RU2560716C1 - Pulse and periodic charging system - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: pulse and periodic charging (PPC) system relates to high-voltage pulse equipment and can be used when developing powerful pulse and periodic accelerators of electrons and UHF generators on their base. The system of pulse and periodic charging contains a high voltage source, a buffer capacitor accumulator, an inductance, a high-voltage diode, a discharger with two fixed and rotating electrodes and a generator of high-voltage impulses. Between the buffer capacitor store and the discharger the high-speed protective relay is connected, and the discharger contains the spaced fixed electrodes and, at least, two spaced electrically connected rotating electrodes and is fitted with the position sensor of rotating electrodes and the sliding contact electrically connected from one side with the rotating electrodes, and from another side - through the current-limiting element with the grounded housing of the discharger.

EFFECT: increase of average power of the pulse and periodic charging system and improvement of reliability of its operation.

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Description

The invention relates to high-voltage pulse technology and can be used in the development of powerful pulse-periodic electron accelerators and microwave generators based on them.

When creating powerful electrophysical installations, in particular, electron accelerators operating in a repetitively pulsed mode with a high average power of the electron beam, a very urgent task is to develop an efficient and reliable system of repetitively pulsed periodic charging (PPE) of capacitive storage devices for high-voltage pulse generators. At average beam power levels of hundreds of kilowatts and above, the most preferable approach is the use of a pre-charged high-voltage buffer capacitive storage, the energy from which is metered through a switch-interrupter to the capacitive storage of a high-voltage pulse generator (working capacity). The speed of energy transfer from the buffer to the high-voltage generator is most easily controlled using inductance, the value of which in combination with the values of the buffer and working capacitance uniquely determines the duration of charging the working capacitance and, accordingly, the pulse repetition rate. An important advantage of this circuit is the ability to work with doubling the voltage on the high-voltage pulse generator. In addition, the circuit breaker at the end of the charging cycle at the moment of zero current (at the maximum voltage on the working capacitance), which positively affects the efficiency and reliability of the entire system.

The main element in the circuit with dosed energy extraction from the buffer storage is a switch-interrupter, the functions of which in high-voltage versions of SIZ can be performed by a rotating electrode discharger (REM), which periodically closes the buffer storage capacitance to the storage of the high-voltage pulse generator and breaks the circuit after charging. The main problems during operation of the electrical equipment and the entire PPE based on it as a whole are the effective quenching of the high-voltage arc at the end of charging, reliable short-circuiting of the gap of the arrester at the beginning of charging and increasing the reliability of the PPE due to the rapid interruption of its operation in case of emergency.

It should be noted that arresters with a rotating electrode for switching a capacitive storage device to a load - a discharge in water - are widely used in industry for crushing crushed stone, cleaning trolleys from scale, etc. (L.A. Yutkin. Electro-hydraulic crushing. - L .: LDNTP, part 1, 1959, 36 pp.). The use of such systems is based on the electro-hydraulic effect. These devices operate in a wide range of energy and supply voltages stored in the buffer, however, the response frequencies are limited to units of Hertz and only with average powers up to 50 kW are modes with a pulse repetition rate of 50 ... 100 Hz implemented.

For the prototype closest to the inventive pulse-periodic charging system in terms of all the features, a pulse current generator with a filter (buffer) capacity and an inductive charging circuit of an electro-hydraulic installation was selected (L.A. Yutkin. Electro-hydraulic installations. - L .: Engineering, 1986. - p. 86-90, fig. 3.1e).

The prototype contains a high voltage source, a capacitive buffer storage, inductance, a high-voltage diode, a spark gap with two stationary electrodes and a rotating electrode, and a high-voltage pulse generator in a grounded housing.

The functioning of the system of pulse-periodic charging, made according to the prototype scheme, is based on the process of dosed energy selection using a switch-interrupter from a buffer storage device previously charged with a high voltage source. As a switch-chopper in the prototype, a spark gap with two fixed electrodes and one rotating electrode is used, for which the amount of switched energy is limited by the electric strength of the structure and the erosion resistance of the electrodes. The distance between the stationary electrodes is determined by the diameter of the rotating electrode. In the prototype PPE circuit, the buffer capacitance through the inductance is electrically connected to the fixed RVE electrode, the second fixed RVE electrode is connected through a diode to the capacitive storage of the high-voltage pulse generator. In this case, one of the stationary electrodes is under the potential of charging the buffer capacity, the second - since the working capacity is not initially charged, is at zero potential. When the rotating electrode approaches the stationary ones due to the potential difference, the breakdown of the air gap between the high-voltage stationary electrode and the rotating one initially occurs. As a result, the movable electrode falls under high potential, which in turn leads to the breakdown of the second interelectrode gap between the movable and the second stationary, associated with the working capacity. Thus, the electric circuit is closed and charging of the generator begins, which is of a resonant nature. The movable electrode continues its rotational movement and the distance between it and the stationary electrodes is continuously increasing. At the same time, the charging current of the working capacity continues to flow through the electric arc formed between the electrodes. As the voltage at the working capacitance rises, the charging current drops, at the moment of the end of charging it becomes equal to zero and in the normal operation mode the arc goes out spontaneously. This is facilitated by the presence in the circuit of a protective high-voltage diode, which prevents the occurrence of an oscillatory process in the system buffer capacity - working capacity - inductance. The presence of a protective diode, in addition, allows organizing a forced time delay between the end of the charging process (current zero) and the switching of the working capacitance to the load to ensure that the high-voltage arc is disconnected in the spark gap with a rotating electrode due to a current pause.

It should be especially noted that in the prototype a single rotating electrode was used as part of the RWE, the stationary electrodes are located opposite each other and the gap between them is determined by the dimensions of the rotating electrode, which limits the electric strength of the structure and the rate of arc extinction.

The system of pulse-periodic charging, made according to the prototype scheme, allows you to get almost any pulse repetition rate at small working capacities up to 0.1 microfarads. This is achieved by the fact that the buffer capacity operates in the partial discharge mode, and the working one is charged for one half-cycle in the oscillatory mode through an inductance with low ohmic losses. In this case, the value of the buffer capacity exceeds the working one by 15 ... 20 times.

At the same time, increasing the average power transmitted to the drive of the high-voltage pulse generator using a periodic periodic charging system according to the prototype scheme requires a significant increase in the capacity of the buffer battery, and hence the energy stored in it, which significantly increases the negative consequences of emergency situations. These abnormal situations in the vast majority of cases are associated with the failure to restore the electric strength to the nominal level or with the self-breakdown of the switch (or switches) of the high-voltage pulse generator and the self-breakdown of the spark gap itself with a rotating electrode to earth. Given the large energy stored in the buffer, the consequences of abnormal operation of key elements are explosive, which is associated with a significantly increasing amplitude and duration of the discharge current of the buffer capacity. In addition, if there is a shorted switch of the working drive or RVE to the ground, it is not possible to cut off the current in the PPE circuit many times higher than the nominal one without taking special measures. The buffer capacity is completely discharged with burnout or damage to the RWE electrodes and switches of the high-voltage generator. Installing a fuse in the PPE circuit can partially solve the protection problem, but its efficiency and performance in pulse circuits are significantly limited. In addition, restoration of the charging system in this case is only possible after replacing the fuse.

The disadvantages of the system of pulse-periodic charging, selected as a prototype, are the relatively low level of average power transmitted to the load, the lack of protection of the circuit from the resulting through current due to the failure to restore the electrical strength of the switch of the generator of high-voltage pulses, as well as the periodic misses of the RWE due to the presence of residual potential on the rotating electrode from the previous pulse.

It should be especially noted that without taking special measures, a further increase in the average power of the pulse-periodic charging system constructed according to the prototype scheme and an increase in the pulse repetition rate will cause even greater difficulties in ensuring its functioning due to the significantly increased probability of emergency situations.

Thus, in order to increase the average level of power transmitted to the load by means of a pulse-periodic charging system based on dosed energy extraction using a spark gap with a rotating electrode, and to increase the reliability of the operation of PPE in this mode, a number of improvements are required to minimize the consequences of incorrect operation of the elements.

The technical task is to improve the design of a pulsed-periodic charging system based on dosed energy extraction from a high-voltage buffer storage using a high-speed protective relay and an arrester with rotating electrodes of improved design.

The expected technical result of the proposed solution is to increase the average power of the pulse-periodic charging system, increase the reliability of its operation and minimize the consequences of incorrect operation of the main elements included in the PPE and high-voltage pulse generator.

The technical result is achieved by the fact that, in contrast to the known pulse-periodic charging system, which includes a high voltage source, a buffer capacitive storage, inductance, a high-voltage diode, a spark gap placed in a grounded housing, containing two stationary electrodes and a rotating electrode, and a high-voltage generator pulses, in the proposed system between the buffer capacitive storage and the arrester, a high-speed protective relay is introduced into the circuit, and the arrester contains two spatial spaced fixed electrode and at least two spaced apart electrically connected rotating electrode is equipped with a position sensor and rotating electrodes and sliding contact, is electrically connected on one side with rotating electrodes, on the other - through a current limiting element with the arrester housing.

Introduction to the circuit of a pulse-periodic charging system between a buffer capacitive storage and a spark gap of a high-speed protective relay allows to significantly increase the average power and increase the reliability of the system as a whole. In the case of abnormal operation of a spark gap with rotating electrodes or switches of a high-voltage pulse generator, there is a through current from the buffer tank to the ground, the amplitude and duration of which significantly exceeds the standard operating values. The threshold current sensor installed in the circuit at the same time generates a signal to start the protective high-voltage relay, which quickly breaks the charging circuit into a pre-selected time interval. This allows you to restore the electrical strength of the switching elements, to avoid the destruction of nodes through current from the buffer tank and to continue the system after the protective relay is closed in normal mode.

The spatial separation of the stationary electrodes and the use of appropriately spaced at least two rotating electrodes can significantly increase the efficiency of arc extinction and the dielectric strength of the structure by increasing the gaps between the stationary electrodes. The separation of the stationary electrodes can be carried out both in angle (electrodes are located in the same plane of rotation) and in height.

Equipping the RWE with the position sensor of the rotating electrodes allows you to quickly adjust the start time and the current pause between the end of the charging process and the start of the switches of the high-voltage generator, which, firstly, facilitates the normal operation of the generator by ensuring full restoration of the electrical strength of the switches, and secondly, by adjusting the delay to quickly change the pulse repetition rate. Equipping the EWR with a sliding electric contact connecting the rotating electrodes through the current-limiting element to the ground ensures that, when they are not closed by an arc to the stationary electrodes, the force is maintained at zero potential. This organization of the spark gap operation significantly stabilizes the starting characteristics and increases its reliability. When rotating electrodes are closed to stationary electrodes (during the process of charging the working capacity), the current-limiting element prevents the charge from draining from the buffer tank to the ground.

Thus, the construction of a powerful high-voltage system of pulse-periodic charging of capacitive storage devices according to the proposed scheme allows to achieve a technical result - increasing the average power of the system of pulse-periodic charging, increasing reliability, operation of the system and minimizing the consequences of incorrect operation of the main elements that make up the PPE.

In FIG. 1 is a diagram of the inventive system of pulse-periodic charging,

Where

1 - high voltage source;

2 - high-speed protective relay;

3 - buffer capacitive storage;

4 - inductance;

5 - high voltage diode;

6 - spark gap with rotating electrodes;

7 - generator of high voltage pulses;

where C _p is the working capacity; K - switch; R is the resistance.

In FIG. 2 shows a circuit of a spark gap with rotating electrodes, an electrode position sensor and a sliding contact electrically connected to rotating electrodes and through a current-limiting element with a spark gap body,

Where

8 - arrester housing;

9 - dielectric shaft;

10 - rotating electrodes;

11 - fixed electrodes;

12 - disk with a position sensor of rotating electrodes;

13 - sliding contact;

14 - current limiting element.

The inventive system of pulse-periodic charging is implemented in practice. The composition of PPE, the circuit of which is presented in FIG. 1, includes: a high-voltage source 1 in the form of a high-voltage rectifier, a buffer capacitive storage 3, composed of parallel-connected energy-intensive high-voltage capacitors, a fast-acting protective relay 2, which is a sealed volume filled with transformer oil, in which switching and opening are carried out using an electromagnet charging circuits using movable electrodes, inductance 4, protective assembly 5 of high-voltage high-current diodes, spark gap with rotating electrodes 6, g generator of voltage pulses 7 with capacitance C _p and the gas discharge controlled switch K. GIN after activation switch in an active load that represented in Scheme resistance R.

A spark gap with rotating electrodes (see Fig. 2) consists of a grounded metal housing 8 with three electrically connected rotating electrodes 10 spatially spaced 120 degrees apart from each other on a dielectric shaft 9, two stationary electrodes 11, also spaced 120 ° apart rigidly connected to the shaft of the RWE of the disk with the position sensor of the electrodes 12 and touching the rotating electrodes of the sliding contact 13 connected to the housing of the spark gap through the current-limiting element 14 in form of a resistor.

The system of periodic repetitive charging is as follows. In accordance with FIG. 1 high voltage source 1 charges the buffer capacitive storage device relatively slowly 3. Before charging is completed, an asynchronous motor with a speed controller spins shaft 9 (see Fig. 2) with rotating electrodes 10. At the end of the process of charging the buffer capacity and reaching the required shaft speed, the control unit generates a pulse to close the high-speed protective relay 2, which connects the buffer capacitance to the fixed input of the RVE through inductance 4 and high-voltage diode assembly 5. In this case, the polarity Connections diode allows current to flow from the buffer tank to the working, but prevents reverse flow. When the moving electrode approaches the stationary electrode, a breakdown occurs and a high potential appears on the mobile electrode, which, in turn, leads to a breakdown from the second movable electrode, electrically connected to the first, to the second stationary one, which is connected to the capacitive storage C _{p of} the high-voltage pulse generator. Charging of the working capacity begins. In this case, the delay time of the full switching of the arrester (the time for switching on the RVE), depending on the voltage at the buffer capacity, is 100 ... 200 μs and does not affect the operation of the PPE. At the end of the charging process, the arc in the interelectrode gaps of the RVE goes out, the current becomes zero and the signal from the position sensor of the rotating electrode enters the delay line in the control unit. With a delay relative to the control pulse, a signal is generated to start the switch K of the high-voltage pulse generator and the energy stored in the working capacitance is released at the active load. The duration of energy release is much shorter than the charging process. In this case, the rotation frequency of the spark gap, the duration of charging, the delay of the control pulse to start the spark gap K are consistent. At the end of the cycle, the charge-discharge with stationary electrodes begins to approach the next pair of moving electrodes and the cycle repeats. In this case, the average switched power is limited only by the erosion resistance of the spark gap electrodes and the capabilities of the motor that ensures the rotation of the electrodes. In the event of an emergency due to the failure to restore the electrical strength of the switch of a high-voltage pulse generator or a high voltage generator, the current from the buffer tank to the ground increases significantly. In this case, the current sensor installed in the PPE circuit will generate a signal at the input of the high-speed protective relay to open the charging circuit with its subsequent closure after a period of time necessary to restore the electric strength, and the PPE will continue to operate normally.

Thus, as a result of experimental studies and computer modeling, it was shown that the inventive powerful pulse-periodic charging system based on dosed energy extraction from a high-voltage buffer storage device using an improved design of a rotating electrode with rotating electrodes is capable of efficiently operating with high average power. At the same time, the reliability of the claimed PPE is significantly higher than systems with obviously lower output characteristics.

Claims (1)

A periodic repetitive charging system comprising a high voltage source, a capacitive buffer storage device, an inductance, a high voltage diode, a discharger located in a grounded housing containing two stationary electrodes and a rotating electrode, and a high voltage pulse generator, characterized in that between the buffer capacitive storage and the spark gap a high-speed protective relay is introduced, and the arrester contains two spatially spaced stationary electrodes and at least two spatially spaced electrically connected rotating electrode and is equipped with a position sensor for rotating electrodes and a sliding contact, electrically connected on one side with the rotating electrodes, and on the other through a current-limiting element with the arrester housing.

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