The variable frequency electric drilling rig electrical control system consists of a power generation system (generator, control cabinet), an AC drive system (variable frequency cabinet, brake cabinet), a control network (PLC cabinet, driller's console, industrial computer, remote computer, AS-i bus system), and an AC motor control center. 1) Power Generation System: This control device consists of four generator control cabinets. Its main functions are: controlling the diesel engine speed and generator excitation current to obtain a 600V, 50Hz stable frequency and voltage current as the power source for the entire well site; the generator control cabinet also has a grid connection control circuit to control the grid connection of multiple generators to achieve synchronous switching operations. The generators can be operated online in pairs or any two or more as needed, with balanced load distribution and smooth load transfer, capable of withstanding the load characteristics of the drilling rig and the impact of motor starting. The generator control device also has functions such as power limiting, self-starting power supply circuit, grounding detection phase sequence protection, overcurrent protection, overvoltage protection, undervoltage protection, overfrequency protection, reverse power protection, short circuit protection, and cabinet fault self-checking. 2) AC Drive System a. Variable Frequency Drive Control The variable frequency main drive system consists of several variable frequency cabinets, which convert 600V, 50Hz constant voltage, and constant frequency AC voltage into continuously adjustable AC voltages from 0 to 800V. These drive the drilling pump, winch, and rotary table in a one-to-one drive configuration. The winch and rotary table motors have reverse rotation capabilities, and the torque limit is adjustable arbitrarily within the range of 0% to 100%. The winch is driven by two motors, ensuring balanced load and synchronized speed during operation. The winch control device includes a braking unit, enabling rapid start and stop. The winch motor has four-quadrant operation characteristics, providing continuous electromagnetic braking torque during drilling operations. Simens frequency converters are widely used in oil drilling rigs. The SIMOVERT masterdrive vector control frequency converter is a voltage source frequency converter using IGBT elements and fully digital technology. b. Automatic Drill Feed Frequency Converter: The automatic drill feed frequency converter converts the 400V, 50Hz constant voltage and frequency AC voltage into a 0-400V variable voltage and frequency continuously adjustable AC voltage, driving the drill feed motor in a one-to-one drive mode. Constant voltage mode enables automatic drill feed. The drill feed motor has forward and reverse rotation functions in constant speed mode, which can be used for emergency raising and lowering of the derrick and drill string, or for constant speed drill feed. The drill feed frequency converter cabinet is equipped with a braking unit and an external braking resistor forming an energy-saving braking device. 3) Driller's Control Console: The driller's control console is controlled by a high-performance programmable controller and bus, allowing the driller to perform various operations during drilling operations. Simultaneously, the operating status of the main equipment in the control system can be monitored through a touch screen and display screen. The driller's control console is internally pressure-proof and has a pressure-reducing device. 4) Touchscreen and Display Screen: In addition to displaying relevant operating and monitoring parameters of the drilling rig system, the touchscreen and display screen also have parameter setting functions: A. Setting automatic drilling parameters, traveling block anti-collision system parameters, etc. B. Viewing the real-time status of all devices on the network. C. Alarm information prompts the driller to pay attention to the status of the equipment. D. Fault information prompts the driller to pay attention to the equipment that has malfunctioned. E. Displaying drilling parameters: suspended weight, drill pressure, well depth, etc. F. Safety defense information. G. Fault diagnosis information. 5) Braking Control: The main functions of the braking unit inside the braking cabinet and the braking resistor outside the cabinet are: When the winch needs to brake, the motor is controlled to enter the generator operation state, so that the motor generates a braking torque in the opposite direction of rotation. The mechanical energy on the load side is converted into electrical energy and transmitted to the DC bus of the frequency converter cabinet through the inverter. When the DC bus voltage is higher than the maximum threshold, the braking control unit automatically connects the braking resistor, so that the excess electrical energy stored in the capacitor between the intermediate DC buses is consumed by the braking resistor in the form of heat energy to maintain the voltage on the DC bus constant. This braking method is called regenerative braking. The braking unit of the automatic drilling system also adopts regenerative braking. 6) Main Control System A Programmable Controller (PLC) Operation Status Bus Control System The system adopts technology to achieve rapid data transmission and can realize functions such as monitoring, fault alarm, parameter modification and diagnosis, and storage records through touch screen, industrial computer, and remote computer. The main parameters that can be monitored are: 1. Generator operating status and parameters 2. Inverter operating status and parameters 3. System operation and running status 4. System fault and alarm information 5. MCC operating status 6. Traveling rig operating status 7. Integrated drilling instrument B Traveling rig Anti-collision System The PLC collects the operating parameters of the main motor and the digital signal of the drum encoder through the bus, calculates the current position and speed of the traveling rig, and when the traveling rig reaches the deceleration point, it instructs the support motor to decelerate to a safe speed through the program; when the traveling rig reaches the parking point, the main motor hovers. If the traveling rig exceeds the parking point and still does not stop, the system automatically stops the inverter cabinet and applies the safety brake. The integrated instrumentation system (C) uses data acquisition units (field sensors, encoders, transmitters, etc.) and a programmable controller to process data, displaying the following drilling rig parameters on a touchscreen, display screen, or remote computer: suspended weight, drill pressure, well depth, mechanical drilling speed, rotary table speed, rotary table torque, pump pressure, mud pit level, outlet return volume, and traveling block position. 7) The main function of the MCC power distribution control system's AC motor control center is to control the AC motors in the drilling rig, drilling fluid circulation tank area, oil tank area, compressor room, and water tank area of ​​the well site, and to provide lighting power to the well site. The AC motor control center system uses soft start for motors above 30KW, operated and monitored via the AS-i bus, while retaining manual soft start and manual direct start functions. The MCC cabinet adopts a modular structure for easy maintenance and replacement. The AC motor control center's power supply comes from the main transformer, a dry-type transformer with a transformation ratio of 600V/400V. The MCC power distribution control system is equipped with a switch cabinet, whose main functions are: to switch the power supply of the 400V AC bus of the AC motor control center, one of which is selected to supply power from the main transformer to the AC bus of the AC motor control center, and the other is selected to supply power from the auxiliary generator to the AC bus of the AC motor control center. The two power supplies are electrically interlocked.