Difference Between Parallel Connection and Grid Connection of Diesel Genset

Nowadays, diesel generator sets are widely used in telecommunications, banks, hospitals, aviation, factories, mines, railways and other fields. Many users may not understand the difference between parallel and grid connection of diesel generator sets. Next, Dingbo Power will introduce it in detail.

1. Parallel operation of diesel generator set

A parallel system is designed to increase the power generation capacity by using two or more diesel generators in parallel when the power of the diesel engines is insufficient. It also achieves automatic parallel operation of two or more diesel gensets and supplies power to the load. When the load load is less than 60% of the rated capacity of a single genset (adjustable), the system will send a "reduction" signal, unload the standby genset, and disconnect the automatic shutdown. If the load is greater than 80% of the rated capacity of a single genset (adjustable), the system will automatically issue an "increase command", and the standby genset will automatically start and merge after automatic synchronization, automatically sharing the active load; The condition for parallel operation is that the instantaneous voltage, frequency, and phase of the two machines are the same.

The advantage lies in the fact that there are not as many devices in normal use, but all devices need to be put into use at the same time when they need to work, which reduces costs and consumption to achieve the premise of meeting the maximum usage power, also known as island operation mode.

2. Grid connection of diesel generator set

The voltage of the municipal power grid is around 3-10KV, usually around 400V for low-voltage power supply. If there are users nearby and the voltage level is appropriate, it is also possible to directly supply power to the users; However, in general, power users are relatively far away, with large gensets having large capacity and generating a large amount of electricity. In order to transmit to remote locations, grid connection is necessary; Small gensets with small capacity should ensure stable voltage and frequency, and also be connected to the grid; Moreover, according to Chinese regulations, power supply business areas are exclusively operated, and power plants must pass through power supply enterprises before selling electricity. Therefore, they must first be connected to the grid and uniformly transmit electricity.

The main grid of the power grid is generally composed of high voltage, and the electricity generated by the power plant needs to be boosted before leaving the factory in order to be connected to the grid. Boosting is achieved through a step-up transformer, so the step-up transformer is the main equipment for grid connection; To control the grid connection process, high-voltage switches need to be installed on both sides of the transformer; In grid connection, we also need to know whether the operation is normal and how much electricity is connected to the grid. We need to install a current transformer to measure high-voltage current, a voltage transformer to measure high-voltage voltage, and use the signals of these two transformers to charge the energy meter to understand how much electricity has been generated; To prevent overvoltage such as lightning strikes during operation, it is necessary to install lightning arresters on both sides of the transformer and on the busbar to limit the overvoltage value; Sometimes, to prevent equipment from being burned down due to excessive short-circuit current, a reactor (inductor) can be connected in series to limit the magnitude of short-circuit current; There should also be some protective devices to ensure that the system can operate automatically and stably. With these devices, the electricity generated by the power plant can be smoothly connected to the grid, transformed into high voltage and transmitted to the grid.

The grid connection of generator sets is a compensation for the electricity consumption of the power grid when the market capacity cannot meet its own production, or for some gas generator sets, excess electricity can be provided to the national power grid for sale when meeting its own electricity consumption.

The essential difference between the two methods lies in the direct connection between machines, the direct connection between machines and the power grid, the use as a backup power source for power supply during power outages, and the use of compensation for the power grid.

The above is about the difference between parallel and grid connection of diesel generator sets. We hope it will be helpful to you. Dingbo Power is a generator set manufacturer that has been deeply involved in the diesel generator set industry for nearly 20 years. In order to meet the requirements of different users, Dingbo Power also provides special functional units such as automatic switching, automatic switching, three remote monitoring, automatic grid connection system, low-noise, trailer and other different voltage and frequency. If you are looking for a high-quality diesel generator set as a backup power supply, please contact us by email dingbo@dieselgeneratortech.com.