JP4109614B2 - Distributed power supply voltage controller - Google Patents

Description

  The present invention relates to a distributed power supply voltage control apparatus that controls output power of a distributed power supply when the distributed power supply is linked to a power system.

Conventionally, a P control method that suppresses the active power P and lowers the connection point voltage when the voltage at the connection point connecting the distributed power source to the power system rises due to the inflow of power from the distributed power source has been proposed. (For example, see Patent Document 1 and Patent Document 2).
In addition, when the connection point voltage is increasing, if the driving power factor is higher than the limit value, the operation to increase the reactive power and lower the connection point voltage is repeated, and the driving power factor decreases and reaches the limit value. In addition, a (Q + P) control method has been proposed that reduces both active power and reactive power while maintaining the driving power factor at or above the limit value (see, for example, Non-Patent Document 1).

JP-A-8-317664 JP 2001-352682 A Takahide Katayama and three others “A Study on Voltage Control of Distribution Lines at Multiple Distributed Power Connections” Proceedings of the Annual Conference of the Institute of Electrical Engineers of Japan, The Institute of Electrical Engineers of Japan, February 2002, 6-231, p. 384

However, the P control method has a problem that the output of the distributed power source cannot be effectively used to suppress the active power.
In addition, the (Q + P) control method increases the phase advance reactive power output when the voltage rises and suppresses the interconnection point voltage. The power output can be used effectively. However, when the driving power factor becomes equal to or lower than the limit value, the active power is suppressed while maintaining the driving power factor equal to or higher than the limit value, so that the reactive power also decreases. Therefore, the voltage rise is not sufficiently suppressed, and the voltage rise is suppressed by repeatedly suppressing the active power and reducing the reactive power. As a result, as in the P control method, effective power suppression becomes significant.
For this reason, when multiple distributed power sources are connected to the power system, the active power must be significantly suppressed from the distributed power source in which the connection point voltage first reached a predetermined default value. In addition, there is a problem that the interconnection operation cannot be performed when the increase of the interconnection point voltage is remarkable.

  An object of the present invention is to provide a reactive power compensator that can be installed as a voltage rise countermeasure device on the power system side, which can reduce the connection point voltage by suppressing less active power when the connection point voltage is rising. The object is to provide a distributed power supply voltage control device capable of reducing the capacity at low cost.

  According to the present invention, there is provided a distributed power supply voltage control apparatus for controlling the output power of a power converter connected to a power system by converting the power of the distributed power supply. A voltage measuring means for measuring the voltage of the interconnection point connected to the power system, a voltage comparing means for comparing the voltage of the measured interconnection point with a predetermined upper limit voltage set value, and a command value Power factor calculation means for calculating the power factor of the output power of the power converter from the active power command value calculated by the calculation means and the phase reactive power command value, and the interconnection point voltage sets the upper limit voltage set value And when the power factor of the output power of the power converter exceeds a predetermined driving power factor limit value, the phase reactive power is determined based on a predetermined first phase reactive power variation. As the increase A reactive power correction amount is calculated. When the interconnection point voltage exceeds the upper limit voltage set value and the power factor of the output power of the power converter is equal to or less than the driving power factor limit value, a predetermined effective power is calculated. An active power correction amount that reduces the active power based on the power change amount, and a reactive power correction amount that increases or decreases the phase advance reactive power based on a predetermined second phase advance reactive power change amount. A correction amount calculation means for calculating, the active power command value for controlling the output power of the power converter based on the active power correction amount and the reactive power correction amount, and the phase advance reactive power command value; The command value calculation means for outputting to the power converter.

  The effect of the distributed power supply voltage control apparatus according to the present invention is that the active power output and the advanced reactive power output of the distributed power supply can be flexibly controlled, and the output of the distributed power supply is effectively interconnected. Can do.

Embodiment 1 FIG.
FIG. 1 is a block diagram of a distributed power supply voltage control apparatus according to Embodiment 1 of the present invention. FIG. 2 is a functional block diagram of the command generator of FIG.
As shown in FIG. 1, a distributed power supply voltage control device (hereinafter referred to as a voltage control device) 1 is a power conversion device that outputs power generated by a distributed power supply 2 in conjunction with a power system 3. 4 has a function of controlling the output power to control the voltage. The voltage control device 1 includes a command generator 5 that generates a power output command value for controlling the power converter 4, a setting device 6 that inputs various setting values to the command generator 5, and a distributed power source 2 that is connected to a power system. And a conversion transformer 7 as voltage measuring means for measuring an interconnection point voltage VE at an interconnection point connected to the signal generator and inputting the value to the command generator 5.

  The power conversion device 4 is an inverter that converts power of a distributed power source, for example, DC power into AC power that is system power. This inverter can control the AC power after conversion and the driving power factor by switching the switching element. The switching timing of the switching element is controlled by the active power command value PG and the phase advance reactive power command value QG. The active power command value PG and the phase advance reactive power command value QG are input from the command generator 5. Note that the phase advance means that the power source is advanced from the viewpoint of the distributed power source 2 (the power source is delayed as viewed from the electric power system 3). It is adjusted to be on the phase side.

  Further, as shown in FIG. 2, the command generator 5 compares the connection point voltage VE measured by the conversion transformer 7 with the upper limit voltage setting value VH input from the setting device 6, and the connection point voltage VE is Voltage comparison means 8 for outputting a voltage over signal when the upper limit voltage set value VH is exceeded, power factor calculation means 9 for calculating the driving power factor, and voltage active power correction amount DPG when the voltage over signal is input And a correction amount calculation means 10 for calculating the reactive power correction amount DQG, and an active power command value by adding the active power correction amount DPG and the reactive power correction amount DQG to the active power command value PG and the advanced reactive power command value QG, respectively. The PG and the phase advance reactive power command value QG are obtained, the apparent power PVA is calculated from the active power command value PG and the phase advance reactive power command value QG, and the VA capacity value of the power converter 4 input from the setting device 6 Compared with CVA And a command value calculation means 11 for calculating the active power command value PG and the fast reactive power command value QG was re changing a power command value PG and the fast reactive power command value QG. The command generator 5 is composed of a computer having a CPU, a RAM, a ROM, and an interface circuit.

The setting device 6 includes a storage unit 12 and an input unit 13. The storage means 12 has an upper limit voltage setting value (VH), an active power output setting value (PSET), a first fast reactive power change amount setting value (ΔQβ), and a second fast reactive power change amount setting value (ΔQα). ), Active power change amount setting value (ΔPα), driving power factor setting value (cos θs), driving power factor limit value (cos θh), and VA capacity value (CVA) of power converter 4 are stored. These values can be set at an appropriate time from a keyboard or the like as the input means 12.
The upper limit voltage set value VH is an upper limit value of the voltage of the power system 3 at the interconnection point. The active power output set value PSET is an active power output when the distributed power source 2 can be efficiently operated. The second phase advance reactive power change amount setting value ΔQα is a single change amount for changing the phase advance reactive power when the driving power factor is smaller than a preset driving power factor limit value cos θh. The second phase advance reactive power change amount setting value ΔQα is set to a positive or negative value. The first phase advance reactive power change amount setting value ΔQβ is a single change amount for changing the phase advance reactive power when the driving power factor is larger than a preset driving power factor limit value cos θh. The active power change amount set value ΔPα is a single change amount that changes the active power when the driving power factor is smaller than a preset driving power factor limit value cos θh. The operating power factor set value cos θs is an operating power factor when the distributed power source 2 can be operated efficiently. The driving power factor limit value cos θh changes the active power and the phase reactive power when the driving power factor is smaller than this value, and increases the phase reactive power to decrease the interconnection point voltage when the driving power factor is smaller than this value. Is the boundary power factor. The VA capacity value CVA of the power conversion device 4 is a maximum capacity value at which the power conversion of the power conversion device 4 can be performed.

FIG. 3 is a flowchart showing a control operation of the power conversion device by this voltage control device. The operation of the voltage control apparatus will be described with reference to FIG.
In step 101, each set value is input from the setter 6, and the value is transmitted to the command generator 5.
Next, in step 102, variables used in the processing after step 103, for example, the values of active power correction amount DPG and reactive power correction amount DQG are initialized to zero. Further, using the active power output set value PSET and the driving power factor set value cos θs, the phase advance reactive power output set value QSET is obtained from the formula of QSET = PSET × tan θs.

Next, in step 103, the active power output set value PSET and the phase advance reactive power output set value QSET are transmitted to the power conversion device 4 as the active power command value PG and the phase advance reactive power command value QG, respectively. The operating point at this time is point d shown in FIG.
Next, in step 104, the voltage comparison means 8 compares the interconnection point voltage VE measured by the conversion transformer 7 with the upper limit voltage set value VH input from the setting device 6, and the interconnection point voltage VE sets the upper limit voltage. When the value VH is exceeded, a voltage over signal is transmitted to the power factor calculation means 9, and the process proceeds to step 105. When the interconnection point voltage VE is equal to or lower than the upper limit voltage set value VH, the process proceeds to step 111.

First, the case where the connection point voltage VE is equal to or lower than the upper limit voltage set value VH will be described. When the interconnection point voltage VE is equal to or lower than the upper limit voltage set value VH, the reactive power output set value QSET obtained from the active power output set value PSET and the operating power factor set value cosθs input from the setter 6 is converged. The power converter 4 is controlled. The operations from step 111 to step 114 are performed by the correction amount calculation means 10.
In step 111, it is determined whether or not the active power correction amount DPG is less than zero. In step 112, if it is less than zero, in step 112, the active power change amount set value ΔPα is added to the active power correction amount DPG and active power is added. The correction amount DPG is changed so as to converge to zero. When the active power correction amount DPG is equal to or greater than zero, the active power correction amount DPG is left as it is, and the process proceeds to step 113.
Next, in step 113, it is determined whether or not the reactive power correction amount DQG exceeds zero. When the reactive power correction amount DQG exceeds zero, in step 114, the second advanced phase reactive power change amount is set from the reactive power correction amount DQG. By subtracting the value ΔQα, the reactive power correction amount DQG is changed so as to converge to zero.

  On the other hand, when the interconnection point voltage VE exceeds the upper limit voltage set value VH, in step 105, the power factor calculation means 9 operates from the active power command value PG and the phase advance reactive power command value QG before this calculation process. The power factor cos θ is obtained. When the power factor exceeds the driving power factor limit value cos θh, the process proceeds to step 106, and when the driving power factor cos θ is equal to or less than the driving power factor limit value cos θh, the process proceeds to step 120. When the driving power factor cos θ exceeds the driving power factor limit value cos θ h, only the phase advance reactive power is increased to reduce the interconnection point voltage VE. That operation is performed in step 106. On the other hand, when the driving power factor cos θ is equal to or lower than the driving power factor limit value cos θh, the interconnection point voltage is decreased by increasing or decreasing the fast reactive power and decreasing the active power. The operation starts from step 120. Note that the processing of steps 106 and 120 to 125 is performed by the correction amount calculation means 10.

  First, control for increasing the fast reactive power and decreasing the interconnection point voltage VE will be described. In step 106, the first fast reactive power change amount setting value ΔQβ is added to the reactive power correction amount DQG. Since the reactive power correction amount DQG is set to zero in step 102 at the first time of this procedure, a value obtained by adding the first phase reactive power change amount setting value ΔQβ to zero is set as a new reactive power correction amount DQG. And

Next, control for increasing or decreasing the fast reactive power and decreasing the active power to decrease the interconnection voltage will be described. In step 120, the active power change amount setting value ΔPα is subtracted from the active power correction amount DPG to obtain a new active power correction amount DPG. Since the active power correction amount DPG is set to zero in step 102 at the first time of this procedure, a value obtained by subtracting the active power change amount setting value ΔPα from zero is newly set as the active power correction amount DPG.
In step 121, the second phase advance reactive power change amount setting value ΔQα is added to the reactive power correction amount DQG. Since the reactive power correction amount DQG is set to zero in step 102 at the first time of this procedure, a value obtained by adding the second advanced phase reactive power change amount setting value ΔQα to zero is set as a new reactive power correction amount DQG. And
In step 122, the active power output set value PSET and the active power correction amount DPG are added to determine whether the value exceeds zero. When the value is less than or equal to zero, the process proceeds to step 123. If the value exceeds zero, the process proceeds to step 124.
In step 123, the active power correction amount DPG is set to a negative value of the active power set value PSET, and the process proceeds to step 124. The active power command value PG is prevented from becoming a negative command value.
In step 124, the reactive power correction amount DQG is added to the advanced reactive power output set value QSET to determine whether or not the value exceeds zero. When the value is less than or equal to zero, the process proceeds to step 125, and when it exceeds zero, the process proceeds to step 131.
In step 125, the reactive power correction amount DQG is set to a negative value of the advanced reactive power set value QSET, and the process proceeds to step 131. The phase advance reactive power command value QG is prevented from becoming a negative command value.

Thus, since the active power correction amount DPG and the reactive power correction amount DQG are obtained, the active power command value PG and the advanced phase reactive power command value QG are obtained from step 131. The processing of steps 131 to 141 and 151 is performed by the command value calculation means 11.
In step 131, the active power command value PG is obtained by adding the active power correction amount DPG to the active power output set value PSET.
In step 132, the reactive power correction amount DQG is added to the phase advance reactive power set value QSET obtained in step 102 to obtain the phase advance reactive power command value QG.

Next, in step 133, the apparent power PVA is obtained from the active power command value PG and the fast reactive power command value QG thus obtained. The apparent power PVA is obtained by obtaining the square root of the sum of the squares of the active power command value PG and the fast reactive power command value QG.
In step 134, it is determined whether or not the apparent power PVA is equal to or less than the VA capacity value CVA of the power converter 4. When the apparent power PVA exceeds the VA capacity value CVA of the power converter 4, in order to protect the power converter 4, the active power command value PG and the phase reactive power command value QG To control. On the other hand, when the apparent power PVA is less than or equal to the VA capacity value CVA of the power converter 4, the process proceeds to step 151.

In step 135, it is determined whether or not the phase advance reactive power command value QG is less than the VA capacity value CVA of the power converter 4. When the phase advance reactive power command value QG alone is equal to or greater than the VA capacity value CVA of the power converter 4, the process proceeds to step 138. When the phase advance reactive power command value QG is less than the VA capacity value CVA of the power converter 4, the process proceeds to step 136. .
In step 136, the square root of the square difference between the VA capacity value CVA of the power converter 4 and the phase advance reactive power command value QG is set as the active power command value PG. In step 137, for the next processing cycle, a value obtained by subtracting the active power output set value PSET from the active power command value PG is obtained again as the active power correction amount DPG.
On the other hand, in step 138, since the phase advance reactive power command value QG is equal to or greater than the VA capacity value CVA of the power conversion device 4, the power conversion device uses the VA capacity value CVA of the power conversion device 4 as the phase advance reactive power command value QG. 4 is protected.
In step 139, the active power command value PG is set to zero because the VA capacity value CVA of the power converter 4 is obtained only by the phase advance reactive power command value QG and active power cannot be output.
In step 140, for the next processing cycle, a value obtained by subtracting the active power output set value PSET from the active power command value PG is obtained again as the active power correction amount DPG.
Further, in step 141, for the next processing cycle, a value obtained by subtracting the phase advance reactive power output set value QSET from the phase advance reactive power command value QG is obtained again as the reactive power correction amount DQG.

  Next, in step 151, the active power command value PG and the phase advance reactive power command value QG obtained in steps 131 and 132, respectively, or the active power command value PG corrected in step 136, or corrected in steps 138 and 139, respectively. The active power command value PG and the phase advance reactive power command value QG are transmitted to the power converter 4. The power conversion device 4 converts the power generated by the distributed power source 2 based on the active power command value PG and the phase advance reactive power command value QG and outputs the converted power to the power system. Then, the process returns to step 104, and similarly the interconnection point voltage VE is measured, and the subsequent processing is performed.

  Next, the voltage control of the first embodiment will be described with a specific example. FIG. 4 shows the range of the active power command value PG and the phase advance reactive power command value QG that can be taken by the command generator 5 of the first embodiment. The horizontal axis represents the active power command value PG, and the vertical axis represents the phase advance reactive power command value QG. Arc a is when the apparent power PVA obtained from the active power command value PG and the phase advance reactive power command value QG is equal to the VA capacity value CVA of the power converter 4. A straight line b is an operating point of electric power when the power factor is the driving power factor set value cos θs. A straight line c is an operating point of electric power when the power factor is the driving power factor limit value cos θh. The points marked with l from the symbols d indicate operating points. Each operating point is determined from the active power command value PG and the phase advance reactive power command value QG.

The operating point d is an initial operating point of voltage control start determined by the active power output set value PSET and the driving power factor set value cos θs, and the phase advance reactive power command value QG is the active power output set value PSET and the driving power factor setting. Using the value cos θs, QSET = PSET × tan θs. Further, the same positive value is set as the second phase advance reactive power change amount setting value ΔQα and the active power change amount setting value ΔPα. The first phase advance reactive power change amount setting value ΔQβ is also set to a positive value.
First, at the operating point d, the connection point voltage VE is larger than the upper limit voltage set value VH, and control is performed so as to lower the connection point voltage VE. Since the power factor is larger than the driving power factor limit value cos θh at this operating point d, control is performed by increasing only the phase advance reactive power. At this time, the first phase reactive power change amount setting value ΔQβ is added to the reactive power correction amount DQG, the phase reactive power command value QG is increased, and power is output to the interconnection point. Even if these are repeated, the operating point e is reached when the interconnection point voltage VE exceeds the upper limit voltage set value VH. At the operating point e, since the power factor becomes equal to or less than the operating power factor limit value cos θh, control is performed to increase the fast reactive power and decrease the active power. When such an operation is repeated, the operation points f and g are advanced.

  In the above-described example, the second phase advance reactive power change amount setting value ΔQα and the active power change amount setting value ΔPα are set to the same positive value, but as the next example, the second phase advance reactive power change amount ΔPα is set. The case where the amount set value ΔQα is a positive value and the active power change amount set value ΔPα is zero will be described. The operation up to the operation point e is the same as described above, but the subsequent points are different. When the phase advance reactive power is increased, the operating point h on the arc a is reached. Thereafter, of the amount of increase in the phase advance reactive power, the portion exceeding the VA capacity value CVA of the power conversion device 4 is compensated by decreasing the active power, so the operating point advances from i to j.

  Further, when the second phase advance reactive power change amount setting value ΔQα is set to zero and the active power change amount setting value ΔPα is set to a positive value, the active power is decreased, so the operating point is changed from k to l. Go ahead.

  In addition, since the second phase advance reactive power change amount setting value ΔQα can be set to an arbitrary positive or negative value, the phase advance reactive power can be reduced. In this manner, the operating point can be moved within the blackened range in FIG. 4 to control the voltage at the interconnection point.

  Such a voltage control device can flexibly control the active power output and the phase reactive power output of the distributed power source, and can effectively use the output of the distributed power source.

Embodiment 2. FIG.
FIG. 5 is a flowchart showing the operation of the voltage control apparatus according to Embodiment 2 of the present invention. The voltage control device according to the second embodiment is different from the voltage control device 1 according to the first embodiment in the amount of change set value used when determining the active power correction value and the reactive power correction amount. That is, in the first embodiment, the second advance reactive power change amount setting value ΔQα, the first advance reactive power change amount setting value ΔQβ, and the active power change amount setting value ΔPα are set in advance and stored in the setting device 6. It is stored in the means 12. However, in the second embodiment, the power change amount set value ΔPQG is given as the power change amount per calculation cycle in the calculation processing of the command generator 5. This power change amount setting value ΔPQG is a positive value. Further, a set value pα of the proportion of the effective part is set. The set value pα of the proportion of the effective portion is a real number not less than zero and not more than 1. The effective power correction amount DPG is obtained by multiplying the power change amount set value ΔPQG by the set value pα of the effective portion ratio. Further, the reactive power correction amount DQG is obtained by multiplying this power change amount setting value ΔPQG by a value obtained by subtracting the setting value pα of the proportion of the effective portion from 1. The other parts are the same as those in the first embodiment, and the description of the same parts is omitted.

Next, the operation of the voltage control apparatus will be described with reference to FIG.
Steps similar to those in the first embodiment are denoted by the same reference numerals as those in FIG.
In step 201, each set value is input from the setter 6, and the value is transmitted to the command generator 5. The values set at this time include an upper limit voltage setting value (VH), an active power output setting value (PSET), a power change amount setting value (ΔPQG), a setting value (pα) of a ratio of the effective portion, and a driving power factor setting. A value (cos θs), a driving power factor limit value (cos θh), and a power converter VA capacity value (CVA).

  In step 104, the measured interconnection point voltage VE is compared with the upper limit voltage set value VH as in the first embodiment, and when the interconnection point voltage VE exceeds the upper limit voltage set value VH, the routine proceeds to step 105. The process proceeds to step 211 when the interconnection point voltage VE is equal to or lower than the upper limit voltage set value VH.

First, the case where the connection point voltage VE is equal to or lower than the upper limit voltage set value VH will be described. When interconnection point voltage VE is equal to or lower than upper limit voltage setting value VH, power converter 4 is controlled in the vicinity of predetermined active power output setting value PSET and reactive power output setting value QSET obtained from driving power factor setting value cosθs. To do.
In step 211, it is determined whether or not the active power correction amount DPG is less than zero. The multiplication value is added to obtain an active power correction amount DPG, and the active power correction amount DPG is corrected so as to approach zero. When the active power correction amount DPG is equal to or greater than zero, the active power correction amount DPG is left as it is, and the process proceeds to step 213.
Next, in step 213, it is determined whether or not the reactive power correction amount DQG exceeds zero. If it exceeds zero, in step 214, the reactive power correction amount DQG and the power change amount set value ΔPQG and 1 are effective. A value obtained by multiplying the value obtained by subtracting the set value pα of the minute is subtracted to obtain a reactive power correction amount DQG, and the reactive power correction amount DQ is corrected so as to approach zero.

  In step 105, as in the first embodiment, the driving power factor cos θ is obtained from the active power command value PG and the phase advance reactive power command value QG, and when the power factor exceeds the driving power factor limit value cos θh, the routine proceeds to step 206. When the driving power factor cos θ is equal to or less than the driving power factor limit value cos θh, the routine proceeds to step 220. When the driving power factor cosθ exceeds the driving power factor limit value cosθh, only the phase advance reactive power is increased to decrease the interconnection point voltage VE. This operation is performed in step 206. On the other hand, when the driving power factor cos θ is equal to or lower than the driving power factor limit value cos θh, the fast reactive power is increased and the active power is decreased to reduce the interconnection point voltage. The operation begins at step 220.

  First, control for increasing the fast reactive power and lowering the interconnection point voltage will be described. In step 206, a value obtained by adding the power change amount setting value ΔPQG to the reactive power correction amount DQG is set as a new reactive power correction amount DQG. Since the reactive power correction amount DQG is set to zero in step 102 at the first time of this procedure, a value obtained by adding the power change amount setting value ΔPQG to zero is set as a new reactive power correction amount DQG.

On the other hand, the control for increasing the fast reactive power and decreasing the active power to decrease the interconnection voltage will be described. In step 220, a multiplication value of the power change amount setting value ΔPQG and the effective ratio setting value pα is subtracted from the active power correction amount DPG to obtain a new active power correction amount DPG. Since the active power correction amount DPG is set to zero in step 102 at the first time of this procedure, a value obtained by subtracting the product of the power change amount setting value ΔPQG and the effective value ratio setting value pα from zero is newly set. Is the active power correction amount DPG.
In step 221, a multiplication value of a value obtained by subtracting the power change amount set value ΔPQG and the set value pα of the proportion of the effective portion from 1 is added to the reactive power correction amount DQG. Since the reactive power correction amount DQG is set to zero in step 102 at the first time of this procedure, the multiplication value of the value obtained by subtracting the power change amount setting value ΔPQG and the setting value pα of the proportion of the effective portion from zero. Is set as a new reactive power correction amount DQG.
In step 222, the active power output set value PSET and the active power correction amount DPG are added to determine whether the value exceeds zero. When the value is less than or equal to zero, the process proceeds to step 223. If the value exceeds zero, the process proceeds to step 131.
In step 223, the active power correction amount DPG is set to a negative value of the active power set value PSET, and the process proceeds to step 131. The active power command value PG is prevented from becoming a negative command value.

  Thus, since the active power correction amount DPG and the reactive power correction amount DQG are obtained, the active power command value PG and the advanced reactive power command value QG are obtained from step 131 as in the first embodiment.

  Next, voltage control of the voltage control apparatus according to the second embodiment will be described with a specific example. FIG. 6 shows ranges of the active power command value and the phase advance reactive power command value that can be taken by the command generator 5 of the second embodiment. The arc a is an operating point when the apparent power PVA obtained from the active power command value PG and the phase advance reactive power command value QG is equal to the VA capacity value CVA of the power converter 4. A straight line b indicates an operating point of electric power when the power factor is the driving power factor set value cos θs. A straight line c indicates an operating point of electric power when the power factor is the driving power factor limit value cos θh. Points with symbols d, m, n, o, p, q, r, s, and t indicate operating points. Each operating point is determined from the active power command value PG and the phase advance reactive power command value QG.

The operating point d is an initial operating point of voltage control start determined by the active power output set value PSET and the driving power factor set value cos θs, and the phase advance reactive power command value QG is the active power output set value PSET and the driving power factor setting. Using the value cos θs, it can be obtained by QSET = PSET × tan θs. Further, a positive value is set as the power change amount setting value ΔPQG, and, for example, 0.5 is set as the set value pα of the effective portion ratio.
First, at the operating point d, the connection point voltage VE is larger than the upper limit voltage set value VH, and control is performed so as to lower the connection point voltage VE. At this operating point d, the power factor cos θs is larger than the operating power factor limit value cos θh, so control is performed by increasing the phase reactive power. At this time, using the value obtained by adding the reactive power correction amount DQG to the power variation setting value ΔPQG as the power variation amount per calculation cycle, the phase advance reactive power command value QG is increased to the interconnection point. Output power. Even if these are repeated, the operating point m is reached when the interconnection point voltage VE exceeds the upper limit voltage set value VH. At the operating point m, since the power factor is equal to or less than the operating power factor limit value cos θh, control is performed to increase the reactive power and decrease the active power. When such an operation is repeated, since the set value pα of the proportion of the effective portion is 0.5, the correction amount per calculation cycle is the same for both the effective portion and the invalid portion, and advances to the operating points n and o. Go.

  In the above example, the setting value pα of the proportion of the effective part is set to 0.5. Next, a case where the setting value pα of the proportion of the effective part is set to 0 will be described. Since the correction amount of the effective amount becomes zero in this way, only the reactive power increases from the operating point m and reaches the operating point p on the arc a. After that, since the reactive power is increased, the active power that exceeds the VA capacity value CVA of the power conversion device 4 has to be decreased, so the operating point advances from q to r.

  Further, when the set value pα of the proportion of the effective portion is 1, the operating point advances from s to t because the effective power is reduced.

In the second embodiment, the operation is performed within the range shown in black in FIG. Since control is performed to decrease the active power command value PG and increase the phase advance reactive power command value QG in this way, there is no cause for increasing the interconnection point voltage. It is possible to suppress an increase in the connection point voltage while effectively using the power output as the maximum source.
Such a voltage control device can not only effectively use the active power output and the phase advance reactive power output of the distributed power source as the maximum source, but also can flexibly control the active power and the phase advance reactive power.

Embodiment 3 FIG.
FIG. 7 is a flowchart showing the operation of the voltage control apparatus according to Embodiment 3 of the present invention. The voltage control device according to the third embodiment differs from the voltage control device 1 according to the second embodiment in the amount of change set value used when obtaining the power correction amount. That is, in the second embodiment, the power change amount set value ΔPQG is given as the power change amount per calculation cycle in the calculation processing of the command generator 5. Further, a set value pα of the proportion of the effective part is set. The set value pα of the proportion of the effective portion is a value not less than zero and not more than 1. In the third embodiment, the set value pβ of the ratio of the second effective portion is further set. The set value pβ of the ratio of the second effective portion is a value exceeding zero and less than 1. The setting value pβ of the ratio of the second effective portion is used when calculating the active power correction amount DPG and the reactive power correction amount DQG when the interconnection point voltage VE is smaller than the upper limit voltage setting value VH. Others are the same as in the second embodiment. In the following description, the set value pα of the proportion of the effective portion is referred to as the first set value pα of the proportion of the effective portion.

Next, the operation of the voltage control apparatus according to the third embodiment will be described with reference to FIG. Steps different from the flowchart of the second embodiment shown in FIG. 5 are 301 and 311 to 314, and the other steps are the same.
In step 301, each set value is input from the setter 6 and transmitted to the command generator 5. The values set at this time include an upper limit voltage setting value (VH), an active power output setting value (PSET), a power change amount setting value (ΔPQG), a setting value (pα) of the first effective portion ratio, These are the setting value (pβ) of the ratio of the effective portion of 2, the driving power factor setting value (cos θs), the driving power factor limit value (cos θh), and the power converter VA capacity value (CVA).

  In step 104, the measured interconnection point voltage VE is compared with the upper limit voltage set value VH as in the first embodiment, and when the interconnection point voltage VE exceeds the upper limit voltage set value VH, the routine proceeds to step 105. The process proceeds to step 311 when the interconnection point voltage VE is equal to or lower than the upper limit voltage set value VH. Steps 105, 206, 220, 221, 222, and 223 are the same as those in the second embodiment.

Next, voltage control performed in steps 311 to 314 when the interconnection point voltage VE is equal to or lower than the upper limit voltage set value VH will be described. When interconnection point voltage VE is equal to or lower than upper limit voltage setting value VH, power converter 4 is controlled in the vicinity of predetermined active power output setting value PSET and reactive power output setting value QSET obtained from driving power factor setting value cosθs. To do.
In step 311, it is determined whether or not the active power correction amount DPG is less than zero. If it is less than zero, in step 312, the power change amount setting value ΔPQG and the set value of the ratio of the second effective portion are added to the active power correction amount DPG. A value obtained by adding the multiplication value with pβ is used as a new active power correction amount DPG, and the active power correction amount DPG is corrected so as to approach zero. When the active power correction amount DPG is zero or more, the active power correction amount DPG is left as it is, and the process proceeds to step 313.
Next, in step 313, it is determined whether or not the reactive power correction amount DQG exceeds zero. If it exceeds zero, in step 314, the reactive power correction amount DQG is changed from the reactive power correction amount DQG to the power change amount setting value ΔPQG and the first value. A value obtained by subtracting the value obtained by subtracting the set value pβ of the proportion of the effective part of 2 is subtracted to obtain the reactive power correction amount DQG, and the reactive power correction amount DQG is corrected so as to approach zero.

  Thus, since the active power correction amount DPG and the reactive power correction amount DQG are obtained, the active power command value PG and the advanced reactive power command value QG are obtained from step 131 as in the first embodiment.

  Next, voltage control of the voltage control apparatus 1 according to the third embodiment will be described with a specific example. FIG. 8 shows ranges of the active power command value and the phase advance reactive power command value that can be taken by the command generator 5 of the present invention. The arc a is an operating point when the apparent power PVA obtained from the active power command value PG and the phase advance reactive power command value QG is equal to the VA capacity value CVA of the power converter 4. A straight line b indicates an operating point of electric power when the power factor is the driving power factor set value cos θs. A straight line c indicates an operating point of electric power when the power factor is the driving power factor limit value cos θh. Points with symbols d, m, n, o, u, v, and w indicate operating points. Each operating point is determined from the active power command value PG and the phase advance reactive power command value QG.

The operating point d is an initial operating point of voltage control start determined by the active power output set value PSET and the driving power factor set value cos θs, and the phase advance reactive power command value QG is the active power output set value PSET and the driving power factor setting. Using the value cos θs, it can be obtained by QSET = PSET × tan θs. Further, a positive value is set as the power change amount setting value ΔPQG, and, for example, 0.5 is set as the setting value pα of the first effective portion ratio. For example, 0.8 is set as the set value pβ of the ratio of the second effective portion.
First, at the operating point d, the connection point voltage VE is larger than the upper limit voltage set value VH, and control is performed so as to lower the connection point voltage VE. At this operating point d, the power factor cos θs is larger than the operating power factor limit value cos θh, so control is performed by increasing the phase reactive power. At this time, using the value obtained by adding the reactive power correction amount DQG to the power variation setting value ΔPQG as the power variation amount per calculation cycle, the phase advance reactive power command value QG is increased to the interconnection point. Output power. Even if these are repeated, the operating point m is reached when the interconnection point voltage VE exceeds the upper limit voltage set value VH. At the operating point m, since the power factor is equal to or less than the operating power factor limit value cos θh, control is performed to increase the reactive power and decrease the active power. When such an operation is repeated, since the set value pα of the ratio of the first effective portion is 0.5, the correction amount per calculation cycle is the same for both the effective portion and the ineffective portion, and the operating point n, Go ahead with o.

  Next, an operation when the interconnection point voltage VE becomes equal to or lower than the upper limit voltage set value VH at the operating point o will be described. At this time, since the setting value pβ of the ratio of the second effective portion is set to 0.8, the active power correction amount DPG is increased by a large amount, and the reactive power correction amount DQG is decreased by a small amount. To the operating point v on the arc a through u. Since the apparent power PVA becomes the VA capacity value CVA of the power conversion device 4 at the operating point v, it moves on the arc a and reaches the operating point w thereafter. Since the active power correction amount DPG becomes zero at the operating point w, only the reactive power correction amount DQG decreases thereafter and returns to the initial operating point d via the operating point m.

In the process of returning to the initial operating point, the voltage control device uses the second effective portion ratio setting value pβ set to a value different from the first effective portion ratio setting value pα. Control such that active power is preferentially controlled or phase reactive power is preferentially controlled becomes possible.
When the active power is preferentially controlled, there is an advantage that the active power output of the distributed power supply can be quickly recovered after the overvoltage is eliminated.
Conversely, when the phase advance reactive power is preferentially controlled, there is an advantage that the active power output is not changed while the voltage is controlled.

1 is a block diagram of a distributed power supply voltage control apparatus according to Embodiment 1 of the present invention. FIG. FIG. 2 is a functional block diagram of the command generator of FIG. 3 is a flowchart illustrating a control operation of the power conversion apparatus by the voltage control apparatus according to the first embodiment. The range of the active power command value and phase advance reactive power command value which the command generator of Embodiment 1 can take is shown. It is a flowchart which shows the control operation of the power converter device by the voltage control apparatus concerning Embodiment 2 of this invention. The range of the active power command value and the phase advance reactive power command value that can be taken by the command generator of the second embodiment is shown. It is a flowchart which shows the control operation of the power converter device by the voltage control apparatus concerning Embodiment 3 of this invention. The range of the active power command value and phase advance reactive power command value which the command generator of Embodiment 3 can take is shown.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Voltage control apparatus (voltage control apparatus) for distributed type power supplies, 2 Distributed type power supplies, 3 Power systems, 4 Power converters, 5 Command generators, 6 Setting units, 7 Conversion transformers, 8 Voltage comparison means, 9 Power factor calculation Means 10 correction amount calculation means 11 command value calculation means 12 storage means 13 input means

Claims (4)

In the distributed power supply voltage control device that converts the power of the distributed power supply and controls the output power of the power converter connected to the power system,
Voltage measuring means for measuring the voltage at the interconnection point where the power conversion device is linked to the power system;
Voltage comparison means for comparing the voltage of the measured interconnection point with a predetermined upper limit voltage set value;
Power factor calculation means for calculating the power factor of the output power of the power converter from the active power command value calculated by the command value calculation means and the phase advance reactive power command value;
When the interconnection point voltage exceeds the upper limit voltage set value and the power factor of the output power of the power converter exceeds a predetermined driving power factor limit value, a predetermined first advance A reactive power correction amount that increases the phase reactive power is calculated based on the phase reactive power variation, and the power of the output power of the power converter is determined while the interconnection point voltage exceeds the upper limit voltage setting value. When the rate is equal to or less than the driving power factor limit value, based on the active power correction amount that reduces the active power based on the predetermined active power variation amount and the predetermined second advance reactive power variation amount A correction amount calculating means for calculating a reactive power correction amount that increases or decreases the phase advance reactive power,
The active power command value for controlling the output power of the power converter based on the active power correction amount and the reactive power correction amount and the phase advance reactive power command value are calculated and output to the power converter Command value calculation means;
A distributed power supply voltage control apparatus comprising:   When the correction amount calculating means is configured such that when the interconnection point voltage is equal to or lower than the upper limit voltage set value, the active power of the power conversion device is based on the active power change amount and the second phase advance reactive power change amount. The active power correction amount and the reactive power correction amount are calculated so that the output and the phase advance reactive power output converge to the predetermined active power output and phase advance reactive power output, respectively. The distributed power supply voltage control apparatus as described. In the distributed power supply voltage control device that converts the power of the distributed power supply and controls the output power of the power converter connected to the power system,
Voltage measuring means for measuring the voltage at the interconnection point where the power conversion device is linked to the power system;
Voltage comparison means for comparing the voltage of the measured interconnection point with a predetermined upper limit voltage set value;
Power factor calculation means for calculating the power factor of the output power of the power converter from the active power command value calculated by the command value calculation means and the phase advance reactive power command value;
When the interconnection point voltage exceeds the upper limit voltage set value and the power factor of the output power of the power converter exceeds a predetermined operating power factor limit value, a predetermined power change amount is obtained. Based on this, the reactive power correction amount that increases the phase advance reactive power is calculated, the interconnection point voltage exceeds the upper limit voltage setting value, and the power factor of the output power of the power converter is the driving power factor. When the amount is less than or equal to the limit value, the amount of power change and the amount of power change that is allocated to the active power are set based on a predetermined ratio so that the active power correction amount and the phase reactive power increase so that the active power decreases. Correction amount calculating means for calculating a reactive power correction amount,
The active power command value for controlling the output power of the power converter based on the active power correction amount and the reactive power correction amount and the phase advance reactive power command value are calculated and output to the power converter Command value calculation means;
A distributed power supply voltage control apparatus comprising:   The correction amount calculating means is configured to enable the power conversion device based on a predetermined second rate different from the power change amount and the rate when the interconnection point voltage is equal to or lower than the upper limit voltage set value. The active power correction amount and the reactive power correction amount are calculated so that the power output and the phase advance reactive power output converge to the predetermined active power output and phase advance reactive power output, respectively. The distributed power supply voltage control apparatus according to claim 3.

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