Smart Grid and Distribution Network Automation Engineering Construction

Smart Grid is a comprehensive information management system that integrates computer technology, data transmission, control technology, modern equipment and management. It is often used to be called grid automation system. The main task of smart grid construction is to promote the promotion and application of intelligent electrical equipment and equipment, to achieve automation and intelligence of the power grid management process, and to promote the overall technical level of power grid equipment.

1. Intelligent electrical equipment is the foundation of smart grid construction

(1) Intelligent equipment is a network information system that effectively connects machines, people, control systems and information systems. It must possess perceptive, cognitive and operational capabilities.

(2) Intelligent equipment is a comprehensive depth perception of industrial data, and has a faster cognitive ability for dynamic transmission and advanced modeling analysis, thus forming intelligent decision-making and control, driving the intelligent equipment manufacturing industry to a comprehensive and intelligent development.

(3) The core concept of intelligent manufacturing, integrating and integrating “lean concept, intelligent manufacturing system, IoT integration, intelligent equipment”, and “data acquisition and processing”, “human-machine, machine-machine communication” ", from data, information to decision-making", "toward predictive intelligent manufacturing" implementation

2, smart grid concept

The smart grid is the intelligentization of the power grid; it is based on the high-speed communication network, and collects various information on the terminal nodes of the electrical equipment through advanced sensors and measurement technologies, that is, reflects the operating state of the grid line segmentation. On the computer display screen, computer technology is used to remotely control the operation status of the network to realize safe, reliable, efficient and economic operation of the power grid.

In the network structure of the power grid, the cable of the power supply line delivers power to the subscriber end, and a circuit is formed between the line structure (line pipe) and the electrical equipment. Each segment of the circuit is called the endpoint of the network link or the node in the network (the common combination of two or more links). In the operation of the network system, the structure can be changed at any time, and the link can be transformed according to the needs. form. If this change is a change that takes place using artificial intelligence technology, the network is called an intelligent network. The management of the grid on the computer is also the management of the control node. The more control nodes on the network, the greater the amount of information that needs to be processed. The power grid is inseparable from the structure of the network, whether it is manual management or computer management. In the manual management, only the line connection diagram is needed, but the computer management must also have a network diagram with directions.

3. Grid connection diagram (grid structure)

Complex distribution network structures are often subject to change only with computers. It is stipulated that the current flowing out of the node is positive, and the current flowing into the node is negative; in the bypass direction of the selected loop, in the bypass direction of the loop, the potential drops to a positive value, and the potential rises to a negative value;

Digital grid system; refers to a system that converts the analog signals measured by the secondary system into digital signals and displays the grid structure on the computer in the form of numbers 1, 0. The digital grid was built to implement field measurements and field operations that required large amounts of manual work directly on the computer in the control room.

During operation of the power system, under the excitation of the power supply potential, current or power flows from the power supply through the components of the system into the load, distributed at each load point of the power network line, called the power flow direction, the current flow is negative, and the current flow is positive. . A design method for evaluating the merits and demerits of a line using standard models and parameters. Evaluate the current system load, loss, voltage drop, etc., and re-adjust the switch position of the constant open point to minimize the power loss and average the line load carrying rate. Each peer-to-peer network management of a distributed architecture has its own independent functions. Multiple tasks can be performed separately, and the supervisory functions are also distributed. All network information, alerts and events are available through any network system.

Distributed network: It is characterized in that any node is directly connected to at least two other nodes and has higher reliability. The digital grid line display system converts the number of the analog meter into digital information, which is converted from manual meter reading to digital signal transmission, and can display the line structure and running state on the liquid crystal screen. The modular design method of standardized distribution network line refers to clearly defining the structure of a certain circuit of the substation, and then finding the associated line of the line, and analyzing the degree of influence on other lines when the line structure changes. . A design method for evaluating the merits and demerits of a line using standard models and parameters. Evaluate the current system load, loss, voltage drop, etc., and re-adjust the switch position of the constant open point to minimize the power loss and average the line load carrying rate.

Centralized network: The use of lines and node devices will be distributed and independent of the network, using the functions of the system to interconnect with each other to achieve resource sharing. Connect multiple devices distributed in different places to form a collection.

4, distribution network automation is the power line structure changes to achieve intelligence and automation

Distribution network automation is based on the primary power supply line grid and field switch equipment, centered on the distribution network automation software system, comprehensively utilizes the communication method, and integrates the switch cabinet information through the application system of the secondary terminal equipment to realize remote pairing. Monitoring and control of the distribution network to achieve rapid response to power failures, quickly handle faults, and restore power in a timely manner.

The reliability of the line is determined by the structure of the line. If a user's equipment fails and causes a power outage, the power supply unit should consider resolving the fault and return the line to the power supply as soon as possible. In the case that the power supply cannot be bypassed, the power outage interval should be reduced and the power supply should be restored in time. The general standard is often used to evaluate line reliability, which is the "N-1" "N-2" "N-3" standard. When many technicians mention the design of the distribution network automation system, it is first necessary to simplify the grid structure of the power supply network. In fact, it is necessary to adapt to the current structure through automated construction according to the actual line conditions. Automated remote operation can only be operated on the one-line diagram. Once the power supply line is laid, the absolute position of the line connection will not change, but the different spacing of the switch cabinet will change the direction of the power flow. The current direction changes the line. The order of the trend has also changed, and the single-line structure of the network structure has changed.

The construction of smart grids will promote the upgrading of distribution network infrastructure and improve the intelligent management level of power grids. The distribution network power supply line is finally connected to the electrical appliances of thousands of households. Improving the safety and reliability of grid power supply line operation, reducing grid line loss, and improving the power quality of user terminals are the basic objectives of smart grid construction. Optimizing the power supply line structure directly affects the power supply reliability of the power grid.

The city distribution network has many lines and complicated structure. In the manual management mode, the line structure cannot change the line structure frequently, and the simpler the line structure management is, the easier it is.

5, distribution network automation project construction

Before implementing the smart grid construction and distribution network automation project, optimize the design of the power supply network and design the power distribution network according to the standardized model. In combination with the development plan of the grid construction, the line control mode is selected according to the actual situation of each line according to local conditions, avoiding the instability of the grid structure, causing the technical misplacement of the distribution network automation system, affecting the quality of the system construction, resulting in great project investment. waste. At present, there are three main types of distribution network structure:

(1) Radial line structure, the power supply line is fed directly from the substation to the customer end, and many intermediate users are connected in series on the line. This structure is simple and easy to find the line fault point. The switch on the radioactive line is mainly based on the circuit breaker, and is divided and protected. When a user fails, the switch is turned off, which will not cause the whole line to be powered off.

(2) The “hand in hand” type simple ring network structure is to add a contact switch between the two feeders, which can realize the transfer when the fault occurs.

(3) Multi-segment multi-contact (grid type) line structure, multiple lines directly have multiple contact points. When one node fails, it can selectively power up from multiple lines. This form of grid structure is adapted to segmented load switches and tie switches, and circuit breaker switches are not used as much as possible.

Through the optimized design of the distribution network line and switchgear, the load can be transferred from the heavy load or even the overload line to the light load feeder. This transfer increases the average load rate of the feeder and enhances the power supply capacity of the distribution network. When the distribution network is subjected to small disturbances, the fault area is judged, the fault area is isolated, and the power supply in the sound area affected by the fault is restored, thereby shortening the power outage time, reducing the power outage area, and improving the power supply reliability. Under normal operating conditions, by monitoring the operating conditions of the distribution network, optimize the operation mode of the distribution network; and when the distribution network is affected by the disaster (such as losing the main power supply, losing the incoming line, substation bus failure, etc.), without threatening the power supply Under the premise of safety, the affected load is transferred to the non-faulty line, so that the primary network has the power supply path and the power-off operation scheme.

Reasonably control the power flow distribution, reactive load and voltage level according to the operational data, reduce the line loss of the distribution network, improve the voltage quality and improve the power supply quality, and achieve the economic operation purpose;

6, the main content of distribution network automation construction

(1) Standardization design of distribution network line structure

(2) Switch operating mechanism is upgraded to electric operation

(3) Upgrade of switch cabinet

(4) Adopting automatic switchgear

(5) Construction of distribution network automation information system

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