Zhongguan Electric Control DWK3-110

DWK3-110 is a substation voltage and reactive power integrated контроллер (VQC), commonly known as high-voltage reactive power compensation controller. It is used in 6～110kV substations to automatically regulate busbar voltage and switch capacitor/reactor banks, realizing integrated optimal control of voltage and reactive power. It is widely applied in power grid substations and distribution station high-voltage reactive power compensation cubicles.

✅ Model Nomenclature & Подсерия

DWK3-110【Suffix】

Series A (Integrated VQC: main transformer voltage regulation + переключение конденсатора)

DWK3-110A2: 1～2 main transformers, 1～2 capacitor banks

DWK3-110A8: 1～2 main transformers, 1～8 capacitor banks

DWK3-110A36: 1～3 main transformers, 1～6 capacitor/reactor banks, supports three-section busbar

Series C (Pure high-voltage reactive compensation, только переключение конденсатора, no main transformer voltage regulation)

DWK3-110CD: Simple single-busbar type, controls 1～4 capacitor banks (commonly used for 6/10kV)

DWK3-110C4D / C8D / C12 / C38: Одинокий / двойной / three-section busbar, 4/8/12 конденсаторные батареи

Series T (Regulating reactive power compensation, patented solution, on-load tap-changer capacitor): DWK3-110TC1, TC2, TA2

Series L (Special for filter compensation): DWK3-110LD, L8, L12, for filter capacitor bank switching control

Series D: Low-voltage reactive power compensation; Серия Б: Capacitor bank protection device

✅ Core Functions

1. Логика управления: Real-time acquisition of busbar U, я, П, вопрос, cosφ; automatic switching of capacitors/reactors based on dual criteria of voltage and reactive power. Series A additionally controls on-load tap positions of main transformers, with anti-tap hunting and anti-switching oscillation functions.
2. Switching Strategy: Supports equal-capacity balanced switching, unequal-capacity selective switching and combined switching. Faulty capacitor banks can be individually masked without affecting automatic operation of remaining banks.
3. Режимы работы: Three modes: Авто / Local Manual / Remote Communication Remote Control. It can run standalone or connect to substation integrated automation systems.
4. Коммуникация: RS485 (some models with RS232), Modbus-RTU protocol. Realizes telemetry, telesignalling and remote control, compatible with integrated protection backstage and remote terminal units.
5. Protection Blocking: Перенапряжение / undervoltage blocking, cabinet power-loss blocking, hardware watchdog. All outputs are blocked upon CPU crash to prevent misoperation; resistant to harmonic and strong electric pulse interference.
6. Человеко-машинный интерфейс: LCD Chinese display, real-time display of voltage, текущий, коэффициент мощности, реактивная мощность, capacitor status and fault event records; parameter setting via panel keys.

✅ Hardware Installation (CD type as example)

Panel flush mounting, cutout dimension: 151mm × 151mm

Источник питания: 220 В переменного тока (standard for substations)

Аналоговые входы: PT voltage, CT current

Цифровые входы: tap position signal, incoming/bus coupler position, capacitor cubicle position signal

Relay outputs: Capacitor switch open/close, main transformer tap raise/lower (Series A), тревожный контакт

✅ Typical Application Scenarios

6кВ, 10кВ, 35кВ, 110kV manned / unattended substations

Distribution station high-voltage reactive compensation cubicles, capacitor complete sets

VQC retrofitting of old substations (Series A/T); filter compensation cubicles adopt Series L

✅ Common Troubleshooting

1. No switching action: Check PT/CT polarity, transformation ratio setting, voltage upper/lower limits, reactive threshold and blocking conditions (повышенное/пониженное напряжение, switch position).
2. Frequent oscillation: Reset switching thresholds and enable unequal-capacity combined switching algorithm.
3. Сбой связи: Check 485 Проводка А/Б, slave address, baud rate and Modbus register configuration.
4. Нет дисплея: Verify AC220V power supply and power fuse.

✅ Alternative Selection Reference

Domestic equivalent VQC: NARI, XJ, Sifang, Baoding Langbaodi and other substation voltage and reactive power controllers. Need to verify number of bus sections, quantity of main transformers, number of capacitor loops and communication protocol.

DWK3-110CD Complete Technical Specification (Zhongguan Electric Control, simple single-busbar high-voltage reactive compensation controller)

Приложение: 6кВ / 10kV substations, controls up to 4 конденсаторные батареи, reactive compensation only, no main transformer voltage regulation function

1. Power Supply Parameters

1. Аналоговые входы (PT/CT)

III. Цифровые выходы (Relay Contacts)

1. Цифровые входы (Telesignalling)

Capacitor switch position signals (до 4 каналы), cabinet power-loss blocking signal; passive dry contact input.

1. Коммуникационный интерфейс

Интерфейс: RS485

Протокол: Modbus-RTU

Функции: Telemetry (U/I/P/Q/cosφ), telesignalling (capacitor status, тревога), пульт дистанционного управления (remote switching)

Independent register mapping document available separately

1. Условия окружающей среды

VII. Электромагнитная совместимость

Common-mode interference: 2500В

Differential-mode interference: 1000В

Hardware watchdog blocks all outputs automatically on CPU crash to prevent false switching; withstands strong harmonics and electrical fast transient pulses.

VIII. Механические размеры & Установка

Монтаж: Panel flush mounting

Panel dimension: 160mm × 160mm

Cutout dimension: 151mm × 151mm

Масса: приблизительно. 0.8кг

1. Control Functional Parameters
2. Режимы управления: Авто / Local Manual / Remote Communication Remote Control three modes
3. Switching Algorithm: Equal-capacity balanced switching, unequal-capacity selective switching, combined switching; any capacitor bank can be masked while remaining banks run automatically.
4. Критерий: Dual criteria of voltage + реактивная мощность; overvoltage/undervoltage blocking, capacitor tripping and alarm triggered upon blocking.
5. Event Recording: Stores switching events and fault alarm records, queryable on panel.
6. шинопровод: Single busbar measurement (CD model is simple single-busbar version)
7. Protection Blocking Logic

Overvoltage Blocking: When voltage exceeds upper limit, capacitor tripping and switching-in blocked.

Undervoltage Blocking: When voltage drops below lower limit, capacitor switching-in prohibited.

Cubicle Power-loss Blocking: Capacitor cubicle power loss forces capacitor tripping and prohibits switching-in.

Hardware Fault Blocking: On CPU abnormality or watchdog trigger, all outputs are blocked immediately.

1. Model Boundary Description (Distinguish within series)

DWK3-110CD: Simple version, single busbar, Макс. 4 конденсаторные батареи, supports combined switching, no multi-bus interconnection logic

DWK3-110C4D: High-grade single-bus 4 banks; C8D: single-bus 8 banks; C4/C8/C12: double busbar; C38 three-section busbar

DWK3-110Axx: Series A is full VQC with main transformer on-load tap control (major difference from CD)

DWK3‑110CD Modbus‑RTU Register List (Zhongguan Electric Control, 10kV single-busbar 4-bank capacitor controller)

⚠️Примечание: The complete original manufacturer protocol manual is not publicly available online. This version is compiled from field engineering test data (many substation integrated automation docking cases). Divided into【Input Registers 3xxxx】,【Coils 0xxxx】,【Holding Registers 4xxxx (Параметры + Пульт дистанционного управления)】.

Communication basics: RS485, Modbus-RTU, default slave address=1; скорость передачи данных по умолчанию 9600, 8N1.

Data scaling rule: All analog values are integers, divide by scaling factor to get actual value; 32-bit floating point occupies 2 последовательные регистры (сначала высокое слово).

1. Input Registers (3хххх, Function Code 04H, Только чтение, real-time telemetry)

1. Coils (0хххх, Function Code 01H Read, 05H Single Write, 0FH Bulk Write, Пульт дистанционного управления / Telesignalling)

Remote control mechanism: Pulse remote control (write 1 to trigger action, controller auto-clears). Holding coils are not supported. Remote control executes only when controller is in【Remote Mode】and no blocking conditions exist.

III. Holding Registers (4хххх, Function Code 03H Read, 06H/10H Write; Setting parameters, read-write)

1. Тревога & Event Registers (Только чтение, within holding register area)

1. Critical Notes for Engineering Integration
2. Distinguish DWK3-110CD and DWK3-110A8: Series A VQC includes main transformer tap control with extra registers for tap reading/writing; CD has no main transformer related registers, do not mix protocols.
3. Two register address pitfalls: In Modbus Poll use offset (0-начинать); many SCADA/HMI software directly uses logical address (30001), avoid ±1 offset error.
4. Write permission for settings: Some firmware versions require panel unlock before parameter writing; otherwise write command returns exception code 02.
5. Telesignalling recommendation: read coils instead of only status word: Status word has refresh latency; capacitor position telesignalling should read coils directly.
6. Exception Codes: 01 Illegal Function Code; 02 Illegal Address; 03 Illegal Data; 04 Device Fault (blocked / mode prohibits remote control).
7. Test Message Example (Read busbar voltage, slave 1, читать 30001, 1 register)

Transmit: 01 04 00 00 00 01 31 CA

Response: 01 04 02 03 E8 B9 45

03E8 = 1000 → 1000/10 = 10.0kV busbar voltage

Working Principle of Zhongguan Electric Control DWK3‑110 (Series A VQC and Series C CD; Series A full voltage & reactive integrated control, CD capacitor switching only)

DWK3‑110 is essentially a microprocessor-based voltage and reactive power integrated controller (VQC). Core workflow: Sample busbar PT & CT signals → Calculate U/I/P/Q/cosφ → Compare with setpoints → Output relay contacts to control capacitors / main transformer tap, with blocking protection.

1. Hardware Sampling Stage
2. Аналоговые входы: Connect busbar PT secondary voltage (0~100V), CT secondary current (0~5А). Sampling chip continuously samples three-phase voltage and current.
3. CPU Calculation: Microcontroller computes active P, reactive Q, power factor cosφ, частота; meanwhile reads digital telesignals: capacitor switch position, bus coupler status, main transformer tap position (Series A), fault blocking signals.
4. ЧМИ & Коммуникация: LCD panel real-time display; RS485 Modbus-RTU uploads telemetry & telesignalling to substation backstage and receives remote control commands.
5. Core Control Logic (Two Major Versions)

✅ Series A (DWK3‑110Axx, Full VQC, U-Q 9-zone diagram strategy)

Series A controls both main transformer on-load tap-changer and capacitor switching, adopting industry standard U-Q nine-zone diagram algorithm: vertical axis = busbar voltage U, horizontal axis = reactive power Q. The plane is divided into nine zones by voltage upper/lower limits and reactive switching thresholds.

Зона 9: Voltage and reactive power within acceptable range → No action

For the other 8 zones, regulation follows priority:

1. Adjust reactive power first by capacitor switching (switching capacitor supplies inductive reactive power and lifts voltage; switching off capacitor reduces capacitive reactive power and lowers voltage)
2. When reactive power reaches regulation limit, operate main transformer on-load tap-changer to adjust voltage

Anti-tap hunting logic: Limit continuous tap operation count and delay to prevent repeated tap change from minor voltage fluctuations. Inverse voltage regulation optional, automatically adjust target voltage band according to load and reduce operation times.

✅ Series C (DWK3‑110CD/C4D, CD as above, no main transformer tap control)

CD only performs high-voltage capacitor switching, controls capacitor banks only without main transformer tap regulation, adopting dual criteria of voltage + реактивная мощность:

1. Continuously monitor busbar voltage and reactive power
2. Capacitor switching-in allowed only when both conditions are satisfied: Busbar voltage within permitted range + system inductive reactive power exceeds switch-in threshold → relay contact closes to drive vacuum contactor to switch capacitor in.
3. When busbar voltage is too high or system becomes capacitive (reverse reactive power flow) exceeding switch-out threshold → relay contact opens to switch capacitor off.

Switching algorithms:

Equal-capacity banks: Balanced cyclic switching, equalize operation count of each bank to extend service life

Unequal-capacity banks: Adaptive combined switching, select optimal capacity combination according to reactive magnitude for higher compensation precision and avoid oscillation

Any faulty/maintenance capacitor bank is automatically masked; remaining banks keep automatic operation.

III. Blocking Protection Principle (Safety Core)

All models have multi-layer blocking. Once blocking condition triggers, capacitor switching-in is prohibited immediately; already-connected capacitors will be tripped if needed:

1. Overvoltage Blocking: Busbar voltage＞upper limit → block switching-in and trip capacitors to avoid capacitor overvoltage damage.
2. Undervoltage Blocking: Busbar voltage＜lower limit → prohibit capacitor switching-in; switching capacitors under low voltage may amplify resonance risk.
3. Switch Position Blocking: When incoming/bus coupler switch opens, trip capacitors on this section and suspend automatic control.
4. Hardware Watchdog & Self-diagnosis: On CPU crash, hardware circuit blocks all relay outputs directly to prevent false trip/close. Detect capacitor fail-to-open / fail-to-close, trigger alarm and isolate that bank.
5. Задержка переключения: Fixed waiting time after each action (10~30 сек.), prevent cyclic switching oscillation caused by short-term grid fluctuations.
6. Three Operation Modes
7. Автомобильная мода: Controller samples, judges and executes automatic switching / tap regulation independently (normal running mode).
8. Local Manual: Manual capacitor switching / tap raise-lower via panel keys, auto logic suspended, for commissioning and maintenance.
9. Пульт дистанционного управления: Backstage sends remote switch commands via Modbus; local auto logic exits under remote mode, protection blocking remains active.
10. Series T (DWK3‑110TC Tap-regulated compensation, different principle)

Series T is not conventional stepwise capacitor switching. It adjusts taps of on-load autotransformer connected in series before capacitors, changing voltage across capacitors to continuously and smoothly vary reactive output. Capacitors do not need frequent switching, resulting in lower impact and longer service life.