JP6440567B2 - Voltage rise suppression device - Google Patents

Description

  The present invention relates to a voltage increase suppression device that suppresses an increase in power system voltage in a power system interconnected with distributed power sources.

  Secondary power transmission systems and distribution systems (hereinafter collectively referred to as power systems) for delivering power to power loads are directed from the transmission system having a higher voltage class than the own system to the end of the own system via a substation for step-down. It is designed on the premise of so-called forward tide where electricity flows.

  That is, according to Ohm's law ΔV = I · Z (ΔV is the voltage difference between two points, I is the current flowing between the two points, Z is the impedance between the two points), the system voltage gradually decreases toward the end It is assumed that

  However, when a large number of various distributed power sources such as solar power generation, wind power generation, and fuel cells are connected to the power system, so-called reverse power flow occurs in which power flows backward in the direction of the substation due to surplus power generated by them. Due to this reverse power flow, the voltage increases toward the end of the power system.

  As a result, the voltage in the vicinity of the power system end may exceed the operation upper limit voltage set in order to protect the range of low-voltage power reception 101 ± 6 V defined by the Electricity Business Law.

  Actually, the distributed power source is obliged to have an output suppression control function that narrows the power generation output by itself when the operation upper limit voltage is reached. For this reason, the possibility of exceeding the operation upper limit voltage is reduced, but if it is a distributed power source, the opportunity for power generation is lost, and particularly in solar power generation and wind power generation, power generated by natural energy is wasted.

  In order to avoid this, some distributed power sources have reactive power that adjusts the driving power factor in a direction that absorbs reactive power from the power system before starting output suppression control of the generated power (active power). There is also a product that combines a mechanism for performing control (referred to as phase advance operation), that is, a voltage rise suppression device. As a result, the system voltage rises due to the reverse flow of the active power generated by the distributed power source, but the voltage rise is offset by flowing the reactive power in the forward direction.

  Many of the distributed power sources having such a voltage rise suppression device exceed the operation upper limit voltage (107 V defined by the Electricity Business Law for low-voltage interconnections) as in the distributed power source disclosed in Patent Document 1. When this happens, reactive power control is started for the first time. However, since the operation upper limit voltage is exceeded only in a part near the end of the power system, only a part of the distributed power source that suppresses the voltage rise by reactive power control. Therefore, the current situation is that the effect of suppressing the voltage rise is extremely low.

  Therefore, as disclosed in Patent Document 2, there is also a distributed power source including a voltage rise suppression device that starts reactive power control from a voltage lower than the operation upper limit voltage. For example, in a low-voltage interconnected distributed power supply, reactive power control is performed step by step from a point of time when the voltage threshold is lower (for example, 106.5 V) so that the connection point voltage does not exceed 107 V, which is the operation upper limit voltage. carry out. As a result, the output control device of the distributed power source in the neighboring area that does not exceed the operation upper limit voltage 107V also participates in the suppression of the voltage rise, so that a greater effect can be expected.

JP-A-8-280136 JP 2008-035640 A

  As described above, reactive power control by the voltage rise suppression device of the distributed power source is expected to avoid a voltage rise of the power system caused by power generation by the distributed power source. However, in the present reactive power control, the voltage rise suppression device of the distributed power source in the grid area where the grid voltage has reached the operation upper limit voltage (for example, 107V in the low voltage interconnection), or the distributed type in the neighboring area close to the voltage state of the area. Since only the voltage rise suppression device of the power supply works, it is insufficient to suppress the voltage rise of the entire power system.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a voltage rise suppression device in which more distributed power sources autonomously contribute to voltage rise suppression.

According to an aspect of the voltage rise suppressing device of the present invention, in a power system in which distributed power sources are interconnected, a voltage threshold at which a connection point voltage at a connection point between the power system and the distributed power source is set in advance is set. A voltage rise suppression device that performs power control of the distributed power source so as to lower the interconnection point voltage to the voltage threshold value or less when exceeded, whether the distributed power source is in a non-power generation state or not. A non-power generation time zone determination unit for determining, and based on a statistical value obtained by statistically processing a measurement value of the interconnection point voltage in a non-power generation time zone in which the distributed power source is in a non-power generation state, A statistical processing unit that sets an upper limit value of the fluctuation range of the system point voltage, and an upper limit value of the fluctuation range set by the statistical processing unit and an operation upper limit voltage value set in advance for the power system are compared. The smaller value is the voltage threshold value. And a threshold update unit for setting said non-power generation time period determination unit, generated power or generator current of the distributed power source, the non-power generation time is equal to or less than a predetermined ratio with respect to the power generation capacity of the dispersed type power supply The generated power is defined by an effective power calculated based on an instantaneous waveform of the interconnection point voltage and an instantaneous waveform of an interconnection point current at the interconnection point, and the generated current is Ru are defined in current effective value calculated based on the instantaneous waveform of the interconnection point current.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to obtain the voltage rise suppression apparatus which contributes to suppression of a voltage rise autonomously, the voltage threshold value which is a start voltage of electric power control can be set dynamically dynamically.

It is a block diagram which shows the structure of the voltage rise suppression apparatus of Embodiment 1 which concerns on this invention. It is a flowchart explaining the process of discrimination | determination of a non-electric power generation time slot | zone and voltage recording in the voltage rise suppression apparatus of Embodiment 1 which concerns on this invention. It is a flowchart explaining the process of the statistical process and the reactive power control threshold value update in the voltage rise suppression apparatus of Embodiment 1 which concerns on this invention. It is a flowchart explaining the process of the reactive power control amount determination in the voltage rise suppression apparatus of Embodiment 1 which concerns on this invention. It is a figure explaining the proportional control system of reactive power control. It is a figure which shows the voltage distribution in a power distribution system. It is a figure which shows the frequency distribution of the connection point voltage in each connection point of a power distribution system. It is a block diagram which shows the structure of the voltage rise suppression apparatus of Embodiment 2 which concerns on this invention. It is a flowchart explaining the discrimination | determination of the non-power generation time slot | zone in the voltage rise suppression apparatus of Embodiment 2 which concerns on this invention, and the process of voltage recording. It is a block diagram which shows the structure of the voltage rise suppression apparatus of Embodiment 3 which concerns on this invention. It is a flowchart explaining the discrimination | determination of the non-electric power generation time slot | zone and the process of voltage recording in the voltage rise suppression apparatus of Embodiment 3 which concerns on this invention. It is a block diagram which shows the structure of the voltage rise suppression apparatus of Embodiment 4 which concerns on this invention. It is a figure which shows an example of the voltage distribution in the power generation time slot | zone of a distribution system, and a non-power generation time slot | zone. It is a flowchart explaining the discrimination | determination of a non-power generation time slot | zone and the process of voltage recording in the voltage rise suppression apparatus of Embodiment 4 which concerns on this invention. It is a flowchart explaining the process of the statistical process and the reactive power control threshold value update in the voltage rise suppression apparatus of Embodiment 1 which concerns on this invention. It is a figure which shows an example of the voltage distribution which prevents generation | occurrence | production of the reverse phenomenon in which the voltage fluctuation range of a power generation time zone falls below the voltage fluctuation range of a non-power generation time zone.

<Embodiment 1>
<Device configuration>
FIG. 1 is a block diagram showing a configuration of a voltage rise suppression apparatus 100 according to Embodiment 1 of the present invention, and also shows a power generation apparatus 200 of a distributed power source and an interconnected power system 300.

  The power generation apparatus 200 shown in FIG. 1 corresponds to an AC converter (inverter) that converts DC power into AC power in the case of a distributed power source that generates power with a DC circuit such as solar power generation or a fuel cell. In addition, in the case of a distributed power source of a rotating machine system that directly outputs high AC power from the rotational energy of a prime mover such as a turbine or engine without going through a DC circuit, a generator equipped with an excitation control unit that adjusts the reactive power amount is used. Applicable.

  In the case of a distributed power source of an AC converter system, a DC power generation circuit is provided, and in the case of a distributed power source of a rotating machine system, a motor is provided, but since it is not a part related to the essence of the present invention, the description is omitted in FIG. doing.

  Current sensor (ammeter) CT and voltage sensor (voltmeter) PT are arranged at the output point (interconnection point with the power system) in both the AC converter system and the rotating machine system. The connection point current and the connection point voltage are detected respectively. In addition, the current sensor CT is configured by a current transformer, and the voltage sensor is configured by a transformer (Potential Transformer).

  The current and voltage at the connection point detected by the current sensor CT and the voltage sensor PT are input to the power measurement unit 1 of the voltage rise suppression device 100 and the voltage is input to the voltage measurement unit 2. Then, the power measuring unit 1 calculates active power that is generated power from the instantaneous waveforms of current and voltage, and the voltage measuring unit 2 calculates an effective voltage value from the instantaneous waveform of voltage.

  The active power calculated by the power measurement unit 1 is input to the non-power generation time zone determination unit 4, and the voltage effective value calculated by the voltage measurement unit 2 is input to the reactive power control amount determination unit 3 and the voltage recording unit 5. .

  The non-power generation time zone determination unit 4 takes in active power from the power measurement unit 1 at a constant cycle (for example, 1 minute cycle), and determines that the power generation device 200 is in a non-power generation state when the value is very small. The determination result is output to the voltage recording unit 5.

  In the voltage recording unit 5, when the non-power generation time zone determination unit 4 determines non-power generation, the voltage effective value at that time (determination time) is taken from the voltage measurement unit 2 and recorded in the voltage database (DB) 8.

  The statistical processing unit 7 takes in the measurement voltage in the non-power generation time zone within a predetermined period (for example, one month) from the voltage DB 8 at a constant period (for example, one day period), calculates the average value and the standard deviation, and performs reactive power control. Output to the threshold update unit 6.

  The reactive power control threshold update unit 6 calculates the upper limit value of the fluctuation range of the measurement voltage based on the average value and the standard deviation calculated by the statistical processing unit 7. If the upper limit value of the fluctuation range of the measured voltage is higher than the operation upper limit voltage value determined in advance discussion with the power company that manages the power system, the operation upper limit voltage value is adopted as the voltage threshold value for starting reactive power control. If the upper limit value of the fluctuation range of the measured voltage is lower than the operation lower limit voltage value, the operation upper limit voltage value is adopted as a voltage threshold value for starting reactive power control, and is registered in the reactive power control amount determination unit 3. .

  The reactive power control amount determination unit 3 takes in the effective voltage value from the voltage measuring unit 2 at a constant period, and performs reactive power control to lower the voltage if the effective voltage value is higher than the registered voltage threshold value. Is lower than the threshold, the power generation apparatus 200 is controlled so as to cancel the reactive power control.

<Operation>
Next, the non-power generation time zone determination operation in the non-power generation time zone determination unit 4 and the recording operation of the voltage recording unit 5 will be described using the flowchart shown in FIG. The non-power generation time zone determination unit 4 is activated at a constant cycle (for example, one minute cycle) as shown in FIG. 2, and takes in the active power value from the power measurement unit 1 at that timing (step S1).

  Next, when the captured active power value is minute, for example, a predetermined value, for example, 3% or less with respect to the rated power generation capacity of the power generation device 200, it is determined that the power generation device 200 is in a non-power generation state, The determination result is output to the voltage recording unit 5 (step S2). On the other hand, when the fetched active power value exceeds the predetermined value, it is determined that the power generation apparatus 200 is in the power generation state, and the determination operation ends.

  Here, the case where the active power value is zero is not determined as the non-power generation state, and the case where it is observed minutely is determined as the non-power generation state because the current sensor CT and the voltage sensor PT include measurement errors. . That is, normally, these sensors include an error of 1 to 2% with respect to the rating, and are set in consideration of this point.

  The voltage recording unit 5 that has received the determination result that the power generation apparatus 200 is in the non-power generation state from the non-power generation time zone determination unit 4 captures the voltage effective value at that time (determination time) via the voltage measurement unit 2 (step S3). ) And recorded in the voltage DB8 (step S4).

  Next, the operation of the statistical processing unit 7 and the operation of the reactive power control threshold update unit 6 will be described using the flowchart shown in FIG. The statistical processing unit 7 is activated at a constant cycle (for example, one day cycle), and takes in a measurement voltage in a non-power generation time zone in a predetermined period (for example, one month) from the voltage DB 8 at that timing (step S11), and as a statistical value An average value Vav and a standard deviation Vσ are calculated (step S12).

  The statistical processing unit 7 outputs the calculated average value Vav and standard deviation Vσ of the measured voltage to the reactive power control threshold update unit 6, and the reactive power control threshold update unit 6 sets the average value Vav and standard deviation Vσ of the measured voltage to Based on this, the fluctuation range upper limit value Vup is calculated (step S13).

  Here, when it is assumed that the fluctuation of the measured voltage follows a normal distribution, Vup = Vav + 2 × Vσ may be obtained to obtain the fluctuation width upper limit value in the 95% confidence interval. It should be noted that Vup = Vav + 1 × Vσ can be obtained to obtain the fluctuation range upper limit value in the 68% confidence interval, and Vup = Vav + 3 × Vσ can be obtained in order to obtain the fluctuation range upper limit value in the 99% confidence interval. The fluctuation range upper limit value can be changed by changing the normal distribution random variable corresponding to the coefficient of the standard deviation Vσ. The above formula can be generalized by setting the random variable to k.

  Thus, by setting the voltage threshold in consideration of the statistical confidence interval, statistical reliability can be included in the voltage threshold.

  Further, the maximum value in the predetermined period described above may be simply adopted as the fluctuation range upper limit value Vup without considering the statistical confidence interval as described above.

  The reactive power control threshold update unit 6 compares the calculated fluctuation range upper limit value Vup with the operation upper limit voltage Vlim determined in advance discussion with the power company that manages the power system (step S14), and the fluctuation range upper limit value. If Vup is equal to or higher than the operation upper limit voltage Vlim, the operation upper limit voltage Vlim is set as a voltage threshold value for starting reactive power control (step S16). If the fluctuation range upper limit value Vup is lower than the operation upper limit voltage Vlim, the variation range upper limit value is set. Vup is set as a voltage threshold (step S15), the result is registered in the reactive power control amount determination unit 3, and the operation ends.

  Next, the operation of the reactive power control amount determination unit 3 will be described using the flowchart shown in FIG. The reactive power control amount determination unit 3 is activated at a constant cycle (for example, 1 second cycle), and takes in an effective value of the measurement voltage via the voltage measurement unit 2 at that timing (step S21).

  Then, the captured measurement voltage is compared with the registered voltage threshold value (step S22), and if the captured measurement voltage is higher than the voltage threshold value, reactive power control is performed on the power generation apparatus 200 to reduce the voltage (step S23). If the captured measurement voltage is equal to or lower than the voltage threshold value, the reactive power control for the power generation apparatus 200 is canceled (step S24).

  Here, when the deviation between the measured effective voltage value of the interconnection point and the voltage threshold, that is, the voltage excess is ΔVovr, there are already many precedent examples as a control method for reducing it to zero. For example, as shown in FIG. 5, a proportional control method for obtaining a reactive power control amount proportional to the excess voltage ΔVovr by multiplying the excess voltage ΔVovr by a predetermined proportional coefficient, or taking into account the current reactive power control amount. However, a PI control (proportional integral control) method for determining the next reactive power control amount can be used. Note that the present invention focuses on a method for setting a voltage threshold value for starting reactive power control, and the above-described known method may be adopted as a method for determining the reactive power control amount. To do.

  In order to avoid control hunting (repetitive execution and release of reactive power control), the threshold for executing reactive power control and the threshold for releasing reactive power control are set separately in the flow shown in FIG. You can keep it. In this case, the threshold for canceling reactive power control may be arbitrarily determined, for example, by setting it to be about 1 V smaller than the voltage threshold described above.

<Effect>
Next, the effect of the present invention will be described with reference to FIG. FIG. 6 schematically illustrates a configuration in which a photovoltaic power generation device, which is a representative of a distributed power source, is connected to a distribution system that is a type of power system, and illustrates a voltage distribution in the distribution system.

  As shown in part (a) of FIG. 6, a high voltage power of 6.6 kV is supplied to the high voltage distribution line HVC connected to the distribution substation LRT, and each of the high voltage distribution lines HVC is connected to a pole. Low voltage distribution lines LVC1 and LVC2 are connected via transformers VT1 and VT2. The low voltage distribution lines LVC1 and LVC2 are supplied with low voltage power that is voltage-converted from 6.6 kV to 100 V or 200 V by the pole transformers VT1 and VT2. A consumer TMA having a solar power generator A and a customer TM not having a solar power generator are connected to the low voltage distribution line LVC1, and a consumer having a solar power generator B is connected to the low voltage distribution line LVC2. The TMB and the customer TMC having the solar power generation device C are connected.

  At the time of non-power generation of the solar power generation devices A to C, power flows from the distribution substation LRT toward the end in the high voltage distribution line HVC, and from the pole transformers VT1 and VT2 in the low voltage distribution lines LVC1 and LVC2, respectively. Since power flows toward the end, the voltage drops toward the end according to Ohm's law in any distribution line. An example thereof is shown in part (b) and part (c) of FIG.

  That is, the part (b) in FIG. 6 shows the voltage distribution on the high voltage side with respect to the distance from the substation (distribution in the range of 6.7 kV to 6.5 kV), and the part (c) in FIG. The voltage distribution (distribution in the range of 101V to 95V) with respect to the distance from the upper transformer is shown. 6B corresponds to the area where the pole transformers VT1 and VT2 shown in FIG. 6A are connected, and in FIG. 6C. Indicates the voltage distribution on the low voltage side in the region. Further, as indicated by “Y” in part (c) of FIG. 6, as a result of stepping down by the transformation ratio of the pole transformer, it is shown that the voltage is 101V.

  Thus, since the voltage drops toward the end, the voltage distribution at each interconnection point (specified by the frequency of occurrence of each voltage value) is different for each interconnection point as shown in FIG. 7, for example. It becomes. That is, as shown in FIG. 7, at the connection point between the low-voltage distribution line LVC1 and the photovoltaic power generation apparatus A, the connection point voltage is distributed between voltages near the average value + 2σ (standard deviation) from around 101V. In addition, at the connection point between the low-voltage distribution line LVC2 and the photovoltaic power generation device B, the connection point voltage is distributed between voltages near the average value + 2σ from around 98V, and the low-voltage distribution line LVC2 and the sunlight At the connection point with the power generation device C, the connection point voltage is distributed between voltages around 95 V and exceeding the average value + 2σ (standard deviation).

  As described above, during photovoltaic power generation, the voltage at each interconnection point may further rise above the average value + 2σ. In such a case, by performing reactive power control on the power generation device 200, the power An increase in the system voltage can be suppressed.

  As described above, in the voltage increase suppressing device 100 according to the first embodiment of the present invention, reactive power control is started when a voltage increase due to the distributed power source is detected. In this distributed power source, the voltage increase is suppressed, and the voltage increase of the entire power system can be sufficiently suppressed.

  In addition, the voltage threshold at which reactive power control is started is automatically updated as needed as a value that provides statistical reliability while measuring the connection point voltage. There is also an advantage that the system administrator does not need to analyze and set the voltage distribution of the system in advance.

  In addition, when assuming a power distribution system, currently most of the distributed power sources are solar power generation, so if the power generated by your own solar power generation is extremely small, other solar power generation power can be judged to be the same. .

  In addition, when assuming a secondary power transmission system, since wind power generation is mainly used at present, when wind power generated by itself is extremely small, it can be determined that other wind power is the same.

  Therefore, the non-power generation time zone of the entire power system can be easily identified from the power generation state of the distributed power source.

<Embodiment 2>
<Device configuration>
FIG. 8 is a block diagram showing a configuration of a voltage rise suppressing apparatus 100A according to the second embodiment of the present invention, and also shows a power generation apparatus 200 of a distributed power source and an interconnected power system 300.

  The voltage rise suppression device 100A shown in FIG. 8 is different from the voltage rise suppression device 100 shown in FIG. 1 in that the current value is used instead of the active power value for the determination of the non-power generation state. A current measuring unit 10 is provided instead of the unit 1. Then, the current at the connection point detected by the current sensor CT is input to the current measurement unit 10 of the voltage rise suppression device 100A. Then, the current measuring unit 10 calculates an effective current value (generated current) from the instantaneous waveform of the current.

  The current effective value calculated by the current measurement unit 10 is input to the non-power generation time zone determination unit 4A, and the non-power generation time zone determination unit 4A calculates the current effective value from the current measurement unit 10 at a constant cycle (for example, one minute cycle). If the value is very small, it is determined that the power generation apparatus 200 is in a non-power generation state, and the determination result is output to the voltage recording unit 5. The configuration other than the current measurement unit 10 and the non-power generation time zone determination unit 4A is the same as that of the voltage rise suppression device 100 shown in FIG.

<Operation>
Next, the non-power generation time zone determination operation in the non-power generation time zone determination unit 4A and the recording operation of the voltage recording unit 5 will be described using the flowchart shown in FIG. As shown in FIG. 9, the non-power generation time zone determination unit 4A starts at a constant cycle (for example, 1 minute cycle), and takes in an effective current value from the current measurement unit 10 at that timing (step S31).

  Next, when the captured current effective value is very small and is a predetermined value, for example, 5% or less with respect to the rated current capacity of the power generation apparatus 200, it is determined that the power generation apparatus 200 is in a non-power generation state (step S32). ), And outputs the determination result to the voltage recording unit 5. On the other hand, when the acquired current effective value exceeds the predetermined value, it is determined that the power generation device 200 is in the power generation state, and the determination operation is terminated.

  Here, the case where the current effective value is zero is not set as the non-power generation state, and the case where it is observed minutely is determined as the non-power generation state because the current sensor CT includes a measurement error. That is, normally, since an error of 1 to 2% is included with respect to the rating, the setting is made in consideration of this point.

  In addition, the setting is made in consideration of the fact that a small amount of current flows even during non-power generation by the auxiliary power source of the distributed power source including the voltage rise suppressing device 100A. That is, in the voltage rise suppression apparatus 100 of the first embodiment, the non-power generation state is determined using the active power value that indicates the direction in which the power flows, so the active power consumed by the auxiliary power supply during non-power generation is If the current effective value that is a scalar quantity and the flow direction is not known is used, it can be excluded in advance. The criterion is set to be larger than the criterion for using the active power value (3% in the first embodiment). In addition, as an auxiliary equipment power supply, the power supply of the apparatus for the maintenance by the side of an electric power grid | system, the maintenance in an electric power generating apparatus, etc. are mentioned.

  Upon receiving the determination result that the power generation apparatus 200 is in the non-power generation state, the voltage recording unit 5 takes in the effective voltage value at that time (determination time) via the voltage measurement unit 2 (step S33) and records it in the voltage DB 8 ( Step S34).

<Effect>
As described above, in the voltage rise suppressing device 100A according to the second embodiment of the present invention, the current value is used instead of the active power value for the determination of the non-power generation state. It is possible to detect a voltage increase due to.

<Embodiment 3>
<Device configuration>
FIG. 10 is a block diagram showing the configuration of the voltage rise suppressing apparatus 100B according to the third embodiment of the present invention, which includes the distributed power generation apparatus 200, the interconnected power system 300, and the operation stop schedule recording unit 400. Show.

  In the voltage rise suppression device 100B shown in FIG. 8, the power value and the current value are not used for the determination of the non-power generation state, and the non-power generation time zone determination unit 4B is based on the operation stop schedule given from the operation stop schedule recording unit 400. Thus, the non-power generation state is determined. The configuration other than the current measurement unit 10 and the non-power generation time zone determination unit 4B is the same as that of the voltage rise suppression device 100A shown in FIG.

  Power generation facilities that generate power using renewable energy, such as solar power generation and wind power generation, have unstable output. For such power generation facilities, there will be light holidays throughout the power system such as Golden Week and New Year holidays. During the period, introduction of scheduled operation that stops all operations is under consideration.

  In other words, a system has been implemented in which a power company can freely command (notify) a power generation stoppage within a range of up to 30 days per year for photovoltaic power generation companies with a power generation capacity of 500 kW or more. , Individual notice until the previous day. In addition, after January 2015, the target of the directive will be expanded to small and medium-sized solar power generation of less than 500 kW, including residential solar power generation. The schedule operation method is used in which the days on which the operation is to be stopped are notified in advance in a calendar instead of being notified. In what region and how long the suspension order can be issued will be deliberated by the New Energy Subcommittee of the Comprehensive Resources and Energy Research Committee (advising organization of the Minister of Economy, Trade and Industry).

  For more information on solar power generation output suppression rules, see the following website: http://www.qool-shop.com/fit/newrule/entry175.html, http://hatsudenkakaku.info/entry96.html It has been published.

  Along with the introduction of such a system, the power company designates the date and time to be stopped as the operation stop schedule for the power generation apparatus 200. The operation stop schedule is recorded in the operation stop schedule recording unit 400, and the power generation apparatus 200 refers to the rolling stop schedule and stops power generation at the date and time when it should be stopped.

<Operation>
Next, the non-power generation time zone determination operation in the non-power generation time zone determination unit 4B and the recording operation of the voltage recording unit 5 will be described using the flowchart shown in FIG. As shown in FIG. 11, the non-power generation time zone determination unit 4B starts at a constant cycle (for example, 1 minute cycle), and takes in the operation stop schedule from the operation stop schedule recording unit 400 at that timing (step S41).

  Next, it is determined whether or not the present time corresponds to the operation stop period based on the information on the date and time to be stopped specified in the acquired operation stop schedule (step S42), and the present corresponds to the operation stop period. If it is determined that the power generation state is not generated, the determination result is output to the voltage recording unit 5. On the other hand, if it is determined that the current time is not the operation stop period, the determination operation is terminated.

  Upon receiving the determination result that the power generation apparatus 200 is in the non-power generation state, the voltage recording unit 5 takes in the effective voltage value at that time (determination time) via the voltage measurement unit 2 (step S43) and records it in the voltage DB 8 ( Step S44).

<Effect>
As described above, in the voltage rise suppression device 100B according to the third embodiment of the present invention, the determination of the non-power generation state is performed based on the operation stop schedule of the power generation device 200, so an ammeter, a power measurement unit, or a current The measurement unit can be omitted, and a voltage increase due to the distributed power source can be detected with a simpler configuration.

<Embodiment 4>
<Device configuration>
FIG. 12 is a block diagram showing a configuration of a voltage rise suppressing device 100C according to the fourth embodiment of the present invention, and also shows a power generator 200 of a distributed power source and an interconnected power system 300.

  In the voltage rise suppression device 100C shown in FIG. 12, when the active power obtained from the power measuring unit 1 is less than or equal to a predetermined value, the non-power generation time zone determination unit 4C determines that no power is generated and outputs the determination result. Within a predetermined period (for example, one month) at a constant cycle (for example, a daily cycle) from the non-power generation voltage recording unit 11, the non-power generation voltage DB 13 for recording a voltage effective value during non-power generation, and the non-power generation voltage DB 13 A non-power generation time zone statistical processing unit 12 (first statistical processing unit) that takes in the measured voltage in the non-power generation time zone, calculates an average value and standard deviation thereof, and outputs the average value and standard deviation to the reactive power control threshold update unit 6 ing.

  Further, when the active power is larger than the predetermined value, the non-power generation time zone determination unit 4C determines that power generation is occurring, and the power generation voltage recording unit 21 that outputs the determination result, and the power generation that records the voltage effective value during power generation From the hourly voltage DB23 and the generated voltage DB23, the measurement voltage in the power generation time zone within a predetermined period (for example, one month) is taken at a constant cycle (for example, one day), and the average value and standard deviation are calculated, and the reactive power A power generation time zone statistical processing unit 22 (second statistical processing unit) that outputs to the control threshold update unit 6 is provided. The other configuration is the same as that of the voltage rise suppressing device 100 shown in FIG.

  In some power systems, the start voltage of the power system (substation transmission voltage) is adjusted by changing the transformation ratio of the substation transformer with an on-road tap changer according to the magnitude of the power flowing through the power system. There is a case.

  That is, when it is estimated that the passing power is large in the forward direction of the transformer and the voltage drop toward the terminal is large, the starting voltage is increased so that the terminal voltage does not fall below the operation lower limit voltage. Also, the passing power in the forward direction of the transformer is small, or the passing power in the reverse direction flows due to the reverse power flow from the distributed power source, and the voltage drop toward the end is small, or the voltage rises toward the end. When it is estimated that it has occurred, the starting voltage is lowered so that the terminal voltage does not exceed the upper limit of operation.

  However, if the starting voltage is raised or lowered according to the passing power of the substation transformer, a reverse phenomenon may occur in which the voltage fluctuation range in the power generation time zone is lower than the voltage fluctuation range in the non-power generation time zone.

  This reverse phenomenon will be described with reference to FIG. In FIG. 13, the high-voltage distribution line HVC connected to the distribution substation LRT, and the voltage fluctuation range in the high-voltage distribution line HVC are shown with the distance from the substation on the horizontal axis. The range is a range sandwiched between the upper limit value MX1 and the lower limit value MN1, and the voltage fluctuation range in the non-power generation time zone is a range sandwiched between the upper limit value MX10 and the lower limit value MN10.

  Moreover, in FIG. 13, the operation upper limit voltage determined by prior consultation with the electric power company is indicated by a broken line as ULM, and the operation lower limit voltage is indicated by a broken line as DLM.

  In addition, when the fluctuation range upper limit value Vup registered in the reactive power control amount determination unit 3 of the voltage rise suppression apparatus 100 of the first embodiment is used as the voltage threshold value, the upper limit value MX10 of the non-power generation time period is the fluctuation range upper limit value Vup. It will be specified in.

  As shown in FIG. 13, the voltage fluctuation range in the power generation time zone extends toward the end, and is ultimately limited by the operation upper limit voltage ULM, which is higher than the upper limit value of the voltage fluctuation range in the non-power generation time zone. Although it is changing at a high voltage, in the vicinity area NR of the distribution substation LRT, the upper limit value of the voltage fluctuation range in the non-power generation time zone is changed in a voltage range higher than the upper limit value of the voltage fluctuation range in the power generation time zone. doing.

  This is because, in the power generation time period, even if the load of the power system is large, the surplus power of the distributed power source is partially covered, so the passing power of the substation transformer becomes small, and the voltage rise suppression device of the first embodiment The voltage threshold set at 100 is higher than the upper limit value of the voltage fluctuation range in the power generation time zone in the vicinity area NR of the distribution substation LRT, and the reactive power control is not performed on the distributed power source in the area. Voltage rise suppression will not work.

  Therefore, in the voltage rise suppressing device 100C according to the fourth embodiment, similarly to the measurement voltage fluctuation range in the non-power generation time zone, the fluctuation range of the measurement voltage in the power generation time zone is also calculated, and between the lower limit values of both fluctuation ranges. The voltage threshold is corrected downward by a deviation (difference value) to obtain a corrected value of the voltage threshold.

<Operation>
Next, using the flowchart shown in FIG. 14, the non-power generation time zone discriminating unit 4C discriminates the non-power generation time zone and the power generation time zone, and the non-power generation time voltage recording unit 11 and the power generation time voltage recording unit 21 record. The operation will be described. As shown in FIG. 14, the non-power generation time zone determination unit 4C is activated at a constant cycle (for example, one minute cycle), and takes in the active power value from the power measurement unit 1 at that timing (step S51).

  Next, when the captured active power value is minute, for example, a predetermined value, for example, 3% or less with respect to the rated power generation capacity of the power generation device 200, it is determined that the power generation device 200 is in a non-power generation state, The determination result is output to the non-power generation voltage recording unit 11 (step S52). Here, the reason why the non-power generation state is not set when the active power value is zero is the same as in the first embodiment.

  The non-power generation voltage recording unit 11 that has received the determination result that the determination result in the non-power generation time zone determination unit 4C is in the non-power generation state is that the voltage effective value at that time (determination time) is passed through the voltage measurement unit 2. (Step S53) and record it in the non-power generation voltage DB 13 (step S54).

  On the other hand, if the captured active power value exceeds the predetermined value in step S52, it is determined that the power generation apparatus 200 is in the power generation state, and the determination result is output to the power generation voltage recording unit 21.

  Upon receiving the determination result that the determination result in the non-power generation time zone determination unit 4C is the power generation state, the power generation voltage recording unit 21 captures the voltage effective value at that time (determination time) via the voltage measurement unit 2 (Step S55), the generated voltage DB 23 is recorded (Step S56).

  Next, the operation of the non-power generation time zone statistical processing unit 12 and the power generation time zone statistical processing unit 22 and the operation of the reactive power control threshold update unit 6 will be described using the flowchart shown in FIG.

  As shown in FIG. 15, the non-power generation time zone statistical processing unit 12 is activated at a constant cycle (for example, a daily cycle), and at that timing, the non-power generation time zone for a predetermined period (for example, one month) from the non-power generation time voltage DB 13. (Step S61), and the average value Vav1 and the standard deviation Vσ1 are calculated (step S62).

  The non-power generation time zone statistical processing unit 12 outputs the calculated average value Vav1 and standard deviation Vσ1 of the measured voltage to the reactive power control threshold update unit 6, and in the reactive power control threshold update unit 6, the average value Vav1 of the measured voltage and A fluctuation range upper limit value Vup1 is calculated based on the standard deviation Vσ1 (step S63).

  Here, when it is assumed that the fluctuation of the measured voltage follows a normal distribution, Vup1 = Vav1 + 2 × Vσ1 may be obtained in order to obtain the fluctuation width upper limit value in the 95% confidence interval. In order to obtain the fluctuation range upper limit value in the 68% confidence interval, Vup1 = Vav1 + 1 × Vσ1 may be used. To obtain the fluctuation range upper limit value in the 99% confidence interval, Vup1 = Vav1 + 3 × Vσ1. The variation range upper limit value can be changed by changing the normal distribution random variable corresponding to the coefficient of the standard deviation Vσ1. The above formula can be generalized by setting the random variable to k.

  The reactive power control threshold update unit 6 calculates the fluctuation range lower limit value Vlow1 based on the average value Vav1 and the standard deviation Vσ1 of the measured voltage (step S64). Assuming that the fluctuation of the measurement voltage follows a normal distribution, the fluctuation width lower limit value Vlow1 may be Vlow1 = Vav1-2 × Vσ1 to obtain the fluctuation width lower limit value in the 95% confidence interval. In order to obtain the lower limit value of the fluctuation range in the 68% confidence interval, Vlow1 = Vav1-1 × Vσ1 may be used. To obtain the lower limit value of the fluctuation range in the 99% confidence interval, Vlow1 = Vav1-3 × Vσ1 may be used, and the fluctuation range lower limit value can be changed by changing a normal distribution random variable corresponding to the coefficient of the standard deviation Vσ1. The above formula can be generalized by setting the random variable to k.

  Thus, by setting the voltage threshold in consideration of the statistical confidence interval, statistical reliability can be included in the voltage threshold.

  Moreover, the power generation time zone statistical processing unit 22 is activated at a constant cycle (for example, one day cycle), and takes in the measurement voltage of the power generation time zone in a predetermined period (for example, one month) from the power generation time voltage DB 23 at that timing (step S1). In step S71, the average value Vav2 and the standard deviation Vσ2 are calculated (step S72).

  The power generation time zone statistical processing unit 22 outputs the calculated average value Vav2 and standard deviation Vσ2 of the measured voltage to the reactive power control threshold update unit 6, and the reactive power control threshold update unit 6 outputs the average value Vav2 and standard of the measured voltage. Based on the deviation Vσ2, the fluctuation range upper limit value Vup2 is calculated (step S73).

  Here, when it is assumed that the fluctuation of the measured voltage follows a normal distribution, Vup2 = Vav2 + 2 × Vσ2 may be obtained to obtain the fluctuation range upper limit value in the 95% confidence interval. Note that Vup2 = Vav2 + 1 × Vσ2 may be used to obtain the fluctuation range upper limit value in the 68% confidence interval, and Vup2 = Vav2 + 3 × Vσ2 may be obtained in order to obtain the fluctuation range upper limit value in the 99% confidence interval. The fluctuation range upper limit value can be changed by changing the normal distribution random variable corresponding to the coefficient of the standard deviation Vσ2. The above formula can be generalized by setting the random variable to k.

  The reactive power control threshold update unit 6 calculates the fluctuation range lower limit value Vlow2 based on the average value Vav2 and the standard deviation Vσ2 of the measured voltage (step S74). Assuming that the fluctuation of the measurement voltage follows a normal distribution, the fluctuation width lower limit value Vlow2 may be Vlow2 = Vlow2-2 × Vσ2 in order to obtain the fluctuation width lower limit value in the 95% confidence interval. In order to obtain the lower limit value of the fluctuation range in the 68% confidence interval, Vlow2 = Vav2-1 × Vσ2 may be set. To obtain the lower limit value of the fluctuation range in the 99% confidence interval, Vlow2 = Vav2-3 × Vσ2 may be used, and the fluctuation range lower limit value can be changed by changing a normal distribution random variable corresponding to the coefficient of the standard deviation Vσ2. The above formula can be generalized by setting the random variable to k.

  The reactive power control threshold update unit 6 compares the fluctuation range upper limit value Vup1 calculated by the non-power generation time zone statistical processing unit 12 with the operation upper limit voltage Vlim determined in advance discussion with the power company that manages the power system. (Step S65) If the fluctuation range upper limit value Vup1 is equal to or greater than the operation upper limit voltage Vlim, the operation upper limit voltage Vlim is set as a voltage threshold value for starting reactive power control (step S67), and the result is set as a reactive power control amount determination unit. 3 to finish the operation. On the other hand, if the fluctuation range upper limit value Vup1 is lower than the operation upper limit voltage Vlim, the fluctuation range upper limit value Vup1 is set as the voltage threshold value. (Step S66).

  Thereafter, the reactive power control threshold update unit 6 compares the fluctuation range upper limit value Vup1 set as the voltage threshold value with the fluctuation range upper limit value Vup2 calculated by the power generation time zone statistical processing unit 22 (step S68). When the width upper limit value Vup1 is larger than the fluctuation width upper limit value Vup2, it is determined that the voltage increase suppression does not work in the distributed power source, and the voltage threshold value Vup1 is corrected downward using the following formula (1). The final voltage threshold Vup1.

  Vup1 = Vup1- (Vlow1-Vlow2) (1)

  In FIG. 16, the use of the final voltage threshold Vup1 corrected as described above prevents the occurrence of a reverse phenomenon in which the voltage fluctuation range in the power generation time zone is lower than the voltage fluctuation range in the non-power generation time zone. An example is shown.

  In FIG. 16, in order to correspond to FIG. 13, the voltage fluctuation range in the high-voltage distribution line HVC is shown by taking the distance from the substation on the horizontal axis, and the voltage fluctuation range in the power generation time zone is the upper limit value MX1. The voltage fluctuation range in the non-power generation time zone is shown as a range sandwiched between the upper limit MX10 and the lower limit MN10 set by the method of the first embodiment. In FIG. 16, the corrected voltage threshold Vup1 is indicated by a thick line, and in the vicinity area NR of the distribution substation LRT, the voltage threshold Vup1 is lower than the upper limit value of the voltage fluctuation range in the power generation time zone. It is moving in the range. As shown in the above formula (1), the voltage threshold Vup1 is corrected downward by the deviation DEV between the fluctuation range lower limit value Vlow1 in the non-power generation time zone and the fluctuation range lower limit value Vlow2 in the power generation time zone. It is a result.

  Note that the reason for using the deviation of the lower limit of the fluctuation range between the non-power generation time zone and the power generation time zone to correct the voltage threshold is that during the power generation time zone, the power generated by the distributed power source is relatively small. This is because the voltage is included, so that the voltage at the moment when the influence of the voltage rise by the distributed power source is relatively small can be acquired. On the other hand, when correcting the voltage threshold downward, the average of the voltage fluctuation width in the power generation time zone is not used, without using the deviation between the lower limit value of the voltage fluctuation width in the power generation time zone and the lower limit value of the voltage fluctuation width in the non-power generation time zone. It is also conceivable to use a deviation between the value and the average value of the voltage fluctuation range in the non-power generation time zone. However, the average value and the upper limit value may be slightly added to the voltage increase due to the distributed power supply, so the accuracy is somewhat lacking, but if this possibility is low, the voltage threshold value It is not denied that it is used for downward revision.

<Effect>
As described above, in the voltage rise suppressing device 100C according to the fourth embodiment of the present invention, even in a power system that raises and lowers the starting voltage according to the power increase / decrease in the power system at the substation transformer, It is possible to set the voltage threshold appropriately and to make the voltage rise suppression function work for almost all distributed power sources connected to the power system.

  In addition, if the reverse power flow from the distributed power source becomes larger than expected at the time of designing the power system by simply raising and lowering the starting voltage according to the power fluctuation of the power system at the substation transformer, the voltage at the end will rise. However, by using the voltage rise suppressing device 100C according to the fourth embodiment of the present invention together, it is possible to reliably suppress the voltage rise at the end portion.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

  4, 4A, 4B, 4C Non-power generation time zone determination unit, 6 Reactive power control threshold update unit, 7 Statistical processing unit, 12 Non-power generation time zone statistical processing unit, 22 Power generation time zone statistical processing unit.

Claims (7)

In a power system interconnected with a distributed power source, when the connection point voltage at a connection point between the power system and the distributed power source exceeds a preset voltage threshold, the connection point voltage is A voltage rise suppression device that performs power control of the distributed power source so as to lower the voltage threshold value or less,
A non-power generation time zone determination unit that determines whether or not the distributed power source is in a non-power generation state;
Based on a statistical value obtained by statistically processing the measurement value of the connection point voltage in a non-power generation time zone in which the distributed power source is in a non-power generation state, an upper limit value of a fluctuation range of the connection point voltage of the distributed power source is determined. A statistical processing section to be set;
A threshold updating unit that compares the upper limit value of the fluctuation range set by the statistical processing unit with an operation upper limit voltage value set in advance for the power system, and sets the smaller value as the voltage threshold value; , equipped with a,
The non-power generation time zone determination unit is
When the generated power or generated current of the distributed power source is equal to or less than a predetermined ratio with respect to the power generation capacity of the distributed power source, it is determined that it is the non-power generation time zone,
The generated power is
Defined by the active power calculated based on the instantaneous waveform of the interconnection point voltage and the instantaneous waveform of the interconnection point current at the interconnection point,
The generated current is
Wherein Ru is defined in current effective value calculated based on the instantaneous waveform of the interconnection point current, voltage rise suppression device. In a power system interconnected with a distributed power source, when the connection point voltage at a connection point between the power system and the distributed power source exceeds a preset voltage threshold, the connection point voltage is A voltage rise suppression device that performs power control of the distributed power source so as to lower the voltage threshold value or less,
A non-power generation time zone determination unit that determines whether or not the distributed power source is in a non-power generation state;
Based on a statistical value obtained by statistically processing the measurement value of the connection point voltage in a non-power generation time zone in which the distributed power source is in a non-power generation state, an upper limit value of a fluctuation range of the connection point voltage of the distributed power source is determined. A statistical processing section to be set;
A threshold updating unit that compares the upper limit value of the fluctuation range set by the statistical processing unit with an operation upper limit voltage value set in advance for the power system, and sets the smaller value as the voltage threshold value; With
The statistical processing unit
The average value Vav and the standard deviation Vσ calculated based on the measured values accumulated by measuring the interconnection point voltage in the non-power generation time period for a predetermined period and at a constant cycle are used as the statistical values,
The upper limit value of the fluctuation range is set based on the following formula (1):
Upper limit value = Vav + k × Vσ (1)
The coefficient k in equation (1) is a random variable in the normal distribution, voltage rise suppression unit. In a power system interconnected with a distributed power source, when the connection point voltage at a connection point between the power system and the distributed power source exceeds a preset voltage threshold, the connection point voltage is A voltage rise suppression device that performs power control of the distributed power source so as to lower the voltage threshold value or less,
A non-power generation time zone determination unit that determines whether or not the distributed power source is in a non-power generation state;
Based on a statistical value obtained by statistically processing the measurement value of the connection point voltage in a non-power generation time zone in which the distributed power source is in a non-power generation state, an upper limit value of a fluctuation range of the connection point voltage of the distributed power source is determined. A statistical processing section to be set;
A threshold updating unit that compares the upper limit value of the fluctuation range set by the statistical processing unit with an operation upper limit voltage value set in advance for the power system, and sets the smaller value as the voltage threshold value; With
The non-power generation time zone determination unit is
Get the outage schedule including information stop time for stopping the dispersed type power supply, if the current is corresponding to the operation stop period, determines that the is a non-power generation time period, voltage rise suppression apparatus. The distributed power source is
The voltage rise suppression apparatus of Claim 3 which is a power supply which produces electric power with renewable energy. In a power system interconnected with a distributed power source, when the connection point voltage at a connection point between the power system and the distributed power source exceeds a preset voltage threshold, the connection point voltage is A voltage rise suppression device that performs power control of the distributed power source so as to lower the voltage threshold value or less,
A non-power generation time zone determination unit that determines whether the distributed power source is in a non-power generation state or a power generation state;
Based on the first statistical value obtained by statistically processing the measured value of the interconnection point voltage in the non-power generation time zone in which the distributed power source is in the non-power generation state, the fluctuation range of the interconnection point voltage of the distributed power source is A first statistical processing unit that sets a first upper limit value and a first lower limit value of a fluctuation range of the interconnection point voltage;
The first upper limit value of the fluctuation range set by the first statistical processing unit is compared with the operation upper limit voltage value set in advance for the power system, and the smaller value is used as the voltage threshold value. A threshold update unit to be set;
Based on a second statistical value obtained by statistically processing the measurement value of the interconnection point voltage in the power generation time zone in which the distributed power source is in a power generation state, a second fluctuation range of the interconnection point voltage of the distributed power source is obtained. And a second statistical processing unit that sets a second lower limit value of a fluctuation range of the interconnection point voltage,
The threshold update unit
In the case where the first upper limit value of the fluctuation range is set as the voltage threshold value, and the first upper limit value of the fluctuation range exceeds the second upper limit value of the fluctuation range, a first value obtained by subtracting the upper limit value of the variation range of the difference value between the second lower limit value of the fluctuation range and the first lower limit value and correction value of the voltage threshold, voltage rise suppression unit. The non-power generation time zone determination unit is
When the generated power or generated current of the distributed power source is equal to or less than a predetermined ratio with respect to the power generation capacity of the distributed power source, it is determined that it is the non-power generation time zone, and when it exceeds the predetermined ratio, the power generation time zone It is determined that
The generated power is
Defined by the active power calculated based on the instantaneous waveform of the interconnection point voltage and the instantaneous waveform of the interconnection point current at the interconnection point,
The generated current is
The voltage rise suppression apparatus of Claim 5 prescribed | regulated by the current effective value calculated based on the instantaneous waveform of the said connection point current. The first statistical processing unit includes:
The average value Vav1 and the standard deviation Vσ1 calculated based on the measured values accumulated by measuring the interconnection point voltage in the non-power generation time period for a predetermined period and a predetermined period are set as the first statistical values,
The first upper limit value of the fluctuation range is set based on the following formula (2),
Upper limit = Vav1 + k × Vσ1 (2),
The first lower limit value of the fluctuation range is set based on the following formula (3),
Lower limit = Vav1-k × Vσ1 (3),
The second statistical processing unit includes:
The average value Vav2 and the standard deviation Vσ2 calculated based on the measured values accumulated by measuring the interconnection point voltage in the power generation time period at a predetermined period and a predetermined period are set as the second statistical values,
The second upper limit value of the fluctuation range is set based on the following formula (4),
Upper limit = Vav2 + k × Vσ2 (4),
The second lower limit value of the fluctuation range is set based on the following formula (5),
Lower limit = Vav2-k × Vσ2 (5),
The voltage rise suppression device according to claim 5 , wherein the coefficient k in the mathematical formulas (2) to (5) is a random variable in a normal distribution.

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