JP5618294B2 - High and low voltage distribution system voltage regulation system - Google Patents

Description

  The present invention relates to a high-voltage / low-voltage distribution system voltage regulation system in which a private power generation facility is connected to a distribution system.

Conventionally, the introduction of distributed power sources that transmit power to and from the distribution system by connecting in-house power generation facilities such as solar power generation systems, wind power generation, fuel cells, micro gas turbines, and engine power generation to the distribution system, Progressing mainly in residential areas.
On the other hand, when such a distributed power source is connected to the power distribution system in large quantities, the reverse power flow from the distributed power source raises the voltage of the power distribution system, and the voltage received by low-voltage consumers is regulated by the Electricity Business Law. There is a risk of deviating from the applied voltage.

  For this reason, when taking a solar power generation system as an example of private power generation equipment, as shown in Patent Documents 1 and 2, the power conditioner and the like suppress an increase in received voltage of low-voltage consumers. A voltage rise suppressing function for the purpose is provided.

  In other words, in a general residential solar power generation system, a solar panel group receives sunlight to generate DC power, which is converted into AC power of 200 V normally by a power conditioner, and is sent to the power system side. . The flow of electric power from the customer side to the power system side caused by this is called reverse power flow. When a large amount of distributed power sources are introduced into the distribution system, the voltage of the distribution system rises due to the reverse power flow from the distributed power source, and the received voltage of the low voltage consumer is the voltage specified by the Electricity Business Law (100 volt system Then, there is a risk of deviating from 101 ± 6 V and 202 ± 20 V in a 200 volt system.

For this reason, when connecting a photovoltaic power generation system to a power distribution system in Japan, as shown in Non-Patent Document 1 below, the power conditioner of the photovoltaic power generation system has a received voltage of a low voltage consumer. It is obliged to provide a voltage rise suppression function for the purpose of suppressing the increase.
Specifically, when the voltage at the connection point between the power distribution system and the photovoltaic power generation system may deviate from the appropriate value, measures to adjust the voltage in the photovoltaic power generation system should be taken, and It is shown that the lower limit value of the driving power factor when there is a reverse power flow is 0.85. The driving power factor is a value obtained by calculating the active power using the square root of the sum of the square of the active power and the square of the fast reactive power.

This power conditioner is composed of control devices such as inverters and protection devices that convert the power generation from solar cells from direct current to alternating current, and is based on the voltage measured at the interconnection point between the distribution system and the photovoltaic power generation system. The power is controlled so as to suppress the voltage rise.
As a method for suppressing the voltage rise, power is generated so as to generate fast reactive power (power whose current phase is 90 degrees ahead of voltage phase and does not contribute to net energy transmission per commercial AC cycle). When the voltage at the interconnection point exceeds the upper limit value, it is possible to suppress the voltage increase at the connection point by increasing the phase advance reactive power. However, if the phase advance reactive power is increased too much in order to suppress the voltage rise, the driving power factor falls below the lower limit value 0.85, and thus there is a limit to the voltage rise suppression due to the increase of the phase advance reactive power. For this reason, in such a case, “output suppression control” for reducing active power (generated power) must be performed.

  If there is no problem of voltage rise, the solar power generation system is usually operated so as to extract the maximum electric energy according to the solar energy incident on the solar panel group (maximum output point tracking operation), and effective according to it. Output power. When reducing the active power, there is incident sunlight that can output more active power, but it is wasted. Therefore, it is desirable to control so that the active power is not excessively reduced. The difference between the active power output when performing the maximum output point following operation and the active power output during the output suppression control is referred to as output suppression loss. When a general residential solar power generation system is connected to the power distribution system in large quantities, reverse power flow increases and the voltage tends to rise. Therefore, output suppression control is frequently performed, and system operation efficiency decreases.

From the above, in a system in which multiple photovoltaic power generation systems are connected to the distribution system, the power conditioner can reliably suppress the increase in voltage at the connection point without excessively reducing the active power. Is an important issue.
Therefore, as seen in Non-Patent Documents 2 and 3 below, voltage adjustment of the high-voltage distribution system by newly installing a high-voltage automatic voltage regulator (SVR), a static reactive power compensator (SVC), and a loop balance controller (LBC) The avoidance of output suppression using a storage battery was studied.

JP 2008-35640 A Japanese Patent No. 4109614 JP 2007-306744 A

“System Interconnection Rules (JEAC9701-2006)”, NEC Association Hirotaka Urata: “Estimation of distribution line voltage countermeasure costs necessary for the spread of distributed power generation”, Quarterly Energy Engineering, Vol. 31, No. 4, pp. 31-39 (2009) Kandenko Co., Ltd .: “Centralized Photovoltaic Power Generation System Demonstration Research”, New Energy and Industrial Technology Development Organization, 2003-2007 Results Report, (May 2008)

However, according to Non-Patent Document 2 described above, expensive equipment / maintenance costs are expected, and a system for the cost burden is required. Moreover, the thing by the said nonpatent literature 3 also has problems, such as the expense of a storage battery, installation space, and generation | occurrence | production of charging / discharging loss.
Therefore, in view of the above-described problems, the object of the present invention is not to rely on the addition / new installation of hardware such as SVR, SVC, and LBC that directly handle power flow, and power conditioners (self-excited inverters) and synchronous generators. An object of the present invention is to provide a high-voltage / low-voltage distribution system voltage adjustment system that establishes a control algorithm for appropriately adjusting the voltage of the entire distribution system by effectively utilizing the reactive power adjustment function of the distributed power source connected to the grid.

In order to achieve the above object, the following technical means were taken in the high-voltage / low-voltage distribution system voltage regulation system of the present invention. That is,
(1) In a specific area distribution system in which a plurality of distributed power sources are connected to a low-voltage distribution system, a high-voltage distribution system monitoring and control device that monitors and controls the high-voltage distribution system in the specific area, and installed in the specific area, A plurality of transformers for transforming a high voltage from the high-voltage distribution system to a low voltage, a low-voltage distribution system monitoring and control device for monitoring and controlling a low-voltage distribution system connected to a secondary side of the transformer, and the distributed type A power conditioner that is provided for each power source and controls the interconnection point voltage of the distributed power source by controlling reactive power, the high-voltage distribution system monitoring control device, the low-voltage distribution system monitoring control device, and the power The conditioners are respectively connected by bidirectional communication means, and the power conditioners transmit the respective interconnection point voltages to the low-voltage distribution system monitoring and control device, and The low-voltage distribution system monitoring and control device is based on the interconnection point voltage so that the interconnection point voltage of each power conditioner can be maintained below the prescribed upper limit value and the operating power factor can be maintained above the prescribed lower limit value. The primary voltage adjustment request amount ΔVri (i = 1,..., N) is calculated for each of the transformers belonging to the low-voltage distribution system and transmitted to the high-voltage distribution system monitoring and control device, and the high-voltage distribution system monitoring is performed. The control device transmits a reactive power adjustment command value ΔQrj (j = 1,..., N) in the low-voltage distribution system to each of the low-voltage distribution system monitoring and control devices based on the primary voltage adjustment request amount, each of the low-voltage distribution system monitoring device, the reactive power adjustment request amount to each of the power conditioner connected to the low-voltage distribution systems on the basis of the low-voltage distribution system to the assigned reactive power adjustment command value ΔQrj Ri was like to shake.

(2) In the high voltage / low voltage distribution system voltage regulation system described above, power line communication (PLC) is adopted as a bidirectional communication means with the low voltage distribution system monitoring and control device and the power conditioner.

(3) In the high-voltage / low-voltage distribution system voltage regulation system, when the high-voltage distribution system monitoring and control device calculates the reactive power adjustment command value ΔQrj of each of the low-voltage distribution systems, the primary voltage adjustment request amount ΔVri And ΔQrj are used to calculate ΔQrj in each low-voltage distribution system so that the sum of squares of errors in the primary voltage adjustment request amount ΔVri is minimized.

(4) In the high-voltage / low-voltage distribution system voltage regulation system, when the high-voltage distribution system monitoring and control device calculates the reactive power adjustment command value ΔQrj of each of the low-voltage distribution systems, the primary voltage adjustment request amount ΔVri In addition to the square sum of errors of the primary voltage adjustment required amount ΔVri, the reactive power from a specific power conditioner does not deviate significantly from the average value of reactive power from other power conditioners. In addition, the term “Qrj” in each low-voltage distribution system is calculated.

(5) Among the power conditioners connected to the low-voltage distribution system on the secondary side of the pole transformer in which the turn ratio of the primary winding and the secondary winding is G in the high-voltage / low-voltage distribution system voltage regulation system, When the power that can be generated is output and the interconnection point voltage exceeds the specified upper limit, the number is s, and the deviation width is Δv _pvk (k = 1,..., S), respectively. The primary voltage adjustment request amount ΔV _ri transmitted by the low-voltage distribution system monitoring and control device of the low-voltage distribution system is set to G times the total sum of −Δv _pvk .

(6) In the voltage regulation system for the high voltage / low voltage distribution system, each low voltage distribution system monitoring device assigns the operating power factor to each power conditioner when allocating the reactive power adjustment request amount to the power conditioner connected to the low voltage distribution system. It was transmitted as a command value, and each power conditioner was designed to output reactive power so that its driving power factor was not more than the command value.

According to the present invention, the power conditioner that controls the interconnection point voltage of the distributed power source by controlling the reactive power transmits each interconnection point voltage to the low voltage distribution system monitoring and control device, and the low voltage distribution system. The grid monitoring and control device, based on the interconnection point voltage, maintains the low voltage so that the interconnection point voltage of each power conditioner can be maintained below the prescribed upper limit value and the operating power factor is above the prescribed lower limit value. A primary voltage adjustment request amount ΔVri (i = 1,..., N) is calculated for each transformer belonging to the distribution system. Based on this primary voltage adjustment request amount, the high-voltage distribution system monitoring and control device transmits a reactive power adjustment command value ΔQrj (j = 1,..., N) to each of the low-voltage distribution system monitoring and control devices for allocation. The reactive power adjustment request amount can be appropriately allocated to each power conditioner based on the reactive power adjustment command value ΔQrj.
Therefore, the reactive power adjustment function of the distributed power source connected to the grid by power conditioners and synchronous generators can be utilized to the maximum extent without adding or newly installing hardware such as SVR, SVC, and LBC that directly handle power flow. Thus, it is possible to appropriately control the voltage of the entire distribution system and improve the operation efficiency of the system.

The figure which shows the high voltage and low voltage distribution system voltage regulation system structure by this invention. The figure which shows the area electrically fed by a high voltage power distribution system. The figure which shows a low voltage | pressure distribution system. The figure which shows the relationship between the voltage of each node in the high voltage power distribution system by conventional control, and power consumption. The figure which shows the relationship of the voltage in the each interconnection point in the low voltage | pressure distribution system by the conventional control, generated electric power, and a power factor. The figure which shows the relationship between the voltage of each node in the high voltage | pressure distribution system by this invention, and power consumption. The figure which shows the relationship of the voltage in the each interconnection point in a low voltage | pressure distribution system, generated electric power, and a power factor by this invention.

  Accordingly, embodiments of the present invention will be described below with reference to the drawings.

In the present embodiment, an area supplied with power by a high-voltage distribution system as shown in FIG. 2 is assumed as a premise.
In this high-voltage distribution system, numbers (numbers enclosed in square brackets) are given to a total of 74 nodes from 0 to 73 as shown in FIG. Among them, there are 48 nodes (indicated by black inverted triangles) where the low-voltage distribution system of FIG. 3 is connected via pole transformers.
In total, three single-phase pole transformers are connected to each node, one between each phase. White triangles indicate three-phase high-pressure loads, and each consumes 300 kW with a power factor of 1. It is assumed that this area is completely three-phase balanced.

  All pole transformers are assumed to have a turns ratio of 6600: 210. In the no-load state, when the primary voltage of the pole transformer is 6600V, the secondary voltage is 210V. The secondary winding has neutral point taps in addition to both ends of the winding, and a total of three terminals are provided. The low-voltage distribution line is composed of three wires, one from each of these three terminals. The 200V system of the low-voltage distribution system is the voltage between the two power lines from both ends of the secondary winding, and the 100V system is the voltage between the line from the neutral point tap and one of the power lines. It is.

  In all the low-voltage distribution systems, as shown in FIG. 3, it is assumed that 15 houses are connected under a 50 kVA pole transformer, and a photovoltaic power generation system is installed in all the houses. The photovoltaic power generation system is linked to the 200V system of the low-voltage distribution system. In addition, numbers (numbers enclosed in square brackets) were attached to these interconnection points. Assume that the load in each house is zero, and the solar power generation system in each house has obtained solar radiation that can output 1.8 kW of effective power.

As described above, in the entire power distribution system of FIG. 2, 48 × 3 × 15 = 2,160 solar power generation systems are connected. The impedance value per line of the line portion in FIGS. 2 and 3 is shown in Table 1 below.
The internal impedance of the 50 kVA pole transformer is assumed to be a resistance component of 1.2% pu and a reactance component of 2.1% pu. The sending terminal voltage of the distribution substation transformer is 6700V.

  In Japan, ordinary houses are often wired with single-phase three-wire 100V / 200V, but in this case 100V is the voltage between the neutral line of one of the 200V series and one of the voltage lines, The restriction is that the upper limit 107V of the 100V system (at this time, the 200V system is 214V or higher) is more severe than the upper limit 222V of the 200V system. In this analysis, the power conditioner is connected to the 200V system of the low-voltage distribution system, but it is assumed that 214V, which is twice the upper limit 107V of the 100V system, is operated as the specified upper limit value.

For comparison, the case of performing the conventional control method was analyzed assuming the operation as follows.
That is, each power conditioner has a power factor of 1 when its own connection point voltage is less than 214V, and when it is about to exceed 214V, the phase advance operation (consumption of delayed reactive power) is first performed to lower the connection point voltage. . However, if the power factor is not less than 0.85 and the interconnection point voltage exceeds 214V even at a power factor of 0.85, the interconnection point voltage is increased to 214V while maintaining the power factor at 0.85. Reduce power generation output (active power) until it drops.

Numerical analysis was performed for the case where all inverters performed the above operations in the assumed area. The resulting voltage and power consumption at each node in the high-voltage distribution system are shown in FIG. 4, and the voltage (resolution 0.1 V), generated power and power factor at each interconnection point in the low-voltage distribution system are shown in FIG. Show.
Since the analyzed low-voltage distribution system in FIG. 3 is symmetric, FIG. 5 shows only the right half of the connection points 0 to 7, and the connection point 0 is directly below the pole transformer. Point 7 is the end of the low voltage distribution system. Further, the low-voltage distribution system has 48 (nodes) × 3 (phases) = 144, but since this area is completely three-phase balanced, only one representative phase of each node is shown in FIG. For this reason, in FIG. 5, the data for 48 nodes are shown, and the data of the power conditioner connected to the same low-voltage distribution system is connected with a straight line.

  In the power consumption of FIG. 4, the reverse power flow due to power generation is represented by a negative value. If a reverse power flow of 1.8 (kW) x 15 (units) x 3 (phase) = 81 kW occurs from the node where the low-voltage distribution system is connected via the pole transformer, the sunlight in the low-voltage distribution system This means that all power generation systems are able to generate the maximum amount of power that can be obtained from solar radiation. In FIG. 4, the reverse power flow is less than 81 kW at some of the nodes to which the low-voltage distribution system is connected via the pole transformer. This indicates that there is a power conditioner in which the interconnection point voltage reaches 214 V and the output suppression control is performed in the low voltage distribution system connected to these nodes.

  From FIG. 5, in each low-voltage distribution system, all the power conditioners connected to the connection point 0 immediately below the pole transformer have an interconnection point voltage of 214 V or less, output 1.8 kW, and a power factor of 1 I am driving in. Some of the power conditioners connected to the connection point 1 are operating at a power factor of less than 1 because the connection point voltage reaches 214 V, but all output 1.8 kW. However, after the connection point 2, there is a power conditioner in which the output is reduced to less than 1.8 kW with a power factor of 0.85. After the connection point 6, the connection point voltages of all the power conditioners have reached 214V, and the operation is performed at a power factor of less than 1. Comparing power conditioners connected to the same low-voltage distribution system, the power conditioner connected to the end of the low-voltage distribution line has a higher interconnection point voltage, lower power factor, and narrows the output power. The reason for this is that when connecting to the downstream (near the end) of the low-voltage distribution line, the line resistance from the power conditioner to the pole transformer is large, so the connection point voltage tends to rise due to reverse power flow, and This is because the voltage rise due to the reverse power flow from the power conditioner upstream (near the pole transformer) is added almost linearly.

  As described above, in the conventional control method, the solar power generation system in the vicinity of the pole transformer in the low-voltage distribution system is used even though most of the solar power generation systems connected to the vicinity of the end of the low-voltage distribution system perform the output suppression control. An inefficient and unfair situation arises in that it operates at a power factor of 1 and does not contribute to the suppression of voltage rise.

On the other hand, about the case where the cooperative control of this invention was performed, it analyzed supposing operation | movement as follows.
The configuration of the high-voltage / low-voltage distribution system voltage regulation system of the present invention is shown in FIG.
FIG. 1 is obtained by adding an information communication and control system to a part of FIG. 2 according to the present invention.
One high voltage distribution system monitoring and control device 2 is installed in an area to which power is supplied by the high voltage distribution system constituted by the high voltage distribution line 1. In addition, a low-voltage distribution system comprising low-voltage distribution lines 4 is connected to the secondary side of the plurality of pole transformers 3 installed in the specific area and transforming a high voltage from the high-voltage distribution system to a low voltage. Each of the low-voltage distribution system monitoring control devices 5 is installed. Each power conditioner 6 only receives a reactive power adjustment command from the low-voltage distribution system monitoring and control device 5 of the low-voltage distribution system to which it is connected, even if its interconnection point voltage is less than the upper limit of 214 V, power factor 1 to 0. The phase advance reactive power is output between 85.

The control algorithm of the present invention is shown below.
A solar power generation system obtains solar radiation enough to output the power p _avail that can be generated, but since the connection point voltage v _{pv of the} power conditioner 6 has reached the upper limit of 214 V, the power factor is set to 0.85, In addition, it is assumed that the power generation output (active power) is suppressed to p _op . When the impedance (secondary side conversion value) from the primary side of the pole transformer 3 to the solar power generation system is r + jx (r is a resistance component and x is a reactance component), this solar power generation system can generate power temporarily. When the voltage upper limit value is gradually increased from 214 V until the power p _avail is output, if the influence on the high-voltage distribution system is ignored, the connection point voltage increases by Δv _pv shown in the following formula 1 (secondary side) Conversion value).

Here, Δp is an increment of the power generation output (active power) of this solar power generation system, and Δq is an increment of the phase reactive power output by this solar power generation system.
Since the voltage fluctuation of the distribution system is almost linear, when a plurality of power conditioners 6 connected to the same low-voltage distribution system output p _avail , the voltage at the end of the low-voltage distribution line increases by the sum of Δv _pv . (However, in the case of a low voltage distribution system that is symmetrically divided from the pole transformer to the left and right sides as shown in FIG. 3, it is half the sum of Δv _pv .)

When the active / reactive power in the low-voltage distribution system does not change, it can be approximated that when the primary voltage (secondary conversion value) of the pole transformer 3 is lowered, the entire line voltage of the low-voltage distribution system is also lowered by the same amount. Therefore, if the primary voltage (secondary side converted value) of the pole transformer 3 decreases by the sum of −Δv _pv of all the photovoltaic power systems connected to the pole transformer 3, those photovoltaic power systems _Can output the electric power p available that can be generated.

Therefore, the low-voltage distribution system monitoring and control device 4 installed in the pole transformer 3 at the node i receives Δvpv from each power conditioner 6 in the low-voltage distribution system connected to itself, and the voltage drop of the primary voltage of the interconnection itself The requested value ΔVri = −GΣΔvpv is transmitted to the high voltage distribution system monitoring and control device. Here, G is the turn ratio (6600/210) of the pole transformer 3.
The high-voltage distribution system monitoring and control device calculates a reactive power adjustment command value ΔQrj for each node j required in the high-voltage distribution system in order to respond to ΔVri from each low-voltage distribution system monitoring and control device. In this method, simultaneous equations representing the relationship between reactive power fluctuations and voltage fluctuations at each node are solved by a method of least squares using a sensitivity coefficient obtained from the line impedance.

Specifically, the number of low-voltage distribution system monitoring and control devices that monitor and control the low-voltage distribution system in the area is N, of which ΔV _ri is not zero (the solar power generation system that performs output suppression control is connected) The number of low-voltage distribution system monitoring and control devices is m (m ≦ N), and the phase reactive power can be increased (the power factor is not 0.85). When the number of low-voltage distribution system monitoring and control devices monitoring the low-voltage distribution system is n (n ≦ N), the simultaneous equations are as follows.

Here, a _ij is a sensitivity coefficient representing how much the voltage at the node i is increased when the reactive power at the node j is increased, and corresponds to q _ij in the equations 9 to 11 in Patent Document 3.
If m = n, since the number of variables to be solved and the number of equations are the same, ΔQ _rj can be calculated by solving Equation 2 above, but otherwise it cannot be solved. Therefore, by the least squares method, when the value obtained by substituting Delta] Q _rj in Equation 2 was [Delta] V _pi, as the square sum of the difference [Delta] V _pi and [Delta] V _ri is minimized, to calculate the Delta] Q _rj. However, the solution solved by this is not practically preferable, for example, ΔQ _{rj at} node j is a positive value, but ΔQ _{r (j + 1) at} adjacent node j + 1 becomes a negative value, which cancels each other's reactive power. The result may be calculated. Therefore, a term for reducing variation in the fast reactive power output between nodes is added to the formula of the square sum of errors U in the least square method. Specifically, the equation of the sum of squared errors U is expressed as the following Equation 3.

Here, Q _rj is the sum of the phase reactive power output from all the power conditioners 6 connected to the low voltage distribution system connected to the node j immediately before sending the reactive power adjustment command, and S _j is the low voltage connected to the node j. This is the total capacity of the power conditioner 6 connected to the power distribution system, and b is a positive number. In Equation 3, the first term on the right side represents the sum of squares of the difference between ΔV _pi and ΔV _ri , and the second term on the right side represents the capacity ratio (Q of the sum of the fast reactive power from the power conditioner 6 at the node j. _rj + ΔQ _rj ) / S _j is related to the deviation from the average value of the capacity ratio of the _fast reactive power of all the nodes capable of adjusting reactive power. When partially differentiated by Delta] Q _rj the U of the equation 3, the simultaneous equations of n book on Delta] Q _rj is obtained, to obtain a Delta] Q _rj by solving it.

The high voltage distribution system monitoring and control device 2 sends a value obtained by multiplying the reactive power adjustment command value ΔQ _rj obtained by this calculation by c, which is a positive number less than 1, to each corresponding low voltage distribution system monitoring and control device 5. The reason for multiplying by c is to avoid sudden reactive power fluctuations. Each low-voltage distribution system monitoring and control device receives the reactive power adjustment command value cΔQ _rj to be output from the low-voltage distribution system from the high-voltage distribution system monitoring and control device, and then the reactive power change amount Δq _k to the photovoltaic power generation system k connected to itself. the allocation to the cΔQ _rj = ΣΔq _k, and sends them to the [Delta] q _k as a command value. By repeating the above, it is possible to suppress voltage increase and thereby reduce output suppression of each photovoltaic power generation system as much as possible. In the repetition, when there is no power conditioner 6 that performs the output suppression control in the area and m = 0, a command is _given to gradually _reduce Q _rj . Thereby, useless reactive power output can be prevented.

  Each low-voltage distribution system monitoring device transmits a driving power factor as a command value to each power conditioner when allocating a reactive power adjustment request amount to the power conditioner 6 connected to the low-voltage distribution system. Then, each power conditioner 6 outputs reactive power so that its driving power factor becomes equal to or less than the command value. When designating by the power factor, even if the capacity (rated output) of each power conditioner 6 is different, phase reactive power proportional to the capacity is allocated. The reactive power output increases the current of the power conditioner 6 and the power loss in the device increases. However, the large capacity means that the reverse flow of the active power due to the power generation is large, and this is a fair reactive power distribution method. .

Numerical analysis was performed for the case where the above control was performed in the assumed area. The resulting voltage and power consumption at each node in the high-voltage distribution system are shown in FIG. 6, and the voltage (resolution 0.1 V), generated power and power factor at each interconnection point in the low-voltage distribution system are shown in FIG. Show.
In the power consumption of FIG. 6, the reverse power flow is 81 kW at all nodes connected to the low voltage distribution system via the pole transformer 3. This indicates that all the power conditioners 6 are not performing the output suppression control in the low voltage distribution system connected to these nodes.

From FIG. 7, in each low-voltage distribution system, all power conditioners 6 connected to the connection point 4 or lower have a connection point voltage of 214 V or less, but all have a power factor of less than 1 and are in the same low-voltage distribution system. Everything is driving at the same power factor. Some power conditioners 6 connected to the connection point 5 or higher have a connection point voltage of 214 V, and operate at a power factor lower than that of the connection point 4 or less of the same low-voltage distribution system. All of them are outputting 1.8kW. Moreover, all the power conditioners 6 are operating at a power factor of 0.85 or more.
Thus, according to the control method of the present invention, the power conditioner 6 whose own interconnection point voltage has not reached the upper limit value can also appropriately adjust the voltage of the entire distribution system by appropriately outputting the phase advance reactive power. . Thereby, all the photovoltaic power generation systems do not perform output suppression control, and can generate the maximum power that can be output according to solar radiation to the solar cell panel group.

  In order to implement the high-voltage / low-voltage distribution system voltage regulation system of the present invention, information on which solar power generation system is connected to the low-voltage distribution system under which pole transformer and bidirectional communication are necessary. is there. The bidirectional communication means between the low-voltage distribution system monitoring control device 5 and the power conditioner 6 may be utilized if there is an existing network, but if a means that does not newly lay a wired information communication line is adopted, Costs for information communication can be reduced. As such means, there are wireless communication using electromagnetic waves and power line communication (PLC) as shown by a broken line in FIG. When the power line carrier communication is used, the frequency used in the power line carrier communication is higher than the commercial frequency (50 Hz or 60 Hz) of the power system, so that the signal is significantly attenuated when passing through the pole transformer. For this reason, if power line carrier communication is used, the communication signal from the power conditioner 6 can be transmitted with sufficient strength only by the pole transformer 3 directly connected to the low voltage distribution system to which the power conditioner 6 is connected. Can be obtained. For this reason, it is possible to easily determine which power transformer 6 is connected to which low voltage distribution system under the pole transformer 3.

  As described above, according to the present invention, power line carrier communication, radio communication using electromagnetic waves, or existing networks can be used without adding or newly installing hardware such as SVR, SVC, and LBC that directly handle power flow. Because the reactive power adjustment function of the distributed power supply that is connected to the grid by power conditioners and synchronous generators can be used to the maximum extent, the voltage of the entire distribution system can be controlled appropriately, so widespread use is expected in the future In a distribution system in a specific area where private power generation equipment such as a photovoltaic power generation system is connected to the distribution system, it can be widely used as a voltage regulation system for high and low voltage distribution systems that drastically enhances the overall energy efficiency. Be expected.

DESCRIPTION OF SYMBOLS 1 High voltage distribution line 2 High voltage distribution system monitoring and control apparatus 3 Pole transformer 4 Low voltage distribution line 5 Low voltage distribution system monitoring control apparatus 6 Power conditioner

Claims (6)

In the distribution system in a specific area where multiple distributed power sources are connected to the low-voltage distribution system,
A high voltage distribution system monitoring and control device for monitoring and controlling the high voltage distribution system in the specific area;
A plurality of transformers installed in the specific area and transforming a high voltage from the high voltage distribution system into a low voltage;
A low-voltage distribution system monitoring and control device for monitoring and controlling the low-voltage distribution system connected to the secondary side of the transformer;
A power conditioner that is arranged for each distributed power source and controls the interconnection point voltage of the distributed power source by controlling reactive power;
The high-voltage distribution system monitoring and control device, the low-voltage distribution system monitoring and control device, and the power conditioner are each connected by bidirectional communication means,
The power conditioner transmits each interconnection point voltage to the low-voltage distribution system monitoring and control device,
The low-voltage distribution system monitoring and control device is based on the interconnection point voltage so that the interconnection point voltage of each power conditioner can be maintained below the specified upper limit value and the operating power factor can be maintained above the specified lower limit value. Calculating a primary voltage adjustment request amount ΔVri (i = 1,..., N) for each of the transformers belonging to the low-voltage distribution system, and transmitting the calculated voltage to the high-voltage distribution system monitoring and control device.
The high-voltage distribution system monitoring and control device sends a reactive power adjustment command value ΔQrj (j = 1,..., N) in the low-voltage distribution system to each of the low-voltage distribution system monitoring and control devices based on the primary voltage adjustment request amount. Send
Each of the low-voltage distribution system monitoring devices allocates a reactive power adjustment request amount to each power conditioner connected to the low-voltage distribution system based on the reactive power adjustment command value ΔQrj assigned to the low-voltage distribution system. High and low voltage distribution system voltage regulation system.   2. The high-voltage / low-voltage distribution system voltage according to claim 1, wherein power line communication (PLC) is adopted as a bidirectional communication means with the low-voltage distribution system monitoring and control device and the power conditioner. Adjustment system. When the high-voltage distribution system monitoring and control device calculates the reactive power adjustment command value ΔQrj for each of the low-voltage distribution systems, the primary voltage adjustment request amount ΔVri is obtained using simultaneous equations relating to the primary voltage adjustment request amounts ΔVri and ΔQrj. 3. The high-voltage / low-voltage distribution system voltage regulation system according to claim 1, wherein ΔQrj is calculated in each low-voltage distribution system so that the sum of squares of the error is minimized. When the high-voltage distribution system monitoring and control device calculates the reactive power adjustment command value ΔQrj for each of the low-voltage distribution systems, the primary voltage adjustment request amount ΔVri is obtained using simultaneous equations relating to the primary voltage adjustment request amounts ΔVri and ΔQrj. In addition to the sum of squared errors, a term that prevents the reactive power from a specific power conditioner from greatly deviating from the average value of reactive power from other power conditioners is added, and ΔQrj in each low-voltage distribution system is The high voltage / low voltage distribution system voltage regulation system according to claim 3, wherein the voltage regulation system is calculated. Among power conditioners connected to the low-voltage distribution system on the secondary side of the pole transformer with the turn ratio of the primary winding and the secondary winding of G, when the power that can be generated is output, the interconnection point voltage is the upper limit specified above When the number of objects exceeding the value is s and the deviation widths are Δvpvk (k = 1,..., S), the primary transmitted by the low-voltage distribution system monitoring and control device of the low-voltage distribution system high pressure and low-voltage distribution system voltage regulation system according to any one of claims 1 to 4, characterized in that the voltage adjustment request amount ΔVri and G times the sum of -Derutavpvk. When each low voltage distribution system monitoring device allocates the reactive power adjustment request amount to the power conditioner connected to the low voltage distribution system, each power conditioner transmits its operating power factor as a command value. 6. The high-voltage / low-voltage distribution system voltage regulation system according to any one of claims 1 to 5, wherein reactive power is output so that a rate is equal to or less than the command value.