Description
Overview of Voltage and Frequency Control System
- The ASF-442H Frequency and Voltage Stabilization Control Unit is a core device for voltage and frequency control in power system, control of frequency and voltage, and professional frequency and voltage control.
- It is designed to disconnect specified power equipment such as transmission lines or unit transformers when system frequency or voltage drops, thereby ensuring the safe and stable operation of the power grid.
- It is a load shedding controller.Its main functions include under frequency load shedding and under frequency and undervoltage load shedding, covering low-frequency/low-voltage disconnection, high-frequency/low-voltage disconnection, and rapid startup of standby units under low-frequency/low-voltage conditions, as well as low-frequency detection, low-voltage detection, over-frequency detection, over-voltage detection, and reverse power detection.
Features
Protection Functions
- Five-stage low-frequency protection: Slip lockout and low-voltage lockout are configurable; low-frequency derating can be set to trip the output or issue an alarm;
- Five-stage low-voltage derating;
- Over-frequency protection: Low-voltage lockout is configurable; over-frequency derating can be set to trip the output or issue an alarm;
Communication Functions
- The device supports four communication modes: RS-485, CAN, wired Ethernet, and fiber-optic Ethernet; (specify when ordering)
- The device uploads real-time data, including measurement data, waveform data, faults, alarm signals, and all protection settings, configurations, and coefficients. Protection settings can be modified and protection functions enabled or disabled remotely online;
- Receives control commands issued by higher-level systems, including: system time synchronization, setting adjustments, and data read/write commands.
Main Functional Specifications
- Protection response time (including the response time of the output relay): Average error in response time: not more than 35 ms;
- Precision operating range: Minimum precision current: 0.08 In, Maximum precision current: 20 In
- Current setting error: When the current exceeds 1.00 A, the error shall not exceed ±2.5%; Voltage setting error: shall not exceed ±3%
- Measurement accuracy: Current (I)/Voltage (U): Class 0.2; Power (P)/Reactive power (Q): Class 0.5
- Remote signal resolution: no more than 2 ms
Event Logging, Fault Recording
- The recorded events include protective action events and device malfunctions;
- Record the type of protection trip, the time of the trip, and the operating parameters at the time of the trip;
- The fault recording data includes: the time of the protection operation, the type of protection operation, and the rms values before and after the recording was initiated;
- Data length of the fault recording: 2 cycles before the fault and 4 cycles after the fault;
- The SOE can retain 48 sets of data after a power loss, and the fault report can retain 16 sets of data after a power loss.
Monitoring Features
- The device is capable of measuring analog quantities such as current, voltage, and frequency;
- Collect position signals from circuit breakers, energy storage systems, isolating switches, and remote/local control switches, as well as other digital signals;
- Control functions of the disconnect switch.
Setting Table
| No. | Display Name | Range | Step | Remark |
|---|---|---|---|---|
| 1 | Under-frequency Stage 1 Setting | |||
| 1.1 | Under-frequency Stage 1 Enable/Disable | 1/0 | — | Undervoltage protection: Enable(1) / Disable(0) |
| 1.2 | Stage 1 Time Delay | 0～120.00s | 0.01s | |
| 1.3 | Stage 1 Setting Value | 46～50.00Hz | 0.01Hz | |
| 2 | Under-frequency Stage 2 Setting | |||
| 2.1 | Under-frequency Stage 2 Enable/Disable | 1/0 | — | Undervoltage protection: Enable(1) / Disable(0) |
| 2.2 | Stage 2 Time Delay | 0～120.00s | 0.01s | |
| 2.3 | Stage 2 Setting Value | 46～50.00Hz | 0.01Hz | |
| 3 | Under-frequency Stage 3 Setting | |||
| 3.1 | Under-frequency Stage 3 Enable/Disable | 1/0 | — | Undervoltage protection: Enable(1) / Disable(0) |
| 3.2 | Stage 3 Time Delay | 0～120.00s | 0.01s | |
| 3.3 | Stage 3 Setting Value | 46～50.00Hz | 0.01Hz | |
| 4 | Special Under-frequency Stage 1 | |||
| 4.1 | Stage 1 Time Delay | 0～120.00s | 0.01s | |
| 4.2 | Stage 1 Setting Value | 46～50.00Hz | 0.01Hz | |
| 5 | Special Under-frequency Stage 2 | |||
| 5.1 | Stage 2 Time Delay | 0～120.00s | 0.01s | |
| 5.2 | Stage 2 Setting Value | 46～50.00Hz | 0.01Hz | |
| 6 | General Under-frequency Setting | |||
| 6.1 | Startup Time Delay | 0～120.00s | 0.01s | |
| 6.2 | Startup Setting Value | 46～50.00Hz | 0.01Hz | |
| 6.3 | Acceleration Time Delay | 0～120.00s | 0.01s | |
| 6.4 | Df/dt1 | 1.0Hz/s～9.9Hz/s | 0.1Hz/s | Slip blocking setting value |
| 6.5 | Df/dt2 | 1.0Hz/s～9.9Hz/s | 0.1Hz/s | Slip blocking setting value |
| 7 | Over-frequency Protection | |||
| 7.1 | Over-frequency Protection Enable/Disable | 1/0 | — | Over-frequency protection: Enable(1) / Disable(0) |
| 7.2 | Over-frequency Trip Enable/Disable | 1/0 | — | Over-frequency: Trip(1) / Alarm(0) |
| 7.3 | Undervoltage Blocking Over-frequency | 1/0 | — | Undervoltage blocking: Enable(1) / Disable(0) |
| 7.4 | Over-frequency Time Delay | 0.1～120.00s | 0.01s | |
| 7.5 | Over-frequency Setting Value | 50～54Hz | 0.01Hz | |
| 8 | Undervoltage Stage 1 Setting | |||
| 8.1 | Undervoltage Stage 1 Enable/Disable | 1/0 | — | Undervoltage protection: Enable(1) / Disable(0) |
| 8.2 | Stage 1 Time Delay | 0～120.00s | 0.01s | |
| 8.3 | Stage 1 Setting Value | 0～100.00V | 0.01V | |
| 9 | Undervoltage Stage 2 Setting | |||
| 9.1 | Undervoltage Stage 2 Enable/Disable | 1/0 | — | Undervoltage protection: Enable(1) / Disable(0) |
| 9.2 | Stage 2 Time Delay | 0～120.00s | 0.01s | |
| 9.3 | Stage 2 Setting Value | 0～100.00V | 0.01V | |
| 10 | Undervoltage Stage 3 Setting | |||
| 10.1 | Undervoltage Stage 3 Enable/Disable | 1/0 | — | Undervoltage protection: Enable(1) / Disable(0) |
| 10.2 | Stage 3 Time Delay | 0～120.00s | 0.01s | |
| 10.3 | Stage 3 Setting Value | 0～100.00V | 0.01V | |
| 11 | Special Undervoltage Stage 1 Setting | |||
| 11.1 | Special Undervoltage Stage 1 Enable/Disable | 1/0 | — | Undervoltage protection: Enable(1) / Disable(0) |
| 11.2 | Stage 1 Time Delay | 0～120.00s | 0.01s | |
| 11.3 | Stage 1 Setting Value | 0～100.00V | 0.01V | |
| 12 | Special Undervoltage Stage 2 Setting | |||
| 12.1 | Special Undervoltage Stage 2 Enable/Disable | 1/0 | — | Undervoltage protection: Enable(1) / Disable(0) |
| 12.2 | Stage 2 Time Delay | 0～120.00s | 0.01s | |
| 12.3 | Stage 2 Setting Value | 0～100.00V | 0.01V | |
| 13 | General Undervoltage Setting | |||
| 13.1 | Startup Time Delay | 0～120.00s | 0.01s | |
| 13.2 | Startup Setting Value | 0～100.00V | 0.01V | |
| 13.3 | Acceleration Time Delay | 0～120.00s | 0.01s | |
| 13.4 | Voltage Difference Setting Value | 0～100.00V | 0.01V | |
| 13.5 | dv/dt1 | 1.0V/s～9.9V/s | 0.1V/s | Voltage difference blocking setting value |
| 13.6 | dv/dt2 | 1.0V/s～9.9V/s | 0.1V/s | Voltage difference blocking setting value |
| 14 | Overvoltage Protection | |||
| 14.1 | Overvoltage Protection Enable/Disable | 1/0 | — | Overvoltage protection: Enable(1) / Disable(0) |
| 14.2 | Overvoltage Trip | 1/0 | — | Trip(1) / Alarm(0) |
| 14.3 | Overvoltage Time Delay | 0～120.00s | 0.01s | |
| 14.4 | Overvoltage Setting Value | 0～120.00V | 0.01V | |
| 15 | General Setting | |||
| 15.1 | Under-current Blocking Load Shedding | 1/0 | — | |
| 15.2 | PT Disconnection | 1/0 | — | PT disconnection detection: Enable(1) / Disable(0) |
| 15.3 | 3P4W Voltage Wiring | 1/0 | — | 3P4W(1) / 3P3W(0) |
| 15.4 | Measuring Voltage 380V | 1/0 | — | 380V(1) / 100V(0) |
| 15.5 | Current Rated 1A | 1/0 | — | 1A(1) / 5A(0) |
| 15.6 | Blocking Load Shedding Current | 0.5～6A | 0.01A | Secondary rated current |
| 15.7 | Undervoltage Setting Value | 0～100.00V | 0.01V | |
| 15.8 | Undervoltage Blocking Value | 0～100.00V | 0.01V | Undervoltage setting for over-current blocking |
Outline and Installation Dimensions
FAQ
Q：How Under-Voltage Load Shedding Controls Circuit Breakers？
A:When a power system suffers frequency or voltage drops caused by active or reactive power deficiency, under frequency load shedding in power system operates automatically.
Referencing typical grid schemes such as Great Britain under frequency load shedding 49.2 Hz and Great Britain under frequency load shedding 49.7 Hz, the low-frequency and low-voltage load shedding system disconnects secondary loads in accordance with preset multi-stage logic, with the initial stage typically activated at 48–48.5 Hz and the final stage at 46–46.5 Hz.
It effectively restores the balance between power generation and load consumption, avoids continuous frequency and voltage decline that may cause grid collapse, and acts as the third line of defense for power grid security and stable operation.
Q：How Under-Voltage Load Shedding Controls Circuit Breakers？
Fault disconnection involves rapidly disconnecting the faulted area from the power grid upon detection of a grid fault or instability to isolate the fault and prevent the impact from spreading;
Emergency frequency and voltage control, on the other hand, involves gradually shedding part of the load or adjusting generation output according to a multi-round strategy when a power deficit causes frequency or voltage deviations, thereby restoring system balance.
The former focuses on fault isolation, while the latter focuses on rebalancing supply and demand.
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