RU2009053C1 - D c power supply system of electric traction - Google Patents

Abstract

FIELD: town electric transport. SUBSTANCE: D C power supply system includes rectifier traction substation connected to contact system and rail, energy storage, control center, pickup of approaching vehicle, pickup of energy recuperation and pickup of contact system voltage. Energy storage is manufactured in the form of switched-over capacitor storage. Its employment makes it possible to improve use of recuperation energy. EFFECT: reduced losses of energy in contact system from recuperated currents, use of recuperated energy for subsequent acceleration of vehicle. 3 cl, 5 dwg

Description

 The invention relates to a DC traction network of electrified transport and can be used in traction networks of urban land transport, subways and suburban sections of electric railways.

 A known traction power supply system (STE) with an energy storage device (NE) (prototype), comprising a vehicle proximity sensor (DPTS), an engine generator, a flywheel.

The disadvantage of this system is the presence of masses (flywheel and rotor of the engine-generator), rotating at high speed, requiring careful balancing, magnetic suspension, vacuum chambers for their placement. A powerful engine-generator is used irrationally. All this translates into low efficiency, not exceeding 0.7
The aim of the invention is to increase the efficiency of STE with NE.

 This is achieved by the fact that in the STE, which contains a stationary NE, DPTS, a device is introduced that records the presence of ripples in the rectified voltage of the traction network, which are present during operation of the substation rectifiers and absent when the rectifiers are locked with the DC voltage of the recovering vehicle, the recovery sensor DR), the voltage sensor of the contact network (DNAS), and as an energy storage device, a capacitive energy storage device (CES) is used, the control outputs of which are connected to the corresponding inputs of the reverse ides node management, and control inputs - the management node to the respective outputs, wherein the sensor and energy recovery catenary voltage sensor connected between the catenary and the second and respectively the third control signal node inputs.

 A device for charging a storage capacitor is known. However, it cannot be used in an STE, since it does not ensure the transition of the charge capacitor charge mode from a constant voltage source (in the STE scheme this corresponds to the charge of the CES from the traction substation) to the charge mode from the current source (in the STE scheme this corresponds to the charge of the CES by the regenerative current vehicle (TS)), and also does not provide a transition from the indicated charge modes of the CES to the mode of its discharge into the traction network to the load.

 The proposed CES scheme in STE is characterized by the presence of current sensors and keys in the circuits of the metering reactors and in the circuit of the storage capacitor bank (BNC), by the presence of newly introduced circuits connecting the plus and minus of the BNK bus through the keys, respectively, to the contact network and rails, and also a control unit that performs broader functions than in the known storage device for the charge of storage capacitors, namely, controlling not only the operation of the thyristors, but also all the keys mentioned.

 From the scientific, technical and patent literature, STE with ENE, performed according to the proposed scheme, is not known, therefore, the proposed STE with ENE has novelty. The presence of keys and current sensors in the CES, which distinguishes it from the known storage capacitor charge circuit, is also not known, therefore, the proposed CES circuit has significant differences.

 In FIG. 1 shows a diagram of a STE with a CES; in FIG. 2 is a diagram of the operation of the CES in the charge mode from the traction substation; in FIG. 3 is a diagram of the operation of the CES in charge mode from a recuperating electric train; in FIG. 4 is a diagram of the operation of the CES in the mode of discharge to traction; in FIG. 5 is a diagram of the CES with added resistance.

 The system contains a rectifying traction substation 1, a contact network 2, a vehicle (TS) 3, rails 4, a vehicle proximity sensor (DPTS) 5, a recovery sensor (DR) 6, a voltage sensor for a contact network (DNA) 7, a control unit (BU ) 8, a capacitive energy storage device (ENE) 9, consisting of the first and second parallel branches, composed of series-connected respectively the first and second keys 10, 11, the first and second metering reactors 12, 13, the first and second current sensors 14, 15, first and second thyristors 16, 17, me the thyristor anodes include a switching capacitor 18 and two counter-connected diodes 19, 20, a common output of the latter through a series-connected third key 21, a block of storage capacitors (BNK) 22, a third current sensor 23 and a fourth key 24 connected to a common output of the first and second keys 10, 11, the common output of the third current sensor 23 and the fourth key 24 through the fifth key 25 is connected to the combined cathodes of the thyristors 16, 17, and the common output of the BNK 22 and the third key 21 through the sixth key 26 is connected to the common output of the first 10, second 11 and quarter 24 keys. The power input of the drive 27, 28 is formed by the common output of the first 10, second 11 and fourth 24 keys and the combined cathodes of thyristors 16, 17, the control inputs of keys 10, 11, 21, 24, 25, 26 and thyristors are used as its control inputs 16, 17, and as control outputs are the outputs of current sensors 14, 15, 23.

In the initial position, all the keys are open, the thyristors are in a non-conductive state, current pulses with a frequency f arrive at their control electrodes, the current does not flow through the reactors, the BNC is charged to a minimum voltage U _co , less than the open circuit voltage of the traction substation U _xx . When TC 3 passes through the connection point of DPTS 5, the latter is triggered and transmits a signal to control unit 8, which collects the charge circuits of BNK 22 using metering reactors 12, 13, for which control unit 8 issues a command to close keys 10, 11, 21, 24. Let this occurs at time t ₁ (Fig. 2), when a current pulse enters the control electrode of thyristor 16. Thyristor 16 opens and current flows along the circuit from the traction substation 1 through the contact network 2, then through bus 27, key 10, reactor 12, DT 14, thyristor 16, bus 28 and rails 4 to traction substation 1. At the same time and through the switch 11, the reactor 13, the DT 15, the thyristor 16 is charged commutating capacitor 18 to the contact voltage. After a certain time, set by the frequency of the control unit 8, at time t ₂ (Fig. 2), a control pulse arrives at the thyristor 17, the last one opens and the voltage of the switching capacitor 18 is applied to the thyristor 16. The thyristor 16 is locked, the charging circuit of the reactor 12 is broken and the metering reactor 12 is discharged simultaneously to the switching capacitor 18 and BNK 22. In this case, the capacitor 18 is recharged, in the BNK 22 is recharged by the amount of energy stored in the reactor 12. Simultaneously with the discharge of the reactor 12 on the BNK 22, another 13 eaktora current from the substation 1 to 2 catenary via the bus 27, the key 11, the DT 15, thyristor 17, the bus 28, the rails 4 to the traction substation 1. After a period of time determined by the time BU 8 t ₃ (FIG. 2) is fed a control pulse to the thyristor 16. The voltage of the switching capacitor is applied to the thyristor 17, locking it. The metering reactor 13 is discharged to the capacitor 18, recharging it, and additionally recharges the BNK 22. At the same time, the process of charging the reactor 12 is repeated and so on until the BNK 22 is charged to the voltage U _{xx of the} traction substation 1.

 The above-described mode is the mode of the CES charge from a constant voltage source (traction substation), which is performed using metering reactors to increase the efficiency.

 When the voltage at the BNC 22 reaches the open circuit voltage of the traction substation 1, the BU 8 puts the CES into standby mode, from which, depending on the situation, the CES can either switch to the charge mode from the current source (recuperating vehicle) or to continue charging from the voltage source (traction substation )

To switch to standby mode, control unit 8 provides opening of keys 10, 11 in dead-time pauses, which are controlled by DT 14 and 15. Suppose BNK 22 was charged to U _xx at time t ₄ (Fig. 4), then when current in reactor 12 reached zero at time t ₅ (as reported by DT 15), the key 11 opens, it must be completed during a dead time pause until time t ₆ . In the same way, the key 10 is opened at time t ₇ . After that, the control unit 8 issues a command to open r _keys 21, 24. Since all shutdowns occur at dead time, there are no special requirements for the keys, except for speed. Therefore, the keys can be mechanical, electromagnetic, static (thyristor). Thus, the BNK 22 goes into standby mode.

There can be two ways out of standby mode. If the vehicle 3 applies regenerative braking with the release of electricity to the contact network 2, and the voltage in the contact network does not rise above the open circuit voltage U _{xx of the} traction substation 1, then this means that the recovered current supplies another vehicle in traction mode, then at the end recovery, after some time after the passage of DPTS, BNK 22 goes from standby to the above-described charge mode using metering reactors 12, 13, which continues until BNK 22 is charged to the maximum possible voltage contact network U _кcmax in order to accumulate energy for a discharge on a moving vehicle. For such energy storage there is enough parking time for the vehicle.

If ТС 3 applies regenerative braking with the release of electric energy to the traction network, the voltage in the contact network becomes higher than the voltage U _xx , then at time t _s (Fig. 3) CES, by the command of DR 6, enters the mode of receiving the recovery current. To this end, the control unit 8 issues commands to close the keys 25, 26, by which the BNK 22 is directly connected to the traction network. As soon as at time t ₉ (Fig. 3), the charge current drops to zero, as reported by DT 23, the control unit 8 sends a command to open the keys 25, 26, thereby putting the BNK 22 into standby mode. It is clear that the parameters of BNK 22 must be calculated in such a way that, during the reception of the recovery current, BNK 22 is charged to a voltage of U _{BNK max} = U _{k max.}
A mode is possible when the recovery current is received by another vehicle and BNK at the same time. In this case, at the end of the recovery, the BNK 22 is recharged to U _x max using the metering reactors 12, 13, as in the first case.

The efficiency of the UGE charge will mainly be affected by losses in the traction network from charging currents (when the BNC is charged from the traction substation). Given the parameters of real STE. The charge efficiency will lie in the range of 0.93-0.97. The energy accumulated in the BNK 22 must be transferred to the moving vehicle, for this purpose the CES must be transferred to the discharge mode. When starting the vehicle at time t ₁₀ (Fig. 4), the voltage in the contact network 2, due to high inrush currents, will stepwise decrease, which will be the signal to control unit 8 from DNA 7. The control unit 8 will issue a command to close the keys 25, 26, thereby transferring BNK 22 from standby to discharge mode. The discharge lasts until the voltage of the BNK 22 is higher than the voltage of the contact network 2. At the end of the discharge (at time t _{11, the} discharge current decreases to zero and DT 23 reports this), the BU 8 gives a command to open the keys 25, 26, transferring the BNK 22 to standby until the next charge-discharge cycle. The discharge efficiency will be maximum, since the BNK is discharged to the traction load located in the immediate vicinity of the CES.

 The CES diagram depicted in FIG. 1, with certain STE parameters, it has the disadvantage of a low utilization factor of the storage capacitor unit.

· ln

; t_рL=

·arctg

;
ω =

;
ω₀= 1/

;
a= (r_L+r_c)/(2˙L);
r_TC - приведенное сопротивление тяговой сети, Ом; r_L,
r_C - активные сопротивления дозирующего реактора и ошиновки модульной конструкции БНК, Ом;
L - индуктивность дозирующего реактора, Гн;
U_xx - напряжение холостого хода тяговой подстанции, В;
I_m - максимальный ток дозирующего реактора, А;
С - емкость БНК, Ф. Допуская для упрощения и не сделав большой ошибки, что (r_L + r_C) -> 0 и принимая во внимание значения параметров реальных систем тягового электроснабжения постоянного тока, переписывают формулу (1):

·ln

≥ L·

, (2) откуда
U_СО≥

(3)
При достаточно низком сопротивлении тяговой сети r_тс (что необходимо во избежание пережогов контактной сети) и небольшом максимальном токе I_m (что необходимо во избежание больших потерь в тяговой сети) величина минимально возможного напряжения "мертвого объема" БНК U_CОmin близка к U_xx. Например, подставляют в (3) параметры реальной СТЭ электрических железных дорог: U_xx = 3600 B, Im = 1000 A, r_тс = 0,15 Ом
U_СО≥

= 3520 В Таким образом, схема заряда БНК при помощи дозирующих реакторов по схеме фиг. 1 сможет работать только лишь начиная с напряжения U_CОmin = 3520 В, что предопределяет низкий коэффициент использования БНК.When charging the BNK 22 from the traction substation using the metering reactors 12, 13, the requirement must be met that the charge time of the metering reactor to the maximum current be greater than or equal to the discharge time of the metering reactor on the BNK (see Fig. 2), i.e., t _3L ≥t _pL (1) where
t _sL =

Ln

; t _pL =

Arctg

;
ω =

;
ω ₀ = 1 /

;
a = (r _L + r _c ) / (2˙L);
r _TC - reduced resistance of the traction network, Ohm; r _L
r _C - active resistances of the dosing reactor and busbars of the modular design of the BNK, Ohm;
L is the inductance of the metering reactor, GN;
U _xx is the open circuit voltage of the traction substation, V;
I _m is the maximum current of the metering reactor, A;
C is the capacity of the BNK, F. Assuming for simplification and without making a big mistake, that (r _L + r _C ) -> 0 and taking into account the values of the parameters of real DC traction power supply systems, rewrite formula (1):

Ln

≥ L

, (2) where
U _CO ≥

(3)
With a sufficiently low resistance of the traction network r _ts (which is necessary to avoid burnouts of the contact network) and a small maximum current I _m (which is necessary to avoid large losses in the traction network), the minimum possible voltage of the “dead volume” of the BNK U _СОmin is close to U _xx . For example, substitute in (3) the parameters of the real STE of electric railways: U _xx = 3600 V, Im = 1000 A, r _tf = 0.15 Ohm
U _CO ≥

= 3520 V Thus, the BNK charge circuit using dosing reactors according to the scheme of FIG. 1 will be able to work only starting from the voltage U _CОmin = 3520 V, which determines the low utilization rate of BNK.

 To eliminate this drawback, an adjustable resistor 29 is included in the CES circuit, included in the circuit 27 for connecting the common output of the first 10, second 11, and fourth 24 keys to the contact network, while the corresponding terminal of the sixth key 26 is connected to the terminal of the resistor 29 from the side of the contact network 2.

The additional resistance decreases the rate of rise of current in the metering reactor, thereby increasing the charge time of the reactors to _Im , i.e., the additional resistance increases t _sL and does not affect it, but t _pL (see formula (1)).

, (4) где r_д - величина переменного сопротивления.Formula (3) takes the form
U _CO ≥

, (4) where r _d is the value of the variable resistance.

= 3230 В . Таким образом, при величине дополнительного сопротивления r_д = 0,55 Ом - U_CОmin = = 3230 В. По мере заряда БНК продолжительность импульса разрядного тока реактора уменьшается, поэтому можно уменьшать и время заряда реактора до I_m уменьшая величину добавочного сопротивления. При заряде БНК до напряжения, при котором выполняется условие (3), необходимость в r_д отпадет и его величина равна нулю.Substitute in (4) the above parameters of the STE and r _d = 0.55 Ohm
U _CO ≥

= 3230 V. Thus, with the value of the additional resistance r _d = 0.55 Ohm - U _CОmin = 3230 V. As the BNC charge, the pulse duration of the discharge current of the reactor decreases, therefore, it is possible to reduce the reactor charge time to I _{m by} decreasing the value of the additional resistance. When the BNK is charged to a voltage at which condition (3) is satisfied, the need for r _d will disappear and its value will be zero.

 The presence of additional resistance will negatively affect the efficiency of the ENE charge, however, the calculations made according to the above example showed that the efficiency of the charge using an adjustable resistor in the ENE circuit will lie in the range 0.85-0.95. (56) Japanese Application N 61-35011, cl. B 60 M 3/06, 1986.

Claims (3)

 1. DC traction power supply system containing a rectifying traction substation connected to a contact network and a rail to which a power input of the energy storage device is connected, a control unit, the first signal input of which is connected to an output of the vehicle proximity sensor, characterized in that, for the purpose of increasing efficiency, an energy recovery sensor and a contact voltage sensor are introduced into it, and the energy storage device is made in the form of a switched capacitive storage device, the control outputs of which are connected Nena to corresponding inputs of the feedback control unit, and control inputs - the management node to the respective outputs, wherein the sensor and energy recovery catenary voltage sensor connected between the catenary and the second and respectively the third control signal node inputs.  2. The system according to claim 1, characterized in that in the switched capacitive storage, the first and second parallel branches are composed of series-connected first and second keys, first and second metering reactors, first and second current sensors, first and second thyristors, between the anodes thyristors included a switching capacitor and two counter-connected diodes, a common output of the latter through a series-connected third key, a block of storage capacitors, a third current sensor and a fourth key connected with the common output of the first and second keys, the common output of the third current sensor and the fourth key through the fifth key is connected to the combined cathodes of the thyristors, and the common output of the storage capacitor unit and the third key through the sixth key is connected to the common output of the first, second and fourth keys, while the drive’s power input is formed by the common output of the first, second and fourth keys and the combined thyristor cathodes, the control inputs of the keys and thyristors are used as its control inputs, and as a control nnyh outputs - the outputs of the current sensors.  3. The system of claims. 1 and 2, characterized in that an adjustable resistor is inserted into the switched energy storage device and is included in the communication circuit of the common output of the first, second and fourth keys to the contact network, while the corresponding terminal of the sixth key is connected to the resistor terminal on the contact network side.

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