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Nowadays, the reliable supply of electric power is vital in all aspects of social life. With the development and participation of distributed generations, not only does an accurate fault location lets repair of a fault line as quickly as possible, but also it is of great significance to ensure the safe and stable economic operation of the power system. This study proposes a method to determine the fault location in distribution networks, which is a combination of Extreme Gradient Boosting and Support Vector Machine. The effectiveness of the proposed method is validated on an IEEE34‐bus distribution network under single‐phase‐to‐ground faults, using voltage measurements available at each node in the distribution network. The comparison in accuracy, precision, recall, F1‐score and time‐cost of the method in this study with K‐Nearest Neighbour and Multi‐Layer Perceptron demonstrates the feasibility of applying the proposed method in distribution system fault diagnosis.

The simulation of complex power grid adopts the method of model segmentation. The system is divided into two or more subsystems. Each subsystem is calculated and solved in different computing units. Because the simulation model runs on different hardware, the time synchronization between subsystems may bring errors and stability problems. In this paper, a time synchronization method based on virtual power is proposed. It is assumed that there is a virtual load composed of resistance and inductance between different simulation subsystems, and two identical voltage sources are set at both terminals of the virtual load. When there is no time error between the subsystems, the power consumed by the virtual load should be zero, otherwise virtual power will be generated. The virtual power is sent to the PI regulator as the error signal, and the output of the regulator is used as the time error correction signal of the subsystem until the virtual power is zero, so as to realize the clock synchronization between multiple computers. In this paper, the theoretical analysis and implementation method of this time synchronization scheme are given in detail, and the simulation results show that the method is correct.

This article aims at the current situation of the research on the evaluation method of the user-side integrated energy system, starting from the overall performance of the integrated energy system. It puts forward a scientific and systematic evaluation index system for the user-side integrated energy system planning scheme from the four aspects of energy efficiency, cost-effectiveness, energy supply quality, and environmental protection. Based on the combination of analytic hierarchy process, entropy weight method and set pair analysis method, comprehensive evaluation of the user-side integrated energy system planning scheme is carried out. Taking the integrated energy system of a commercial-residential mixed zone in a northern city as an example, a simulation analysis was carried out to verify the effectiveness of the proposed evaluation method. The results show that the proposed evaluation method can provide a basis for the decision-making of the user-side integrated energy system planning scheme.

With the development of automatization and informationization, distribution network has gradually become into a typical Cyber Physical System (CPS). For the deep integration system of communication and power physical system, this paper proposes a hybrid simulation architecture of distribution network CPS based on the combination of information control layer, communication layer and physical layer, and a digital analog hybrid simulation platform of distribution network CPS is bulit. At the same time, based on the data of actual distribution network, a 62 node CPS test example is designed. The performance of digital analog hybrid simulation platform of distribution network CPS is verified through the CPS concurrent fault scenario, and the feasibility of 62 node CPS test example is evaluated through the hybrid simulation platform.

In order to solve the problem of optimal dispatching between source, network and flexible loads, and improve the safety and stability operation level of distribution network, this paper proposes a two stage multi-objective control method for distribution network. The first stage optimization control is the day ahead scheduling, the control objectives is source and load balance, and minimum of the longest path of feeder in distribution network. The second stage is hourly control, the control objectives of static voltage stability margin and the active power loss are used to effectively improve the coordination, safety, and economy of distribution network. An improved multi-objective harmony search algorithm is proposed to solve this two stage multi-objective optimization model. Finally, the effectiveness of the proposed two stage multi-objective control method is verified by IEEE 33 bus system with distributed generations.

It has become crucial to investigate the uncertainty and sensitivity of building loads (peak cooling load, peak heating load, annual cooling demand and annual heating demand) for meeting the risk assessment of building energy planning. Therefore, a new Monte Carlo (MC) method based on building performance simulation (BPS) is proposed to solve the problem of building loads forecasting at planning phase. Furthermore, the sensitivity of building loads is examined using two global sensitivity analysis (GSA) methods, including meta modeling method based on tree Gaussian process (TGP) and regression method based on standard regression coefficient (SRC). Finally, a case study of office building is conducted. The results show that the MC method constructed by the combination of R language platform and EnergyPlus software can generate models rapidly and simulate accurately building loads. Note that it is necessary to assess the stability of results as a function of sample size from uncertainty analysis in applying the MC method into building loads assessment. The TGP-based GSA method is applicable to identify and analyze key variables affecting building loads. It is recommended that at least two inherently different GSA methods should be applied to provide robust sensitivity results. Moreover, this study also provides insight on building energy planning and energy conservation design according to the results of uncertainty and sensitivity analysis for case study.

With the development of intelligent distribution network construction and transformation, the traditional distribution network has gradually evolved into a closely related integration system composed of electric power physical network, information communication network and information control network, which has typical characteristics of Cyber-Physical System (CPS). This paper studies the the overall architecture and Information-Physical coupling characteristics of CPS in distribution network, constructs a CPS simulation framework consisting of RT-LAB, OPNET and control platform, and proposes a method of joint modeling and risk simulation analysis of distribution network considering network attack based on CPS. Finally, an example is given to verify the rationality of the platform and the effectiveness of the simulation method.

The coupling effect between power system and communication system is becoming more and more complex. While the controllability of distribution network has been strengthened, it also has a stronger dependence on information control system. This paper presents a method of distribution network fault simulation based on cyber physical system (CPS). A terminal CPS fusion model based on finite state machine is constructed. Distribution network fault simulation is carried out under Distributed Denial of Service (DDOS) attack. The feasibility of terminal CPS fusion model based on finite state machine is verified, and the actual distribution network fault handling is realized. The simulation fully simulates the interaction process between physical and information in the actual distribution network fault handling process, verifies the correctness of the method proposed in this paper, and analyzes the impact of communication environment on fault handling.

The close integration of distributed renewable energy and the close integration of cyber physical system bring challenges for power system modeling. In this paper, Firstly, the topology and control strategy of power electronic transformer (PET) are proposed. Secondly, this paper develops a modeling method about the hybrid distribution network PET based on finite state machine (FSM) and the joint simulation platform of cyber Physical system (CPS) based on RT-LAB, OPNET and control platform. Taking the hybrid distribution network based on PET with different penetration of photovoltaics (PV) as an example, the validity of PET model and control strategy is verified by comparing physical simulation results with joint simulation results of cyber physical system.

Offshore wind is experiencing rapid growth around the world, and is moving towards large-scale and far-reaching sea. Grid connection has become an important challenge for large-scale development of offshore wind power. In this paper, technology and regulatory framework of offshore wind grid connection are systematically summarized and complied. Europe has accumulated rich experience in this field, therefore taking UK, Denmark and Germany as examples, the practical experience of offshore wind grid integration is analyzed in terms of technology choice, framework, operation and maintenance, and recovery of connection costs. which is a good reference for China when dealing with the coming challenges.

China has a cumulative installed offshore wind capacity of 6.8 GW, making it the third largest in the world. Compared with Europe, which is the largest offshore wind power market, there are still gaps to substantially tapping the offshore wind potentials of China. This paper aims to investigate advanced experience of offshore wind power, and explore innovative approaches for offshore wind deployment and grid integration in China. Development and issues caused by offshore wind power in UK, Germany and Denmark have been investigated, including technological progress, curtailment, and network congestion and redispatch needs. The grid integration approaches to re-enforcement of network to accommodate offshore wind power are also analysed. Contrastive analysis is taken about stakeholders and planning process of offshore wind among UK, Germany, and Denmark. Construction suggestions are proposed for the development of offshore wind power in China during the 14th Five Year Plan period.

The reactive power coordinated optimisation problem for distribution network (DN) with the integration of renewable distributed generation (DG) is investigated in this study. By actively participating in reactive power control together with an under-load tap changer and shunt capacitors, DG can operate more effectively in the DN. Non-dispatchable DG is considered in the coordinated optimisation method. The objective of the proposed reactive power coordinated optimisation method is to minimise active power loss and to decrease the number of switching device operations while maintaining the grid voltage within the allowable range. The optimisation problem is to solve a variable combination including integers and continuous variables, which will formulate a mixed integer non-linear programming (MINLP) problem. The control variable includes operations of traditional reactive power control devices and the reactive power adjustments of DGs. To solve the MINLP problem, a heuristic searching method, an improved harmony search algorithm is proposed with adaptive parameters process. Numerical tests on a standard 10-kV distribution system and a real distribution system demonstrate the applicability of the proposed reactive power coordinated optimisation method.

This study investigates the typical configuration mode and optimal allocation method for photovoltaic (PV), wind generator and energy storage (ES) in Microgrid system. Firstly, the six typical scenarios of the hybrid integration modes are discussed. By considering the objectives of minimum PV-Wind-ES investment cost, minimal expectation of energy not supplied (EENS) and minimal line loss, the proposed optimal allocation of PV-Wind-ES is a multi-objective optimization problem. In order to get a comprehensive solution, an improved NSGA-II algorithm is proposed to solve the multi-objective planning problem. Several experiments have been made on the IEEE 33-bus test case and a real implementation of State Grid Corporation of China (SGCC) with the consideration of multiple DG units and ES. The computational result and comparisons indicate the proposed algorithm for optimal allocation of PV-Wind-ES in distribution system is feasible and effective.