JP2014017945A - Consumer voltage stabilization system in low voltage system of power distribution system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a consumer voltage stabilization system in a low voltage system of a power distribution system that coordinately performs appropriate reactive power compensation on every no-load power compensation device in the case of distributed installation of a plurality of reactive power compensation devices in correspondence with low voltage system consumers.SOLUTION: The consumer voltage stabilization system so configured that a plurality of reactive power compensation devices 9A-9F distributedly installed in a low voltage system I regulate individual voltages at consumer ends P2 is configured to reduce the low voltage system I into an equivalent low voltage system in which a pole transformer 3 connects to a single consumer via a low voltage distribution line 14 and a single incoming line, then on the reduced low voltage system, compute a reactive current component of reactive power required to cancel a variation in voltage in the low voltage system on the basis of a primary side voltage of the pole transformer 3, an impedance of the reduced low voltage system and a current of the consumer end P2, and divide the computed reactive current component by the number of consumers 6A-6F to produce a proportional compensation current to be supplied.

Description

  The present invention relates to a demanded voltage stabilization system in a low-voltage system of a distribution system, and is particularly useful when applied to a case where a plurality of reactive voltage compensators are distributed in a low-voltage system of a distribution system.

  When residential photovoltaic power generation facilities (PV) and electric vehicles (EV) become widespread, it becomes difficult to adjust the voltage of the distribution system due to voltage increase due to reverse power flow from PV and voltage decrease due to simultaneous charging of EV There are concerns. For this reason, techniques for adjusting the voltage of the entire distribution system using SVR, SVC, etc. have been mainly studied.

  On the other hand, as a compensation system for reactive power in the distribution system, reactive power compensation devices that perform reactive power compensation individually are distributed for each customer connected to each distribution line on the low voltage side of the transformer in the distribution system. A method for autonomously compensating reactive power for each consumer has been proposed (see Non-Patent Document 1).

  As described above, when reactive power compensation devices that perform reactive power compensation individually for each consumer are distributed and the reactive power compensation is autonomously performed for each consumer, the nearest to the location that causes the voltage fluctuation In addition to being able to respond to spots where there is a problem, it is possible to reduce the breakdown voltage performance of the semiconductor elements constituting the reactive power compensator and reduce the overall cost. Can be reduced. As a result, even when a PV or EV distributed power source that causes voltage fluctuation is connected to the load side, it is possible to achieve stabilization of consumer voltage in the distribution system at low cost. Can do.

Kentaro Fukushima, Atsushi Noda, Yuichiro Serizawa, Koshiro Nemoto, “Basic concept of μSTATCOM, a distributed reactive power compensator installed at the consumer end”, 2011 IEEJ Power and Energy Division Conference, No. 224, pp. 17-18, 2011

  However, the reactive power compensator as described above is arranged in each of a plurality of low voltage systems corresponding to only one customer of a low voltage system (in this specification, a pole transformer, a low voltage distribution line, and a lead-in line). However, there is no problem at all, but multiple reactive power compensators are distributed in a low-voltage system on the secondary side of the distribution transformer, such as pole transformers, corresponding to multiple customers. In such a case, it may be a problem how to control each reactive power compensator. That is, when reactive power is generated by individual control for each reactive power compensator arranged in a distributed manner, the voltage may increase excessively (in the case of PV) or excessively decrease (EV). . In this case, optimal voltage control becomes difficult.

  In view of the above-described prior art, the present invention provides an appropriate reactive power compensation in cooperation with each no-load power compensation device when a plurality of reactive power compensation devices are distributed in correspondence with low-voltage customers. An object is to provide a consumer voltage stabilization system in a low-voltage system of a power distribution system that can perform power supply.

The first aspect of the present invention for achieving the above object is as follows:
In a low-voltage system composed of a transformer that steps down from a high voltage to a low voltage in a distribution system, a low-voltage distribution line connected to the transformer, and a plurality of service lines connected to the low-voltage distribution line, the low-voltage distribution line via the service line This is a consumer voltage stabilization system in the low voltage system of the distribution system that is configured to adjust the voltage at the customer end, which is the connection point between the service line and the customer, with multiple reactive power compensators arranged in a distributed manner. And
For each customer, based on the information on the distance from the delivery point of the distribution substation to the connection position of each service line connected to the low voltage distribution line via the high voltage distribution line and the distance of each service line, from the service point Calculate the impedance of the distribution system leading to the lead-in line, and connect a plurality of consumers connected to the low-voltage system from the delivery point through the high-voltage distribution line, the transformer, the low-voltage distribution line, and the lead-in line And reduced to an equivalent power distribution system leading to
Calculate the amount of fluctuation of the voltage applied to the power distribution system using the impedance based on the supply voltage to the power distribution system, the reduced impedance of the power distribution system, and the sum of the current at each consumer end, The reactive power compensator is controlled so as to calculate the reactive current component of the reactive power necessary for canceling and distribute the reactive current component by the number of consumers and supply the distributed reactive current component to each consumer end. It is in the customer voltage stabilization system in the low voltage | pressure system of the power distribution system characterized by being comprised.

  According to this aspect, the low-voltage system reactive power is replaced by equivalently replacing the low-voltage system having a plurality of consumers connected to the plurality of service lines with one service line and one customer connected to the service line. Therefore, the compensation amount can be calculated easily and accurately.

The second aspect of the present invention is:
In the customer voltage stabilization system in the low voltage system of the power distribution system described in the first aspect,
In the consumer voltage stabilization system in the low voltage system of the distribution system, the voltage on the primary side of the transformer is used as the delivery voltage, and the low voltage system impedance is used as the impedance of the distribution system.

  According to this aspect, attention is paid to the fact that the impedance of the high-voltage distribution line hardly influences the voltage fluctuation at the consumer end due to PV or EV, and the impedance of the low-voltage system mainly contributes, and this characteristic is used. As a result, the compensation amount of each reactive power compensator distributed and installed at each customer end can be calculated using only the reduced low-voltage impedance, so that the calculation of the compensation amount can be simplified. That is, in this aspect, since parameters such as the impedance of the high-voltage distribution line are not used at all, the necessary compensation amount can be calculated without being affected by the change of the parameter due to the change of the structure of the high-voltage distribution line. . By the way, on the high-voltage distribution line side, the increase and decrease of the line length due to the installation and removal of the high-voltage distribution line and the system change of the high-voltage distribution line, etc. may occur relatively frequently compared to the low-voltage system, The impedance of high-voltage distribution lines is frequently changed. That is, when the impedance of the high voltage distribution line is used as a parameter for calculating the compensation amount, it is necessary to change the parameter for calculating the compensation amount every time the high voltage distribution line is changed.

The third aspect of the present invention is:
In the customer voltage stabilization system in the low-voltage system of the power distribution system described in the first or second aspect,
The calculation of the reactive current component in the contracted low-voltage system is performed by calculating the consumer end voltage V ₂ using the formula (3) or (4) given by the formula (1) or (2). It is in the customer voltage stabilization system in the low voltage system of the distribution system characterized by

The fourth aspect of the present invention is:
In the consumer voltage stabilization system in the low voltage system of the power distribution system described in any one of the first to third aspects,
The customer voltage stabilization system in the low voltage system of the distribution system is configured to exchange information of other customers necessary for the contraction using power line communication.

  According to this aspect, information necessary for reduction of the low-voltage system can be automatically and appropriately performed between the reactive power compensators in the consumer as necessary. In particular, even when a new customer is added to the low-pressure system or when a customer is removed, the parameter can be changed quickly and flexibly. it can. Furthermore, since the power line is used as the communication path, the equipment cost can be reduced as much as possible.

  According to the present invention, attention is paid to the fact that the impedance of the high-voltage distribution line hardly affects the voltage fluctuation at the consumer end due to PV or EV, and the impedance of the low-voltage system contributes mainly, and this characteristic is utilized. By using the reactive power compensator distributed at the end of each consumer, the customer can target the reactive power compensator of multiple customers connected to a single distribution transformer such as a pole transformer. Appropriate reactive power compensation can be performed every time. In other words, the amount of reactive power compensation required for voltage adjustment is calculated by reducing the low-voltage system connected to one distribution transformer, and this is equally divided by multiple reactive power compensators. Since the output is shared and coordinated, the customer end voltage can be adjusted appropriately.

It is explanatory drawing which shows notionally the power distribution system which applies the consumer voltage stabilization system which concerns on embodiment of this invention. It is explanatory drawing at the time of extracting one of the low voltage | pressure systems of FIG. 1, and contracting this to one service line and one customer. It is explanatory drawing for demonstrating the aspect of PLC in the low voltage | pressure system of FIG. It is a figure for demonstrating the reactive current generate | occur | produced when load is PV, (a) is the circuit block diagram, (b) is the equivalent circuit schematic. In the case shown in FIG. 4, it is an equivalent circuit diagram at the time of connecting a reactive power compensator with PV. It is a figure for demonstrating the reactive current generate | occur | produced when load is EV, (a) is the circuit block diagram, (b) is the equivalent circuit schematic. It is a block diagram which shows the reactive power compensation apparatus applied to the consumer voltage stabilization system which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram conceptually showing a power distribution system to which a customer voltage stabilization system according to an embodiment of the present invention is applied. As shown in the figure, the distribution system includes a distribution substation 1, a high voltage distribution line 2 connected to the distribution substation 1, and a pole transformer 3 that is a distribution transformer. And a plurality of low-pressure systems I (only one system is shown in the figure). The low-voltage system I includes a pole transformer 3, a low-voltage distribution line 4, and a lead-in line 5. At the ends of the lead-in lines 5A, 5B, 5C, 5D, 5E, and 5F, consumers 6A, 6B, 6C, 6D, 6E, 6F is connected. A group of consumers 6A to 6F that are a plurality of loads connected to one pole transformer 3 in this way is called a bank. Each consumer 6A-6F has normal loads such as lighting together with PV7A, 7B, 7C, 7D, 7E, 7F and EV8A, 8B, 8C, 8D, 8E, 8F, and at the consumer end with PV7A-7F Reactive power compensators 9A, 9B, 9C, 9D, 9E, and 9F are provided in order to suppress voltage rise and voltage drop at the consumer end due to EVs 8A to 8F. That is, in the low-voltage system I in this embodiment, a plurality of (six in this embodiment) are invalid on the secondary side of the pole transformer 3 in correspondence with a plurality (six in this embodiment) of consumers 6A to 6F. The power compensation devices 9A to 9F are distributedly arranged.

  Here, when the distribution system is expected from the consumers 6A to 6F, the impedance of the high-voltage distribution line 2 is extremely small and can be ignored compared to the impedance of the low-voltage system. From this, it is safe to ignore the high-voltage distribution line 2 and consider that the primary side of the pole transformer 3 is a voltage source. In FIG. 1, the distribution substation 1 is replaced with the primary side of the pole transformer 3, and the impedance R + jX of the high voltage distribution line 2, the pole transformer 3, the low voltage distribution line 4 and the lead-in wires 5A to 5F is changed to the pole transformation. It can be set as the sum total of the impedance of the container 3, the low voltage distribution line 4, and the lead-in wires 5A to 5F. In this way, the voltage adjustment problem can be simplified by dividing it into problems for each bank of the pole transformer 3.

  However, several customers 6A to 6F are connected to each bank of the pole transformer 3, and the low-voltage system I cannot satisfy the condition that there is only one customer. If there is one customer 6A-6F connected to each bank of the pole transformer 3, there is no room for a problem as to how to control the reactive power compensator.

  That is, in order to further simplify the problem and satisfy the condition that only one customer exists, the several customers 6A to 6F connected to each bank of the pole transformer 3 are approximately reduced. In short, as shown in FIG.

  The present embodiment focuses on the above-mentioned points. As shown in FIG. 2, a plurality of consumers 6 </ b> A to 6 </ b> F (see FIG. 1) connected to the pole-mounted transformer 3 are contracted and equivalent 1 Replace with low-pressure system II with eaves customers 6. That is, the low-voltage system II reaches one consumer 6 via the pole transformer 3 through the low-voltage distribution line 4 and one service line 5. Here, the consumer 6 has PV7 and EV8 as loads together with normal loads such as lighting, and suppresses voltage increase at the customer end P2 due to PV7 and voltage drop at the customer end P2 due to EV8. The reactive power compensator 9 is provided.

An equivalent low-pressure system II in which a plurality of consumers 6A to 6F as shown in FIG. 1 is reduced to a single customer 6 as shown in FIG. 2 can be obtained by the following procedure.
(Procedure 1) The length of the low voltage distribution line 4 viewed from each of the consumers 6A to 6F is different. Therefore, the average length of the low-voltage distribution line 4 viewed from each of the consumers 6A to 6F is obtained, and the equivalent low-voltage distribution line 14 is simulated by the impedance of the low-voltage distribution line 14 having this average length.
(Procedure 2) Since the lengths of the service lines 5A to 5F are different for each of the consumers 6A to 6F, the average length is obtained. Considering that the service lines 5A to 5F are connected in parallel, the equivalent service line 15 is simulated by a value obtained by dividing the impedance of the average length of the service line 15 by the number of consumers 6A to 6F.
(Procedure 3) The reverse flow / charge current of the equivalent customer 6 is simulated by taking the sum of the reverse flow currents of PV7A-7F existing in the consumers 6A-6F or the sum of the charge currents of EV8A-8F.

This contraction procedure will be described more specifically by taking the low-pressure system I composed of the six customers 6A to 6F in FIG. 1 as an example. Now, assuming that the length of the low-voltage distribution line 4 is 0 m when viewed from the consumers 6A and 6B, 40 m when viewed from the consumers 6C and 6D, and 80 m when viewed from the consumers 6E and 6F, the average length is obtained. And 40m. When the 80 m impedance of the low voltage distribution line 4 is Z _LV , the equivalent impedance of the low voltage distribution line 14 after contraction is Z _LV / 2 corresponding to 40 m.

Next, about the service lines 5A-5F, if it is 15 m in all the six customers 6A-6F, the average length will be 15m, and if this is further divided by the number of customers 6A-6F, it will be 2.5m Become. Assuming that the impedance of the lead wires 5A to 5F for 15 m is Z _SDL , the equivalent impedance of the lead-in wire 15 after contraction is Z _SDL / 6 corresponding to 2.5 m.

Finally, the reverse flow current of PV7A-7F is reduced. In Figure 1, when the whole of the consumer 6A~6F is generating reverse flow current I _PV uniformly, by taking the sum, the value of equivalent reverse flow current after contraction is 6 × I _PV . It should be noted that EV8A to 8F can be contracted in a similar manner.

  The equivalent low-pressure system II obtained by the above procedure after contraction is the low-pressure system II shown in FIG. By such a procedure, multiple customers 6A to 6F are reduced to one customer 6 for each bank of pole transformer 3, so that voltage rise due to reverse power flow of PV7 or voltage drop due to EV8 charging. Reactive power required to compensate for is calculated.

  Here, if the installation points of the reactive power compensators 9A to 9F are the customer ends P2, the information on the reverse flow current of PV7A to 7F or the charging current of EV8A to 8F measured by each reactive power compensator 9A to 9F. Can be exchanged with each other by a high-speed PLC (Power Line Communication) of the low-pressure system I and used for calculation of reactive power. Such an information exchange mode is shown in FIG. As shown in the figure, each reactive power compensator 9A to 9F distributes the calculated reactive power by the number of reactive power compensators 9A to 9F.

  In this way, if a plurality of consumers 6A to 6F is contracted and reactive power compensators 9A to 9F installed in the respective consumers 6A to 6F inject reactive power, “PV or EV in a certain low voltage system” It is possible to perform autonomous decentralized control for each bank of pole transformers in the form of “compensating for voltage fluctuations that occur with a plurality of reactive power compensators μSTATCOM installed in the low voltage system”.

The operation of the reactive power compensators 9A to 9F using the PLC as described above is summarized as follows.
1) Information on the low-voltage distribution line 4 and the service lines 5A to 5F by the contraction method as described above for the consumers 6A to 6F connected to the same bank of the pole transformer 3 when the reactive power compensators 9A to 9F are installed. The equivalent impedance is obtained from the above and the value is set.
2) When there is a possibility that the voltage at the customer end P2 deviates from the range of the predetermined specified voltage, the reverse flow current of PV7A-7F or the charging current of EV8A-8F measured by each reactive power compensator 9A-9F Are exchanged by the high-speed PLC of the low-pressure system I, and the sum is calculated.
3) Each reactive power compensator 9A to 9F calculates reactive power required to compensate for a voltage rise or a voltage drop by a method described in detail later, and this is equally divided by the number of reactive power compensators 9A to 9F. And output.

  Note that the high-speed PLC used in this method is communication within the range of the low-voltage system I and does not need to go beyond the pole transformer 3, so there is no technical problem.

  Here, as shown in FIG. 2, voltage increase or voltage decrease in the low-voltage system II reduced to a form in which only one customer 6 is connected to the low-voltage distribution line 14 connected to the pole transformer 3. The basic operation principle of the reactive power compensator 9 that compensates for the above will be described. Here, the knowledge that the impedance of the high-voltage distribution line 2 is extremely small compared to the impedance of the low-voltage system I and can be ignored when the distribution system is expected from the consumers 6A to 6F in FIG. Therefore, the explanation will proceed by ignoring the high-voltage distribution line 2 and assuming that the primary side of the pole transformer 3 is a voltage source.

  The reactive power compensator 9 is a device that is installed at the low voltage system II, particularly at the customer end P2, and adjusts the voltage by reactive power compensation in order to cope with voltage fluctuations at the customer end P2 due to PV7 and EV8. At this time, the reactive power to be injected is determined as follows.

The reactive power compensator 9 can cope with both a voltage rise due to PV7 and a voltage drop due to EV8. First, a method for dealing with a voltage rise due to PV7 will be described. In general, a large number of PVs 7 are installed in one low-voltage distribution line 4 and each affects the system voltage. However, here, for the sake of simplicity, the low-pressure system II after contraction as shown in FIG. 2 will be considered. That is,
In the configuration in this case, as shown in FIG. 4 (a), the primary side of the pole transformer 3 is considered as a voltage source, so that the customer end P2 is located at a length l from the voltage source P1. Consider a situation in which a PV 7 is installed in a consumer 6 existing in the factory and the PV 7 generates power with a power factor of 1.

The power output (reverse power flow) from the customer 6 to the low-voltage system II is power obtained by subtracting the power consumption in the customer 6 from the generated power of the PV 7. In this case the current flowing from the consumer 6 to the low-pressure system II side and I _2.

This situation is shown in the equivalent circuit of FIG. As shown in the figure, when the impedance of the low-pressure system II from the voltage source P1 up to the consumer terminal P2 and R + jX, the voltage V ₂ of the customer terminal P2 is the voltage source P1 by voltage rise caused by the current I ₂ It is higher than the voltage V ₁ by (R + jX) · I ₂ . That is, the voltage _{V 2} of the customer terminal P2 is (11).

This voltage rise makes it difficult to adjust the voltage _{V 2} of the customer terminal P2 within a predetermined voltage range (101 ± 6V, 202 ± 20V ). Therefore, it sets up a reactive power compensation device to consumer end P2, equal to the absolute value and the absolute value of the voltage V ₁ of the voltage V ₂ by injecting reactive power. In other words, considering that equal to the voltage V ₁ of the voltage V ₂ and the voltage source P1 of the consumer end P2.

The situation where the reactive power compensator is installed at the consumer end is shown in FIG. Here, the current I ₂ flowing from the customer 6 into the low voltage system II is considered with reference to the phase of the voltage V ₂ at the customer end P2. Of the current I ₂ , a component in phase with the voltage V ₂ (active current) is decomposed into I _2d , and a component orthogonal to the reactive current (reactive current) is decomposed into I _2q . That is,

It is expressed.

Assuming that the PV 7 is operated at a power factor of 1 and the reactive power compensator 9 outputs only reactive power, the active current I _2d is a current corresponding to the active power from the PV 7, and the reactive current I _2q is a reactive power compensator. 9 corresponds to the reactive power from 9. So that the voltage is adjusted by decreasing the voltage V ₂ of the customer terminal by the reactive current I _2q. Now, 'when the changes in the voltage _{V 2'} voltage consumer end by injecting reactive current _{I 2q} from the voltage _{V 2} voltage _{V 2} is given by equation (13).

From the above equation (13), the absolute value of the voltage V ₂ ′ is given by equation (14).

From the above equation (14), the reactive current I _2q is obtained.

It becomes. Here, equation (15) has two solutions, but the device capacity of the reactive power compensator 9 can be reduced when the reactive power injected is smaller,
And However, the voltage V ₂ ′ is a voltage at the consumer end P2 in a state where the reactive power compensator 9 is injecting reactive power. In the equation (16), the absolute value of the voltage V ₂ ′ is made equal to the absolute value of the voltage V ₁ . That is, if | V ₂ ′ | = | V ₁ |, the compensation current I _ST corresponding to the reactive power to be injected by the reactive power compensator 9 when the reverse flow current is supplied from the PV 7 to the low voltage system II is set. Can be determined. Thereby, the voltage rise of the consumer 6 in which PV7 was installed can be compensated.

Next, how to deal with voltage drop due to EV will be described. As shown in FIG. 6 (a), an EV 8 is installed at the consumer 6 existing at the consumer end P2 at a distance l from the voltage source P1, and this EV 8 uses a power factor of 1 to charge the current I ₂ for charging. Suppose you are taking from II. This situation is shown in the equivalent circuit of FIG. EV8 voltage _{V 2} of the installed customer terminal P2 is becomes even (R + jX) only · _{I 2} lower than the voltage _{V 1} of the voltage source P1 by voltage drop caused by the current _{I 2.} That is, the voltage _{V 2} of the customer terminal P2 is (17).

To compensate for the charge voltage drop due to the EV8, injecting reactive power from the consumer end the installed reactive power compensator to P2 9 (see FIG. 5), the absolute value of the voltage V ₂ of the customer terminal P2 and the voltage source Given that equal the absolute value of the voltage V ₁ of the P1. Assuming that the EV 8 is charged with a power factor of 1 and the reactive power compensator 9 outputs only reactive power, it is noted that the sign of the current I ₂ is opposite (14) to (14) in the case of PV. It is possible to derive an expression similar to the expression 17). As a result, the current I _2q corresponding to the reactive power to be injected is

It becomes. However, the voltage V ₂ ′ is a voltage at the consumer end P2 in a state where the reactive power compensator 9 is injecting reactive power. In the equation (18), the absolute value of the voltage V ₂ ′ is made equal to the absolute value of the voltage V ₁ . That is, if | V ₂ ′ | = | V ₁ |, the compensation current I _ST corresponding to the reactive power to be injected by the reactive power compensator 9 when the EV 8 is sucking current from the low voltage system II is determined. be able to. Thereby, the voltage rise of the consumer 6 in which PV7 was installed can be compensated.

Here, the reactive power compensator 9 is intended to deal only with voltage fluctuations at the customer end P2 due to PV7 and EV8. Therefore, in the equations (11) and (17), the voltage V of the voltage source P1 is used. to obtain a voltage V ₂ of the customer end P2 ₁ on whether adding the voltage rise due to PV7, or in the form of subtracting the charge voltage drop due to the EV8. Voltage V ₂ of the customer terminal P2 is, of course, can be measured in the consumer 6, it is considered to use the measured value, reactive power compensator 9, dare (11) and (17) It is set to obtain a voltage V ₂ of the customer end by. Voltage V ₂ of the consumer terminal P2 to be measured by the consumer 6, not only the influence of the consumer 6, greatly influenced by other customers 6. That is, as shown in FIG. 4B and FIG. 6B, the situation greatly deviates from the situation where only the PV 7 or EV 8 of the customer 6 exists.

On the other hand, (11) calculating the voltage _{V 2} of the customer terminal P2 by formula and (17), only the voltage rise and drop according to PV7, EV8 the current of the consumer 6 is considered, Ya FIG 4 (b) The situation shown in FIG. That is, (11) and (17) the voltage V ₂ of the customer terminal P2 by formula is a value that reflects only the voltage fluctuation due to the consumer 6, the customer value of the voltage V ₂ based on If the reactive power compensator 9 installed at 6 injects reactive power, “the voltage fluctuation caused by PV7 or EV8 of a certain consumer 6 is compensated by the reactive power compensator 9 installed at the consumer 6. Autonomous decentralized control in the form of “Yes” is possible. To enable such an autonomous distributed control, instead of the measured value of the voltage V ₂ at the reactive power compensator 9, the consumer end, the voltage V ₂ of the customer end by (11) and (17) calculate.

FIG. 7 is a block diagram showing a reactive power compensator applied to the consumer voltage stabilization system according to the embodiment of the present invention. As shown in the figure, the reactive power compensation device is intended to be installed to each customer 6A-6F, a control unit 21 for calculating a compensation current I _ST. The control unit 21 includes a parameter storage unit 21A, a PLC 21B, a contraction information calculation unit 21C, a consumer end voltage calculation unit 21D, and a compensation amount calculation unit 21E. Here, in the parameter storage unit 21A, predetermined information such as distance information about the low-voltage distribution line 4 for contraction of the low-voltage system I, distance information about the service lines 5A to 5F, and the number of customers 6A to 6F is ( 16), the voltages V ₁ and V ₂ for calculating the compensation current I _ST based on the equations (18) and information on the impedance (R + jX) of the low voltage system I are stored. The distance information and the like for the contraction of the low-pressure system I as described above is acquired by the PLC 21B. That is, it is acquired and stored by exchanging information as shown in FIG. The contraction information calculation unit 21C executes a predetermined procedure as described above based on the stored contents of the parameter storage unit 21A, and calculates parameters when the low pressure system I is contracted to the low pressure system II. Consumer end voltage calculation unit 21D calculates a voltage V ₂ of the customer terminal P2 based on with reference to the predetermined parameters stored in the parameter storage section 21A (11) or (17).

The compensation amount calculation unit 21E calculates the equation (15) or (18) based on the parameters of the parameter storage unit 21A, the contraction information calculation unit 21C, and the consumer end voltage calculation unit 21D, and calculates the calculated compensation current. customer each reactive power proportionally by the number of 6A~6F also reactive power compensator 9A~9F seeks compensation current _{I ST} to be compensated.

In the present embodiment, the PWM generation circuit 22 and the main circuit control signal 23 are formed so that the compensation current _IST is supplied to each consumer terminal P2.

Incidentally, in the above embodiment, the information such as impedance of the low-pressure system II for a parameter necessary for calculating the compensation current I _ST to be acquired by PLC21B between customer 6A~6F another, to It is not limited. The same information can be exchanged not only using the PLC 21B but also using a normal communication system using a transmitter and a receiver. However, in the case of PLC 21B, the power line can also be used as a communication path, which is most advantageous in terms of equipment costs. Furthermore, the operator may change the stored contents of the parameter storage unit 21A whenever necessary. However, when necessary information is exchanged using any communication method such as PLC 21B, even if a new customer is added to or removed from the low-voltage system I, it is prompt and accurate. Therefore, it is possible to perform optimal control in response to the change in the state.

In the above embodiment, the voltage V ₁ on the primary side of the pole transformer 3 is used as the sending voltage, and the impedance (R + jX) of the low-voltage system I is used as the impedance of the distribution system. The case where the voltage sent from the substation to the high-voltage distribution line 2 and the impedance of the distribution system including the high-voltage distribution line 2 are used are also included in the technical idea of the present invention.

Furthermore, and low-voltage impedance (R + jX), the voltage V ₁ of the voltage source P1 may be estimated based on the reactive power compensator 9 to the state of the low-pressure system II of the case which supplied with not charged to the system.

  INDUSTRIAL APPLICABILITY The present invention can be effectively used in the industrial field where the power distribution system is operated and maintained when the reactive power compensator is distributed in the power distribution system.

I, II Low voltage system 3 Pillar transformer 4, 14 Low voltage distribution line 5A-5F, 15 Lead-in line 6A-6F, 6 Customer 7A-7F, 7 PV
8A-8F, 8 EV
9A to 9F, 9 Reactive power compensator P1 Voltage source P2 Customer end I _ST compensation current

Claims (4)

In a low-voltage system composed of a transformer that steps down from a high voltage to a low voltage in a distribution system, a low-voltage distribution line connected to the transformer, and a plurality of service lines connected to the low-voltage distribution line, the low-voltage distribution line via the service line This is a consumer voltage stabilization system in the low voltage system of the distribution system that is configured to adjust the voltage at the customer end, which is the connection point between the service line and the customer, with multiple reactive power compensators arranged in a distributed manner. And
For each customer, based on the information on the distance from the delivery point of the distribution substation to the connection position of each service line connected to the low voltage distribution line via the high voltage distribution line and the distance of each service line, from the service point Calculate the impedance of the distribution system leading to the lead-in line, and connect a plurality of consumers connected to the low-voltage system from the delivery point through the high-voltage distribution line, the transformer, the low-voltage distribution line, and the lead-in line And reduced to an equivalent power distribution system leading to
Calculate the amount of fluctuation of the voltage applied to the power distribution system using the impedance based on the supply voltage to the power distribution system, the reduced impedance of the power distribution system, and the sum of the current at each consumer end, The reactive power compensator is controlled so as to calculate the reactive current component of the reactive power necessary for canceling and distribute the reactive current component by the number of consumers and supply the distributed reactive current component to each consumer end. A customer voltage stabilization system in a low-voltage system of a power distribution system, characterized by being configured to do so. In the customer voltage stabilization system in the low voltage system of the power distribution system according to claim 1,
A customer voltage stabilization system in a low-voltage system of a distribution system, wherein the voltage on the primary side of the transformer is used as the delivery voltage and the low-voltage system impedance is used as an impedance of the distribution system. In the customer voltage stabilization system in the low voltage system of the power distribution system according to claim 1 or claim 2,
The calculation of the reactive current component in the contracted low-voltage system is performed by calculating the consumer end voltage V ₂ using the formula (3) or (4) given by the formula (1) or (2). The customer voltage stabilization system in the low voltage system of the power distribution system characterized by
In the consumer voltage stabilization system in the low voltage | pressure system of the power distribution system as described in any one of Claims 1-3,
A customer voltage stabilization system in a low-voltage system of a distribution system, characterized in that information on other customers necessary for the contraction is exchanged using power line communication.