What is the overall structure of the supervisory control system?
(1) Monitoring of 110kV booster station
The digital monitoring system for photovoltaic power plants is based on the lEC61850 communication technical specification, and realizes information sharing and interoperability among intelligent electrical equipment in digital power plants according to layers and distribution. It is divided into three layers as a whole: the station control layer, the bay layer, the process layer, the IEC61850 communication protocol is used between the station control layer and the bay layer protection measurement and control devices, and between the bay layer and the process layer combiner equipment, the bay layer and the process layer The GOOSE communication protocol is adopted between intelligent interface devices.
The station control layer is the center of monitoring, measurement, control and management of the entire grid-connected photovoltaic power station equipment. It is connected to the control bay layer of the booster station and each photovoltaic and is connected to the inverter by using shielded twisted pair, coaxial cable or optical cable. The control bay layer of the booster station is distributed in each power distribution room or the main control room according to different voltage levels and electrical bay units. In the case of station control layer and network failure, the bay layer (including the inverter) can still independently complete the monitoring of the bay layer and the protection and control functions of the circuit breaker.
There can be more than two main control stations of the computer monitoring system (NCS). That is, a local monitoring master station and more than one remote dispatching station can realize the monitoring and control of the photovoltaic power station in the local and remote (power grid dispatching), and their control operations need to be locked with each other.
The 110kV system adopts electronic transformers and on-site intelligent switch equipment, and the output digital current and voltage signals are directly sent into each compartment merging unit of the electrical equipment room through optical fibers, which greatly improves the accuracy and avoids mutual interference; each intelligent The switchgear is connected to the process layer network, and the mechanical and electrical status information and opening and closing commands of the switch are transmitted through the optical fiber to realize the intelligent control strategy of the circuit breaker.
Corresponding intelligent protection and measurement and control devices are installed on the switch cabinets of the 110kV system, and relevant information is connected to the monitoring system through the network switches in the 10kV power distribution room.
The information of public equipment such as DC system, UPS system, watt-hour meter screen, low-current grounding line selection device, backup generator ATS switching device and fire alarm system is connected to the monitoring system through the communication management machine.
The station control layer equipment includes the background monitoring master station, the computer anti-mistake locking device, the printer, the GPS timing device and the network equipment chip. The bay layer equipment is composed of electrical equipment measurement and control unit, electrical microcomputer protection device communication unit, inverter controller, combiner box string current monitor, network communication unit, network system, etc. The process layer equipment is mainly composed of 110kV system and main transformer. Each local intelligent unit is composed.
(2) Monitoring of solar photovoltaic power generation units
According to the site conditions, the photovoltaic power generation units (square arrays) of the power station project are distributed in situ, and the same unit (square arrays) are arranged in a centralized manner. Detection signals such as the temperature of the solar cell array of each unit and the string current of the DC distribution box (combiner box) need to be collected to the centralized inverter. On the LCD liquid crystal display on the panel of the centralized inverter cabinet installed on site, you can observe the detailed operating status of the inverter and each string of photovoltaic power generation units. Operating parameters of each photovoltaic power generation unit (including DC input voltage and current, AC output voltage and current, power, grid frequency, fault code and information, etc., solar cell module operating temperature, regional irradiance, ambient temperature, and solar cell arrays) String current, etc.), through the communication controller of the centralized inverter, the Ethernet transmission method is used to upload to the computer monitoring system network of the whole station through the corresponding communication management machine, and the operator station of the computer monitoring system is used in the main control room of the booster station. It realizes the monitoring, alarming, and historical data storage of the above operating parameters, which can be displayed on the large screen.
On the operator station of the total station computer monitoring system, the parameters of each inverter can be set individually, and the startup and shutdown sequence of the inverter system can be set according to the actual weather conditions, so as to make the operation of the entire power station reach the highest level. Excellent performance and maximum power generation capacity.