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I. Introduction to the protection of biogas generator sets
(1) The 400KW biogas generator set has a complete safety control system. It meets the requirements of JB/T9583.1-1999, NYT1223-2006 biogas generator set, and has the following safety protection devices:
1. Low engine oil pressure alarm, stop
2, engine overspeed alarm, stop
3, the engine cold water temperature is high alarm
4. High methane concentration alarm in the engine room
5. High engine cooling water temperature alarm
6, high engine oil temperature alarm
7, Ignition system fire alarm
8. Generator reverse power protection
9, generator undervoltage protection
10, generator overcurrent protection
11. All rotating parts are protected by steel mesh cover as a protective device.
(2) Brief introduction of control screen function:
1. The control panel of the biogas generator set is a floor cabinet structure. The intelligent automatic air circuit breaker (AH) is selected, which has automatic over-current protection and reverse power protection. When over-current or reverse power occurs, it can automatically disconnect the main switch and send out an audible and visual alarm signal. The control panel is equipped with controllers, various display instruments, adjustment buttons, unit protection indicators, emergency stop buttons, etc., which are used to control and monitor the working conditions of the generator set. The start of the generator set is manually operated at the side of the machine, and the shutdown can be controlled at the side of the set, or by the emergency stop button on the control panel.
2. The control system is equipped with imported automatic paralleling control module (optional for users), which can automatically monitor and synchronize to meet manual and automatic paralleling. When multiple units are running in parallel, it can realize automatic load distribution function to meet grid and parallel operation Working conditions. The speed of the unit is automatically adjusted by the electronic speed control system, and it can also be adjusted in a small amount through the speed fine-tuning knob on the control panel; the unit voltage is automatically adjusted, and the voltage is adjusted by the voltage setting potentiometer on the control panel. The control panel is equipped with a floating charging device to provide charging power for the battery.
II. Description of the grid-connected protection of the Green Ring biogas generator set
1.Short-circuit protection: Use the electromagnetic release of the main circuit low-voltage circuit breaker for short-circuit protection, and the operating current is set to 8-10 times the rated current.
2.Overcurrent protection: Use the delay release of the low-voltage circuit breaker of the main circuit to set it at 1.25 times the rated current of the generator.
3.Under-voltage protection: Install a voltage-loss release on the low-voltage short-circuit device of the main circuit to open the main circuit breaker when the generator voltage is lower than 50%-60% of the rated voltage.
4.Reverse power protection: When reverse power of 5%-15% of rated power occurs during parallel operation, the reverse power protection device opens the main circuit breaker within 10s.
5. Generator thermal protection: When the stator temperature exceeds 145℃, an audible and visual warning signal will be issued, and the main circuit breaker will be opened when the temperature exceeds 155℃.
III. Grid-connected biogas generator set
(1) The grid connection of generators should meet three conditions:
1. The voltage of the generator to be paralleled is equal to the voltage of the system.
2. The weekly rate of the generator to be paralleled is equal to the weekly rate of the system.
3. The phase angle of the generator to be paralleled is consistent with the phase angle of the system.
(two) grid-connected plan
Primary system plan (specifically subject to the generator manufacturer's configuration and the primary system design requirements of the electrical industry department) Plan 1: Generator-generator control cabinet-grid-connected protection cabinet-metering and outgoing circuit breaker cabinet- Incorporate into the low-voltage 400V power grid; Option 2: Generator-Generator control cabinet-Metering and outlet circuit breaker cabinet-Step-up transformer (10KV/35KV)-Metering and PT cabinet-Grid-connected protection cabinet-High voltage Isolating switch-power grid; 2. Relay protection configuration plan (specifically subject to the configuration of the generator manufacturer and the relay protection design requirements of the electrical industry department) In addition to the manufacturer’s standard configuration at the outlet of each generator, a relay is installed On the side of the electrical protection cabinet, an independent overcurrent protection device, an overcurrent protection device in the low-voltage direction, and a low-frequency protection are installed; in order to ensure the safe operation of the generator and prevent the system from sending power back to the generator, it must be at the generator outlet Install a reverse power protection device at the place. (Preferably the grid-connected comprehensive protection device commonly used in power systems) (The grid-connected cabinet of the generator is an "ordinary" high-voltage switch cabinet with a built-in circuit breaker. Because it is connected to the generator system and the grid system, it is installed with complete grid-connected protection The device plays the role of generator grid-connected, and is called "grid-connected cabinet"; the special point of this cabinet is that the protection installed is different from other outgoing switch cabinets, and it is generally equipped with directional overcurrent protection and current time limit quick-break protection , Low-voltage and low-cycle oscillating unloading protection, etc.) Conclusion: Optimal option one.
IV. Design of external power grid lines
The cross-sectional area of the external power grid line is considered according to the maximum load of the plant area and the capacity of the generator assembly. The grid-connected location is the low-voltage side or the high-voltage inlet side of the plant substation.
For example: the capacity of the project's generator set is 2X400KW, the maximum load in the biogas station is 120KW, and the transformer type of the station is 400KVA, then the line of the external power grid is based on 2X400KVA, and the selection can be calculated according to the design specification.
V. generator configuration requirements
Generator configuration: biogas engine, Stanford/Siemens generator, public chassis, control panel, radiator, ignition system, mixer, battery pack, control start signal cable, generator starter, battery charging unit, fan cooling system The control unit (including cables within 50 meters), one waste heat boiler, two circulating water pumps, a generator biogas buffer tank and an indoor piping system, generator spare parts and information;
2. Provide two generator control panels One contact cabinet, one dedicated isolation switch cabinet for grid-connected outlets;
3.one control box screen for each of the and 400GF units and one set of automatic grid-connected devices.