Uninterruptible Power Supply (UPS)

The power UPS uninterruptible power supply, together with the power DC operating power supply system, forms a dedicated uninterruptible power supply for power plants and substations, supplying power to microcomputers, communication, carrier waves, accident lighting, and other equipment that cannot be powered off. Taking power from existing DC operating power sources in power plants or substations does not require a separate battery pack like conventional uninterruptible power supplies (UPS), thus avoiding duplicate investment in batteries, reducing system maintenance, and lowering operating costs.

1、 Working principle:

The working principle and output characteristics of an uninterruptible power supply (UPS) are exactly the same as those of a traditional UPS. However, due to its connection to a DC operating power system, its DC input characteristics must meet the specific requirements of the power system. Uninterruptible Power Supply (UPS) is designed for the power industry such as power plants and substations. In power systems such as power plants, DCS (distributed control system), monitoring systems, automation instruments, dispatch communication systems, microcomputer systems, and other core equipment have high requirements for power supply quality and reliability, requiring dedicated UPS power supply. The vast majority of these loads are single-phase loads.

The uninterruptible power supply (UPS) system generally consists of three parts: the UPS host, bypass voltage regulator cabinet, and output feeder cabinet (which can also be combined into one for low power).

1. Uninterruptible power supply (UPS) main cabinet: input and output isolation transformer, rectifier, inverter, static bypass switch, bypass switch, check diode;

2. Bypass isolation voltage regulator cabinet: bypass isolation transformer, bypass voltage regulator, manual/bypass maintenance switch;

3. feeder cabinet: circuit distribution unit, monitoring instrument, control switch, and signal indication, etc;

2、 Types of Uninterruptible Power Supply (UPS):

1. Type of power supply for power plant system:

(1) DC operating power supply: The DC power supply operating system, abbreviated as the DC screen, provides power for controlling loads, power loads, and DC accident lighting loads, and is the foundation of power plant system control and protection;

(2) Hydrogen production system power supply;

(3) Secondary acid electrolysis power supply;

(4) Power UPS power supply: Power UPS power supply provides reliable backup power support for core equipment such as power system DCS (distributed control system), monitoring system, automation instrument, dispatch communication system, microcomputer system, etc;

(5) Excitation power supply;

(6) Communication power supply;

(7) High voltage variable frequency power supply;

(8) High pressure desulfurization power supply,

2. Substation:

(1) DC operating power supply

(2) Communication power supply

(3) Inverter power supply

(4) Power UPS power supply

(5) Combination power supply

(6) Monitoring power supply

3、 Protection plan:

The dedicated power supply for uninterruptible power supply (UPS) adopts a 1+1 redundant power supply system, which is an industrial grade AC protection power supply manufactured with advanced technology for power system application loads and environments. It can fully meet the reliability requirements of power supply for loads such as power DCS system.

Advantages of the plan:

(1) A professional UPS tailored for the power industry, adapted to the harsh power grid environment within the industry, not only meets the load needs of the power industry, but also eliminates the need for users to worry about three-phase imbalance of the load.

(2) The 1+1 redundant parallel operation mode adds another safety lock to the already reliable power supply system, meeting the extreme needs of power industry users for high reliability indicators of UPS.

(3) By fully utilizing the 220V/110V high-capacity battery pack in the power industry, the backup time of UPS can be maximized, and the installation space and initial investment of the battery pack can be saved.

(4) Optional bypass isolation transformer can achieve complete isolation between input and output, and ensure that the zero ground voltage of the output is less than 1V.

(5) Rich dry contact monitoring signals can be incorporated into the DCS monitoring system of the power plant itself; Report any issues promptly to facilitate real-time monitoring of UPS by on duty personnel.

4、 Basic components of uninterruptible power supply (UPS):

The uninterruptible power supply (UPS) mainly consists of the following systems, which use two-stage conversion. The first stage transformation uses a rectifier (AC-DC),

Convert the AC power that has passed through the input isolation transformer into stable DC power. The second stage transformation (DC-AC) uses an inverter power supply to convert the rectified output DC power into sine wave AC power, which is isolated and output to the load.

Isolation section: The input isolation transformer separates the AC input from the DC, protecting the DC side equipment; The output isolation transformer separates the AC and DC inputs from the AC output to protect the load end equipment. Dual isolation ensures true and complete electrical isolation of the DC input, AC input, and AC output ports.

Rectification section: Transforms the input AC mains power into stable DC and sends it to the inverter equipment.

Inverter section: Transforms an external DC or rectified DC power supply into a stable sine wave AC power supply.

Control part: Control the inverter power supply to follow the reference mains power and maintain the same phase and frequency, automatically adjust, and make the power supply operate or protect within the specified range according to the set protection value.

Display section: LCD and LED status simulation panels are used to accurately reflect the equipment's operating status and fault information.

Switching section: Use relays or static electronic switches to automatically switch between bypass, mains, and inverter output power sources.

5、 Basic introduction:

UPS uninterruptible power supply is a third-generation power frequency pure online intelligent uninterruptible power supply (UPS) developed with new digital technology to meet the reliability requirements of power supply for power grid environment, network monitoring, network systems, medical systems, etc., and to overcome the increasingly harsh power grid environment caused by centralized power supply of medium and large computer network systems. A DC power supply is a device that maintains a stable and constant current in a circuit. Such as dry batteries, batteries, DC generators, etc. Uninterruptible power supply (UPS) and DC power supply are important power supply guarantee equipment for enterprises.

1. Traditional maintenance management includes:

(1) Daily appearance inspection, regular replacement of batteries, filter capacitors, fans and other vulnerable parts, and battery activation during major repairs;

(2) Transform or adopt replacement equipment and use advanced tools to test battery performance. This management method has high investment costs for enterprises, a large workload for maintenance personnel, difficulty in real-time grasping equipment operation status and key data, and low ability to prevent equipment accidents. Implementing online maintenance management can avoid the shortcomings of traditional methods and achieve good benefits.

2. System composition

(1) The main control station (backend) consists of a monitoring station, engineering maintenance station, system interface, etc., and uses management analysis software to process the received data and publish it through the web. Engineering maintenance personnel can log in to the server to view the operational status of all online equipment in the entire factory, as well as complete historical and real-time data analysis and statistics.

(2) The on-site equipment control station (ES) can choose a monitoring function instrument or an equipment operation status information acquisition instrument (EII) according to the needs of the on-site equipment. EII communicates with smart devices such as energy meters, battery acquisition modules, DC screens, UPS, etc. through RS-232/485 ports, converts monitoring data into data packets that comply with communication protocols, connects to the local area network, and transmits them to the main control room server. The independent and complete ES includes the following parts.

(2.1) System host. It consists of a downlink serial port channel, a data processor, a display, and an uplink serial port channel. The downlink serial port channel accesses the battery voltage acquisition module through the RS-485 bus, collects data, manages the voltage acquisition module, and the data processor completes data decompression, calculation, and storage management. It sends a portion of the processed data to the display, while the other portion is sent to the protocol processor through the uplink serial port channel or to the upper layer management system.

(2.2) Data collection module group. Data collection requirements and corresponding collection instruments can be determined according to user needs, generally composed of battery voltage collection modules, current, temperature, power, etc. The modules have good isolation, strong insulation, high reliability, and safety. Data collection can be grouped, and each module can collect voltage from a certain number of batteries. It can be equipped with current and temperature sensors, and modules are generally connected to the system host using RS-485.

(2.3) Protocol processor. An interface board with protocol processing programs that handle various communication protocols. Can achieve:

① Encode, package, and send the battery voltage, current, temperature, and other information sent by the host to a remote server according to the agreed protocol;

② Decode the remote control and remote adjustment instructions issued by the remote server and send them to the host for real-time control.

(2.4) Discharge module. It can quickly measure the DC internal resistance of the battery, instantly test the battery performance, and the high-power discharge module can provide instantaneous high current impact loads.

(2.5) Remote servers. Realize computer data communication within the local area network, remotely access the on-site battery monitoring system through the local area post, receive and analyze data, and publish data through a web server.

(3) Each substation (collection and monitoring station) of communication network networking on-site equipment uses optical fiber as the data communication backbone, forming a local area network for online monitoring of uninterrupted power supply (UPS) and DC power supply throughout the factory.

3. Composition

The uninterruptible power supply (UPS) system consists of five parts: main circuit, bypass, battery and other power input circuits, rectifier (REC) for AC/DC conversion, inverter (INV) for DC/AC conversion, inverter and bypass output switching circuit, and energy storage battery.

The voltage stabilization function of its system is usually completed by a rectifier. The rectifier device uses a thyristor or high-frequency switching rectifier, which has the function of controlling the output amplitude according to the changes in external electricity. Therefore, when the external electricity changes (which should meet the system requirements), the output amplitude of the rectifier voltage remains basically unchanged.

The purification function is completed by the energy storage battery. Due to the inability of the rectifier to eliminate instantaneous pulse interference, there are still interference pulses in the rectified voltage.

In addition to its function of storing direct current energy, energy storage batteries are like a large container capacitor connected to a rectifier. The size of its equivalent capacitance is directly proportional to the capacity of the energy storage battery. Due to the fact that the voltage at both ends of the capacitor cannot suddenly change, it utilizes the smooth characteristics of the capacitor to eliminate pulse interference, playing a purification function, also known as shielding interference.

The stability of frequency is achieved by the converter, and the frequency stability depends on the stability of the oscillation frequency of the converter.

For the convenience of daily operation and maintenance of uninterruptible power supply (UPS) systems, a system working switch, an automatic bypass switch for self checking faults in the host, and a maintenance bypass switch have been designed for switch control.

When the voltage of the power grid is working normally, power the load as shown in the figure, and at the same time, charge the energy storage battery; When there is a sudden power outage, the UPS power supply starts to work, and the required power for the load is supplied by energy storage batteries to maintain normal production; When the load is severely overloaded due to production needs, the grid voltage is rectified to directly supply power to the load.