Electrical secondary part of large centralized on grid photovoltaic power station
The photovoltaic power station project adopts an integrated centralized control method, and realizes the remote measurement, remote observation, remote control, remote signaling and remote adjustment of all electrical equipment in the centralized control room of the power station.
1. Integrated automation system
A set of integrated automation system is set up in the electrical complex building of the photovoltaic power station. The system includes a computer monitoring system and has a telecontrol function. According to the requirements of dispatching operation, various real-time data and information collected by the power station can be transmitted to the upper-level dispatching after processing. Center. Realize few people, no one on duty, and can analyze and print various reports.
The photovoltaic power station is integrated into the regional public grid by boosting to 10kV. Install an electric energy metering device on the on grid side of the 10kV line. Connect to the multi-function watt-hour meter through the secondary side of the special voltage transformer and current transformer, measure the power generation of the photovoltaic power station through the special multi-function watt-hour meter, and set the current, voltage, active power, reactive power and power factor, etc. The meter is used to monitor the operating parameters of the system. The special multi-function watt-hour meter for metering has a communication function and can upload real-time data to the integrated automation system of the power station. The signal on the line side of the booster station is connected to the regional public power grid dispatching automation system.
A communication management machine needs to be configured, and the main screen is installed in the centralized control room to collect the operation data of each inverter, 10kV power distribution device, and step-up transformer. The integrated automation system communicates with the electrical equipment in the station through the communication management machine. Collect and analyze the data uploaded by each subsystem, and realize the remote control of each subsystem at the same time.
The integrated automation system transmits all important information to the monitoring background of the centralized control room, which is convenient for the on-duty personnel to monitor and manage each inverter and photovoltaic array, and display parameters such as operation, fault type, and electric energy accumulation on the LCD. The project company can also realize remote signaling and telemetry of photovoltaic power plants through this system.
2. Comprehensive protection
The main electrical equipment in the photovoltaic power station is protected by microcomputer to meet the information uploading requirements. Component protection is configured in accordance with “Technical Regulations for Relay Protection and Safety Automatic Devices” (GB14285-1993).
The transformer is set with high temperature alarm and over temperature trip protection, and the low voltage side switch will be tripped after the action. The thermostat has a communication interface for uploading information.
The 10kV high-voltage switchgear is equipped with measurement and control protection devices. Over-current protection, zero-sequence over-current protection, and direction protection are provided, and the measurement and control protection device uploads all information to the integrated automation system by means of communication.
A frame circuit breaker with four-stage protection function is installed on the low-voltage switchgear, and a communication module is configured to upload all information to the integrated automation system by communication.
The inverter has reverse polarity protection, short circuit protection, islanding effect protection, overheating protection, overload protection, grounding protection, etc., and automatically disconnects from the system when the device is abnormal.
The 10kV on grid tie line is equipped with a microcomputer current protection device on the corresponding line. The specific configuration should also be configured according to the requirements of the access system design and approval documents during the design of the construction drawing.
3. Station DC system
In order to supply power to control loads such as control, measurement, signal, relay protection, automatic devices, etc., and power loads such as AC uninterrupted power supply of the unit, provide DC power, and set up a 220V DC system.
The DC system adopts the combined power supply mode of power and control. A set of 220V valve-regulated lead-acid maintenance-free battery packs should be installed in the photovoltaic power station, and two sets of high-frequency switching power supply charging devices and microcomputer DC insulation monitoring devices should be installed for the batteries. 220V battery Capacity can be determined. or 100A·h.
4. Uninterrupted power supply system
In order to ensure the reliability of the photovoltaic power station monitoring system and the power supply of the telecontrol equipment, a set of AC uninterruptible power supply (UPS) is set up in the photovoltaic power station project, and the capacity can be 5kV·A. Its DC power is provided by the DC system, and its AC power is provided by the station power supply.
5. intra-station communication
The municipal communication is connected to the photovoltaic power station complex building. It is initially considered to be connected to several telephone networks, and the integrated wiring system is adopted.