Substation Layer Research Articles

A High Performance Communication Architecture for a Smart Micro-Grid Testbed Using Customized Edge Intelligent Devices (EIDs) With SPI and Modbus TCP/IP Communication Protocols

This paper presents a high performance 4-layer communication architecture for a smart micro-grid testbed which consists of a 2 kVA Distributed Energy Resource (DER) inverter with PV and battery channels capable of advanced grid supportive and grid forming functions in the Process layer, a Raspberry Pi computer in the Interface layer, a customized Edge Intelligent Device (EID) in the Sub-station layer, and an end-to-end solar energy optimization platform (e-SEOP) in the Supervisory layer. The Raspberry Pi serves as a communication interface which communicates with the DER inverter using Serial Peripheral Interface (SPI) communication and talks to the EID using Modbus TCP/IP protocol. This paper provides a convenient and comprehensive solution to SPI and Modbus TCP/IP communication implementation in a smart micro-grid. The challenges of coordination between communication and system control and between different communication protocols have been addressed, which leads to a boost in the communication efficiency and makes the system highly scalable, flexible and adaptive. The proposed communication architecture as well as the micro-grid test bench have been validated through hardware experiments. The results indicate a reliable and efficient communication among different layers, which facilitates large-scale status monitoring of edge devices and coordinated control of the entire system.

Time Series Association State Analysis Method for Attacks on the Smart Internet of Electric Vehicle Charging Network

A robust, integrated and flexible charging network is essential for the growth and deployment of electric vehicles (EVs). The State Grid of China has developed a Smart Internet of Electric Vehicle Charging Network (SIEN). At present, there are three main ways to attack SIEN maliciously: distributed data tampering; distributed denial of service (DDoS); and forged command attacks. Network attacks are random and continuous, closely related to time. By contrast, when analyzing the alarm in malicious attacks, the traditional Markov chain based model ignores the association relationship in the time series between states of alarm, so that the analysis and prediction of alarms are not suitable for real situations. This paper analyzes the characteristics of the three types of attack and proposes an association state analysis method on the time series. This method firstly analyzes alarm logs at different locations, different levels, and different types, and then establishes the temporal association of scattered and isolated alarm information. Secondly, it tracks the transition trend of abnormal events in the SIEN’s main station layer, the channel layer, and the sub-station layer. It also identifies the real attack behavior. This method not only provides a prediction of security risks, but, more importantly, it can also accurately analyze the trend of SIEN security risks. Compared with the ordinary Markov chain model, this method can better smooth the fluctuation of processing values, with higher real-time performance, stronger robustness, and higher precision. This method has been applied to the State Grid of China.

Research on the Process Layer and Substation Layer Relay Protection in Smart Substation Relay Protection

The intelligent substation relay protection facility is a fundamental element in construction of modern power system, based on the principles of flexibility, security and accuracy, and it can be divided into process layer and substation layer according to specific equipment. The former is suitable for individual sampling of disposable equipment, can be separated from the base station synchronization sampling, with the help of synchronous digital system and ping-pong algorithm to achieve synchronization of the overall sampling, that is to take the distribution protection components, through the separate transmission medium to realize the information transmission; the latter is for variable power plant components centralized backup protection, taking online real-time tuning technique.

Study on Relay Protection of Process Layer and Substation in Relay Protection of Intelligent Substation

The relay protection facilities of the intelligent substation are the basic elements of modern power system construction. Based on the principles of flexibility, safety and accuracy, it can be divided into process layer and substation layer according to specific equipment. The former is suitable for single sampling of disposable equip-ment, which can be separated from the base station synchronization sampling, with synchronous digital system and ping-pong algorithm to achieve the overall sampling of synchronization, that is, the distribution configuration to protect the various components, through a separate transmission medium to achieve information transmission; For the substation components centralized backup protec-tion, take the online real-time tuning technology.

Hierarchical Optimization for the Double-Sided Ring Structure of the Collector System Planning of Large Offshore Wind Farms

High reliability double-sided ring collector systems have been applied in practice for long distance and off the coast large-capacity offshore wind farms. To reduce investment and improve reliability, it is important to optimize and evaluate the double-sided ring collector systems. In this paper, a capital cost optimization model is developed to solve the mutual coupling effects among the system structure, power flow, and short circuit current in the collector system constraints. Based on the characteristics of the offshore electrical collector systems, the optimization model is divided into the offshore substation layer, the wind turbine layer, and the submarine cable layer. The fuzzy clustering algorithm, single parent genetic algorithm, and multiple traveling salesman solution technique are integrated and applied to solve the hierarchical optimization model. Finally, the proposed model and the optimization algorithms are tested in a real, large-scale offshore wind farm. The simulation results are compared with the radial collector systems from an economics and reliability point of view. The simulation results show that the double-sided ring design will achieve more profit with higher reliability in the long run. The results can also provide a benchmark for the collector system design of large-scale offshore wind farms.

A Closed-Loop Test System for Network Performance of Smart Substation

The key support technology of smart substation testing technology is analyzed, the concrete application of smart substation is combined with the traditional network testing, and the function of real-time network packet analysis is introduced, which has make the process of smart substation layer network test form a closed loop system, extend and improve the system of smart substation performance test. And links to the reality, to the transformer substation switchboard network storm suppression function, the time delay, lost projects and so on the frame rate to carry on the statistics, the contrast has confirmed this plan feasibility and the validity.

Research on the Network Topology and Reliability of the Communication System in Smart Substations

Communication network plays a vital role in smart substations. Different network topology provides different network performance, while the quality of network performance directly impacts the reliability of the entire system. In view of the network topology of smart substations, this paper compares the advantages and disadvantages of different network topologies as well as different network schemes of substation layer and process layer, and also analyzes the relationship between the reliability of network system and network topology, which play an important role in establishing a reliable and efficient smart substation system.

Research on IEC 61850 Gateway Based on MMS Mapping

IEC 61850 is an international standard developed by the International Electrotechnical Commission TC57 substation automation communication networks and systems. It uses MMS (Manufacturing Message Specification) as a real-time communication protocol of the application layer, and achieves the communication between the substation layer and the spacer layer. This paper describes the features and functions of the IEC 61850 and MMS technology and focuses on the principle of MMS mapping in the application of IEC 61850 , then preliminarily leads to the overall design framework of the IEC 61850 gateway.

The Discussion of 500kv Centralized Monitoring System For Large Operation and Large Maintenance Mode

The establishment of a centralized monitoring system is an effective means to achieve the goal that no or fewer people are on duty. The function of the current 500kV centralized monitoring system is not enough mature to meet the requirement of the large-scale operation and large-scale maintenance model proposed by the State Grid. In order to fully utilizing the function of the centralized monitoring system, an improved design scheme is presented for the current 500kV centralized monitoring of the Jiangxi Power Grid. The improved centralized monitoring system is divided into three layers: monitoring center layer, operating team layer, and substation layer, which not only has the advantages of high security, high reliability, and easy maintenance, but also realizes the management model of regional control. So it can perfectly meet anti-misoperation requirement in the large operation and large maintenance mode, which can provide reference and guidance for the design of the 500kV centralized monitoring system of Jiangxi Power Grid.

Digital Control of the Substations Based on IEC61850

The promulgation and promotion of IEC61850 provide a basic platform for the development of the digital substation. In this paper, the present situations and problems of the digital substation 220KV Baicheng are introduced and analyzed, And some schemes are proposed including the configuration of DF1900 monitoring system in substation layer and DF1925 controlling system in interval layer, and the optimization of communication networks and the access of the electronic transformer.The evaluations of successful transformation are summarized from the reliability and availability and flexibility in the end. From evaluations of the scheme, this transformation makes the reliability and availability of the digital substation 220KV baicheng improve greatly, but also enhances the flexibility of system. Moreover, the transformation also saves much money to purchase equipment of substation, so it also provides a new method to change for a large number of old substations to digital ones.

Study on Relay Protection of Process Layer and Substation in Relay Protection of Intelligent Substation

The relay protection facilities of the intelligent substation are the basic elements of modern power system construction. Based on the principles of flexibility, safety and accuracy, it can be divided into process layer and substation layer according to specific equipment. The former is suitable for single sampling of disposable equip-ment, which can be separated from the base station synchronization sampling, with synchronous digital system and ping-pong algorithm to achieve the overall sampling of synchronization, that is, the distribution configuration to protect the various components, through a separate transmission medium to achieve information transmission; For the substation components centralized backup protec-tion, take the online real-time tuning technology.