Steady-state control systems can be divided into local stability control and regional stability control systems.
Steady-state control systems can be classified according to different classification standards. In the field of power system control, safety and stability control systems are usually classified according to the scale of the power grid and the functions between each plant and station, mainly including the following two categories:
1. Local stability control:
- Definition: Local stability control devices are usually only used in systems that can be equivalent to single-machine-infinity, and are used to solve the stability problems of a single plant or local power grid.
- Structure: This type of system usually includes a control decision determination device and an execution device. The control decision determination device is equipped with a pre-set control strategy table, which is responsible for receiving the fault information and network information of the protected component, determining the control strategy, and issuing control commands to the execution device. The execution device is responsible for receiving control commands and executing operations such as cutting the machine, fast closing the steam valve, electrical braking, and load shedding.
- Application: General low-frequency and low-voltage emergency control devices, out-of-step decoupling devices, etc. are all local safety and stability control devices. However, with the development of the power grid structure, the typical mode of the single-machine-infinite system has been difficult to find in the power system, so the application scope of the local stability control device is relatively limited.
2. Regional stability control system:
- Definition: The regional stability control system is a system composed of safety and stability control devices installed in two or more plants to solve the stability problem of a regional power grid, which are connected through information channels and communication interface devices.
- Structure: The regional stability control system usually consists of a master station, several substations and several terminal stations. The master station is responsible for summarizing the operating condition information of each substation, performing state estimation and dynamic safety estimation of the regional power grid, forming a safety and stability control strategy table, and transmitting the relevant information and control strategy table to each substation. The substation is responsible for collecting the operating condition information of the substation and issuing control commands to the master station and each substation according to the control strategy table. The terminal station receives the control commands from each station and performs local control.
- Application: The regional stability control system can take into account the stability of the entire region and realize the stability control of the regional power grid through decentralized decision-making or centralized decision-making. With the development of technology, regional stability control systems have become an indispensable part of the power system, which is of great significance for ensuring the safe and stable operation of the power grid.
In summary, the steady-state control system in the field of power system control is mainly divided into two categories: local stability control and regional stability control system. These two types of systems have their own characteristics and application scenarios, and together constitute an important part of the safe and stable control of the power system.