Abstract: Microgrid is an autonomous system that can self-control, protect and manage. According to the reliability of microgrid itself and its impact on system reliability after access to power distribution system, System reliability evaluation and reliability assessment of microgrid, the main problems that need to be solved are studied, and the reliability assessment of distribution system with distributed power supply is proposed, and various types of distributed power supply reliability assessment models need to be established. Micro-grid islanding operation also need to consider the micro-power capture technology, control technology, the smooth transition of operating conditions, power output randomness and other factors; With the development of micro-grid and smart distribution network technology, real-time collection of information will be easier , Load modeling will have new changes. On the basis of the existing research, it is necessary to further evaluate the reliability evaluation index system of microgrid, the operation mode of microgrid and the influence mechanism of operating characteristics on the reliability of power distribution system , Reliability modeling of distributed generation and energy storage device operating characteristics, reliability of multiple power distribution systems Accurate and efficient models and algorithms estimate the in-depth study.
1 Introduction
Micro-grid (microgrid), also known as micro-grid, refers to a small-scale distribution system composed of distributed power supply, energy storage device, energy conversion device, related load and monitoring and protection devices, An autonomous system that realizes self-control, protection and management can be operated both in the grid with the external power grid and in isolation.
Micro-grid is a relatively traditional concept of large power grid. The United States, Europe and other countries and regions on the definition of micro-grid are not the same. 1) The definition of microgrid in the United States: Microgrid is a system composed of load and micro-power. Its internal power supply is mainly responsible for energy conversion by power electronics and provides the necessary control. When micro-grid and main-network When the fault is suddenly resolved, the microgrid can also maintain its own internal power supply until the fault is rectified. 2) Europe's definition of microgrid: The use of primary energy, the use of miniature power supply is divided into three kinds of uncontrollable, partially controlled and full control, and cold, heat, electricity triple; with energy storage devices, the use of power electronics Device for energy regulation.
The technical parameters of micro-grid components and economic research is still at the experimental stage, is an important part of the new power system research. It integrates technologies such as distributed generation, new power electronics, energy storage and renewable energy. Its main components include micro-power (distributed power), energy storage devices, load and central control systems with autonomous, stable and compatible Flexible features. The microgrid has two operation modes of grid connection and autonomous operation. When the grid operation is in operation, the external power grid and the internal distributed power supply can jointly supply power to the load. When the external power grid fails or there is a power quality problem, the microgrid control system can be controlled by the microgrid control system Disconnected from the main network to achieve autonomous operation, that is, only by the internal distributed power supply to the load, when the fault is lifted, the microgrid regains grid-connected operation.
However, the reliability level of microgrid itself and its impact on the reliability of the system after it has been connected to the power distribution system have drawn the close attention of electric power researchers. However, there is not much research on the microgrid, especially for the micro The reliability assessment of the grid itself is still rare at home and abroad. This paper explores the reliability assessment of distribution system with microgrid, which is briefly introduced below.
Reliability Evaluation of a New Distribution System with a Microgrid
With the introduction of microgrids, the traditional single-source radial distribution network has become a multi-source new distribution network covering power and load, changing the radial distribution structure of the distribution network and increasing the distribution network's trend Uncertainty. Meanwhile, the output power of distributed power in the microgrid is random and intermittent. These problems have a series of effects on the operation and control of the system, and also pose a huge challenge to the reliability assessment of the distribution system containing the microgrid. Therefore, the assessment theory and method of the reliability of distribution system will also be changed. This paper studies the reliability evaluation of distribution system with microgrid as follows:
1) Reliability Evaluation Model of Distributed Power Supply
Compared with the traditional power supply, distributed generation has such features as primary energy diversity, flexible access location and operation mode, different power output characteristics, and the main distributed power sources such as wind power and photovoltaic have obvious intermittence and randomness. Therefore, the modeling of all types of DGs is the most important issue in the reliability assessment of the power distribution system with DG.
For wind power, photovoltaic and other intermittent, random distributed power modeling research. Commonly used method is to distribute power equivalent for the conventional power supply to deal with the establishment of distributed power multi-state probability model. The actual wind turbine, photovoltaic cell output with wind speed, sunshine intensity and other factors in real time changes in amplitude from zero to rated constant random changes. Through the multi-state probability model, the wind turbine with continuous output change is equivalent to the discrete multi-state generator model, so as to calculate the system reliability index by simulation or analytic method.
Similarly, this idea can be applied to establish a reliability model for energy storage devices that takes into account control strategies.
2) Distributed power islanding
When the main network fails or needs to be safe and stable, the microgrid can enter the islanding operation. This mode has important influence on the reliability of the load point in the island, but the islanding needs to consider the randomness of the distributed power output, Uncertainty and protection of configuration and other factors.
At present, the commonly used islanding strategy simply considers the power balance between distributed power and load in microgrids. In fact, the operation of the island needs to consider the micro-power capture technology, control technology, smooth transition of operating conditions, randomness of power output and other factors.
3) Load and component reliability parameters of the uncertainty
The characteristics of load have an important impact on the reliability assessment. In the traditional reliability assessment, the load is often treated as a fixed value, average load or peak load. For the reliability parameters of the components, the corresponding expected value . When distributed generation is added into the distribution network, the deterministic loads and component parameters will not be able to adapt to the dynamic characteristics of distributed generation. Especially in the island operation mode, the study of load characteristics is particularly important for the safe and stable operation of islanding. In the current study, most of the stochastic fluctuations of load are processed by statistical or heuristic prediction methods, which depend on historical load data. With the development of microgrid and smart distribution network technology, the interaction between load and power grid will be closer and the real-time information collection will be easier. In this case, load modeling will also bring about new changes.
Usually, after the key problems such as the reliability model of distributed generation, the reliability model of energy storage equipment, the islanding strategy, the relevance and randomness of load and power output are solved, the traditional reliability assessment method can be applied , Such as; Failure Mode and Effect Analysis (FMEA
Wireless Remote Control for Crane Parts does not take up floor space. Crane Pendant allows for independent control of crane operation by operators. This ensures improved operating accuracy and constant Overhead Crane motion without stop.
Product Features:
- Comply with the safety standard EN954-1 Catalog 4.This standard is generally recognized as the highest of all crane-related safety standards.
- One emergency stop
- Rechargeable NI-MH battery with no memory effect
- Rugged plastic enclosure with IP65 rating
- Active and passive emergency stop systems for quick response and ultimate protection
- Machine status monitoring and address code rectification are performed by using communication protection and initial start-up protection.
- Under abnormal operating conditions where the transmitter system incurs problems such as power supply under voltage or signal dropout, the receiver system would automatically stop working with a responding time no more than 0.55 seconds.
Crane Pendant,Crane Pendant Control Station,Pendant Control with buttons
EUROCRANE GLOBAL , https://www.overhead-crane.com