DE4204229C3 - Phase synchronous control device - Google Patents

Description

The invention is based on a phase synchronism control device according to the preamble of the patent claim 1.

A phase-coherent control of frequency generator ren is always indispensable if two or more generators on the same frequency operated in parallel.

Also in so-called single-wave broadcasting, in which several re radio station the same program on the same Broadcast frequency, it is paramount Meaning, frequency and phase of each Single-wave transmitters with high accuracy on each other vote to in the overlap zones of reception to preserve the interference zones that are as stationary as possible.

A transmission system of this kind, with which over a single-wave transmitter network both analog modulati content and digital data with only a small amount Error rate can be transmitted is from the US Patent No. 4,188,582 known.

In this system, several are connected to each other distant locations positioned stations with the same Carrier frequency operated and each over a phase re gel loop (phase lock loop) with that of a Zen tralender broadcast control frequency synchroni based on the corresponding special recipients on received and processed the respective station location becomes.

Use in those in wireless communication technology transmit frequencies whose wavelength in the ratio nis to the length of the transmission paths is small in the coverage area of the single-wave transmitter network necessarily an interferent field strength ver division with pronounced extinction zones, in which no or undisturbed reception is possible. These zones can be selected for the location bypass the antennas of the receiving devices in principle; however, this only makes sense if certain can be put that these extinction zones do not change their position. requirement of it is on the one hand, a phase-locked synchronous control of all transmitting stations operated on the same frequency - e.g. B. according to the proposal cited here after State of the art - as well as the choice of egg ner such transmission frequency at which a room wave or multi-way transmission, such as B. in short and medium wave range, can not occur.

Under the circumstances, it then plays not matter if the different phase locked controlled single-wave transmitters as a result of differing distances from the central station at a time Lich differing beginning accordingly phasing can be controlled; because it results only one, depending on the phase difference, but again a constant shift in time the extinction zones in the coverage area, the positioning the receiving antennas let bypass. Because of these connections said U.S. Patent No. 4,188,582 also does not No reference to any problem obviously the absolute one in absolute time scale Phase positions of the synchronous control signals.

Particularly high demands on the frequency and pha there is a lack of coherence of frequency generators Application of so-called audio frequency ripple control systems, with which the energy supply companies additionally Liche control signals over the power line network to install multi-tariff Electricity meters and switching relays, depending on the load conditions, to be able to control centrally.

In the z. The currently applied procedure becomes the supplier supply voltage a pulse-gated control signal added in the audio frequency range (e.g. 170 to 500 Hz). With the Ampli required at the entry points tude of the control signal of about 5% of the nominal network voltage the impulse power to be applied is added audio frequency signal 0.25% of the maximum Power supply performance. To the total to keep the required audio frequency control power small and that with increasing distance from the entry point given decrease in the available control signal amplitude to compensate, the ripple control signals are more common wise at several distant locations fed in simultaneously.  

At the low signal frequency of only 170 to 500 Hz - corresponding to a wavelength of more than 500 km - remain the phase differences of the Taxig starting from several entry points nale comparatively low compared to the ratio in a high-frequency single-wave transmitter network. Therefore arise in the supply area at approximation wise in-phase control of the generators practically no total erasures due to interference of the control signals. Still it comes in the overlap areas between the entry points depending on the ampli tude and phase difference of the different signal com components even with only small phase deviations corresponding interference, which considerable lei cause power losses and that to the consumer Reduce the available control signal amplitude.

In the event of one over the entire energy supply network result in approximately even load distribution then the most favorable conditions in this regard, when the phase of the at the different feeders connected ripple control signals is the same.

The synchronization of the control signals to the various which entry points have so far been generally about existing separate line connections between them gen realized, the maturity differences by ent speaking phase control devices compensated who have to. As a result of the diverse external influences on the long lines, however, they are open this achieved short and long-term stability of the Phase coherence proved unsatisfactory. Especially Another disadvantage is the fact that the one necessary phase correction devices require empirical attitude and control to those in the more critical areas of care range available signal amplitude to a sufficient set a high value and keep it.

To improve the stability of control generators general as well as specifically for the purpose of round control for energy supply networks, are several known technical suggestions.

In the unpublished EP 0 543 028 a Method for generating a frequency stable signal in a ripple control device of a power supply network proposed in which at least one as the base signal Transmission signal from a satellite transmitter is used. Signals from the satellites are preferred in this method of the Global Positioning System (GPS) with their highly accurate time stamps evaluated.

The previously published EP 0 362 406 relates to a system for determining the fault location, especially in the event of interruptions of power supply lines. Also be here Satellite signals from the Global Positioning System used to generate a highly accurate time signal with the help of the runtime measurements of the fault location the faulty lines is determined.

To be more general with an oscillator or frequency to achieve the highest possible frequency consistency, it is known from U.S. Patent No. 4,525,685, as a control signal the frequency of a terrestrial time evaluate signal transmitters and their time code modulation, such as B. the signals of the WWVB station of the NBS (National Bureau of Standards) in the United States. The special advantage of the system proposed here is that the when receiving the carrier frequency of the time standard transmitter as a result of the selection means of the recipient avoidable phase jitter within one through time modulation given time frame on their statistical Average integrated to approximately zero and thus not on the frequency of the oscillator to be synchronized be transmitted.

This allows oscillators with the transmit side realize the given frequency accuracy of the time signals, those for a variety of research tasks and development as well as in industrial manufacturing to be needed.

With this system to control secondary oscillators and generators of high frequency accuracy, however not possible, their vibration also in the phase in to set the absolute time scale. As for the previously ge named use cases on the one hand only with any Phase rigidity given frequency accuracy of Significance is and on the other hand a simultaneous absolute phase due to the selection-related jitter disturbances of the time signal receiver in this way also technically is not feasible, takes the aforementioned U.S. Patent 4,525,685 in this regard also no reference to any problems of such Art.

Regardless of the limitations shown this Systems is such an arrangement designed for syn Chronization of ripple control systems have been proposed namely by evaluating the signals of the Time stamp transmitter DCF 77 of the physical-technical Federal Institute of Braunschweig. To reduce the on flow of selective jitter interference in the receiver the Meinberg assembly PZF 535 is used here (see magazine "Elektronikpraxis", No. 5/1988, p. 118).

Despite the improvement indicated here as achievable the accuracy of the timing at the receiver output the resulting phases can be a factor of 100 deviations of the control generators not for round controls within the permissible tolerance range. Thereon will be referred to later in more detail later.

From the company's own publication from Ball Efratom Division, edition 1/89, pp. 14.9 to 14.11, it is also known a 10 MHz rubidium oscillator by the Check the time signal of a GPS satellite. The takes place here with the help of a divider in the ratio 10⁷: 1, by passing a 1 Hz signal derived from the oscillator the GPS clock signal is set in phase becomes.

By changing the divider ratio, with this circuit other frequencies than Generate 1Hz, but only a few integer values that allow synchronization by the GPS timing.

A timing synchronization of these frequencies a defined, freely selectable initial phase value, based on the GPS timing, is with this circuit not possible.

Based on this state of the art, it is a task of the invention, for audio frequency ripple control systems Power supply networks a phase synchronous control to develop a direction that allows any Synchronous ripple control signals in enter the network, its frequencies freely selectable and whose initial phases are stable with high accuracy and can be preset in a defined offset to each other.

This task is carried out according to the characteristic features of claim 1 solved.

Compared to the prior art shown, the solution according to the invention has the advantage that low technical effort not only all integer, but also all rationally broken signal frequency values displayed directly controlled by the GPS timing can be.

Another advantage is with a ripple control network the individual generators at the various entry points with fixed phase difference amounts to be able to operate at every GPS timing be controlled with high precision. So it works, too in energy supply networks with one over the entire Network of very different load distribution one as possible little location-dependent amplitude of the ripple control signals ensure low power requirements at the same time.

Especially also in comparison with the state of the art Technique called proposal, the signals more terrestrial Clock transmitters, such as B. DCF 77, for synchronization of ripple control signals can be used to advantage the arrangement according to the invention by the following calculation prove example; because even using a correlative Averaging phase jitter caused by selection, such as it succeeds with the use of the Meinberg assembly PZF 535, the accuracy of the DCF-77 clock is not sufficient, to feed various ripple control signals Points of the supply network unacceptable performance losses to avoid.

So there is z. B. for the practical case of only two entry points of a ripple control network, at which one signal power each of the value N for infeed comes, the dependent on the phase difference Δϕ additional Power requirement - with a given signal amplitude in the middle of the network - too

N _z = N · 6 · sin² ϕ / 2

This means that even with a phase difference of Δϕ = 30 ° 40% more signal power is used. This value increases and increases with increasing phase deviation at Δϕ = 45 ° already 75%.

With the generous assumption that there is a phase deviation of Δϕ = 30 ° max. with an additional performance requirement of 40% may still be acceptable, but is easy to show that a time control based on the DCF-77 signals even with the one that can be achieved with the PZF-535 module Improvement is not enough.

As a result of the indispensable selection means in the inbox of the DCF-77 receiver and the related ones Phase jitter must have a second clock accuracy of Received DCF-77 signal of 30 msec which are then only at the output of the PZF-535 unit is still 0.3 msec.

This already results in a ripple tax frequency of only 277 Hz is the required limit for the Tolerance too

Δϕ = 360 ° 0.3 · 10 ^-3 · 277 = 30 °

The maximum permissible phases become practical here tolerance fully exhausted by the system and already higher at signal frequencies higher than 277 Hz steps. A "power reserve" in the event of a fault Failure of the timing signals is on this way not feasible.

In contrast, with the application of the invention Solution with an accuracy of one second of the received GPS signal of 100 nsec and with the direct phases synchronization of the digitally generated signal frequency and at a z. B. high signal frequency of 900 Hz a maximum system tolerance of

Δϕ = 360 ° x 10 ^-7 x 900 = 0.032 °

ensured.

With this solution, which is cheaper by a factor of 10 ^-3 , the phase deviation Δϕ can therefore always be kept practically at zero or at a desired phase offset value in the middle of the permissible tolerance range. This is then fully available for a correspondingly long-term power reserve in the event of a satellite signal failure.

Even if more than two entry points are approached in In principle, a ripple control network arises the same results as shown above.

The basis of each phase normal control generator of the phase synchronous control device according to the invention is a digital signal generator 1 which is operated by a quartz-controlled reference oscillator 2 operated by a constantly controlled heating furnace temperature. This is based on a frequency stability of 5 × 10 ^-8 / month.

With the further and primarily brought synchronization of each digital frequency generator 1 by clock signals supplied by a satellite receiver 3 , the initial phase position of the digitally generated vibration of each generator, z. B. because every second, set to a fixed value. The further waveform follows the clock signal determined by the reference oscillator 2 .

By entering one for the frequency and the initial phase characteristic code word for the selection of Start address for reading the voltage values from the Processor signal value memory is both the ge desired frequency, as well as the desired, possibly non-zero phase value, with which the digitally generated vibration to a defined, timing point derived from the GPS signal starts and then continues through the after controls or corrects the following time cycles becomes.

A first further development of the invention includes the teaching according to the characterizing part of patent claim 2.

In a processor circuit 4 , the frequency of the reference oscillator 2 is measured via a gate circuit controlled by the timing signal of the satellite receiver 3 in the gate time defined in this way and compared with the target frequency, the value of which is stored in the processor circuit 4 . From the frequency deviation, a correction voltage is built up digitally in a process that is dependent on its initial amount and is graded in time, with the help of which gradual correction of the frequency of the reference oscillator 2 is brought about in the direction of the theoretical target value.

This ensures that the waveform of the signal voltage of the reference oscillator 2 of each generator also in the entire period between the - z. B. every second - for priority synchronization evaluated satellite timing signals with high precision keeps the desired course beibe. The value of the phase jump of the reference oscillation caused by this forced synchronization at each time pulse strives towards the value zero with each step of this automatic fine-tuning process.

A second development of the invention lies in Application of the teaching according to the characteristic of the patent claim 3.

This is - after previous, sufficient run-in time and extensive approximation of the automatic fine tuning of the reference oscillators 2 to the target frequency - achieved that the phase normal control generators of the synchronous control device, the desired te phase position of the generated vibration even in the event of failure of the satellite clock signals with a tolerance maintained, which is up to an order of magnitude better than with previously known arrangements.

Fig. 1 shows the block diagram of a phase normal control generator, as it is used several times in the phase synchronous control device according to the invention, with the most important data bus and Steuerver connections. In it is:

1 digital synthesizer (DDS)
2 reference oscillator
3 satellite receivers (e.g. GPS)
4 processor (gate, counter, memory, D / A converter)
5 control keyboard with display.

Claims (3)

1. phase synchronous control device for audio frequency ripple control systems of the energy supply networks, which are operated in parallel at several entry points of the network, with a frequency generator provided at each of the entry points for generating the ripple control signals, and with a satellite receiver ( 3 ) for receiving the timing signals of one or more communications -, Weather or navigation satellites, characterized in that a phase normal control generator is provided at each of the feed points with a digital synthesizer ( 1 ) whose clock control signals are supplied by a reference oscillator ( 2 ) with high frequency accuracy, and that the satellite receiver ( 3 ) decoded timing signals to synchronize the digital synthesizer ( 1 ) with each timing in priority and in such a way that the initial phase of the output voltage of the digital synthesizer ( 1 ) of each phase normal control generator by input of a corre genuinly defined code word for the selection of the start address for reading out the voltage values from the signal value memory of a processor circuit ( 4 ) is preset to a freely selectable phase value at any point in time. 2. phase synchronous control device according to claim 1, characterized in that each phase normal control generator contains a gate circuit ( 4 ), the gate time is also controlled by the satellite timing signals and via which the frequency of the reference oscillator ( 2 ) is measured by means of a counter, and that the frequency deviation of the reference oscillator ( 2 ) determined in the processor circuit ( 4 ) from the target frequency is used to obtain a digitally prepared correction voltage which is supplied to the reference oscillator ( 2 ) as a retuning voltage. 3. phase synchronous control device according to claim 1 or 2, characterized in that the retuning voltage for the reference oscillator ( 2 ) of each phase normal control generator by means of a digital-to-analog converter ( 4 ) is processed in such a way that in the event of a failure of the satellite Timing signals of the last value of the retuning voltage provided by the processor circuit ( 4 ) remains unchanged as a fixed value for the retuning until timing clock signals are available again.