Photovoltaic Power Plant Secondary Equipment and System Introduction

Power secondary system: It is a system composed of relay protection, safety automatic control, system communication, dispatching automation, etc. The secondary system is an indispensable and important part of the power system. It is to realize the contact monitoring and control between people and the primary system, so that the primary system can run safely and economically. The power secondary system is a guarantee for the service of the power primary system, ensuring the safe and stable operation of the power primary system. Primary power system: refers to a system composed of generators, power transmission lines, transformers, circuit breakers and other equipment for power generation, transmission, transformation, and distribution. Secondary, relay protection and automatic devices, secondary equipment and control room layout The communication of this project adopts wireless, and the control, measurement and dispatch signals are sent to the comprehensive building through optical fiber. The photovoltaic power station electrical centralized control room and Secondary equipment room. The monitoring of the inverters, isolated step-up transformers, 35kV system, station power system, automatic fire alarm system and security monitoring system of each power generation electronic system are all centrally set in the control room. The centralized control room is equipped with a microcomputer monitoring system console, LED display screen, engineer station and operator station, monitoring host of security monitoring system and background device of automatic fire alarm, etc. The electrical equipment in the electronic equipment room includes: DC cabinets, telecontrol cabinets, network equipment cabinets and access system equipment control cabinets, etc. Control, measurement, signal monitoring method This photovoltaic power station adopts a manned computer monitoring method. The inverter measurement signal uses the power carrier to extract the signal from the low-voltage side of the isolation step-up transformer. The transformer measurement signal is connected to the Huawei PLC device through the armored 485 line, and the PLC is sent to the data collector through Ethernet!

The main scope of application of photovoltaic secondary equipment

Photovoltaic secondary equipment is mainly suitable for distributed photovoltaic power station projects. Distributed photovoltaic power generation projects are generally divided into 380V and 10KV according to the voltage level of grid connection. The general voltage level is 380V, and the low-voltage grid-connection basically does not involve any secondary products. It can usually be solved by using photovoltaic grid-connected cabinets. The common grid-connected equipment is mainly anti-islanding protection devices and online power quality monitoring devices. However, projects with 10KV grid-connected photovoltaic capacity generally between 1MWP and 10MWP need to be used for photovoltaic secondary equipment. The common secondary equipment involved in this includes photovoltaic background monitoring system, telecontrol communication screen, dispatching data network screen, photovoltaic secondary security screen, photovoltaic secondary equipment prefabricated cabin, anti-islanding protection device, power quality online monitoring device, fault Disassembly device, etc.

The following is an introduction to the main functions of these photovoltaic secondary equipment.

Generally, it is composed of a host computer, a monitor, a keyboard, a mouse, a printer, and an audio system. The function is to monitor the data in the substation in real time. At the same time, it can remotely control the closing and opening of some power station switches, adjust the parameters of electrical equipment, and so on. The photovoltaic background monitoring system is to connect the inverters, combiner boxes, irradiators, meteorological instruments, electric meters, microcomputer protection devices and other equipment of photovoltaic power plants through data lines, and use photovoltaic power plant data collectors, communication management machines, data gateways, etc. The equipment collects data and uploads it to the user server or local computer through GPRS, optical fiber, etc., so that users can view relevant data on the Internet or local computer, which is convenient for power plant managers and users to view and manage the operating data of photovoltaic power plants. It can monitor and control the battery array, combiner box, inverter, AC and DC power distribution cabinet, and other equipment in the solar photovoltaic power station in real time, and quickly grasp the operation status of the power station through various styles of charts and data. Its friendly users The interface, powerful analysis function, and perfect fault alarm ensure the completely reliable and stable operation of the solar photovoltaic power generation system.

Photovoltaic remote screen

It is generally composed of telecontrol communication devices, protocol converters, switches, lightning protection devices, etc. The telecontrol communication screen is a device for remote monitoring of plant and station information and remote removal of power grid loads invested based on the safety construction of the power grid; It is composed of moving device, communication management machine, switch, GPS time synchronization device, digital channel lightning protector, analog channel lightning protector, screen cabinet and accessories and other equipment. The substation telecontrol communication system refers to a system that monitors and controls the production process in a wide area. It includes all equipment and functions such as the collection, processing, transmission, display, and execution of necessary process information. The equipment constituting the telecontrol system includes the station-side telecontrol device, the dispatching-side telecontrol device and the telecontrol channel. Photovoltaic dispatch data network is used to transmit power grid automation information, dispatch command instructions, relay protection and safety automatic device control information, etc. This service is completed by the router, the power vertical encryption equipment is responsible for encrypting the data, and the switch is the supporting equipment. Dispatching data network equipment is generally composed of 2M services and 100M services, each group is equipped with 1 router, 2 vertical encryption devices dedicated to electric power, and 2 switches. The router is responsible for data service transmission, two vertical encryption devices divide real-time information area and non-real-time information area, and one vertical encryption device is matched with one switch for business processing. A complete set of dispatching data network equipment for the power main network is generally configured with 2 routers, 4 vertical encryption devices dedicated to power, and 4 switches.

Photovoltaic secondary security screen

The secondary security screen is to ensure the security of the power information system, power real-time closed-loop monitoring system and dispatching data network. , secondary system accidents or large-scale power outages and other accidents. It is a complex system composed of business systems widely distributed in generators and substations at all levels geographically through close or loose connections. Its support environment includes heterogeneous computer systems and local area networks of dispatching networks and plant stations, and Including the power system industry extranet connected to various local area networks. Therefore, the security of power information system is different from the security of pure computer system or communication system. In order to ensure the security of power system business, it is necessary to consider the interaction between widely distributed and interconnected business systems and basic support systems such as computers and communications.

Photovoltaic secondary equipment prefabricated cabin

The secondary equipment prefabrication cabin is composed of prefabrication cabin, secondary equipment screen cabinet, secondary equipment and so on. The prefabricated cabin of the secondary equipment integrates the photovoltaic secondary equipment, and completes the related wiring between the screen cabinets in the prefabricated cabin, and transports it to the project site as a whole, and realizes the docking with the primary equipment and civil engineering on site. The secondary equipment of the prefabricated cabin combination is generally modularized according to the characteristics of the secondary system and the primary objects served

Other equipment

The anti-islanding protection device is mainly used for the islanding phenomenon caused by abnormal voltage or frequency in the photovoltaic power station, and predicts the occurrence of the phenomenon in advance, and quickly cuts off the grid-connected point switch, so that the photovoltaic power station and the grid are quickly separated. At the same time, it can play a role of intelligent grid connection. The power quality online monitoring device mainly solves the power quality problems such as waveform distortion, voltage fluctuation and flicker, and three-phase unbalance due to the sharp increase of power load, especially the continuous growth of impact and nonlinear load capacity. The fault disconnecting device is mainly used to monitor the voltage and current of the grid-connected point of power generation. When a fault occurs, the device makes logical judgments in time, reacts accurately, and quickly trips the grid-connected switch. The three-in-one photovoltaic box change measurement and control device is used to collect the data of combiner boxes, inverters, transformers and other equipment, and transmit the data to the telecontrol communication screen after processing. At the same time protect the main transformer equipment from damage. The microcomputer protection device protects the primary equipment such as the switchgear of the photovoltaic booster station. When the current, voltage, and frequency are abnormal, it can quickly cut off the faulty circuit to ensure that the primary equipment is not damaged and avoid electrical accidents. Telecontrol communication equipment is used to collect information of secondary equipment such as electrical protection devices and instruments, and process the collected information into the communication method we need, and then transmit it to the background monitoring system. The dispatching data network equipment transmits the telecontrol data to the dispatching supervision department of the power supply bureau.