RU2428789C1 - METHOD BY MR KI GUTIN AND MR SA TSAGAREYSHVILI OF INPUT OF SIGNAL CURRENTS TO 0,4 kV THREE-PHASE POWER TRANSMISSION LINE AS PER "PHASE-PHASE" DIAGRAM WITH "PHASE-PHASE" POWER SOURCE - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention is intended to supply telecontrol signals from dispatch station (DS) installed at 35/10/0.4 kV substation to distributed controlled stations (CS) which are connected to 0.4 kV power transmission lines. Signals of remote indication of position of controlled switches and signals of remote measurements, which contain information on values of currents, voltages, cosφ and readings of metres of electric energy of consumers, are transmitted from CS to DS.

EFFECT: reducing generator power consumption.

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Description

The invention relates to the field of electrical engineering and is intended for transmitting telecontrol signals from a control room (DP) installed at a substation 35/10 / 0.4 kV to distributed control points (KP) that are connected to 0.4 kV power lines. From the CP to the DP transmit the signaling signals of the position of the controlled switches and the telemetry signals, which contain information on the values of currents, voltages, cosφ, readings of electricity consumers' counters.

The well-known "Passive-active method of inputting signal currents into a three-phase electric network" patent RU 2224363. Bull. No. 5. This analogue has the following disadvantages:

1. The presence in the generator that implements the method, an air transformer, in the manufacture of which it is difficult to obtain a coupling coefficient between its windings, close to unity, due to the large dimensions.

2. Large power consumption during the formation of current introduced into the line of 0.4 kV.

Also known is the “Method of Gutin K.I. input signal currents into a three-phase power line ”, which is adopted as a PROTOTYPE. Patent RU 2224365 H04B 3/54. Bull. No. 5, 2004, which has the same disadvantages as the analogue.

The aim of the invention is to reduce the power consumption of the generator compared to the PROTOTYPE without the use of an air transformer.

This goal is achieved by the fact that the signal currents i ₀ are introduced into the three-phase 0.4 kV line using a resonant circuit, which consists of a coil 4, a capacitor 5, a ground wire and a low-voltage phase A, a transformer 10 / 0.4 kV, currents The signal i _{0 is} transformed into a 10 kV line, and two currents are obtained: direct - I ₁ and reverse - I ₂ sequences, which are received at the receiving point by direct and negative sequence filters that are tuned to the frequency f ₀ .

The drawing shows a diagram of a generator that implements the claimed technical proposal, where:

1. Three-phase transformer 10/04 kV (transformer), which has a low-voltage phase A, B, C.

2. Three-phase power line 10 kV.

3. Three-phase power line 0.4 kV (line 0.4 kV).

4. The first air inductor (coil), its inductance is equal to - L ₄ .

5. The first capacitor, its capacity is - C ₅ .

6. Half-wave rectifier bridge.

7. The second capacitor, its capacity is - C ₇ .

8. The second coil, its inductance is equal to - L ₈ .

9. The third capacitor, its capacity is equal to - With ₉ .

10. Managed key (key).

11. The control unit.

12. The grounded neutral of the transformer 10 / 0.4 kV (wire "Earth").

We determine the power consumption by the prototype generator from the 0.4 kV line, while for simplicity of presentation, we neglect the active resistances and inductance of the windings of the air transformer.

From the description of the prototype it follows that the amplitude of the current flowing along the circuit: bridge, primary winding of the air transformer, resistor, key, bridge, is 17 A, while the transformation coefficient of the air transformer is unity.

The power consumption in the prototype, subject to assumptions, is:

where I _m = 17 A is the amplitude of the prototype current through a closed key at the time of its opening;

R ₉ = 10 Ohm - resistor resistance;

_straight 0,25T τ = ₀ - the duration of the closed position of the prototype key generator.

- the period of frequency f _{0 of the} prototype.

Due to the fact that energy from the 0.4 kV network is consumed only in the time interval τ _pr , when the key is closed, a coefficient of 0.25 is entered in expression (1), since the key is closed for the time τ _pr = 0.25T ₀ .

Initial data for the calculation of the generator

The frequency of information currents introduced into the 0.4 kV line is:

The power of the transformer that powers the generator is:

Capacitors 5 and 7 are equal to:

The inductance of coils 4 and 8 is equal to:

The active resistance of coils 4 and 8 is equal to:

where Q = 10 is the quality factor of coils 4 and 8.

The total inductance of coils 4 and 8 is equal to:

The total active resistance of coils 4 and 8 is equal to:

The claimed generator

The values of the inductance of coil 4 and capacitor 5 are selected from the resonance condition in the oscillatory circuit: circuit 4 - capacitor 5 - phase B - ground wire at a frequency f ₀ = 1000 Hz with an open key, while the windings have inductance and active resistances transformer neglected due to their smallness.

The values of the inductance of the coil 8 and the capacitance of the capacitor 7 are selected from the resonance condition in the oscillatory circuit with the key closed in the circuit: coil 8 - key - capacitor 7.

The capacitor 9 and the coil 8 are designed to create a resonant circuit in order to prevent the failure of the key 10 when it is opened due to the stored electromagnetic energy in the coil 8.

Define the capacitance of the capacitor 9 from the expression:

whence follows:

We determine the frequency of the current in the resonant circuit (L ₈ -C ₉ ), which decays exponentially:

At time t ₁ , when the potential of phase A is greater than the potential of phase B, then the diodes D ₁ and D ₃ will be open, we will connect the generator to the 0.4 kV line, and capacitor 7 will begin to be charged with current i ₁ along the circuit: phase A - coil 4 - diode 1 - "plus" capacitor 7 - "minus" capacitor 7 - diode 3 - phase C - wire "Earth". The capacitor 7 will be charged to a voltage of E ₀ :

where E ₀ is the voltage amplitude of 380 V.

After charging the capacitor 7 to a voltage of E ₀ , the generator circuit will be in a stable state.

At time t ₂ > t ₁ , the key begins to commute with a frequency f ₀ when the key is closed for a time τ = 0.08 T ₀ , while current i ₂ will flow through it along the circuit: phase A - coil 4 - diode 1 - coil 8 - key - diode 3 - phase C - wire "Earth". At the same time, the discharge current of capacitor 7 will flow along the circuit: “plus” capacitor 7 — coil 8 — key –– “minus” capacitor 7, and the charging current of capacitor 7 will flow through its charge circuit with current i ₁ , while the charge current is equal to the discharge current which are equal to each other and directed towards each other, maintaining the voltage across the plates of the capacitor 7 equal to E ₀ .

We determine the amplitude of the current through the key at the time of opening the key, taking into account (2), (7), (8), (9) and the adopted value τ = 0.08 T ₀ from the expression:

where B ₀ = 536 V; R _Σ = 1.58 Ohms; τ = 0.08T ₀ ; L _Σ = 2.52 · 10 ^-3 G.

Define the power loss from the network of 0.4 kV of the claimed generator by analogy with the expression (1):

Let us determine, taking into account (1), how many times the power consumption from the 0.4 kV network decreased when using the claimed generator:

Thus, the goal set by the invention has been achieved, since the power consumption of the inventive generator from the 0.4 kV network has been reduced by 20 times without the use of an air transformer. It should be noted that the power of the transformer 10 / 0.4 kV, the frequency of the currents f ₀ , the amplitude of the current I _m through the key at the time of its opening in PROTOTYPE and the claimed generator are taken equal to each other.

Claims (1)

The method of inputting signal currents to a 0.4 kV three-phase power line according to the “Phase” - “Phase” circuit with a “Phase” - “Phase” power supply, according to which current flows through the circuit: phase A, input of a three-phase two-half-wave rectifier bridge, plus bridge output bus, second coil of the air transformer, resistor, closed key in the interval 0≤t≤0.25 T ₀ , minus bridge bus, phase B, Earth wire, characterized in that when current flows through the circuit: phase A first coil, a diode D _1, a two-phase full-wave rectifier the first bridge, the closed switch in a time interval T ₀ 0≤t≤0,08, diode D _3, phase C is carried out "Earth" W accumulate electromagnetic energy in the first coil, at the time the key opening due to the energy W in the resonant circuit, which is tuned to frequency f ₀ , free damped oscillations of the signal current begin

along the circuit: phase A, first coil, first capacitor, phase B, ground wire, while in the 0.4 kV line receive direct currents - I ₁ and reverse - I ₂ sequences at a frequency f ₀ that transform into line 10 kV, where they will be received by filters of the forward and reverse sequence, which are tuned to the frequency f ₀ at the receiving point, where
I _m - the amplitude of the signal current,
ω ₀ = 2πf ₀ is the angular frequency,
f ₀ - signal current frequency,

- period of the signal current frequency,

- attenuation coefficient of the current amplitude I _m ,

,
R _L4 is the active resistance of the first coil,
L ₄ - inductance of the first coil,

- the energy that was accumulated in the first coil at the time of opening the key.