In the process of coal mine production, mine hoist is a very important part. As an important equipment, the safety and reliability of mine hoist control system will play an extremely important role in the safe production of the mine. All along, the electric control system of AC hoist still has some lag. This paper analyses the expansion of electric control system of mine hoist, makes clear the vector control AC-AC frequency conversion scheme based on SIMADYN-D controller and domestic power cabinet, and understands the interface problem between SIMADYN-D controller and domestic power components, and practices at the same time. Experience shows that this scheme can reduce the cost of AC-AC frequency conversion system, promote the capacity of hoist and reduce energy consumption.
In mine safety equipment, hoist is an important component, its operation effect will have a direct impact on the overall production efficiency of the mine, but also related to the safety of mine production. Previously, our country used winding motor rotor series resistance system and thyristor converter DC drive system as the main control system of mine hoist. The winding motor rotor series resistance system is not technically strong and energy consumption is large. Although the thyristor converter DC drive system has good performance, it is subject to manufacturing technology. Limited, power will also be subject to certain constraints, need less than 3000kW. Under the guidance of long-term analysis and practical demonstration, the frequency conversion system in this paper regards the localized technology as the main part of its power, and forms a vector control AC-AC frequency conversion system with Siemens SIMADYN-D controller and domestic power cabinet as the main contents. The main circuit of single-phase output AC-AC converter is reversible, and it is a three-phase bridge rectifier without circulating current in reverse parallel. But if there is a control signal whose amplitude and frequency can be changed, the output voltage of rectifier can be changed into AC voltage whose amplitude and frequency can be changed, so that the function of frequency conversion can be realized smoothly.
By commutating the AC voltage of the power supply, the thyristor can be closed and disconnected. This kind of converter has no DC link, so it is called AC-AC direct converter. The three-phase output AC-AC converter is mainly composed of three single-phase output AC-AC converters, and the output voltage will be 120 degrees different from each other. [1] There are two main circuit wiring methods, the first is the public bus method, and the second is the output Y connection method. The components of vector control AC-AC frequency conversion system in mine hoist are mainly divided into the following parts: SIMADYN-D controller, high voltage switch outlet cabinet, stator transformer, stator power cabinet, isolation switch, excitation transformer, excitation power cabinet, synchronous motor, etc. as shown in Figure 1. QF1, QF2 and QF3 are high-voltage switchgear cabinets with 10 kV power output. Stator transformers are mainly T1, T2, T3, T4, T5 and T6. The connection groups of T1, T2 and T3 are Dd0, 10kV/950V, and the connection groups of T4, T5 and T6 are Dy5, 10kV/950V. The excitation transformer is T7. G1, G2, G3, G4, G5 and G6 are stator power cabinets and excitation power cabinets are G7. Q1, Q2, Q3 and Q4 are isolated switching switches. The double winding synchronous motor is M. Combining domestic power cabinets with imported controllers, a control system is formed. The most important problem of realizing the control system is the interface between them. The system has five interfaces, which are current detection interface, DC voltage detection interface, zero current signal detection interface, grounding protection interface and reactive power compensation.
Interface. The input current detection interface is to detect the input current of power cabinet. The detection tool is current transformer. The input current detection interface takes part in the current closed loop and vector control of SIMADYN-D. DC voltage detection interface uses Lyme block as the detection means of power cabinet outlet voltage, carries on vector control to SIMADYN-D, so that the voltage can be output normally. Zero current signal detection interface can ensure the commutation of thyristor, improve its reliability, detect the voltage at both ends of thyristor, and combine with the pulse signal, so as to know whether there is current in it, with high accuracy, and the complexity of the circuit is relatively strong.
Grounding protection interface is a necessary function of the main circuit. Its function is realized by detecting the ground resistance.
Reactive power compensation interface, the reactive power of power grid will be affected and impacted by the AC-AC frequency conversion system. Usually, if the AC-AC frequency conversion system has large power, it needs to set up a set of measures separately, so as to improve the overall quality of the power grid. In 2008, Siemens SIMADYN-D controller and vector control AC-AC frequency conversion application scheme combined with domestic power cabinet began to be applied in mine hoist. The main system and parameters of mine hoist are as follows. The mine hoist is a JKM-4*4 tower multi-rope friction hoist.
[3] The hoist is lifted by skip, its height can reach 530 meters, the maximum hoisting speed is 10.5 m/s, and the maximum acceleration and deceleration is ( 0.75 m/s2). The main type of motor is TBP2800-20 AC-AC synchronous motor. Its rated power is 2800 kW, voltage is 1500V, current is 1152A, rated speed is 50r/min, maximum overload of excitation voltage is less than 400V, and the phase difference between the two stator windings is about 30 degrees. Combining Siemens SIMADYN-D controller with domestic split power device, the converter has real three-phase non-circulating, reversible thyristor. Siemens S7 double PLC double-line production as the main control, and with the network operation control platform, to promote the smooth realization of mine hoist control system functions. This system takes Profibus as bus structure, combined with operation and transmission system, can reduce the amount of wiring in wellbore, reduce the workload of installation and maintenance, ensure the safety of communication, and avoid the failure of cable contact in wellbore.
Practice has shown that this scheme is extremely beneficial to improve the efficiency of mine hoist, thermostatic element can reduce energy consumption, and promote the upgrading and progress of hoist technology.
The combination of Siemens SIMADYN-D controller and vector control AC-AC frequency conversion of domestic power cabinet can reduce the cost consumption of AC-AC frequency conversion system, make it more safe and reliable in operation, strengthen its control level, get the technical support of the country, and have a good application prospect.