1、 Product Overview:

The YH series DC screen provides power for controlling loads, power loads, and DC emergency lighting loads, and is the foundation of contemporary power system control and protection. The DC screen consists of an AC distribution unit, a charging module unit, a step-down silicon chain unit, a DC feeding unit, a distribution monitoring unit, a monitoring module unit, and an insulation monitoring unit. It is mainly used in small and medium-sized power plants, hydropower stations, various substations, and other users who use DC equipment (such as petrochemicals, mines, railways, etc.) in the power system. It is suitable for switch opening and closing, as well as instruments, meters, relay protection, and fault lighting in secondary circuits. DC screen is a new type of digital control, protection, management, and measurement DC system. The monitoring host is highly integrated and adopts a single board structure (All in one), which includes functions such as insulation monitoring, battery inspection, grounding line selection, battery activation, silicon chain voltage stabilization, and microcomputer central signal. The host is equipped with a large LCD touch screen, and various operating states and parameters are displayed in Chinese characters. The overall design is convenient and simple, with a user-friendly interface that conforms to user habits. The DC screen system provides powerful functions for remote detection and control, and has remote control, remote adjustment, telemetry, remote signaling functions, and remote communication interfaces. Through a remote communication interface, the operating parameters of the DC power system can be obtained remotely, and the operating status and settings can also be set and modified through this interface to meet the requirements of power automation and unmanned substations in the power system; Equipped with standard RS232/485 serial interface and Ethernet interface, it can be easily integrated into the power station automation system.

2、 Characteristics of YH series DC screen system:

① High reliability:

Adopting modular design with switch mode power supply and N+1 hot backup.

The charging module can be equipped with hot swapping, greatly reducing the average maintenance time.

The power bus and control bus can be directly powered separately by the charging module and can be backed up through a voltage reduction device.

Hardware low tolerance autonomous current sharing technology, with an output current imbalance between modules of less than 5%.

Reliable lightning protection and electrical insulation measures, insulation monitoring devices can monitor the insulation status of the system in real time, ensuring system and personal safety.

The system design adopts international standards such as IEC and UL, ensuring sufficient reliability and safety.

② High intelligence:

The monitoring module adopts a large screen LCD Chinese character display and sound and light alarms.

Parameter settings for various parts of the system can be made through the monitoring module. The module has the function of smoothly adjusting the output voltage and current, and has the function of compensating for battery charging temperature.

It has multiple extended communication ports and can be connected to various external intelligent devices (such as battery testers, insulation monitoring devices, etc.).

The combination of modern power electronics and computer network technology provides support for "telemetry, remote control, remote signaling, and remote adjustment" of power systems, achieving unmanned operation.

Automatic management and protection of batteries, real-time automatic detection of battery terminal voltage, charging and discharging current, and intelligent control of battery float charging. It is equipped with sound and light alarms for battery overvoltage, undervoltage, and charging overcurrent.

The system adopts monitoring devices with built-in insulation monitoring, battery detection, grounding line selection, battery activation, silicon chain voltage regulation, central signal and other functional units, greatly facilitating user use; The system adopts a unique "one wire connection" wiring technology, which greatly facilitates the on-screen wiring of high-capacity DC systems and facilitates user maintenance.

The charging module adopts natural cooling method, which greatly improves the average time between failures and can be used in relatively harsh environments;

The charging module can be plugged and unplugged with power, significantly reducing the average maintenance time;

Adopting international soft switching technology, the main components are high-quality products;

Hardware low tolerance autonomous current sharing technology, with output current imbalance between modules better than ± 5%;

Reliable lightning protection and high electrical insulation protection measures, with insulation monitoring devices monitoring the insulation status of the system in real time to ensure system and personal safety;

The monitoring module adopts a large screen LCD touch screen display and human voice alarm;

The monitoring program adopts an object-oriented design concept and modular programming, which is conducive to program maintenance and upgrading;

The monitoring module can be used to set the parameters of various parts of the system, with detailed online help functions;

Equipped with advanced functions such as smooth adjustment of output voltage and current, and automatic temperature compensation for batteries;

Combining modern power electronics technology with computer technology to achieve "telemetry, remote control, remote signaling, remote adjustment" of power systems and unmanned operation;

● Automatic management and protection of batteries, real-time monitoring of battery terminal voltage, charging and discharging current, and control of battery equalization and float charging. Equipped with sound and light alarms for battery overvoltage, undervoltage, and charging overcurrent.

The device can provide program support through public telephone lines to achieve remote maintenance diagnosis - DC screen monitoring module.

3、 Main technical parameters

3.2.1 AC power supply device

(1) AC input voltage: three-phase 380V ± 20%

(2) Rated frequency: 50Hz ± 1%

(3) System grounding method: TN-S

3.2.2 DC power supply device

(1) AC input voltage: three-phase 380V ± 20%

(2) Rated frequency: 50Hz ± 1%

(3) System grounding method: TN-S

(4) Rated DC output voltage: DC220V

(5) Voltage ripple coefficient ≤ 0.5%

(6) Voltage stabilization accuracy ≤± 0.5%

(7) Steady current accuracy ≤± 1%

(8) Noise ≤ 55dB (1 meter away from the device)

(9) Comprehensive efficiency ≥ 90%

3.2.3 Design lifespan

Design lifespan: 30 years.

3.3 Technical performance and requirements of AC power supply device

3.3.1 Operation mode

The AC power supply device adopts a single busbar connection, and two power supplies are introduced from two sections of the AC400V busbar of the distribution transformer in this station as the incoming power supply of the AC power supply device. A dual power automatic switching device is installed.

3.3.2 AC incoming circuit breaker

The two incoming circuit breakers should be selected from reliable brands, equipped with electric operating mechanisms, shunt and voltage loss release devices, as well as phase loss protection and voltage detection relays. The overcurrent protection of the incoming circuit breaker should have the function of interlocking automatic switching device. The incoming line and bus tie circuit breaker adopt 4 levels; Rated capacity of circuit breaker: 100A; The short-circuit current breaking capacity of the circuit breaker shall not be less than 40kA.

3.3.3 AC feedback loop

The power distribution adopts busbar mode, and each output is equipped with high breaking circuit breakers with alarm auxiliary contacts. Each output is configured with signal indicators and other components, and the signal lights are energy-saving. The short-circuit current breaking capacity of the feedback circuit breaker shall not be less than 10kA, and reliable brand products shall be selected for the circuit breaker.

3.3.4 Automatic device

Each communication panel is equipped with a dual power automatic switching device. When one power supply fails, it automatically switches to the other power supply. The dual power automatic switching device can be manually or automatically switched on and off. The dual power automatic switching device must have a 3C certification report. The rated current shall not be lower than that of the incoming circuit breaker; The number of poles is 4; The electrical lifespan shall not be less than 6000 cycles, and the mechanical lifespan shall not be less than 10000 cycles.

3.3.5 Signal

Signals include two types: fault signals and working status indication signals.

3.3.5.1 Work status indication

Connect all power sources

Two power supply input

Mother Union Investment

Position signals of each feeder switch

3.3.5.2 Fault Signal

One power supply loses voltage

Overcurrent tripping of one power supply

Voltage loss of two-way power supply

Overcurrent tripping of two-way power supply

Fault in the mother coupling automatic switching device

3.3.6 Measurement Meter

There should be a voltmeter for one incoming power supply, a voltmeter for two incoming power supplies, and a three-phase ammeter on the panel.

3.4 Technical performance and requirements of DC power supply device

3.4.1 System composition

The DC power supply device consists of a charging device, a set of batteries, a feeder switch, an automatic (manual) voltage regulating device for the DC bus (the voltage regulating device is configured with two sets of main and backup), a microcomputer insulation monitoring device, and an intelligent monitoring unit. The charging device adopts high-frequency charging modules and hot redundancy (N+1) parallel configuration. When one charging module fails, it automatically switches to the backup module and displays a fault alarm on the touch screen, giving the reason for the alarm. The capacity of the charging device should meet the requirements of the system's regular load and battery charging current

The AC side of the charging device is connected to a three-phase AC380V power supply through an AC power supply device. During normal power supply, the charging device charges or float charges the battery pack, while providing power to the regular DC load of the entire station, which is supplied by the battery to the impact load. After the communication loses power, the battery supplies power to all loads inside the station (including regular loads and impact loads).

The DC bus adopts a single bus segmented connection method.

3.4.2 Charging device

The high-frequency switching power supply modular charging device is adopted, and its functional requirements are as follows:

The device should have charging (constant current, limited current and constant voltage), float charging, balanced charging, automatic switching of operation mode, autonomous current sharing function, and have soft start characteristics. The soft start time can be set according to user requirements.

The frequency of the switch power module is 20~300kHz.

The charging characteristics of the charging device should meet the requirements of the battery's characteristics.

The main technical parameters of the charging device should meet the requirements in Table 2.

3.4.2.1 Voltage and current limiting characteristics

3.4.2.1.1 Voltage limiting characteristics

1) Voltage limiting setting range: can be selected within the range of 105% to 145% of the rated voltage;

2) When the floating charging device operates in steady current charging mode, the device should be able to automatically limit the voltage and switch to constant voltage charging operation when the output DC voltage reaches the set voltage limit. The voltage stabilization accuracy of the voltage limiting characteristic should meet 1.5 times the requirements in Table 2

3.4.2.1.2 Current limiting characteristics

2) Current limiting setting range: 50% to 110% of the rated output current;

2) When the charging float charging device operates in a stable voltage charging mode, it should have charging current limiting and output total current limiting functions. If the load current exceeds the set value of the current limiting, the device should be able to automatically limit the output current, and the output current should immediately drop below the set value.

3.4.2.2 Stable voltage regulation range

1) Voltage regulation range in float charging state: 95% to 115% of rated voltage;

2) Voltage regulation range under balanced charging state: 105% to 120% of rated voltage.

3.4.2.3 Efficiency

The efficiency of the high-frequency switching power supply type charging device should be ≥ 94%.

3.4.2.4 Requirements for current equalization

When multiple high-frequency switching power supply modules of the same specification and model are operated in parallel, their current imbalance should meet the requirements of Table 3.

High frequency switching power module output current

>50％In

（10%～50%）In

Uniformity

≤±5%

≤±10%

3.4.2.5 Power factor

When the output power of a single module is ≥ 1500W, the power factor should be>0.95;

When the power output of a single module

3.4.2.6 Other requirements for charging module

(1) It should be able to operate independently without the monitoring unit.

(2) Compensate for battery charging voltage based on temperature changes.

(3) It has protective measures such as overcurrent, overvoltage, short circuit, phase loss, high/low AC voltage shutdown, etc.

(4) Can be plugged and unplugged with power.

(5) There are good ventilation, heat dissipation, dust and moisture prevention measures.

(6) The function of preventing overcharging of the battery.

3.4.3 Functional requirements for DC power supply devices

Load capacity and continuous power supply

(1) The equipment operates under normal float charging conditions. When providing an impulse load, it is required that the voltage on its DC bus should not be lower than 90% of the DC nominal voltage during the impulse discharge time.

(2) During normal operation of the equipment, if the AC power supply suddenly interrupts, the DC bus should continue to supply power, and the fluctuation of the DC bus should not be lower than 90% of the nominal DC voltage.

3.5 Function of Voltage Adjustment Device

Adopting a primary and backup automatic voltage regulation device, when the main voltage regulation device fails, the backup voltage regulation device will automatically activate and send alarm signals to the local and remote areas. The voltage regulation value of each level is less than ± 3% of the rated voltage, and the voltage regulating device should have manual and automatic voltage regulation functions. The DC bus voltage during charging should not exceed 10% of the rated voltage.

3.6 Insulation Supervision Requirements

Adopting a microcomputer based insulation monitoring device, the insulation monitoring level should not be less than 50k Ω. The insulation monitoring device should be able to measure and judge the insulation resistance of the busbar to ground and the insulation condition of each feeder branch. When a grounding fault occurs in the DC system of the equipment (positive grounding, negative grounding, or both positive and negative grounding), and the insulation level drops beyond the normal range, a light alarm signal should be issued locally and uploaded to the comprehensive automation system. The device should be able to correctly indicate the faulty feeder branch and grounding polarity, directly display the bus to ground resistance, and manually set the threshold for grounding resistance.

3.7 Voltage Monitoring Requirements

The voltage insulation monitoring device should be able to monitor the voltage of the control bus and issue alarm signals locally and remotely when the DC bus voltage is higher or lower than the specified value. The voltage insulation monitoring device should be equipped with instruments or LCD screens with direct reading function. The return coefficient of overvoltage relays should not be less than 0.95, and the return coefficient of undervoltage relays should not be greater than 1.05.

3.8 Fault alarm requirements

When the AC power supply loses voltage (including phase failure), the charging float charging device malfunctions, or the battery pack fuse (circuit breaker) trips, the equipment should be able to reliably issue an alarm signal.

Functional requirements for monitoring unit

3.9 Control Function

The monitoring unit adopts a microcomputer type product and should have control programs for charging, long-term operation, and AC interruption. According to the charging characteristic curve and characteristics of the battery, the charging module should be controlled to automatically complete the charging and charging mode conversion of the battery. Effectively control the charging voltage and current of the battery to extend its lifespan.

3.10. Measurement display function

The monitoring unit should have measurement display function. The device display should be able to display AC incoming voltage, output voltage and current of the charging device, DC bus voltage and current, float charging voltage, charging current, battery pack voltage and output current, as well as insulation voltage, etc. Within the measurement range, the accuracy of the voltage measurement is ± 0.5% for a four and a half meter, ± 1% for a current measurement, and the accuracy of the additional shunt is not less than level 0.5.

3.11 Protection and alarm functions

The monitoring unit should be able to set and modify its parameters. The monitoring unit protects the equipment from the following conditions and issues alarms: abnormal AC voltage, charging float charging device failure, abnormal bus voltage, abnormal battery voltage, bus grounding, etc.

3.12 The monitoring unit should have self diagnosis and self recovery functions after power failure.

Feed out circuit

Each output is equipped with a high breaking DC circuit breaker, with alarm auxiliary contacts and signal indication components. The short-circuit current breaking capacity of each feeder circuit breaker shall not be less than 10kA.

Signal display

The signal includes two types: working status display signal and fault status display signal.

The working status should have at least the following indications:

Connect one power supply and connect two power supplies to the position signals of each feeder switch

The fault status indication signal shall have at least the following contents:

L incoming line voltage loss fault floating charging fault DC bus voltage too high DC bus voltage too low

DC power supply insulation drop, battery voltage low limit, battery fault, short circuit fault in the feeding circuit

The normal/fault signals of the DC system should not only be displayed on this panel, but also transmitted to the comprehensive automation system of the substation through digital communication. The specific signal quantity will be determined during the design liaison. The local signal should be able to reset locally or automatically reset after the fault disappears, but the historical records displayed in Chinese should be retained, and the fault display should be equipped with a light test

Verify button.

3.13 Structural Requirements

3.13.1 Requirements for Components

The power module should be certified, have mature usage experience, and provide valid proof documents.

Wires, wire colors, indicator lights, buttons, cable trays, and painting should all comply with the relevant industry standards. The wire should be selected as low smoke, halogen-free, flame-retardant soft copper wire, and selected according to the long-term continuous working system at room temperature of 40C. The cross-sectional area of the two incoming lines should meet the requirements of long-term working current. The DC busbar should be selected as copper busbar, and the cross-sectional area must meet the system capacity requirements. All wire numbers are standardized and machine printed for clarity and durability

The measuring range of the panel configuration meter should be within the measurement range, and the measured value should be below 85% of the full range.

DC circuit breakers and fuses should have a coordination level difference of more than 2 levels in the ampere second characteristic curve.

Fuses and circuit breakers in important locations should be equipped with auxiliary contacts.

The feeder switch should be connected in parallel to the DC busbar and should be easy to maintain and replace.

The connectors of similar components should have universality and interchangeability, reliable contact, and easy insertion and removal. The contact resistance, insertion and extraction force, allowable current, and service life of the connector should meet the requirements of the current industry standards.

3.13.2 Panel layout

The layout of the panel should be neat, concise, and aesthetically pleasing. The front and back of each panel adopt a full door opening method, with tempered glass single door on the front and steel plate double door on the back.

The upper part of the communication panel is equipped with measuring meters, fault display devices, indicator lights, voltage conversion measurement switches, incoming power selection switches, etc. The installation height should consider the convenience of operation. The position signals of each feed switch should correspond to the switch for maintenance personnel to operate and inspect. The lower part of the panel door is equipped with a power supply switch, and each switch should have a circuit name at the bottom. The specific arrangement will be determined during the design liaison.

The upper part of the DC panel is equipped with measuring meters, fault signal indicator lights, buttons, voltage measurement switches, rectifier device operation manual/automatic selection switches, bus manual/automatic voltage regulation switches, etc. The lower part of the panel door is equipped with a power supply switch, and each switch should have a circuit name at the bottom.

3.13.3 Electrical clearance and creepage distance

The electrical clearance and creepage distance between two live conductors inside the cabinet, as well as between a live conductor and an exposed non live conductor, shall meet the requirements of relevant standards.

3.13.4 Electrical insulation performance

insulation resistance 

The insulation resistance of the following parts shall be measured using a testing instrument with an open circuit voltage as specified in Table 6, and the following requirements shall be met:

The insulation resistance between each independent live circuit inside the cabinet and the ground (metal frame), between each independent live circuit, and between the DC busbar and voltage busbar inside the cabinet, when all other connecting branches are disconnected, shall not be less than 10M.

Dielectric strength

Between each independent live circuit in the cabinet and the ground (metal frame), between each independent live circuit, and between the DC busbar and voltage busbar in the cabinet, when all other connecting branches are disconnected, the working voltage should be able to withstand the power frequency test voltage specified in Table 6 for 1 minute, and there should be no breakdown or flashover during the test.

3.13.7 Moisture and heat resistance performance