JP5693164B2 - Power system and power system monitoring and control method - Google Patents

Description

  The present invention relates to an electric power system and a monitoring control method for the electric power system, and more particularly to an electric power system and an electric power system monitoring and controlling method that can quickly reduce the influence of harmonics when harmonics are generated.

  With the rapid advancement of power electronics technology in recent years, semiconductor applied devices (non-linear loads) (such as rectifiers and inverter power supplies) have become widespread, and even in power system systems, the harmonic currents generated by these devices have led to the system. The problem of generating harmonic voltage distortion is significant.

  As an aspect of this harmonic problem, the harmonic current increases in proportion to the load current, the harmonic current flowing in the system causes an excessive current to flow through the power capacitor and series reactor, causing vibration, noise and overheating, In the worst case, burnout may occur, so various countermeasures such as installation of an active filter on the load side have been implemented.

  In addition, it is possible to identify the source by the phase of the harmonic current relative to the harmonic voltage. On the system side, countermeasures by harmonic monitoring control that reduces the influence of the generated harmonic based on the analysis of the harmonic analysis program Has been implemented. However, in the case where there are a plurality of generation sources, it is difficult to specify the generation source. In the “harmonic analysis device and the harmonic analysis program” (Patent Document 1) and the “power quality evaluation system” (Patent Document 2), Various proposals have been made.

JP 2010-48707 A JP 2008-191108 A

  However, in the technology based on the analysis of the conventional harmonic analysis program, there is a situation that a large amount of processing and time are required for complicated analysis. In addition, there is no technique for quickly determining which load should be restricted when a technique for restricting the use of a load is adopted as one technique for reducing the influence of the generated harmonics.

  The present invention has been made in view of the above-described conventional circumstances, and can quickly determine which load should be limited when harmonics are generated, and can quickly reduce the influence of harmonics and It aims at providing the monitoring control method of an electric power system.

In order to solve the above problems, the present invention employs the following means.
The power grid system according to the present invention is a power grid system including a power supply, a plurality of loads, a switchboard, and a monitoring control device, wherein the switchboard detects a bus voltage of the power supply. And a circuit breaker connected in series to each power supply line for supplying power from the bus of the power supply to each load, and a current detection means for detecting each current flowing in each power supply line, The monitoring control device includes a voltage distortion rate calculation unit that calculates a voltage distortion rate based on a detection value of the voltage detection unit, and a harmonic that calculates a harmonic current distortion in each power supply line based on the detection value of the current detection unit. Wave current distortion calculation means and when the voltage distortion rate exceeds the first threshold, voltage distortion for each load is estimated based on the relative ratio of harmonic current distortion in each power supply line, and power is supplied to some loads Block And characterized by comprising control means the sum of the voltage distortion estimation value operating load to below a first threshold value, a.

  According to the present invention, when harmonic voltage distortion occurs in the system and the voltage distortion rate exceeds the first threshold, the power supply to some loads is cut off and the loads are selectively operated. Since the sum of the estimated voltage distortion values of the load is less than the first threshold value, it is possible to quickly reduce the influence of the generated harmonics and protect the load-side electrical equipment.

The power grid system according to the present invention further includes output limiting means for individually limiting the outputs of the plurality of loads, and the control means is configured such that when the voltage distortion rate exceeds a first threshold value, A voltage distortion for each load is estimated based on a relative ratio of harmonic current distortion in the power supply line, and is set for each of the estimated voltage distortion for each load and each voltage distortion for the load from the voltage distortion rate. Determining the output limit coefficient such that the sum of the estimated voltage distortion values of the operating load obtained by subtracting a value obtained by multiplying the output limit coefficient by 1 to 1 is less than a first threshold; The output of a partial load other than the partial load that cuts off the power supply is limited at a rate determined based on the determined output limit coefficient .

  According to the present invention, when harmonic voltage distortion occurs in the system and the voltage distortion rate exceeds the first threshold value, the power supply to some loads is cut off or the output of some loads is limited. The load is operated at the same time, and the sum of the estimated voltage distortion values of the working load is less than the first threshold, so that the influence of the generated harmonics can be quickly reduced and the electrical equipment on the load side can be protected. Can do.

  Further, according to the present invention, in the power system described above, the monitoring and control device includes a setting unit that sets an operation priority of each load, and the control unit performs power in order from a load having a lower operation priority. The supply is cut off or the output is limited.

  According to the present invention, it is possible to automatically select a load to cut off power supply or limit output according to the characteristics of the system and each load, and it is possible to more quickly take measures against harmonic problems and This can be done flexibly and accurately.

  The power grid system according to the present invention is characterized in that the operation priority is set for each operation mode of the power grid system.

  According to the present invention, the harmonic problem can be taken more quickly by cutting off the power supply in accordance with the operation mode of the power system or by selecting the load to be output-restricted, and flexibly and accurately according to the situation. Can be done.

  Further, according to the present invention, in the power system described above, the monitoring and control device includes a state detection unit that detects an operation state of the power system, and the control unit is configured to detect an operation state of the power system. The operation mode is determined accordingly.

  According to the present invention, it is possible to take measures against the harmonic problem dynamically and quickly by cutting off the power supply according to the detected operation status of the power system system or by preferential selection of the load whose output should be limited, and depending on the situation. Flexible and accurate.

  In the power grid system according to the present invention, when the voltage distortion rate is less than the first threshold value and exceeds a second threshold value lower than the first threshold value, the control unit supplies each power supply. The voltage distortion for each load is estimated based on the relative ratio of harmonic current distortion in the line, and the power supply is cut off or the output is limited so that the sum of the estimated voltage distortion values of the operating load falls below the second threshold. It is characterized by notifying the power.

  According to the present invention, when harmonic voltage distortion occurs in the system and the voltage distortion rate exceeds a lower second threshold value, power supply to some loads is cut off or output restriction on some loads is performed. Since it is notified that it should be performed, it is possible to take measures against the harmonic problem more quickly and step by step.

  The power system monitoring and controlling method according to the present invention includes a power source, a plurality of loads, voltage detection means for detecting a bus voltage of the power source, and each power for supplying power to each load from the bus of the power source. Monitoring control of an electric power system comprising: a switchboard including a circuit breaker connected in series to each supply line; and current detection means for detecting each current flowing through each power supply line; and a monitoring control device. A voltage distortion rate calculating step for calculating a voltage distortion rate based on a detection value of the voltage detection means, and a harmonic for calculating a harmonic current distortion in each power supply line based on the detection value of the current detection means. A current distortion calculating step, and when the voltage distortion rate exceeds the first threshold, the voltage distortion for each load is estimated based on the relative ratio of the harmonic current distortion in each power supply line, and power to some loads By blocking the feed, the sum of the voltage distortion estimate the operating load, characterized in that it comprises a control step to be lower than the first threshold value, a.

  According to the present invention, when harmonic voltage distortion occurs in the system and the voltage distortion rate exceeds the first threshold, the power supply to some loads is cut off and the loads are selectively operated. Since the sum of the estimated voltage distortion values of the load is less than the first threshold value, it is possible to quickly reduce the influence of the generated harmonics and protect the load-side electrical equipment.

The present invention also provides a monitoring control method of the power system as described above, the output of the previous SL plurality of loads having an output limit step of individually limited, the control step, the voltage distortion factor first threshold value Is exceeded, the voltage distortion for each load is estimated based on the relative ratio of harmonic current distortion in each power supply line, and the voltage distortion for each load and the voltage distortion for each load estimated from the voltage distortion rate. Determining the output limit coefficient such that the sum of the estimated voltage distortion values of the operating load obtained by subtracting the set value of the output limit coefficient from 0.1 to 1 is less than the first threshold; The output limiting step limits output of a partial load other than the partial load that cuts off power supply at a rate determined based on the determined output limiting coefficient .

  According to the present invention, when harmonic voltage distortion occurs in the system and the voltage distortion rate exceeds the first threshold value, the power supply to some loads is cut off or the output of some loads is limited. The load is operated at the same time, and the sum of the estimated voltage distortion values of the working load is less than the first threshold, so that the influence of the generated harmonics can be quickly reduced and the electrical equipment on the load side can be protected. Can do.

  The power grid system monitoring control method according to the present invention further includes a setting step for setting an operation priority of each load, wherein the control step supplies power in order from a load having a lower operation priority. It is characterized by blocking or limiting the output.

  According to the present invention, it is possible to automatically select a load to cut off power supply or limit output according to the characteristics of the system and each load, and it is possible to more quickly take measures against harmonic problems and This can be done flexibly and accurately.

  The power system monitoring and control method according to the present invention is characterized in that the operation priority is set for each operation mode of the power system.

  According to the present invention, the harmonic problem can be taken more quickly by cutting off the power supply in accordance with the operation mode of the power system or by selecting the load to be output-restricted, and flexibly and accurately according to the situation. Can be done.

  The power system monitoring and control method according to the present invention further includes a state detection step of detecting an operation state of the power system, wherein the control step is performed according to the operation state of the power system. The operation mode is determined.

  According to the present invention, it is possible to take measures against the harmonic problem dynamically and quickly by cutting off the power supply according to the detected operation status of the power system system or by preferential selection of the load whose output should be limited, and depending on the situation. Flexible and accurate.

  Further, the present invention is the monitoring control method for an electric power system described in the above, wherein the control step is performed when the voltage distortion rate is lower than the first threshold value and exceeds a second threshold value lower than the first threshold value. Estimating the voltage distortion for each load based on the relative ratio of the harmonic current distortion in each power supply line, and shutting off the power supply so that the sum of the estimated voltage distortion values of the operating load falls below the second threshold, or It is characterized by notifying that the output should be limited.

  According to the present invention, when harmonic voltage distortion occurs in the system and the voltage distortion rate exceeds a lower second threshold value, power supply to some loads is cut off or output restriction on some loads is performed. Since it is notified that it should be performed, it is possible to take measures against the harmonic problem more quickly and step by step.

  According to the present invention, when harmonic voltage distortion occurs in the system, the load is selectively operated by cutting off the power supply to some loads or limiting the output of some loads. Since the sum of the voltage distortion estimated values is set to be lower than the first threshold value, it is possible to quickly reduce the influence of the generated harmonics and protect the load-side electrical equipment. In addition, it is possible to preferentially select loads that should cut off the power supply or limit the output according to the characteristics of the system and each load, so that it is possible to take measures against the harmonic problem more quickly and flexibly and accurately according to the situation. It can be carried out.

It is a lineblock diagram of an electric power system concerning a 1st embodiment of the present invention. It is a flowchart explaining the monitoring control method of the electric power system which concerns on this invention. It is a flowchart explaining the manual load limiting process in 1st Embodiment. It is a flowchart explaining the automatic load limiting process in 1st Embodiment. It is explanatory drawing (the 1) which illustrates the operation | movement priority of each load, a harmonic current distortion rate, and a voltage distortion estimated value. It is a block diagram of the electric power grid | system system which concerns on 2nd Embodiment of this invention. It is a flowchart explaining the manual load limiting process in 2nd Embodiment. It is a flowchart explaining the automatic load limiting process in 2nd Embodiment. It is explanatory drawing (the 2) which illustrates the operation | movement priority of each load, a harmonic current distortion rate, and a voltage distortion estimated value.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a power system and a monitoring control method for a power system of the present invention will be described in detail in the order of a first embodiment and a second embodiment with reference to the drawings. In the following description, the power system is assumed to have no connection with other power transmission systems, and a power system in a locally closed vehicle such as a vehicle, a ship, or a small plant is assumed.

[First Embodiment]
FIG. 1 is a configuration diagram of a power system according to the first embodiment of the present invention.
In the figure, the power system 1 of the present embodiment includes a power source 11, a plurality of loads (load 1 to load M) 17-1 to 17 -M, a switchboard 13, and a monitoring control device 15. It is configured.

  The switchboard 13 includes a circuit breaker 21, a bus 22, and circuit breakers connected in series to power supply lines 23-1 to 23 -M that supply power to the loads 17-1 to 17 -M from the power bus. 24-1 to 24-M, current detection means 25-1 to 25-M for detecting currents flowing through the power supply lines 23-1 to 23-M, and voltage detection means 26 for detecting the bus voltage of the power source. And.

  The monitoring control device 15 includes a voltage distortion rate calculation unit 32, a harmonic current distortion calculation unit 33, a control unit 31, and an operation panel 34. The voltage distortion rate calculation means 32, the harmonic current distortion calculation means 33, and the control means 31 are programs executed on a processor such as an MPU (microprocessor) or DSP (digital signal processor) included in the monitoring control device 15. It is embodied as a functional unit.

  Here, the operation panel 34 serves as an interface with the operator. The operation panel 34 receives an operation / setting input by the operator and notifies the operator of various information via the display unit 35. The operation panel 34 corresponds to the setting means in the claims, and the operator sets the operation priority of each load via the operation panel 34. The setting contents of the operation priority order are registered in a storage unit (not shown) in the control means 31 (processor).

  Further, the voltage distortion rate calculation means 32 calculates the voltage distortion rate [%] based on the detection value of the voltage detection means 26 in the switchboard 13.

Further, the harmonic current distortion calculation means 33 is based on the detection values of the current detection means 25-1 to 25-M in the switchboard 13, and the harmonic current distortion for each load in each of the power supply lines 23-1 to 23-M. Is calculated. That is, using the fast Fourier transform, the harmonic current for each order (order i = 2 to Q; the fundamental wave is 60 [Hz]) is calculated for each load 17-1 to 17-M, and the following equation is used. The harmonic current distortion [A] for each of the loads 17-1 to 17-M is calculated. Here, Q is an arbitrary natural number of 3 or more, but is generally about 100th.
[Equation 1]
Q
Harmonic current distortion = (Σ (order i × i-order harmonic current) ² ) ^1/2 (1)
i = 2
In order to cope with a sudden change in current, the detection values of the current detection means 25-1 to 25-M used for calculation are average values for a certain period (for example, 1 to 2 [seconds]).

  In addition, the control unit 31 determines the harmonic current distortion in each of the power supply lines 23-1 to 23 -M obtained by the voltage distortion rate calculation unit 32 when the voltage distortion rate by the voltage distortion rate calculation unit 32 exceeds the first threshold. The voltage distortion for each of the loads 17-1 to 17 -M is estimated based on the relative ratio of the power, the power supply to some of the loads is shut off, and the sum of the estimated voltage distortion values of the operating load is less than the first threshold value. To. In the present embodiment, referring to the limit value of the harmonic regulation of the general power equipment, the first threshold value to limit the use of the load is set to 5 [%] as an example, but is not limited to this value.

That is, the relative ratio of harmonic current distortion (harmonic current distortion ratio) is obtained from the harmonic current distortion [A] for each of the loads 17-1 to 17-M, and the loads 17-1 to 17- The estimated voltage distortion value [%] for each M is calculated. The relative ratio of harmonic current distortion (harmonic current distortion ratio) is such that the sum of the relative ratios of harmonic current distortion of the loads 17-1 to 17 -M is 1.
[Equation 2]
Voltage distortion estimated value = voltage distortion rate × harmonic current distortion ratio (2)
Further, based on the set operation priority, the estimated voltage distortion value [%] corresponding to the load is subtracted from the voltage distortion rate [%] in order from the load with the lowest priority, and the priority is low. When the result of subtracting the estimated voltage distortion value [%] of each load from the first to the jth (j = 1 to M; M is the number of loads) falls below the first threshold, the first with the lowest priority To power supply to each of the loads from j to j.

  Further, the control means 31 determines each of the voltage distortion rate calculation means 32 when the voltage distortion rate by the voltage distortion rate calculation means 32 is less than the first threshold value and exceeds the second threshold value lower than the first threshold value. Based on the relative ratio of the harmonic current distortion in the power supply lines 23-1 to 23-M, the voltage distortion for each of the loads 17-1 to 17-M is estimated, and the power supply to some loads is cut off to operate. Notify that the sum of the estimated voltage distortion values of the load should fall below the second threshold. In the present embodiment, the second threshold value that should give an alarm to the operator is set to 3 [%] as an example, but is not limited to this value.

  That is, based on the set operation priority order, the voltage distortion estimated value [%] corresponding to the load is sequentially subtracted from the voltage distortion rate [%] sequentially from the load with the lowest priority order, and the priority order is low. When the result of subtracting the estimated voltage distortion value [%] of each load from the first to the jth falls below the second threshold, the power supply to each of the first to jth loads having a low priority is cut off. As a result, the operator is notified of this through the display unit 35 of the operation panel 34.

  Next, a monitoring control method for a power system including the above components will be described with reference to FIGS. Here, FIG. 2 is a flowchart for explaining the monitoring control method of the power system according to the present invention, FIG. 3 is a flowchart for explaining the manual load limiting process in the present embodiment, and FIG. 4 is an automatic load limiting process in the present embodiment. FIG. 5 is an explanatory diagram (part 1) illustrating an operation priority order, a harmonic current distortion rate, and a voltage distortion estimated value of each load.

  First, the outline of the monitoring control method of the power system will be described with reference to FIG. First, in the switchboard 13, the voltage detection means 26 detects the bus voltage of the power source, and the current detection means 25-1 to 25 -M detects the current flowing through the power supply lines 23-1 to 23 -M, respectively (step S 101). ).

  Next, the harmonic current distortion calculation means 33 calculates the harmonic current for each order (i = 2 to Q) for each of the loads 17-1 to 17-M, and each load 17-1 to 17-M. Is calculated (step S102). Further, the voltage distortion rate [%] of the power supply bus voltage is calculated by the voltage distortion rate calculation means 32 (step S103).

  Then, it is determined whether or not the voltage distortion rate [%] of the bus voltage is less than the second threshold value (step S104). If not, the voltage distortion rate [%] of the bus voltage is less than the first threshold value. Is determined (step S105). Here, if the voltage distortion rate [%] of the bus voltage is less than the second threshold value in step S104, the problematic harmonics are not generated, and the process is terminated.

  When the voltage distortion rate [%] of the bus voltage is greater than or equal to the second threshold value in step S104 and the voltage distortion rate [%] of the bus voltage is less than the first threshold value in step S105, that is, the voltage in the present embodiment. When the distortion rate is 3 [%] or more and less than 5 [%], the process proceeds to the manual load limiting process in step S106, and it is quickly determined which load should be cut off and notified to the operator.

  When the voltage distortion rate [%] of the bus voltage is greater than or equal to the second threshold value in step S104 and the voltage distortion rate [%] of the bus voltage is greater than or equal to the first threshold value in step S105, that is, in this embodiment When the distortion rate is 5 [%] or more, the process proceeds to the automatic load limiting process in step S107, and it is quickly determined which load should be interrupted and the corresponding circuit breaker is forcibly tripped.

  Next, with reference to FIG. 3, the manual load limiting process by the control means 31 will be described more specifically. First. The harmonic current distortion [A] for each of the loads 17-1 to 17-M obtained in step S102 in FIG. 2 is converted into a relative ratio of harmonic current distortion (harmonic current distortion ratio) (step S201). Next, the voltage distortion estimated value [%] for each of the loads 17-1 to 17-M is calculated using the above-described equation (1) (step S202).

  Next, based on the set operation priority, the estimated voltage distortion value [%] corresponding to the load is subtracted from the voltage distortion rate [%] in order from the load with the lowest priority. It is determined whether or not the result of subtracting the estimated voltage distortion value [%] of each load from the first to jth (j = 1 to M; M is the number of loads) lower than the second threshold (step S203). ). Specifically, the voltage distortion estimated value [%] of the load with the j-th lowest priority is set as Y (j) (step S204), and the first to j-th lowest priority from the voltage distortion rate [%]. The result obtained by subtracting the estimated voltage distortion value [%] for each load is compared with the second threshold value (step S205).

  If the result of subtracting the estimated voltage distortion value [%] of each of the first to jth loads having the lower priority from the voltage distortion rate [%] is less than the second threshold value in step S203, the process proceeds to step S206. Thus, the operator is notified by displaying on the display unit 35 of the operation panel 34 that the power supply to the first to jth loads having a low priority should be cut off. Note that it is theoretically impossible that the result obtained by subtracting the estimated voltage distortion value [%] of all loads from the voltage distortion rate [%] in step S203 does not become less than the second threshold value, and the process ends on the flowchart. I am doing so.

  Next, the automatic load limiting process by the control means 31 will be described more specifically with reference to FIG. First. The harmonic current distortion [A] for each of the loads 17-1 to 17-M obtained in step S102 of FIG. 2 is converted into a relative ratio of harmonic current distortion (harmonic current distortion ratio) (step S301). Next, the voltage distortion estimated value [%] for each of the loads 17-1 to 17-M is calculated using the above-described equation (1) (step S302).

  Next, based on the set operation priority, the estimated voltage distortion value [%] corresponding to the load is subtracted from the voltage distortion rate [%] in order from the load with the lowest priority. It is determined whether or not the result of subtracting the estimated voltage distortion value for each load from the first to the jth lower than the first threshold value is below (step S303). Specifically, the voltage distortion estimated value [%] of the load having the lowest j-th priority is set as Y (j) (step S304), and the first to j-th low-priority order from the voltage distortion rate [%]. The result obtained by subtracting the estimated voltage distortion value [%] of each load up to the first threshold is compared (step S305).

  If the result obtained by subtracting the estimated voltage distortion value [%] of each of the first to jth loads having the lower priority from the voltage distortion rate [%] is less than the first threshold value in step S303, the process proceeds to step S306. In order to cut off the power supply to the first to jth loads having a low priority, the corresponding circuit breaker is forcibly tripped and the process ends. In Step S203, when the result of subtracting the estimated voltage distortion value [%] of all loads from the voltage distortion ratio [%] does not become less than the first threshold, the voltage distortion ratio [%] is much higher than the first threshold. In step S307, the power supply to all loads is cut off and the process ends.

  Next, specific numerical values will be exemplified and described with reference to FIG. Here, the number of loads is four from load 1 (17-1) to load 4 (17-4), and the operation priority is set in the order of load 1, load 2, load 3, and load 4 from the lowest. Has been. Moreover, the calculation result of the voltage distortion rate by the voltage distortion rate calculation means 32 (step S103) is 7 [%], and the calculation result of the harmonic current distortion [A] for each load by the harmonic current distortion calculation means 33 is Load 1 was 100 [A], load 2 was 200 [A], load 3 was 300 [A], and load 4 was 400 [A].

  In this case, the automatic load limiting process of FIG. 4 is executed, and the calculation results of the harmonic current distortion ratio in step S301 are 0.1 for load 1, 0.2 for load 2, and 3 for load 3, respectively. Is 0.3, and the load 4 is 0.4. In addition, the calculation result of the voltage distortion estimated value in step S302 is that load 1 is 0.70 [%], load 2 is 1.40 [%], load 3 is 2.10 [%], and load 4 is 2. .80 [%].

  Further, in the process in step S303, the total value 0.70 [%] + 1.40 [%] of the voltage distortion estimated values of the load 1 and the load 2 having the first and second lowest priorities from the voltage distortion rate 7 [%]. ] = 2.10 [%] is subtracted to 4.90 [%] and falls below the first threshold value (5 [%]), so in step S306, load 1 (17-1) and load 2 (17- The circuit breakers 24-1 and 24-2 are forcibly tripped in order to cut off the power supply to 2).

  As described above, in the power system and the monitoring control method for the power system of the present embodiment, the voltage distortion rate is calculated based on the detection value of the voltage detection unit 26 by the voltage distortion rate calculation unit 32 (voltage distortion rate calculation step). The harmonic current distortion in each power supply line 23-1 to 23-M is calculated by the harmonic current distortion calculation means 33 (harmonic current distortion calculation step) based on the detection values of the current detection means 25-1 to 25-M. When the voltage distortion rate exceeds the first threshold, the control means 31 (control step) causes the voltage distortion for each load based on the relative ratio of the harmonic current distortion in each of the power supply lines 23-1 to 23-M. And the power supply to some loads is cut off by the circuit breaker so that the sum of the estimated voltage distortion values of the operating load falls below the first threshold.

  In this way, when harmonic voltage distortion occurs in the system and the voltage distortion rate exceeds the first threshold, the power supply to some loads is cut off and the loads are selectively operated. Since the sum of the voltage distortion estimated values is set to be lower than the first threshold value, it is possible to quickly reduce the influence of the generated harmonics and protect the load-side electrical equipment.

  In the power system and the monitoring control method for the power system of the present embodiment, the operation priority order of each load is set by the operation panel 34, and the control means 31 (control step) sequentially sets the load from the lowest operation priority order. Since the power supply is cut off, it is possible to automatically select a load to cut off the power supply or to limit the output according to the characteristics of the system and each load, and it is possible to take measures against the harmonic problem more quickly, It can be performed flexibly and accurately according to the situation.

  Further, in the power system and the monitoring control method for the power system of the present embodiment, when the voltage distortion rate is lower than the first threshold and exceeds the second threshold that is lower than the first threshold, the control means 31 (control Step), the voltage distortion for each load is estimated based on the relative ratio of the harmonic current distortion in each of the power supply lines 23-1 to 23-M, and the sum of the estimated voltage distortion values of the operating load is less than the second threshold value. To notify that the power supply should be cut off. In this way, when the harmonic voltage distortion occurs in the system and the voltage distortion rate exceeds the lower second threshold, it is notified that the power supply to some loads should be cut off. The problem can be dealt with more quickly and step by step.

[Second Embodiment]
Next, FIG. 6 is a configuration diagram of a power system according to the second embodiment of the present invention.
In the figure, a power system 2 of the present embodiment includes a power source 11, a plurality of loads (load 1 to load M) 17-1 to 17-M, output limiting means 18-1 to 18-M, and a switchboard. 13, a monitoring control device 15, and a state detection means 19. In terms of configuration, in the configuration of the first embodiment (see FIG. 1), output limiting means 18-1 to 18-M for limiting the output of the load to the specified output, and the state of the power system (to determine the operation mode) The state detection means 19 for detecting the information) is added.

  Since the switchboard 13 is the same as that of the first embodiment, the description thereof is omitted. The monitoring control device 15 has a configuration including a voltage distortion rate calculation means 32, a harmonic current distortion calculation means 33, a control means 31, and an operation panel 34, as in the first embodiment.

  Here, the operation panel 34 serves as an interface with the operator. The operation panel 34 receives an operation / setting input by the operator and notifies the operator of various information via the display unit 35. Further, the operator sets the operation priority order of each load via the operation panel 34. The difference from the first embodiment is that the power system 2 of the present embodiment has a plurality of operation modes, and the operation priority of each load is set according to the plurality of operation modes. In the present embodiment, the load output is limited. However, depending on the type of load, the load output may not be limited, and whether or not the output can be limited is set in advance via the operation panel 34.

  Moreover, the voltage distortion rate calculation means 32 calculates voltage distortion rate [%] based on the detected value of the voltage detection means 26 in the switchboard 13 similarly to 1st Embodiment. Moreover, the harmonic current distortion calculation means 33 is based on the detection value of the current detection means 25-1 to 25-M in the switchboard 13 as in the first embodiment, and each power supply line 23-1 to 23-M. The harmonic current distortion for each load at is calculated.

  In addition, the control unit 31 determines the harmonic current distortion in each of the power supply lines 23-1 to 23 -M obtained by the voltage distortion rate calculation unit 32 when the voltage distortion rate by the voltage distortion rate calculation unit 32 exceeds the first threshold. Based on the relative ratio, the voltage distortion for each of the loads 17-1 to 17-M is estimated, and the power supply to some loads is cut off, or the output of some loads is limited to thereby reduce the voltage of the operating load. The sum of the distortion estimation values is set to be lower than the first threshold value. In the present embodiment, the first threshold value is set to 5 [%] as an example, but is not limited to this value.

  That is, based on the set operation priority, the output distortion coefficient k (k = 0.1 to 1.0) is sequentially added to the estimated voltage distortion value [%] corresponding to the load from the load with the lowest priority. The voltage distortion rate [%] is subtracted from the voltage distortion rate [%], and each of the first to j-1th (j = 1 to M; M is the number of loads) having a low priority. When the load voltage distortion estimated value [%] and the result obtained by subtracting the voltage distortion estimated value [%] of the load having the j-th lowest priority multiplied by the output limit coefficient k are below the first threshold. The power supply to the first to j−1th loads having the lowest priority is cut off, and the output of the jth lowest load is limited to (1−k) × 100 [%].

  Further, the control means 31 determines each of the voltage distortion rate calculation means 32 when the voltage distortion rate by the voltage distortion rate calculation means 32 is less than the first threshold value and exceeds the second threshold value lower than the first threshold value. Estimate the voltage distortion for each of the loads 17-1 to 17-M based on the relative ratio of harmonic current distortion in the power supply lines 23-1 to 23-M, and cut off the power supply to some loads, or By limiting the output of the partial load, it is notified that the sum of the estimated voltage distortion values of the operating load should be less than the second threshold value. In the present embodiment, the second threshold value is set to 3 [%] as an example, but is not limited to this value.

  That is, based on the set operation priority, the output distortion coefficient k (k = 0.1 to 1.0) is sequentially added to the estimated voltage distortion value [%] corresponding to the load from the load with the lowest priority. The voltage distortion rate [%] is subtracted from the voltage distortion rate [%], the voltage distortion estimation value [%] of each load from the first to j-1th having the lowest priority, and the priority When the result obtained by subtracting the output distortion coefficient k multiplied by the voltage distortion estimated value [%] of the load having the lowest j-th rank falls below the second threshold value, the first to j-1 th order having the lowest priority order The power supply to each load is cut off, and the output of the load with the j-th lowest priority is to be limited to (1-k) × 100 [%], and this is indicated through the display unit 35 of the operation panel 34. To inform the operator.

  Further, the control unit 31 determines the operation mode based on the state of the power system detected by the state detection unit 19. For example, assuming the case of a ship, the operation mode can be a cruise mode in which navigation is performed normally or at a high speed, and a specific mode in which the ship is stopped or traveled at a slow speed in order to perform a specific operation. In the cruise mode, the propulsion load is the most important load and the operation priority is high, but the specific work load is a load with low use frequency and the operation priority is low. On the other hand, in the specific mode, the specific work load is the most important load and the operation priority is high, but conversely, the propulsion load becomes a load that can suppress the output low, and the operation priority is also low. In the case of this specific example, the state detection means 19 can be realized by, for example, a speed sensor. In addition, by changing the setting of the operation priority according to the operation mode of the power system, the harmonic monitoring control adapted to the system state can be performed more flexibly.

  Next, a monitoring control method for a power system including the above components will be described with reference to FIGS. 2, 5, and 7 to 9. Here, FIG. 7 is a flowchart for explaining the manual load limiting process in the present embodiment, FIG. 8 is a flowchart for explaining the automatic load limiting process in the present embodiment, and FIG. 9 is an operation priority order of each load and a harmonic current distortion rate. FIG. 6 is an explanatory diagram (part 2) illustrating a voltage distortion estimated value.

  Since the outline of the monitoring control method of the power system of this embodiment is the same as that of the first embodiment (see FIG. 2), detailed description thereof is omitted. In the manual load limiting process in step S106, one of the loads is shut off and the load is to be quickly determined and notified to the operator. In the automatic load limiting process in step S107, , Quickly determine which load should be cut off and which load should be output limited, forcibly trip the corresponding circuit breaker and limit the output of the corresponding load by the output limiting means .

  Next, the manual load limiting process by the control means 31 will be described more specifically with reference to FIG. First. The harmonic current distortion [A] for each of the loads 17-1 to 17 -M obtained in step S <b> 102 of FIG. 2 is converted into a relative ratio of harmonic current distortion (harmonic current distortion ratio) (step S <b> 401). Next, the voltage distortion estimated value [%] for each of the loads 17-1 to 17-M is calculated using the above-described equation (1) (step S402).

  Next, based on the set operation priority order, the voltage distortion rate [%] is obtained by multiplying the estimated voltage distortion value [%] corresponding to the load by the output restriction coefficient k sequentially from the load having the lowest priority order. ] And output to the voltage distortion estimated value [%] of each load from the first to j−1th having the lowest priority, and the voltage distortion estimated value [%] of the load having the lowest priority j It is determined whether or not the result of subtracting the product of the limiting coefficient k is below the second threshold value (step S403).

  Specifically, the voltage distortion estimated value [%] of the load having the j-th lowest priority is set as Y (j), and the voltage distortion estimated value [%] multiplied by the output limiting coefficient k is Y ( j) Set k (step S404). Further, while increasing the output limiting coefficient k (k = 0.1 to 1.0) in predetermined increments (step S405), each load from the voltage distortion rate [%] to the first to j−1th items having the lowest priority order. And the second threshold value is compared with the result obtained by subtracting the voltage distortion estimated value [%] of the j-th lowest load and the output distortion coefficient k multiplied by the voltage distortion estimated value [%]. S406). It should be noted that a load whose output restriction is not possible due to the output restriction setting is processed with the output restriction coefficient fixed at k = 1.0.

  When the subtraction result is less than the second threshold value in step S403, the process proceeds to step S407 to cut off the power supply to the first to j−1th loads having the lowest priority and the priority is j. An indication that the output of the second lowest load should be limited to (1-k) × 100 [%] is displayed on the display unit 35 of the operation panel 34 to notify the operator. Note that it is theoretically impossible in step S403 that the subtraction result does not become less than the second threshold value, and the processing ends as it is on the flowchart.

  Next, the automatic load limiting process by the control means 31 will be described more specifically with reference to FIG. First. The harmonic current distortion [A] for each of the loads 17-1 to 17-M obtained in step S102 of FIG. 2 is converted into a relative ratio of harmonic current distortion (harmonic current distortion ratio) (step S501). Next, the voltage distortion estimated value [%] for each of the loads 17-1 to 17-M is calculated using the above-described equation (1) (step S502).

  Next, based on the set operation priority order, the voltage distortion rate [%] is obtained by multiplying the estimated voltage distortion value [%] corresponding to the load by the output restriction coefficient k sequentially from the load having the lowest priority order. ] And output to the voltage distortion estimated value [%] of each load from the first to j−1th having the lowest priority, and the voltage distortion estimated value [%] of the load having the lowest priority j It is determined whether or not the result of subtracting the product of the limiting coefficient k is below the first threshold value (step S503).

  Specifically, the voltage distortion estimated value [%] of the load having the j-th lowest priority is set as Y (j), and the voltage distortion estimated value [%] multiplied by the output limiting coefficient k is Y ( j) Set k (step S504). Further, while increasing the output limiting coefficient k (k = 0.1 to 1.0) in predetermined increments (step S505), each load from the voltage distortion rate [%] to the first to j−1th items having the lowest priority order. And the first threshold value is compared with the result obtained by subtracting the output distortion coefficient k multiplied by the voltage distortion estimated value [%] of the j-th lowest load and the voltage distortion estimated value [%]. S506). It should be noted that a load whose output restriction is not possible due to the output restriction setting is processed with the output restriction coefficient fixed at k = 1.0.

  When the subtraction result is less than the first threshold value in step S503, the process proceeds to step S507, and the corresponding circuit breaker is selected in order to cut off the power supply to the first to j-1th loads having a low priority. Is forcibly tripped, and the output of the corresponding load is limited by (1-k) × 100 [%] to limit the output of the j-th lowest priority load to the output by the output limiting means. . The case where the subtraction result does not become less than the first threshold value in step S503 is a case where the voltage distortion rate [%] is a value much larger than the first threshold value. Shut off the supply and finish.

  Next, specific numerical values will be exemplified and described with reference to FIGS. 5 and 9. Here, the number of loads is four from load 1 (17-1) to load 4 (17-4), and loads 1 (17-1) to 3 (17-3) are loads that cannot be output limited. Is set. Further, two types of operation priorities are set according to the operation mode of the power system 2 as shown in FIG. 5 and FIG. 9. In FIG. 5 (cruising mode), load 1, load 2, load 3 and load 4 are set in this order, and in FIG. 9 (specific mode), load 4, load 3, load 2, and load 1 are set in order from the lowest.

  Moreover, the calculation result of the voltage distortion rate by the voltage distortion rate calculation means 32 (step S103) is 7 [%], and the calculation result of the harmonic current distortion [A] for each load by the harmonic current distortion calculation means 33 is Load 1 was 100 [A], load 2 was 200 [A], load 3 was 300 [A], and load 4 was 400 [A]. In this case, in any of the operation modes, the automatic load limiting process of FIG. 8 is executed, and the calculation results of the harmonic current distortion ratio in step S501 are 0.1 for load 1 and 2 for load 2, respectively. Is 0.2, load 3 is 0.3, and load 4 is 0.4. In addition, the calculation result of the voltage distortion estimated value in step S502 is 0.70 [%] for load 1, 1.40 [%] for load 2, 2.10 [%] for load 3, and 2 for load 4 respectively. .80 [%].

  In the process in step S503, in the case of FIG. 5 (in the cruise mode), the voltage distortion estimated values of the load 1 and the load 2 having the lowest priority from the voltage distortion rate of 7 [%] are the first and second. When the total value 0.70 [%] + 1.40 [%] = 2.10 [%] is subtracted, it becomes 4.90 [%], which is below the first threshold (5 [%]). Circuit breakers 24-1 and 24-2 are forcibly tripped to cut off the power supply to load 1 (17-1; specific work load) and load 2 (17-2; specific work load). It will be.

  On the other hand, in step S503, in the case of FIG. 9 (in the specific mode), the output is limited to the voltage distortion estimated value 2.80 [%] of the load 4 having the lowest priority from the voltage distortion rate 7 [%]. Since the value 2.10 [%] multiplied by the coefficient k = 0.75 is 4.90 [%] and falls below the first threshold (5 [%]), the load 4 (17− 4; the propulsion load) is forcibly limited via the output limiting means 18-4 in order to limit the output to 25 [%].

  As described above, in the power system and the monitoring control method for the power system of the present embodiment, the voltage distortion rate is calculated based on the detection value of the voltage detection unit 26 by the voltage distortion rate calculation unit 32 (voltage distortion rate calculation step). The harmonic current distortion in each power supply line 23-1 to 23-M is calculated by the harmonic current distortion calculation means 33 (harmonic current distortion calculation step) based on the detection values of the current detection means 25-1 to 25-M. When the voltage distortion rate exceeds the first threshold, the control means 31 (control step) causes the voltage distortion for each load based on the relative ratio of the harmonic current distortion in each of the power supply lines 23-1 to 23-M. The power supply to some loads is cut off, or the output of some loads is limited, so that the sum of the estimated voltage distortion values of the operating load falls below the first threshold value.

  In this way, when harmonic voltage distortion occurs in the system and the voltage distortion rate exceeds the first threshold, the power supply to some loads is cut off or the output of some loads is limited to selectively load Since the sum of the estimated voltage distortion values of the operating load falls below the first threshold, the influence of the generated harmonics can be quickly reduced and the electrical equipment on the load side can be protected. .

  In the power system and the monitoring control method for the power system of the present embodiment, the operation priority order of each load is set by the operation panel 34, and the control means 31 (control step) sequentially sets the load from the lowest operation priority order. Since the power supply is cut off or the output is limited, it is possible to automatically select the load that should cut off the power supply or limit the output according to the characteristics of the system and each load. It can be performed more quickly and can be performed flexibly and accurately according to the situation.

  Further, in the power system and the power system monitoring and controlling method according to the present embodiment, the operation priority is set for each operation mode of the power system. It is possible to preferentially select a load to be output-limited, and to deal with the harmonic problem more quickly and to perform flexibly and accurately according to the situation.

  Further, in the power system and the power system monitoring and control method of the present embodiment, priority is given to a load that should be cut off of power supply or output restricted in accordance with the operation status of the power system detected by the status detection means 19. In addition, it is possible to take a countermeasure against the harmonic problem dynamically and quickly, and flexibly and accurately according to the situation.

  Further, in the power system and the monitoring control method for the power system of the present embodiment, when the voltage distortion rate is lower than the first threshold and exceeds the second threshold that is lower than the first threshold, the control means 31 (control Step), the voltage distortion for each load is estimated based on the relative ratio of the harmonic current distortion in each of the power supply lines 23-1 to 23-M, and the sum of the estimated voltage distortion values of the operating load is less than the second threshold value. To notify that the power supply should be cut off or the output should be limited. In this way, when harmonic voltage distortion occurs in the system and the voltage distortion rate exceeds the lower second threshold, the power supply to some loads should be cut off or the output of some loads should be limited. Since the effect is notified, it is possible to take measures against the harmonic problem more promptly and stepwise.

[Modification]
As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, this invention is not limited to these embodiment and its deformation | transformation, There exists a design change etc. of the range which does not deviate from the summary of this invention. Are also included in the present invention. For example, in the second embodiment, the operation priority order is dynamically switched according to the operation status of the power system detected by the status detection unit 19, but the system depends on time factors such as date, month, or season. When the operation status changes, it is also conceivable to switch the operation priority order based on history data such as a load curve and time information of date and time.

DESCRIPTION OF SYMBOLS 1, 2 Power system system 11 Power supply 13 Distribution board 15 Monitoring and control apparatus 17-1 to 17-M Load 18-1 to 18-M Output restriction means 19 State detection means 22 Bus 23-1 to 23-M Power supply line 21, 24-1 to 24-M Circuit Breakers 25-1 to 25-M Current detection means 26 Voltage detection means 31 Control means 32 Voltage distortion rate calculation means 33 Harmonic current distortion calculation means 34 Operation panel 35 Display unit

Claims (12)

An electric power system comprising a power source, a plurality of loads, a switchboard, and a monitoring control device,
The switchboard is
Voltage detecting means for detecting a bus voltage of the power source;
Circuit breakers connected in series to each power supply line for supplying power to each load from the bus of the power source,
Current detecting means for detecting each current flowing in each of the power supply lines,
The monitoring and control device includes:
Voltage distortion rate calculation means for calculating a voltage distortion rate based on a detection value of the voltage detection means;
Harmonic current distortion calculation means for calculating harmonic current distortion in each power supply line based on the detection value of the current detection means;
When the voltage distortion rate exceeds the first threshold, the voltage distortion for each load is estimated based on the relative ratio of harmonic current distortion in each power supply line, the power supply to some loads is cut off, and the operating load Control means for causing the sum of the estimated voltage distortion values to fall below a first threshold;
A power grid system characterized by comprising: Output limiting means for individually limiting the output of the plurality of loads,
When the voltage distortion rate exceeds a first threshold, the control means estimates a voltage distortion for each load based on a relative ratio of harmonic current distortion in each power supply line, and is estimated from the voltage distortion rate. The total sum of the estimated voltage distortion values of the operating load obtained by subtracting the value obtained by multiplying the voltage distortion for each load by the output limit coefficient of 0.1 to 1 set for each voltage distortion of the load is first. Determining the output limiting factor to be below a threshold;
The output limiting means limits the output of some other loads other than the some loads that have cut off power supply at a rate determined based on the determined output limiting coefficient. Item 4. The power system according to Item 1. The monitoring control device has a setting means for setting the operation priority of each load,
3. The power system according to claim 1, wherein the control unit cuts off the power supply or limits the output in order from a load having a low operation priority. 4.   The power system according to claim 3, wherein the operation priority is set for each operation mode of the power system. The supervisory control device has status detection means for detecting the operating status of the power system.
The power system according to claim 4, wherein the control unit determines an operation mode according to an operating state of the power system.   When the voltage distortion rate is lower than the first threshold value and exceeds a second threshold value that is lower than the first threshold value, the control means is configured for each load based on a relative ratio of harmonic current distortion in each power supply line. The voltage distortion is estimated, and the fact that the power supply should be cut off or the output should be limited is reported so that the sum of the estimated voltage distortion values of the working load falls below the second threshold. The electric power system of any one of Claim 5. A power source, a plurality of loads, voltage detection means for detecting a bus voltage of the power source, a circuit breaker connected in series to each power supply line for supplying power from the bus of the power source to each load, and each power A current control means for detecting each current flowing in a supply line, a distribution board provided with a monitoring control device, a monitoring control method for a power system comprising:
A voltage distortion rate calculation step of calculating a voltage distortion rate based on a detection value of the voltage detection means;
A harmonic current distortion calculation step of calculating a harmonic current distortion in each power supply line based on a detection value of the current detection means;
When the voltage distortion rate exceeds the first threshold, the voltage distortion for each load is estimated based on the relative ratio of harmonic current distortion in each power supply line, the power supply to some loads is cut off, and the operating load A control step for causing the sum of the voltage distortion estimated values of the following to fall below a first threshold;
A monitoring control method for an electric power system characterized by comprising: The output of the previous SL plurality of loads having an output limit step for individually limiting,
When the voltage distortion rate exceeds a first threshold, the control step estimates a voltage distortion for each load based on a relative ratio of harmonic current distortion in each power supply line, and is estimated from the voltage distortion rate. The total sum of the estimated voltage distortion values of the operating load obtained by subtracting the value obtained by multiplying the voltage distortion for each load by the output limit coefficient of 0.1 to 1 set for each voltage distortion of the load is first. Determining the output limiting factor to be below a threshold;
8. The output limiting step limits output of a partial load other than the partial load that cuts off power supply at a rate determined based on the determined output limiting coefficient . A monitoring control method for a power system. A setting step for setting the operation priority of each load;
The power control system monitoring control method according to claim 7 or 8, wherein the control step cuts off the power supply or limits the output in order from a load having a low operation priority.   10. The power system monitoring and control method according to claim 9, wherein the operation priority is set for each operation mode of the power system. A situation detecting step for detecting an operating situation of the power system;
The power control system monitoring control method according to claim 10, wherein the control step determines an operation mode according to an operating state of the power system. When the voltage distortion rate is less than the first threshold value and exceeds a second threshold value that is lower than the first threshold value, the control step is based on a relative ratio of harmonic current distortion in each power supply line for each load. The voltage distortion is estimated, and notification is made that the power supply should be cut off or the output should be limited so that the sum of the estimated voltage distortion values of the operating load falls below the second threshold value. The monitoring control method of the electric power system of any one of Claim 11.

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