate unbalanced voltage and reduce power losses due to neutral line current in a bipolar direct current (DC) distribution network by introducing a DC electric spring (DC-ES). The coupling relationship between positive and negative pole voltages are investigated given the resistance of neutral line in the bipolar DC distribution network. The coupling matrixes of the positive and negative pole voltages and the DC-ES output voltages are deduced. And this matrixes demonstrate that the DC-ES control system is composed of double inputs of pole voltages and double outputs of DC-ES voltages. The small-signal model of the bipolar DC distribution network with DC-ESs is derived further. Subsequently, the control system with double inputs and outputs is transformed into two independent control systems by introducing the decoupling control variables, thereby increasing its rapidity and anti-interference performance significantly. The proposed unbalanced voltage suppression method and decoupling control of DC-ESs are validated by simulations and experiments.

The use of bipolar direct current (DC) distribution systems introduces the possibility of unbalanced voltage (current). This situation increases the voltage deviations and power losses at each node owing to the presence of a neutral line current. This study proposes a method that mitigates the unbalanced voltage caused by constant power loads (CPLs) by DC electric springs (DC—ESs). A linearized model is used in the small-signal analysis of CPLs. On this basis, the coupling relationship between positive and negative pole voltages is analyzed. After DC—ESs are introduced, the positive and negative pole voltages and DC—ES output voltages are found to be closely related, thereby increasing the complexity of the control system. Therefore, a feedforward decoupling control block diagram is introduced on the basis of the small-signal model analysis of DC—ESs in a single node of the bipolar DC system. The control system is simplified, and different control loops can be independently controlled. Thus, the rapidity and anti-interference performance of the control system are greatly enhanced. Simulation and experimental results of the unbalanced voltage suppression in the bipolar DC system are used to verify the effectiveness of the proposed scheme.

The massive accessing of unbalance and nonlinear loads to a power distribution network may cause serious problems on power quality and result in additional power loss and safety risks. Distributed generation (DG) with a converter interface has a flexible adjusting ability and can provide certain unbalance and harmonic compensations to power distribution networks. In this study, an optimal operation method of an active distribution network (ADN) involving the unbalance and harmonic compensation of a converter was proposed. First, the power regulating characteristics of DG were analyzed. Second, an optimization model was constructed to minimize ADN power loss, sum of harmonic voltage squares, and total unbalance of the negative sequence voltage, and multiple constraints, such as converters and network, were considered in the model. Third, the optimization model was transformed into a semidefinite programming model based on the characteristics of the nonconvex and nonlinear original model, thus assuring global convergence and decreasing difficulties in problem solving. Finally, the validity of the proposed algorithm was verified by using IEEE 33-node and 123-node test systems.