Analysis of Changing Fully Digital DC Speed ​​Regulating System of Rail Planer DC Generator Set

The electric drive adopts the all-digital thyristor reversible DC speed control system controlled by a PLC (programmable logic controller). The PLC of the electronic control system adopts the CPM2A integral type PLC of Japan OMRON Corporation. It is responsible for the completion of the given signal processing of the peripheral of the full digital DC speed controller, the logic control of the machine button station signal, various limit signal and system fault signal. deal with.

All-digital thyristor reversible DC speed controller adopts British Continental's 590+ series 500A four-quadrant logic non-circulation (reversible) all-digital DC motor speed regulator. Its internal main circuit is composed of two sets of anti-parallel three-phase full-controlled thyristors. The rectifying unit is composed of two logic logic interlocks to form a four-quadrant logic loopless (reversible) DC variable-speed electric drive system. All of its control algorithms are completed by a high-speed 16-bit microprocessor to achieve superior dynamic control performance; the self-tuning algorithm can automatically calculate the P, I constants and current interruption points of the current loop to achieve the best dynamic performance of the system. The self-adaptive function of the current loop enables a smooth speed response when the system changes greatly. The transformation of the speed control system uses a photoelectric encoder to constitute the speed negative feedback speed closed-loop control, to improve the speed stability of the electrical speed control system, expand the system speed range, reduce the speed of static error rate.

Speed ​​range

The DC generator set drag method (JF-F-D) controlled by the railroad planer cross-magnetic amplifier adopts voltage negative feedback and current feedback control, and its speed range D≤20. All-digital thyristor reversible DC speed control and dragging method (KZ-D) uses photoelectric encoder to make negative feedback of speed, and its speed range D≤50.

Steady-state accuracy

The steady-state accuracy of the JF-F-D system can only reach 1%, while the steady-state accuracy of the KZ-D system can reach 0.1% (optical encoder feedback).

Operational reliability

Because JF-F-D system has many adjustment resistances, the logic control mode adopted by the relay is more than the inherent connection points, which results in a high probability of faulty circuit connection. The DC generators, magnetic amplifiers, and exciters of the JF-F-D system all have commutators and brushes. The faults caused by poor brush contact are numerous. After the high-speed microprocessor-controlled KZ-D system adopts a programmable logic controller (PLC), the entire electronic control system is better than JF-F because the entire control system is an industrial computer suitable for harsh industrial environments to complete all control algorithms. D system is greatly simplified, the original control circuit in the logic control of the relay is replaced with a soft contact with the PLC, the original main circuit of the DC generator set, magnetic amplifier, exciter, start resistance, etc. to replace the circuit concise All-digital thyristor rectifier. The simplification of the control circuit and the reduction of high-current contacts will certainly further improve the operational reliability of the rail planer electric drive system.

Maintainability

The JF-F-D system has many adjustable resistances and many control motors. There are many parts to be adjusted. It is difficult to debug and difficult to maintain. High-speed microprocessor-controlled KZ-D system adopts all-digital devices, giving full play to the advantages of computer software flexibility, with perfect digital control and protection functions; fewer digital control adjustment points, self-tuning of debugging parameters, and accurate after failure Fault information display shortens maintenance time.

Efficiency and equipment volume

The efficiency of the DC generator set driven by the AC induction motor of the JF-F-D system can only reach about 93%; in addition to the electric control cabinet, the electric transmission system of the AC generator has a DC generator set with an area of ​​up to 3 square meters, and the magnetic flux is enlarged. Machines, exciter, starting resistor box and other peripheral equipment, and the unit running noise. High-speed microprocessor-controlled KZ-D electric drive system efficiency of up to 98%; all of its control devices are installed in the original electrical control cabinet, no other peripheral devices, and no noise operation. After the reformation of the 12-meter rail planer, it was reported by the operators that the previously disturbing crew noise was gone and the working environment was greatly improved.

Energy-saving analysis and investment benefits

On August 27th, 2005, we installed a three-phase four-wire active power meter and a three-phase four-wire reactive power meter on each of the rebuilt No. 1 rail planer and the unmodified No. 2 rail planer. The table collects power-saving data. The schedule of the two rail planers and the processed products are almost the same. On September 28, 2005, meter readings were recorded after one month. The monthly power consumption of the modified rail planer: active power is 43×60 (transformer ratio of current transformer)=2580KW·h, reactive power is 120×60 (transformer ratio of current transformer)=7200KVar•h; unmodified 2nd rail Monthly power consumption of the planer: The active power is 98×60 (transformer ratio of current transformer)=5880KW·h, and the reactive power is 398×60 (change ratio of current transformer)=23880KVar•h.

From the above data, it can be seen that the rail planer adopting the all-digital thyristor reversible DC speed regulation system has an average monthly electricity saving compared with the rail planer that uses the DC generator set electric transmission: the active power is 3300KW•h, and the reactive power is 16680KVar•h. The significance of effective power saving is that electricity can be directly saved every year: 3300 (KW•h/month)*12(months)*0.5(yuan/KW•h)=19800(yuan). Based on this estimate, the electricity cost can be saved directly after the transformation. The project, the transformation of 93,000 yuan investment can be completely recycled in 5 years. The significance of reactive power saving is to reduce the line loss of the power supply busbar in the workshop and to reduce the secondary current of the distribution transformer in the workshop. The saved reactive current can be transferred to the newly installed equipment in the power grid, thus eliminating the workshop equipment after adding new equipment. Electric transformer capacity increase problem. From the above energy-saving data, it can be seen that the reactive power saved after the transformation of the rail planer is much larger than that of the active power. The indirect benefits of reactive power saving to the power grid in the workshop are also very obvious.

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