JP3104242B2 - Lighting shared power generator with unbalance compensation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of the Invention The present invention is configured such that the output current of a generator that supplies power to a three-phase four-wire system for low-voltage distribution line for lighting is limited to a positive-phase current. The present invention relates to a common light generator with unbalance compensation.

B. Summary of the Invention The present invention relates to an autotransformer having a Y-connection ungrounded three-phase generator and an intermediate tap connected between two phases of the three-phase generator, or a Δ-connection generator having an intermediate tap in one phase. And a light source for use in connection with a three-phase four-wire low-voltage power distribution line mounted on a mobile power supply vehicle. The three-phase generator is connected to the output side of the three-phase generator via a reactor. An inverter with a capacitor connected to the DC side,
Compensation current signal forming means for detecting a current flowing from the generator, extracting a negative phase component current from the detected current, and controlling an inverter to flow a current corresponding to the negative phase component current to the distribution line. Constitutes an unbalance compensation unit, the unbalance compensation unit is mounted on the mobile power supply vehicle, and the inverter is controlled so that the load current of the generator is only for the positive phase. The single-phase load capacity that can be loaded by balancing the voltage is increased.

C. Conventional technology The distribution system and distribution voltage of low-voltage distribution lines include single-phase two-wire systems.
0V, single-phase two-wire 200V, single-phase three-wire 100 / 200V, single-phase three-wire 200
V, three-phase four-wire system 100 / 200V, etc., and among them, the three-phase four-wire system for distributing power to a lighting shared load is the most common.

In this three-phase four-wire low-voltage distribution line shared by lights, the pole transformer is configured with a different capacity Δ connection or a different capacity V connection. Tenth
The figure shows the state of a group of consumers connected to a three-phase four-wire low-voltage distribution line composed of V-connection transformers with different capacities. In the case of FIG. 10, the single-phase transformer between the S and T phases is made larger (different capacity) than the single-phase transformer between the R and S phases, and the neutral wire is drawn out from the middle of the winding to obtain a single-phase transformer. It constitutes a line circuit.

The load connected to the three-phase four-wire low-voltage distribution line is S-
A single-phase 100V or 200V load (light load group) concentrates on a single-phase three-wire circuit between the N and T phases, and a three-phase circuit on the three-phase circuit between the R and S phases
200V load (power load group) is mixed. Such a low-voltage distribution system generally has a tree-type distribution system. Looking at the secondary side of a pole transformer in one bank as shown in Fig. 10, three-phase unbalanced load (single-phase load + three-phase load group) It is.

Here, for example, when repairing the low-voltage distribution line such as replacing the pole transformer in the distribution line of FIG. 11, it is necessary to temporarily disconnect the low-voltage distribution line from the service power supply (high-voltage distribution line) side. .

In this case, during the construction of the distribution line, in order to prevent the power outage of the construction work of the corresponding low-voltage customer, as one means, a mobile power generation device including a three-phase AC synchronous generator driven by a prime mover or a power vehicle mounted on a vehicle is used. There is a case where the secondary side of the pole transformer is opened to supply power to a corresponding group of low-voltage consumers temporarily from a power supply vehicle or the like.

D. Problems to be Solved by the Invention By the way, focusing on the three-phase unbalanced current flowing through the generator winding of the conventional power-supply vehicle, a single-phase load group equivalently between two lines of the generator output is connected. Where the three-phase load is superimposed.

Therefore, a positive-phase current and a negative-phase current flow in the generator equivalently, and the generator uses the negative-phase rotating magnetic field due to the negative-phase current and the secondary rotating harmonic rotating magnetic field to generate a negative-phase current. Depending on the value of the current, the following adverse effects occur,
It causes practical problems.

Abnormal heating occurs on the braking winding of the generator rotor, the surface of the field pole, and the like.

In the generator induced voltage, a harmonic component is superimposed on a fundamental component to cause output voltage waveform distortion.

Pulsation may occur in the rotating system due to the harmonic torque.

Since a negative phase component is generated in the generator internal induced voltage, the generator output voltage causes three-phase imbalance, and cannot be corrected by the automatic voltage regulator.

In order to regulate such adverse effects, for example, from the viewpoint of regulating the abnormal heating phenomenon of the generator, the negative-sequence current is limited to an allowable value or less. Examples of allowable values defined in domestic standards for AC synchronous generators include, for example, JEM1354
(1982) "Diesel engine driven land-based synchronous generator" specifies that the reverse phase current is 15% or less.

If a three-phase imbalance of the generator output voltage occurs,
Since an unbalanced voltage is applied to the connected load, a load-side failure may occur depending on the value.

For example, even if a single-phase load is connected between the two lines of the shared lamp generator and the voltage is automatically adjusted by an automatic voltage regulator so that the line voltage becomes constant, the other two-line voltages are unbalanced. Therefore, an unbalanced voltage is applied to the three-phase loads connected thereto.

The most common three-phase power load in this case is a three-phase induction motor. When a three-phase unbalanced voltage is applied to a three-phase induction motor, the current value of each phase is significantly different, and for example, a failure such as motor burnout occurs.

As an allowable value for the three-phase unbalanced voltage of this three-phase induction motor, for example, the ratio of the negative-phase divided voltage to the positive-phase divided voltage (voltage unbalance rate) is set to 2% or less in the BS standard. Is often used as one index for regulation.

If the negative-sequence component current is limited to 15% or less and the three-phase voltage imbalance rate is limited to 2% or less, the actual single-phase load is relatively large in the actual lighting and low-voltage distribution line. Because it is general, measures such as preparing a generator with an apparently larger rated capacity were required, but for example, in the case of a power supply vehicle, it is not possible to make the generator size too large due to restrictions on mounting on the vehicle. As a result, inconveniences such as load limitation are made.

The present invention has been made in view of such a conventional problem, and an object of the present invention is to eliminate a negative-phase component and an unbalance component of a generator load current and to reduce a load by a generator having the same rating as the conventional one. It is an object of the present invention to provide a lighting shared power generation apparatus with unbalance compensation that can greatly increase a possible single-phase load capacity.

E. Means for Solving the Problems In order to achieve the above-mentioned object, an unbalanced-compensated lighting shared power generator of the present invention comprises a Y-connection non-grounded three-phase generator and a two-phase generator of the three-phase generator. An auto-ignition transformer having an intermediate tap connected thereto and mounted on a mobile power supply vehicle and connected to an illuminated three-phase four-wire low-voltage distribution line for use, wherein the three-phase generator An inverter connected to the output side via a reactor and a capacitor connected to its DC side;
A current flowing out of the generator is detected, a negative-phase current is extracted from the detected current, and a compensation current signal for controlling the inverter to flow a current corresponding to the negative-phase current to the following distribution line. The means constitutes an unbalance compensation unit, and the unbalance compensation unit is mounted on the mobile power supply vehicle.

Alternatively, a light-sharing power generator in which a Δ-connection three-phase generator having a one-phase winding provided with an intermediate tap is mounted on a mobile power supply vehicle and connected to a light-sharing three-phase four-wire low-voltage distribution line for use An inverter connected to a three-phase output side and an intermediate tap output side of the three-phase generator via a reactor, and a capacitor connected to a DC side thereof, and a current flowing out of the generator is detected. And a compensating current signal forming means for controlling the inverter so that a current to be three-phase balanced based on the single-phase load current flows through the distribution line. The unbalance compensation unit is mounted on the moving power supply vehicle.

F. Operation When the inverter is not functioning, a load current including an unbalanced component due to a single-phase load flows through the Y-connection ungrounded three-phase generator. Since the neutral point of the generator is not grounded, the zero-phase current is not included, so that this load current can be decomposed into a positive phase component and a negative phase component. The compensation current signal forming circuit calculates the negative phase current based on the load current of the generator, and controls the inverter to output the negative phase current. The negative phase current of the inverter cancels the negative phase current of the load current. Therefore, only the positive-phase current flows through the generator.

When the inverter is not functioning in the Δ-connection three-phase four-wire generator, an unbalanced component due to the single-phase load flows through the winding having the intermediate tap of the generator. The single-phase current can be three-phase balanced by reducing the single-phase current of the winding and increasing the intermediate tap current and the phase current through which the single-phase current does not flow. The compensation current signal forming circuit performs an operation for three-phase balancing of the single-phase current and controls the inverter. The inverter sends a compensation current to the single phase and absorbs the compensation current from the neutral phase and the phase where no single phase current flows to balance the unbalanced current of the generator.

G. Embodiment An embodiment of the present invention will be described with reference to the drawings.

First Embodiment FIG. 1 shows a circuit of a shared power generator according to a first embodiment. In FIG. 1, reference numeral 1 denotes a common light generator, and reference numeral 2 denotes a common three-phase four-wire low-voltage power distribution line to which power is supplied from the power generator.

The power generator 1 includes a three-phase generator G, which is directly connected to the prime mover, and is not connected to the ground, a Y-connection, an unbalance compensation unit 3, and an autotransformer connected between the V-W phases of the generator G and having an intermediate tap. And a current transformer CT for detecting a phase current.

The U, V, W phases of the generator G are connected to the R, S, T phases of the distribution line 2,
The intermediate tap of the autotransformer 6 is connected to the grounded neutral line N of the distribution line 2.

The unbalance compensation unit 3 includes a reactor for each phase of the generator G.
Inverter 4 connected via ACL and U of generator G
A compensation current signal forming circuit 5 for calculating a negative phase component current from the detected load current from the current transformer CT for detecting the phase and W phase load currents and controlling the gate of the inverter control circuit 4;
In the inverter 4, a capacitor C connected to the DC side is charged by a generator G via a diode D connected in anti-parallel to the switching element and functions as a DC power supply.

 Next, the operation of the first embodiment will be described.

In FIG. 1, when a single-phase (100 V and 200 V) load and a three-phase load are mixedly loaded, a three-phase unbalanced current is supplied to each phase on the power supply side (generator side) from the autotransformer 6.
_R ′, _S ′, and _T ′ flow.

Since the neutral point of the generator G is not grounded, the three-phase unbalanced currents _R ′, _S ′, and _T ′ do not include the zero-phase current, and therefore the positive-phase currents _1R , _1S , _1T , And can be decomposed into the negative phase currents _2R , _2S , and _2T .

This three-phase unbalanced current _R ', _S ', _T '
The current is detected by CT, and the negative phase current is calculated by the compensating current signal forming circuit 5 in the unbalance compensating unit 3.
Control to send _2R , _2S , _2T .

Therefore, in this case, the current flowing through each phase winding of the generator G
_{Since U} , _V , and _W flow only the positive-phase currents _1R , _1S , and _1T , the generator itself is equivalent to a three-phase balanced load. Will be released from the evils of

For simplicity, in FIG. 1, vectors of each phase load current, unbalance compensation unit output current, and power generation winding current when only a single-phase load with a power factor of 1.0 is applied between the ST phases of the distribution line 2 are shown. The figure is shown in FIG.

2, when the unbalance compensation unit 3 is not connected, only the unbalanced currents _LS and _LT flow through the generator G. However, when the unbalance compensation unit 3 is connected, the single-phase A three-phase balanced current can flow regardless of the load.

3 (a) and 3 (b) show actual measurement examples of the generator phase voltage and each phase current waveform when the unbalance compensation unit 3 in FIG. 1 is used (on) and when it is not used (off). When the unbalance compensation unit 3 is used, it can be seen that the phase current values of the generator become equal, and the unbalance current is eliminated.

FIG. 4 is a comparison of the characteristic examples of the use of the unbalanced unit (the present invention) and the absence of the unbalanced unit (conventional). FIG. 4A shows an example of the single-phase load input capacity-generator three-phase voltage unbalance rate characteristic example. (B) shows an example of single-phase load input capacity-allowable three-phase power transmission capacity characteristics.

Since the generator is normally limited to 15% or less of the reverse phase current from the permissible reverse phase current withstand capability, the single phase load input capacity of the present invention is larger than that of the conventional apparatus as shown in FIG. 4 (b). Can be taken.

Second Embodiment FIG. 5 shows a circuit of a shared power generation device according to a second embodiment. The same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will not be repeated.

In FIG. 5, G ₂ is a Δ-connected three-phase four-wire generator having an intermediate tap in the VW interphase winding directly connected to the prime mover, 3 ₂
In imbalance compensation unit, the auxiliary current transformer on the secondary side of the CT for detecting the phase currents of the generator G ₂ and the generator inverter 4 ₂ connected via a reactor ACL to the three-phase 4-wire G ₂ AUX-CT is connected, the R-phase current is subtracted from the difference current between the S-phase current and the T-phase current of the distribution line, and the S-phase current is superimposed on the three-phase balanced load current.
Phase, and a compensation current signal forming circuit 5 ₂ which to output the compensation current with respect to the difference between the single-phase load current to the inverter circuit 4 ₂ detects the difference between T The phase-phase load currents.

Next, the operation of the second embodiment will be described. For simplicity, the description will be made assuming that only a single-phase load is connected to the distribution line 2 between the S-N-T phases as shown in FIG.

In FIG. 6, it is assumed that load currents _S ′, _N , and _T ′ are flowing through the S-phase, N-phase, and T-phase by a single-phase three-wire load group, and the load current _S ′ is used as a reference vector. It is assumed that the vector diagram of the phase load current flows as shown in FIG.

Next, as shown in FIG. 7 (b), _S 'and _T ' flowing in the S phase and the T phase are, as shown in FIG. Can be considered.

Of the above, in-phase current Is the VW of the generator G to make the neutral line N a common return.
The interphase winding is circulated between the load and the neutral point.

In this case, the same in-phase current flows in one direction (between the V and W phases) of the generator winding in the opposite direction due to the neutral point distribution. This does not particularly affect the unbalance of the three-phase output voltage of the generator.

In addition, the voltage between the VN and NW phases also differs by a small amount of leakage impedance, but is in a practically negligible range.

Therefore, from the viewpoint of countermeasures for balancing the generator output voltage,
The in-phase component (FIG. 8) having the neutral line N as a common return can be ignored.

On the other hand, the 180 ° phase inversion in FIG. However, since a magnetomotive force is generated only in the V-W phase winding of the generator, three-phase balancing of this current is required.

The operation of three-phase balancing of the single-phase current (180 ° phase inversion) will be described below.

In the sixth view, connecting the imbalance compensation unit to the generator output circuit, R-phase and N-phase of the compensation current _RC, captures _NC (absorption side) S phase and another in the T-phase of the compensation current _SC,
It is assumed that _TC is sent (sending side) (FIG. 7 (c)).

 The compensation current on the absorption side flows through the path shown in FIG.

When the unbalance compensation unit is connected to the generator output side and the above compensation current is absorbed and transmitted, the virtual output current from the connection point of each phase winding of the generator body connected in Δ (neutral point N is set to the common return path) The single-phase load current does not contribute to the three-phase output voltage imbalance of the generator.
_U , _V , and _W are as shown in FIG. 7D when only a single-phase load is used.

As described above, the single-phase load current excluding the in-phase component can be three-phase balanced.

Therefore, even if a three-phase load is mixed with a single-phase load, the difference between the two-wire single-phase load currents is detected, and a compensation current is applied based on the difference, so that the single-phase load current excluding the in-phase load is detected. The three-phase balance can be achieved, and as a result, the unbalance of the generator three-phase output voltage can be suppressed.

That is, in FIG. 5, the compensation current signal forming circuit 5 _2,
S and T from S and T auxiliary current transformers AUX-CT
Incorporating a three-phase load current component of the phase load current differential and R-phase auxiliary current transformer AUX-CT, the compensation current by the inverter 4 _2
RC, it is possible to balance the load current of the generator G ₂ compensation current _SC, by controlling the inverter 4 ₂ by the gate signal for controlling so as to sent the _TC with to absorb the _NC.

H. Effects of the Invention Since the present invention is configured as described above, the following effects can be obtained.

(1) When a generator having the same size (same rated capacity) as the conventional system is used, the load capacity of a single-phase load that can be loaded can be greatly increased. When the unbalance compensation unit is set to the generator rated capacity, the total value of the single-phase load input capacity and the three-phase load input capacity can be loaded up to the generator rated capacity.

(2) Within the permissible unbalanced load range, the generator-side current and the three-phase output voltage are also balanced regardless of the load-side current imbalance, so the protection device of the power generation device (for example, overvoltage or overload protection) Can function properly over the entire range of use.

(3) Similarly, since the generator-side current and voltage are balanced, the generators can be easily connected in parallel, and active and reactive power can be shared even in an unbalanced load state.

(4) Single-phase 100V, single-phase 200V, single-phase three-wire 100 / 200V, three-phase three-wire 200, except low-voltage power distribution method other than light / light three-phase four-wire 100 / 200V
Applicable to V circuit.

(5) The present invention can also be applied to power generation equipment that supplies power to unbalanced loads other than low-voltage distribution line loads.

[Brief description of the drawings]

1 to 4 relate to a first embodiment of the present invention.
FIG. 1 is a block circuit diagram of a common light generator, FIG. 2 is a vector diagram for explaining the operation of the lamp generator, and FIGS. 3 (a) and (b) are voltages for explaining the effect of the unbalance compensation unit. FIG. 4 (a) and (b) are current waveform diagrams, and are diagrams showing the unbalance rate and the transmission capacity characteristics. 5 to 8 relate to the second embodiment, FIG. 5 is a block circuit diagram of a common lamp generator, FIG. 6 is a current explanatory diagram of the same device when only a single-phase load is used, and FIG. FIG. 8 is a vector diagram for explaining the operation of the device, FIG. 8 is an explanatory diagram of an in-phase current path of the device, and FIG. 9 is an explanatory diagram of a compensation current path of the device. 10 and 11 relate to a conventional example. FIG. 10 is a circuit diagram of a three-phase four-wire low-voltage power distribution line shared by lights, and FIG. 11 is a schematic diagram of use of a low-voltage power supply vehicle shared by lights. Reference numeral 1 denotes a common power generation device for lighting, 2 ... distribution line, 3,3 ₂ ... unbalance compensation unit, 4,4 ₂ ... inverter, 5,5 ₂ ... compensation current signal forming circuit, 6 ... single Winding transformer, G, G ₂ …… Generator.

Continuation of the front page (56) References JP-A-53-106431 (JP, A) JP-A-56-159936 (JP, A) JP-A-59-44934 (JP, A) , U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02P 9/00

Claims (2)

(57) [Claims] 1. A mobile power supply vehicle for use in a three-phase four-wire distribution line shared by lights, in which a pole transformer of a power system is configured with different capacity △ connection or different capacity V connection. A three-phase four-wire low-voltage power distribution line for lighting is mounted on a power vehicle equipped with a Y-connected ungrounded three-phase generator and an autotransformer having an intermediate tap connected between two phases of the three-phase generator. In the lamp-sharing power generator used by connecting to the three-phase generator, an inverter connected to the output side of the three-phase generator via a reactor and a capacitor connected to the DC side thereof, and detecting the current flowing out of the generator. An unbalance compensation unit is configured by extracting a negative phase component current from the detected current, and compensating current signal forming means for controlling the inverter to flow a current corresponding to the negative phase component current through the distribution line. The unbalance compensation unit is connected to the Imbalance compensation with Akarido shared power generation apparatus characterized by mounted to. 2. A mobile power supply vehicle used for a three-phase four-wire distribution line shared by lights, wherein a pole transformer of a power system is configured with different capacity △ connection or different capacity V connection. A power shared vehicle is equipped with a △ connection three-phase generator in which an intermediate tap is provided in a one-phase winding, and is connected to a three-phase four-wire low-voltage distribution line for lighting and used for lighting. An inverter connected to the three-phase output side and the intermediate tap output side of the three-phase generator via a reactor, and a capacitor connected to the DC side thereof, and a current flowing out of the generator is detected. A single-phase load current is calculated, and an unbalance compensation unit is configured by compensation current signal forming means for controlling the inverter so that a current to be three-phase balanced based on the single-phase load current flows through the distribution line. The unbalance compensation unit is connected to the power supply Imbalance compensation with Akarido shared power generation apparatus characterized by mounted to.