Waste heat power generation is a technology that generates electricity using residual heat produced during industrial production, widely applied in high-energy-consuming enterprises such as cement plants, steel mills and chemical plants, where Generator Relay Protection ensures unit safe operation.
Waste heat generating units are generally connected to the enterprise power system via 10kV or 35kV busbars for grid-connected operation, where reliable generator relay protection is essential for safe operation.
Centralized Panel-mounted Equipment for Generator Relay Protection
Generator Protection & Control Panel
Types of distributed generator protection relays and function
| Protection Device | Main Functions | Operation Mode |
|---|---|---|
| Generator Differential Protection | Differential high-speed tripping, Percentage differential (2nd harmonic restraint, CT disconnection blocking) | Instant tripping |
| Generator Backup Protection | Composite voltage restrained overcurrent, Negative sequence overcurrent, Overload, Overvoltage, Undervoltage, Overfrequency, Underfrequency, Reverse power, Loss of excitation, Stator earth fault | Delayed tripping / Alarm signal |
| Rotor Earth Fault Protection | Rotor single-point earth fault, Rotor two-point earth fault | Alarm / Tripping |
| Generator Measurement & Control Device | Acquisition and remote transmission of voltage, current, power, frequency and other parameters | Real-time monitoring |
It should be noted that generator pole slipping protection relays are recommended for generating units with a capacity of 300 MW and above.
Installation of Generator Relay Protection is generally not mandatory for medium and small generator units, and relevant faults can be dealt with manually by operators.
Generator protection relay codes
ANSI:21,32,40,46,49,50/51,59,59N,64G,78,87G
Generator relay protection setting calculation instruction
Generator differential protection relay setting calculation determines the operating values and time delays of differential, overcurrent, overvoltage, loss-of-excitation and other protection devices by calculating fault current and voltage based on generator rated parameters, system short-circuit capacity and operation specifications, so as to ensure selectivity, quick-action performance and sensitivity.
Supervisory Control and Data Acquisition (SCADA)
Data Acquisition: Real-time collection of generator operating parameters including voltage, current, power, frequency and temperature.
Remote Control: Remote operations such as generator start/stop, circuit breaker switching and excitation regulation.
Event Recording: Log switch status changes, protection trips and operation records, with SOE function supported.
Curves & Reports: Generate load curves, operation reports and fault reports.
Alarm Management: Trigger audible and visual alarms when parameters exceed limits or equipment malfunctions.
Synchronization Panel
When a generator is connected to the grid, three conditions must be met: equal voltage, equal frequency and consistent phase. The synchronizing panel is the key equipment to realize this function.
Panel Cabinet Composition
Microcomputer Automatic Synchronizing Unit (Model 1201)
Synchronism Check Relay
Voltage Transformer
Frequency Converter
Manual Synchronizing Operating Components
Cabinet Body and Accessories
Functional Features
Automatic Synchronizing: The unit automatically tracks grid voltage and frequency, and issues a closing command when synchronizing conditions are satisfied.
Manual Synchronizing: Supports manual operation and serves as the backup for automatic synchronizing.
Frequency Tracking: Adopts AC sampling with frequency tracking technology to improve synchronizing accuracy.
Closing Angle Control: Accurately calculates the advance time to minimize the phase difference at the moment of closing.
Communication Panel
Panel Cabinet Composition
Communication Manager: Core device for protocol conversion. It converts data from devices of different manufacturers with diverse protocols into standard protocols such as IEC 60870-5-104 and Modbus TCP.
Industrial Ethernet Switch: Builds on-site optical fiber ring networks or star networks.
Longitudinal Encryption Device: Ensures communication security of the dispatching data network.
GPS/Beidou Clock Synchronization Device: Provides a unified time reference for all secondary equipment in the substation.
Optical-Electric Conversion Module
Main Functions
Collect data from generator protection panel, excitation panel, fault recording panel and other equipment.
Transmit data to the SCADA system and power grid dispatching center.
Forward dispatching commands to each executive device.
Realize clock synchronization for all equipment in the station.
Communication Protocols
Support mainstream protocols including IEC 60870-5-101/104, IEC 61850, Modbus RTU/TCP and DNP3.0.
Fault Recording Panel
| Category | Item / Function | Detailed Description |
|---|---|---|
| Panel Cabinet Composition | Fault Recorder Main Unit | Core host device of the fault recording system |
| Panel Cabinet Composition | Analog Acquisition Module (Voltage, Current) | Module for collecting voltage and current analog signals |
| Panel Cabinet Composition | Digital Input Acquisition Module | Module for collecting switch status digital signals |
| Panel Cabinet Composition | Large-Capacity Memory | High-capacity storage device for saving fault waveform and event data |
| Panel Cabinet Composition | Data Analysis Software | Professional software for fault data processing, analysis and report generation |
| Main Functions | Waveform Recording | Automatically record voltage and current waveforms when a fault occurs, with a typical recording duration of 4 cycles before the fault and 10 cycles after the fault |
| Main Functions | Fault Diagnosis | Automatically determine the fault type and fault location based on the captured fault waveforms |
| Main Functions | Sequence of Events (SOE) Recording | Record the time sequence of protection trips and switch status changes, with a resolution up to 1ms |
| Main Functions | Data Analysis | Provide professional analysis tools including harmonic analysis, vector analysis, impedance trajectory analysis, etc. |
Excitation Panel
The excitation panel is the core equipment for controlling generator excitation current. It precisely regulates the generator output voltage, reactive power and system stability by adjusting the excitation current.
| Category | Item | Description |
|---|---|---|
| Panel Cabinet Composition | Control Unit | Adopts microprocessor or PLC to perform PID regulation, logic control and other functions |
| Panel Cabinet Composition | Power Unit | Consists of thyristor rectifier bridge, IGBT and other power devices to convert control signals into excitation current |
| Panel Cabinet Composition | Measuring Module | Real-time monitoring of generator voltage, current, power factor and other parameters |
| Panel Cabinet Composition | Human-Machine Interface (HMI) | Touch screen for parameter setting, status display and manual operation |
| Panel Cabinet Composition | Protection Circuit | Includes fuse, overvoltage protector, high-speed circuit breaker and other components |
| Panel Cabinet Composition | De-excitation Unit | Quickly cuts off the excitation circuit and absorbs magnetic field energy |
Separately Mounted Equipment
Station Service Fast Transfer Device
The station service fast transfer device is key equipment to ensure continuous power supply for auxiliary power systems. When the working power supply trips due to faults, it can rapidly switch loads to the standby power supply within 100 ms, keeping critical auxiliary machinery running without power interruption.
Motor Protection Device
Waste heat power stations are equipped with critical auxiliary machines such as circulating fans, feed water pumps, condensate pumps and cooling tower fans. Complete protection devices shall be installed for these high-voltage motors.
Line Protection Device (Tie Line Protection)
Waste heat generator units are generally connected to the 10kV or 35kV busbars of the enterprise substation via tie lines, which shall be equipped with comprehensive protection devices.
UF/UV Islanding Device
When abnormalities such as frequency drop and voltage drop occur in the power system, the islanding device operates to trip the generator circuit breaker and disconnect the waste heat generating unit from the power system, preventing fault escalation.
Commissioning Method for Secondary Equipment
Joint commissioning of secondary equipment including generator relay protection for waste heat power stations shall follow the procedures below:
The generator protection relay testing procedure firstly requires completing preparations for documents, instruments, personnel and safety measures, and then performing communication joint commissioning to verify network connectivity, consistent protocols and accurate data point lists, as well as ensure the time synchronization error of the whole station is less than 1 ms.
Then conduct joint commissioning of protection devices, including setting parameter downloading and functional tripping tests for differential protection, backup protection and non-electrical quantity protection, as well as verification of output matrix and circuit breaker operation.
After that, verify the functions of generator relay protection as well as automatic devices including synchronizing devices, fast transfer devices and excitation systems.
Carry out joint commissioning of the SCADA system to check data acquisition, remote control, alarms and event records.
Finally, perform overall group tripping tests and on-load tests for generator relay protection to confirm intact fault tripping links and correct current and voltage phases. Compile a commissioning report to record test results, problem handling details and issue a qualification conclusion.
