JP5508796B2 - Power supply system control method and power supply system control apparatus - Google Patents

Description

  The present invention relates to a power supply system control method and a power supply system control apparatus that can maintain the stability of a power supply system when a disturbance occurs.

  Generally, when connecting a power generator such as a diesel power generator, a gas engine power generator, or a secondary battery or a fuel cell to a power system, the diesel power generator or the gas engine power generator or the like directly connects the synchronous generator to the electric system. Secondary batteries and fuel cells are connected to an electric system via an inverter. In the following description, a power generator that directly connects a synchronous generator or induction generator to an electric system is referred to as a “rotary power generator”, and a power generator that is connected to the electric system via an inverter is referred to as “inverter power generation”. Referred to as an "apparatus".

  In the power supply system in which a plurality of the above-described power generators are interconnected, control is generally performed as follows. For convenience of explanation, as shown in FIG. 8, a power supply system 100P in which one rotary power generator and one inverter power generator are interconnected will be described as an example. The rotary power generator and the inverter power generator function as either the main control power generator 1P or the sub-control power generator 2P.

  FIG. 8 is a schematic diagram illustrating an example of a power supply system and a premises system of a customer having a plurality of power generation devices. The power supply system 100P shown in FIG. 8 includes an inverter power generator (denoted as a main control power generator 1P), a rotary power generator (denoted as a sub-control power generator 2P), a control device for each power generator, A step-up transformer for power generation 4 that transforms the power of the power generation device to the same voltage class as the local bus 3, a resistance load and an inverter load (INV load) connected to the local bus 3 via the load transformer 5, and a motor load Power load 6 such as power supply circuit breaker 8 that is closed when the system is connected to the commercial system 7, and is opened when the local system is independently operated. The power receiving transformer 11 is configured to transform the received power from the commercial system 7 into the same voltage class as the local system. The steady output of the power generator is set based on an output command 13 from the operator or the automatic power supply system 12, and is normally updated on the order of several minutes to several tens of minutes.

  Here, a description will be given assuming a state in which the power receiving circuit breaker 8 is opened and the customer's premises system alone operates independently without receiving power supply from the commercial system 7.

  When a customer's premises system is operated independently, the conventional power supply system control method uses each power generator as a main control power generator that operates as a voltage source in the autonomous system and maintains the frequency and voltage at predetermined values. Alternatively, it is operated as a sub-control power generator that outputs a constant electrical output or current.

  When the rotary power generator (synchronous generator) operates as a voltage source and maintains the frequency and voltage, the inverter power generator performs current control according to the output command. In addition, when the inverter power generator performs constant voltage constant frequency control and operates as a voltage source, the rotary power generator performs electric output constant control. In general, by performing such control, the frequency and voltage in the independent system are maintained at predetermined values, and each power generator is operated stably.

  Note that when comparing characteristics such as followability to transient load fluctuations and short-time overcurrent tolerance between the rotary power generator and the inverter power generator, the inverter power generator generally has better followability. On the other hand, the rotary power generator has a larger overcurrent withstand capability. Regarding the overcurrent capability, a general-purpose inverter allows about 1.2 to 1.5 times the rating, and a synchronous generator allows several times.

  Next, the response of the power generation device when a disturbance such as a transient load fluctuation (motor start, etc.) or an excitation rush current at the time of turning on the transformer occurs will be described. The frequency and voltage of the main control power generation device become predetermined values. The output is adjusted as described above, but the sub-control power generator is controlled so as to keep the output constant.

JP-A-8-223799

  However, the magnitude of the frequency change and voltage change when a disturbance occurs differs depending on the type of power generation device that is the main control power generation device.

  For example, when the inverter power generation device operates as a main control power generation device, the followability is good, and therefore the frequency change and voltage change are smaller than when the rotary power generation device is the main control power generation device. However, the inverter power generator has a smaller overcurrent tolerance than the rotary power generator. Therefore, if the load fluctuation amount is large or the output before the load fluctuation is close to the rated value, the overcurrent withstand capability is exceeded, so that the operation of the inverter power generator is stopped to protect the inverter. In addition, since a very large magnetizing inrush current (inrush current) flows when the transformer is turned on, the overcurrent withstand capability may be exceeded even in such a case, and the operation may be stopped.

  In other words, when the inverter power generation device is a main control power generation device, the overcurrent withstand capability is small, so it is necessary not to be over the limit of the overcurrent withstand capability. For example, it is necessary to take measures such as suppressing the output during operation to widen the output adjustable range, increasing the capacity, increasing the number of units to give a margin, or setting a limit on the load fluctuation amount. is there. However, in this case, problems such as a reduction in the load factor of the power generation device, excessive capital investment, and increased operational restrictions arise.

  Note that when the overcurrent withstand limit is reached, overcurrent protection is immediately activated, and the inverter power generator stops operation. In this case, the frequency change or the voltage change suddenly increases or the voltage source is lost, and the subordinate control power generator may not be able to continue operation and the on-site system may be completely stopped.

  On the other hand, when the rotary power generation device is a main control power generation device, followability is inferior, and therefore frequency changes and voltage changes tend to be large. For example, if a motor is connected as a power load, the number of revolutions changes and the quality of the product using that power decreases, the electronic device such as a PC stops due to the voltage drop, or the light is dark Problems occur.

  There are various types of rotary power generators, such as diesel power generators, gas engine power generators, and gas turbine power generators, but there is no power generator that has the same level of follow-up as an inverter power generator. Therefore, even if different types of rotary power generators are combined, the effect of improving the followability is small. In addition, if the number and capacity are increased, the followability can be improved, but the load factor is lowered and efficient operation cannot be performed.

  If the inertia of the generator is increased, the frequency change rate and the maximum and minimum values of fluctuation can be reduced. However, if the ratio of the load fluctuation amount to the power generation equipment capacity is large, the improvement effect is small. In addition, there is a limit in the configuration of the generator to increase the inertia.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a power supply system control method and a power supply system control apparatus that can maintain the stability of the power supply system when a disturbance occurs.

In order to solve the above problems, the present invention provides a master control power generator that operates so that the output value of the system frequency and system voltage of the local system becomes a predetermined value, and the slave control power generation that reduces the burden on the master control power generator. A power supply system control method for controlling a power supply system including a device, wherein the occurrence of a disturbance in the local system is detected, and the occurrence of a disturbance indicating that a change in the amount of electricity in the local system is equal to or greater than a predetermined value. when detecting, it controls the output of the main control power generating device, detecting the occurrence of the disturbance in the local end of the slave control power generator, to converge the operating point corresponding to the inclination of the drooping characteristic, the driven control generator A power supply system control method for autonomously controlling the output of a device is provided.

<Action>
Therefore, the present invention autonomously controls the output of the slave control power generator until it detects the occurrence of disturbance in the local system at its own end and converges to the operating point corresponding to the slope of the droop characteristic. Therefore, the burden on the main control power generator can be reduced, and the stability of the power supply system when a disturbance occurs can be maintained.

<Terminology>
In the present invention, the “rotary power generator” refers to a power generator that directly connects a synchronous generator or an induction generator to an electric system. Further, the “inverter power generation device” is a power generation device linked to an electric system via an inverter.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the power supply system control method and power supply system control apparatus which can maintain the stability of the power supply system at the time of disturbance generation.

1 is a schematic diagram showing a configuration of a power supply system 100 according to a first embodiment of the present invention. It is a schematic diagram which shows the structure of the subordinate control apparatus 2a which concerns on the same embodiment. It is a figure which shows the control block of the subordinate control apparatus 2a which concerns on the same embodiment. It is a flowchart for demonstrating the control method of the electric power generation system 100 which concerns on the embodiment. It is a figure which shows the example of the speed droop characteristic in each electric power generating apparatus which concerns on the same embodiment. It is a figure which shows the example of the voltage droop characteristic in each electric power generating apparatus which concerns on the same embodiment. It is a schematic diagram which shows the structure of the power supply system 100S which concerns on the 2nd Embodiment of this invention. It is a schematic diagram which shows the structure of the conventional power supply system.

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

<First Embodiment>
(Configuration of power supply system 100)
FIG. 1 is a schematic diagram showing a configuration of a power supply system 100 according to the first embodiment of the present invention. In FIG. 1, an example of a power supply system and a premises system of a customer having a plurality of power generation devices is shown.

  The power supply system 100 includes a main control power generation device 1, a sub control power generation device 2, a main control device 1a, a sub control device 2a, a power generation step-up transformer 4, a power load 6, a power reception breaker 8, a power reception bus 10, and a power reception The transformer 11 is used.

  The main control power generator 1 is a power generator that operates so that the output values of the system frequency and system voltage of the local system become predetermined values. For example, the steady output of the main control power generator 1 is set based on the output command 13 from the operator or the automatic power feeding system 12 and is updated in order of several minutes to several tens of minutes. Here, it is assumed that the main control power generator 1 is an “inverter power generator”. Examples of the inverter power generator include a secondary battery and a fuel cell.

  The sub-control power generation device 2 is a power generation device for reducing the burden on the main control power generation device. Here, it is assumed that the sub-control power generation device is a “rotary power generation device”. Examples of the rotary power generator include a diesel power generator and a gas engine power generator.

  1 illustrates the power supply system 100 in which one rotary power generation device and two inverter power generation devices are connected, but the number and combination of the connection are not limited to this.

  The main control device 1a detects the occurrence of disturbance in the local system and controls the output of the main control power generation device 1.

  The slave control device 2a detects the occurrence of disturbance in the local system at its own end, and autonomously outputs the output of the slave control power device 2 until it converges to the operating point corresponding to the slope of the droop characteristic. It is something to control.

  Specifically, the slave control device 2a includes a disturbance detection unit 21 and a power generation output control unit 22, as shown in FIG.

  The disturbance detection unit 21 measures one or a plurality of electric quantities of voltage, current, frequency, active power, reactive power as the electric quantity measurable at the own end of the sub-control power generator 2a. Then, the disturbance detection unit 21 detects the occurrence of the disturbance based on conditions such as whether the measured amount of electricity or the calculated change is greater than or equal to a predetermined value or less than a predetermined value. For example, the disturbance detection unit 21 detects the occurrence of a disturbance based on whether the magnitude of the voltage is less than a predetermined value, whether the change in active power is greater than or equal to a predetermined value, or whether the change in frequency is greater than or equal to a predetermined value. To do. Alternatively, the occurrence of disturbance may be detected by a combination of these.

  The power generation output control unit 22 controls the sub-control power generation device 2 according to the droop characteristic according to the detection result of the disturbance detection unit 21. For example, when the power generation output control unit 22 adjusts the output in proportion to the frequency deviation, the control block is as shown in FIG. In this control block, the output adjustment amount ΔP is calculated as shown in the following equation (1). Here, Δf is a frequency deviation from the reference frequency, δ is a settling rate, P0 is an output command value to the slave control power generator 2 set in accordance with an output command 13 from an operator or the automatic power feeding system 12, and P is a slave control. The output of the power generator 2 is shown.

ΔP = Δf × (1 / δ) (1)
For example, when the settling rate δ is set to 4% and the frequency deviation Δf is −1 Hz (2%), the power generation output control unit 22 increases the output adjustment amount by ΔP = + 0.5 PU (self-capacity basis). Give the control command as follows. Note that there is a correlation between the supply / demand imbalance and the frequency change, and when the supply / demand imbalance is large, the frequency change also increases. From this, when the frequency change is large, that is, when the supply and demand imbalance is large, the power generation output control unit 22 adjusts so that the output of the sub-control power generator 2 is increased.

  The power generation step-up transformer 4 transforms the power of the power supply system 100 to the same voltage class as the local bus 3 as necessary.

  The power load 6 is a motor load, a resistance load, an inverter load (INV load) or the like connected to the local bus 3 via the load transformer 5.

  The power receiving circuit breaker 8 is closed when the commercial system 7 is connected to the grid, and is opened during the independent operation of the local system alone.

  The power receiving bus 10 receives power from the commercial system 7 via the power transmission line 9.

  The power receiving transformer 11 transforms the received power from the commercial system 7 to the same voltage class as the local system.

(Control method of power supply system 100)
Next, a control method of the power generation system 100 according to the present embodiment will be described with reference to the flowchart of FIG. As a premise, a control method of the power supply system 100 in a state where the customer's premises system alone operates independently without receiving power supply from the commercial system will be described. Further, in the power supply system 100 according to the present embodiment, the power generators 1 and 2 are controlled according to the droop characteristics shown in FIGS. 5 and 6. Here, FIG. 5 is a diagram showing an example of velocity droop characteristics. The speed droop characteristic indicates a characteristic that the frequency f decreases as the load increases (= the active power output P increases). FIG. 6 is a diagram illustrating an example of voltage droop characteristics. The voltage droop characteristic indicates a characteristic that the terminal voltage V decreases as the reactive power output Q increases. For convenience of explanation, it is assumed that the load is only effective. Moreover, (a) and (b) of FIG.5 and FIG.6 has shown the state of the main control power generator 1 and the sub control power generator 2, respectively. Based on this premise, the details will be described below.

  In a normal state, the power supply system 100 uses the inverter power generator of the main control power generator 1 as a voltage source. The main control power generation apparatus 1 is controlled by the main control apparatus 1a so that the frequency and voltage of the local system become predetermined values (step S1).

  When the load increases from such a normal state, as shown in the state transition T1 in FIG. 5A, a frequency drop occurs in the local system (step S2).

  When a frequency drop occurs due to an increase in load, as shown in a state transition T2 in FIG. 5A, the main controller 1a increases the output of the main control power generator 1 in order to maintain the frequency and voltage, The frequency target value is adjusted according to the droop characteristic (step S3).

  On the other hand, the slave control device 2a also measures the frequency at its own end of the slave control power generation device 2 and, as shown in the state transition T1 of FIG. The output is increased (step S4). As a result, the state of the sub-control power generator 2 changes as indicated by T3 in FIG. At this time, the output adjustment amount ΔP in the slave control power generator 2 is calculated from the frequency measured at its own end. For example, when the output is adjusted in proportion to the frequency deviation, the output adjustment amount ΔP is calculated by the above equation (1). Here, the slave control device 2a increases the output adjustment amount by ΔP = + 0.5 PU (self-capacitance basis) if the frequency deviation Δf is −1 Hz (2%) when the settling rate δ is 4%, for example. A control command is given to the controlled generator 2 so as to do this.

  When the sub control device 2a increases the output of the sub control power generation device 2, a decrease in the frequency of the main control power generation device 1 is suppressed. Therefore, the main control device 1a adjusts the frequency target value of the main control power generation device 1, and decreases the output of the main control power generation device 1 by an amount corresponding to the increase in the sub control power generation device 2 (step S5). As a result, the state of the main control power generator 1 changes as indicated by T4 in FIG.

  Finally, the outputs of the main control power generation device 1 and the sub control power generation device 2 are balanced and converge to an operating point corresponding to the slope of the droop characteristic (the regulation rate δ) (step S6).

(Effect of the power supply system 100)
As described above, according to the power supply system 100 according to the present embodiment, the rotary power generation device that is the sub-control power generation device 2 operates autonomously during a large disturbance, so that the burden on the main control power generation device 1 is reduced. . For example, according to the power supply system 100, when the frequency changes due to the occurrence of a disturbance, the sub-control power generation device 2 operates autonomously, and the burden on the main control power generation device 1 is reduced. Therefore, in the power supply system 100, even when the overcurrent withstand capability of the main control power generator 1 is small, the allowable load fluctuation amount is expanded, so that the operation restriction can be relaxed. In other words, driving continuity (stability) during a large disturbance can be improved.

  Further, in this power supply system 100, since the surplus power of the slave control power generator 2 is used, the load factor of the power generation equipment is improved, and the capacity of the power generation equipment can be used to the maximum.

  In addition, the inverter power generator which is the main control power generator 1 according to the present embodiment has a small overcurrent withstand capability. For this reason, during a large disturbance or when a disturbance occurs near the rated operation, the current control for protecting the inverter acts and the main control power generator 1 is controlled so that the output current is less than the allowable value. That is, if only the inverter power generator is used, the power supply is insufficient, and the frequency reduction continues. On the other hand, in the power supply system 100 according to the present embodiment, the output is autonomously adjusted using the amount of electricity that can be measured at the own end of the rotary power generation device that is the sub-control power generation device 2. The burden on the main control power generator 1 can be reduced.

(Modification of power supply system 100)
In the power supply system 100, the rotary power generator may be the main control power generator 1, and the inverter power generator may be the sub-control power generator 2. In this case, since the inverter power generator has good followability, the followability as the power supply system 100 can be improved.

  Specifically, when a disturbance is detected in the inverter power generation device that is the sub-control power generation device 2, the output adjustment amount ΔP is calculated from the frequency measured at its own end, and the output is adjusted. For example, when the output is adjusted in proportion to the frequency deviation, the output adjustment amount ΔP is calculated by the above equation (1). Since the frequency and voltage fluctuations increase as the supply and demand imbalance increases, the secondary control device 2a quickly adjusts the output of the inverter power generation device 2 with good followability according to the magnitude of the frequency change.

  In short, when a disturbance occurs, an inverter power generation device (subordinate control power generation device) with good followability operates autonomously, so that followability is improved in the power supply system 100 in which the rotary power generation device is the main control power generation device 1. As a result, the effect of suppressing frequency fluctuations and voltage fluctuations is improved.

  Moreover, in this power supply system 100, since the surplus capacity of the sub-control power generator 2 is used, the load factor of the power generation facility is improved, and the capacity of the power generation facility can be used to the maximum.

  In addition, the inverter power generator may be the main control power generator 1, and the inverter power generator and the rotary power generator may be the sub-control power generator 2. In short, any combination of an inverter power generation device and a rotary power generation device can be applied to the main control power generation device 1 and the sub control power generation device 2.

<Second Embodiment>
FIG. 7 is a schematic diagram showing a configuration of a power supply system 100S according to the second embodiment of the present invention.

  The power supply system 100S according to the present embodiment includes a transmission device 14. The transmission device 14 transmits output information of the power generation device and the like to the control device of another power generation device in the local system via the network. In FIG. 7, output information of the inverter power generation device that is the main control power generation device 1 is transmitted to the sub control device 2 a of the rotary power generation device that is the sub control power generation device 2 via the transmission devices 14 a and 14 b. .

  Moreover, in the sub control apparatus 2a which concerns on this embodiment, the received output information of the main control electric power generating apparatus 1 is preserve | saved. Then, the slave control device 2a determines the convergence of the disturbance under the condition that the voltage returns within a predetermined range, and uses the stored output information of the main control power generator 1 to calculate the output change before and after the occurrence of the disturbance. The output of the control power generator 2 is adjusted so that the change is zero. Note that the response speed of output adjustment is arbitrarily set, and is set so that frequency fluctuation due to output adjustment is minimized.

  Next, a control method of the power supply system 100S according to the present embodiment will be described.

  First, in the power supply system 100S, when the slave control device 2a detects a disturbance such as a transient load fluctuation or a transformer being turned on in the slave control power generation device 2, the slave control device 2a autonomously uses an electric quantity measurable at its own end. The output of the sub-control power generator 2 is adjusted to absorb disturbance.

  Thereafter, when the disturbance converges, the slave control device 2a uses the output information of the main control power generation device 1 received by the transmission device 14b, and the output of the main control power generation device 1 is the output before the occurrence of the disturbance (steady output). The output of the sub-control power generator 2 is adjusted so that

  In short, according to the power supply system 100S according to the present embodiment, since the sub-control power generation device 2 absorbs the load sharing of the main control power generation device 1 when a disturbance occurs, the instantaneous reserve capacity of the main control power generation device 1 is increased. It can cope with disturbances that occur continuously.

  Moreover, since the surplus capacity of the sub-control power generator 2 is used, the load factor of the power generation facility is improved, and the capacity of the power generation facility can be utilized to the maximum.

  As described above, according to the power supply system 100S according to the present embodiment, when the frequency changes due to the occurrence of a disturbance, the slave control power generator 2 operates autonomously and reduces the burden on the main control power generator 1. That is, in the power supply system with a small overcurrent withstand capability of the main control power generator 1, the allowable load fluctuation amount is expanded, so that operational restrictions can be relaxed.

<Others>
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine a component suitably in different embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Main control power generation device, 1a ... Main control device, 2 ... Subordinate control power generation device, 2a ... Subordinate control device, 3 ... Local bus, 4 ... Step-up transformer for power generation 5 ... Load transformer, 6 ... Power load, 7 ... Commercial system, 8 ... Receiving circuit breaker, 9 ... Transmission line, 10 ... Receiving bus, 11, ... Power receiving transformer, 14 ... transmission device, 21 ... disturbance detection unit, 22 ... power generation output control unit, 100, 100S ... power supply system.

Claims (10)

A power supply system that controls a power supply system that includes a main control power generator that operates so that a system frequency and a system voltage output value of a local system become predetermined values, and a sub-control power generator that reduces the burden on the main control power generator A control method,
Detecting the occurrence of a disturbance indicating that the amount of change in the amount of electricity in the premises system is a predetermined value or more ,
When detecting the occurrence of the disturbance, control the output of the main control power generator,
Detecting the occurrence of the disturbance in the local end of the slave control power generator, to converge the operating point corresponding to the inclination of the droop characteristic, autonomously controls the output of the follower control power generator,
A power supply system control method. The power supply system control method according to claim 1,
The main control power generator is an inverter power generator,
The slave control power generator is a rotary power generator,
A power supply system control method. The power supply system control method according to claim 1,
The main control power generator is a rotary power generator,
The sub-control power generator is an inverter power generator,
A power supply system control method. The power supply system control method according to any one of claims 1 to 3,
The output of the slave control power generator is autonomously controlled using a frequency as an electric quantity measurable at its own end,
A power supply system control method. The power supply system control method according to any one of claims 1 to 4,
Output information of the main control power generator is acquired and stored via a network, and when the disturbance converges, an output change before and after the occurrence of the disturbance is calculated using the stored output information, and the change is zero. The power supply system control method characterized by controlling the subordinate control power generator so that it may become. A power supply system that controls a power supply system that includes a main control power generator that operates so that a system frequency and a system voltage output value of a local system become predetermined values, and a sub-control power generator that reduces the burden on the main control power generator A control device,
Means for detecting the occurrence of a disturbance indicating that the amount of change in the amount of electricity in the premises system is equal to or greater than a predetermined value ;
When detecting the occurrence of the disturbance, main control means for controlling the output of the main control power generator,
Detecting the occurrence of the disturbance in the local end of the slave control power generator, to converge the operating point corresponding to the inclination of the drooping characteristic, and slave control means for autonomously controlling the output of the follower control power generator,
A power supply system control device comprising: In the power supply system control device according to claim 6 ,
The main control power generator is an inverter power generator,
The slave control power generator is a rotary power generator,
A power supply system control device. In the power supply system control device according to claim 6 ,
The main control power generator is a rotary power generator,
The sub-control power generator is an inverter power generator,
A power supply system control device. The power supply system control device according to any one of claims 6 to 8,
The slave control means autonomously controls the output of the slave control power generator using a frequency as an electric quantity measurable at its own end,
A power supply system control device. The power supply system control device according to any one of claims 6 to 9,
The slave control means acquires and stores the output information of the main control power generator via a network, and when the disturbance converges , calculates the output change amount before and after the occurrence of the disturbance using the stored output information, Controlling the slave control power generator so that the change is zero;
A power supply system control device.

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