PV grid-connection system refers to the system that converts solar power to electric power and transmits to the grid. It mainly consists of solar array, PV combiner box, PV grid-connected inverter, metering and control devices, and grid-connection system. The grid-connected inverter is one of the key equipments in the PV grid-connection system, and it is responsible for making the highest power output by solar cell panel, also converts the output DC electric energy to AC electric energy and transmits it to the power grid.
PCS-9563 series PV grid-connected inverter consists of advanced IGBT controlled inverter, protection & control equipment and I/O switchgear etc. The system power capacity portion is designed in modularized structure featuring easy extension, convenient installation and maintenance, optimal layout, and less land occupation. The system control portion is based on the professional control & protection platform featuring abundant hardware resources, complete software functions, and flexible configuration of control/operation parameters, to maximally meet the extension demand of on system flexibility and extensibility.
Soft grid-connected control
The control system can accurately control the inverter output voltage in real-time based on the detected grid voltage and eliminate dynamic/static error to realize impulse-free grid-connection.
Maximum Power Point Tracking (MPPT) control
The system can search the maximum Power Point automatically based on the collected PV cell information, and control the real-time tracking of inverter to achieve the maximum power efficiency.
Dynamic reactive power control and compensation
In case of voltage drop in the grid, the control system can provide automatic reactive power compensation to maintain the grid voltage based on the voltage dip and duration.
The system can rapidly detect the occurrence of islanding and handle it according to the preset strategy.
Low voltage ride through (LVRT) operation
The PCS-9563 inverter can maintain grid-connection operation and realize LVRT in case of low voltage fault in the grid.
Power quality (PQ) control
The PV inverter is designed with grid-connection power optimization stability to ensure power quality.
Various operating modes
The PCS-9563 has three working modes—Standby, Run and Stop, two self-check statuses—Normal and Fault, several running control modes—PQ control, Voltage Frequency control and Low voltage ride through (LVRT) etc, and several auto control logics—Auto run, Auto stop, Emergency stop etc.
The PCS-9563 PV grid-connection inverter is designed with auto grid connection and manual control is not required. The inverter automatically detects the DC/AC system data in standby mode and automatically shifts to ‘Run’ mode for grid connection when the running conditions are fulfilled. It tracks the PV array Maximum Power Point (MPP) in real-time and maintains the maximum power output during running.
Auto fault processing
During grid-interconnection operation, the inverter detects the self-operation condition and the status of PV array and AC grid in real-time. Once any fault or abnormal condition is detected in the PV power generating system, the inverter will stop running, send out alarm signals and enter fault emergency stop mode. The detailed fault information will be displayed on the LCD of control devices. The inverter will continuously detect the system status in fault mode and automatically restore running after the system fault is cleared for 5 minutes.
Product testing and certification
The PCS-9563 inverter has passed the LVRT field test by SGEPRI and Qinghai Electric Power Research Institute in Qinghai PV Power Station. Furthermore, the inverter of PCS- 9563 has passed the test and got the certificates from TUV, CQC and NESC.
High reliable and long-life system design
The primary/secondary components of the inverter have good quality and long operation life. The component selection, power design, and heat dissipation design are all based on high altitude and extreme adverse conditions with margin to ensure the reliable system operation and working life. The inverter adopts modular design to ease installation and maintenance, including IGBT module and other major equipment. The large capacity IGBT modules are used to reduce parallel connections and increase equipment reliability. The optical triggering method has strong anti-interference capability and the patented heat dissipation scheme is employed to achieve high reliability and efficiency.
High-performance and reliable control devices
The control & protection devices features well performance, high reliability and mature hardware/software technologies. The core controller is equipped with the most advanced floating controller which has advantages of high main frequency, large memory capacity, and high computation and control accuracy. The control system fully supports IEC61850 and IEC60870-5-103 etc. The equipment uses integrated front panels and enclosed rack that it can protect against dust and ensure the safe and reliable operation of control system during the service life of PV power station.
High power quality
The grid-connection power quality controlled by PCS-9563 is far higher than that defined in the relevant codes and standards. In the certified test by CGC-SOLAR, both the total harmonic distortion of voltage (Uthd) and current (Ithd) are smaller than 2%, the voltage on connected network is even smaller than 1% at rated power.
Complete and reliable protection functions
PCS-9563 system has inherent protection for IGBT modules by detecting abnormal dv/dt and di/dt in IGBT and blocking the triggering pulse instantly. As a result, it can ensure safe and reliable operation or rapid and safe shutdown even in severe environment.