MAS Series Microprocessor-based Automatic Quasi-synchronization Unit

Introduction

MAS series microprocessor-based automatic quasi-synchronization unit include MAS-2 model and MAS-3 model, the unit of MAS-2 model suits for multiply synchronization object and the condition of needing centralized organizing screen, such as substation etc; the unit of MAS-3 model is mainly designed for combing network of the power plant's dynamotor. The centralizing controlled machine sets can have one and the unit controlled machine sets can have one for each set.

This series unit is based on the INTEL 80C196 SCM as its core, combining high precise AC sampling and calculating technology, precisely calculated voltages on both sides of the switch, frequency and phase-angle difference, input/output photoelectricity isolation and high-reliable multi-logic controlled middle relay as the output of closing switch. The unit technology is advanced and it has a strong ability of anti-disturbing.

Functions

• Depend on automatic regulation of speed and voltage of the generator which is waiting for paralleled in grid to realize the automatic track of the frequency and voltage, Thus to make fg>fs (fg-- frequency of generator ; fs-- frequency of grid) and get frequency difference and voltage difference into quasi-synchronization permission area rapidly. The phase angle difference is measured every half power frequency period. The switching-in pulse will be send when =dq=*Tdq+'*Tdq*Tdq/2, i.e. T=Tdq, to realize synchro-switching-in with lightening speed. Here Tdq is the lead-time of the switch in the equation. On account of calculating the angular velocity() and angular acceleration('), the difference of phase angle approximates to 0 in the switching-in moment.
• Frequency-difference (f) lock, voltage-difference (U) lock and acceleration (df/dt) lock function are provided.
• The double-circuit lines measuring results of the input voltage and frequency must be consistent, then the accuracy of the measurement and calculation is guaranteed. There is an inner independent analogy circuit of Synchro-watch-relay (TJJ). Employed it in control the synchronization switching-in angle permission area. Zero angle switching-in occasion is precisely calculated by a microprocessor-based circuit. The double circuit design obviously enhances the reliability of the switching-in.
• Our equipment can be applied independently, or together with the supervision system to realize remote control. Parameter settings can be read and written; switching-in reports and records can be transmitted through the communication to the supervision system. The communication interface is serial port RS-232 or RS-485 with random baud rate, usually 9600bit/s.
• Non-voltage checking function (one side or two sides) and automatic fast switching-in function of the ring grid connection (especially suitable for substation ) are provided.
• Dealing with the centralized synchronization for multi-synchro-point, point-selection switching method of the input voltage and switching-in output of the breaker is adopted to realize the quasi-synchronic switching-in at any point. Two kinds of operation mode are provided: remote control point-selection switching by the supervision system or local control by the manual selection switching of the equipment.
• Automatically frequency and voltage regulation function of the generator: the output of the frequency and the voltage regulation all are empty relay contact. Parameter of the contact switching-in and tripping time (width and interval of the regulation pulse) can be set manually. When this generator parallel in this function will be automatically jump in, but this function need manual selection when the other synchro-point is necessary.
• The device is provided with Chinese or English characters liquid crystal screen menu display that consist of 64*128 lattice, which is convenient for watching, fixing or modifying of the parameters . Setting parameters will not lose if the device loses electricity.
• The device is provided with synchronization switching-in track record function. All data of every synchronization switching-in process is recorded. Maximally eight historic records can be indexed. It can automatically check the switch action time after every switching-in, which is convenient for correct the lead-time of breaker.
• The software setting compensation function of the voltage and angle is provided. Angle compensation can be realized without angle-convert transformer.
• The simulation self-testing and self-checking function enables the equipment to detect without extra checker, which is convenient for maintenance.
• MS-2 manual quasi-synchronization device can be applied at the same time, which share the switching loop of the automatic synchronization.

Technical condition and parameters of the equipment

• Power supply
  Power supply input: 220V20%, DC or AC, 50~60Hz, power consumption 20W
  AC Input: line voltage and phase voltage of the PT on either side of the synchro-point 100V (or 100/3V), 50~60Hz
  Measuring accuracy of voltage: 0.2%
  Measuring accuracy of frequency: 0.01Hz
  Measuring accuracy of phase-angle difference: 0.5
• Point-selection startup signal:
  Supervision system output is instantaneous action contact signal (with 220V operation power
  source +, or empty contact) . The device self-hold, or by startup point-selection button on the equipment.
• Output signals are in the form of relay contact with the capacity not less than DC220V/2A,
  resistance load
• Main settings:
  PT ratio: determined by user , usually Us=100V, Ug=100V
  Self-resetting settings of the point-selection startup: recommending value Trs=60s
  Main lock settings of synchronization checking:
  Values can be set manually, recommending values: f=0.4Hz, U=10%Un,
  df/dt=1.0Hz/s
  The equipment will lock the output if the real measuring value is larger than
  the above ones.
  Breaker action time (lead-time): Tdq1,Tdq n, n=sum of the synchro-points.

Engineering Application

It has been successfully applied in many substations and power plants, etc.