JP3259296B2 - Reverse power prevention method for cogeneration system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse power prevention system for a cogeneration system that uses both private power generation and power received from a system (commercial power supply). The present invention relates to a reverse power prevention system that prevents generated power from flowing to the system side in response to a load change.

[0002]

2. Description of the Related Art A cogeneration system generates electric power by a heat engine such as a gas engine, a diesel engine, or a gas turbine. High efficiency system.

[0003] This system is often used for buildings as a private power generation facility, but is often connected to a power system to supply power to a load for stable power supply. In the case of interconnection with the power system, the received power constant control is performed, but the installer of the private power generation equipment may request that the set value of the received power constant control be minimized.
In order to prevent reverse power transmission to the grid, it is necessary to consider a margin for the unit maximum value of the load fluctuation for the minimum received power value.

FIG. 5 is an explanatory diagram for examining the minimum value of the received power. The range shaded in the figure is the unit maximum value. It is necessary to provide a margin equivalent to the unit maximum value of the load fluctuation between the reverse feed point.

[0005]

The set value of the received power constant control is determined by the load fluctuation and the response of the control as described with reference to FIG. 5, but the constant control value of the received power is low and the load fluctuation of the load is constant. If the value is large, the generated power is temporarily the reverse power that is supplied to the grid side, and according to the system-specific guidelines, the system-side circuit breaker or the power-generating side circuit breaker should be cut off directly under specified conditions. It has become. This reverse power is determined to be within 0.5 to 2 seconds at 10% of the output of the normal generator. For example, when the load fluctuation is 115 kW off when the received power is 30 kW and the power generation output is 150 kW, the reverse power is temporarily 85%.
kW, and the power generation output is reduced to the normal control response (1
(00% → 0% is 10 to 15 seconds), the reverse power relay operates and the system is separated.

In the conventional system, after the output of the generator is detected, the output is controlled so as to become the power output set by the generated power constant control device, and the response time is 0 → 100% or 1
00 → 0% is 10 to 15 seconds, the load balance in the case of parallel operation of two units, the frequency adjustment time in the case of system parallel, etc. are determined comprehensively, and the responsiveness is accelerated only to avoid reverse power. Was impossible. This is related to the governor type ranging from fuel adjustment to load (speed) fluctuation, and the conventional mechanical governor could not cope with the electric response time by only slightly improving the electric response time.

In view of the above, the applicant of the present application first applies a reverse power prediction signal to an electronic governor output reduction command switching setting for a sudden load change, thereby rapidly reducing the generator output. A method was proposed to prevent the reverse power by controlling the received power to the normal value before the operation of the reverse power relay. (Japanese Patent Application No. 1-312096) This reverse power prevention method is effective for a device in which a sudden load change can be predicted for each load. It is not a fluctuation, but if a large number of loads fluctuate at the same time and fluctuate as an accumulation (aggregation), it must be dealt with by setting a certain condition such as fluctuation of a certain width or more, or the frequency etc. Challenges had arisen.

[0008] For example, in a cogeneration system that has a specific supply contract, when the ratio of the load to the entire load is １ ／ (25%), the contract power is reduced to zero in a constant condition. (For example, on a regular holiday at a department store), it is necessary to detect the load power and accurately grasp the situation of the load fluctuations individually to control the generator output corresponding to the entire load fluctuations. Was.

The present invention has been made in view of the above-described circumstances, and when a large number of loads of a specific supply exist, it is an object of the present invention to perform a generator output control corresponding to a change in the load and to provide a stable power supply.

[0010]

Means for solving the above-mentioned problems in the present invention are as follows. In a cogeneration system that operates in parallel with a system, a large number of specially required load information such as a load of a specific supply is continuously provided. By controlling the output by continuously or stepwise switching the output of the generator by grasping the fluctuations of the average value and the instantaneous value, the reverse power prevention control is performed while the received power is kept constant.

[0011]

The present invention adopts the above-mentioned control method, so that when there are a large number of loads such as a load of a specific supply or a special load, the control of the received power is performed while only the individual load fluctuation is performed. Instead, it is possible to prevent reverse power by controlling the generator output in response to a change (in particular, a decrease) in the load of the set.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the drawings. FIG. 1 is a wiring diagram of one embodiment of the present invention, showing an example of power supply to a load in a general cogeneration system for building management.
V from the system V via the circuit breaker 52R, and the private power is generated by two engine generators AG of, for example, 400 KVA.
1. It has a private power generation facility equipped with AG2, and the received power and the generated power are interconnected via a bus communication breaker 52B,
Power is supplied to a load connected to the plurality of feeders. 5
2F2 to 52Fn are feeders each having a feeder breaker CB. 1A to NA, 1B to 3B, BG, 1AG
ＮnAG indicates loads of various pumps, air conditioners, exhaust fans, elevators and the like.

P ₁ is a power detector for starting the engine,
P ₂ is the received power constant control power detector, P ₃ is generated power constant control power detector, P ₄ is an engine generator halting power detector, MPC1 the reception power constant control unit, MPC2 the generated power constant control The device is shown, and W ₁ , W ₂ , and W ₃ are power detectors for switching the generator output in association with specific power generation. Here, Sy is an automatic synchronizer, which takes signals from the same numbers surrounded by circles.

Now, the operation plan of the entire system is, for example, (1) supplied by the received power until the load power reaches 310 kW, and (2) when the received power exceeds 310 kW, the NO. 1 generator AG1 and the received power
(3) The power generated by the generator AG1 is 3
When the power exceeds 20 kw, the constant control of the received power is stopped,
(4) When the received power exceeds 310 kW again, NO. The second power generator AG2 is operated, and constant control of the received power is performed in parallel.

In this case, the operation / stop of the generator is performed according to the flowchart shown in FIG.

In other words, power is supplied by the received power up to 310 kW. (1) When the received power exceeds 310 kW, the power is detected by the power detector P _{1 as} shown in FIG.
E is driven to start the generator AG1. Then, synchronization control is performed by the automatic synchronization device Sy. When synchronization is achieved, the circuit breaker 52G1 is turned on, and power reception and parallel operation are performed. At this time, the received power is controlled to be constant at 150 kW by the received power constant control device MPC1.

[0017] (2) then the generator AG1 is generated power in parallel operation and the power receiving becomes less 80 kW, the generator AG1 by the engine generator halting power detector P ₄ as shown in FIG. 2 (b) The load is shifted to the power receiving side, and the circuit breaker 52G1 is cut off and stopped. At this time, the constant control of the received power by the MPC 1 is stopped.

(3) When a power failure occurs on the power receiving side, the generator AG1 is started as shown in FIG. 2 (c), the busbar circuit breaker 52B is cut off, and when a selective cutoff is performed, except for an emergency load, the power is cut off. Supply to the emergency load and the generator AG2
Is started, synchronous control is performed with the generator AG1 that has been operated first, and when synchronization is established, the circuit breaker 52G2 is turned on to perform parallel operation. And when the power receiving side is restored,
The automatic synchronization device Sy synchronizes the above-mentioned 52B to perform parallel operation.

Next, the switching of the output power accompanying the specific supply power generation will be described with reference to FIG. FIG. 3 is an explanatory diagram of a main part of FIG.

(1) In the case of normal constant received power and constant generated power control, as shown in FIG. 3, the set value of the engine start start power P ₁ is P ₂ +160 kW (50% of the generator output).
%), The set value of the received power constant control target power P ₂ is 15
0 kW, (determined by the performance of the magnitude and the control device of the load change), generated power constant control target value P ₃ is 50-100
% Variably setting (65P ₁₎ where setting Once set,
There can be no changes other than changes in the middle period etc., 280-320 kw
Is desirable. Set value of the engine stop command to the power P ₄ performs operation control of power P ₁ to P ₄ to 25% (80 kW) of the generator output each set.

When the generator is started and stopped (rise and fall), the received power is basically controlled to be constant.
When it reaches 00%, the power generation output constant control is performed.

(2) In the case of power generation output switching control when the self-consumption load is reduced, the determination of the switching signal is performed not by central monitoring but by the power generation equipment. FIG. 4 is an explanatory diagram of the switching of the power generation output when the self-consumption load is reduced. The switching signal is determined not by the central monitoring panel but by the power generation equipment.

The feeder 52F ₃ loads a specific supply of FIG. 1
Power ～52F ₅ is detected by the power detector W ₁ to _W-3, asked to the detection signal to the generator equipment, added in the adder 40,
The set value of the setting device 41 assuming the output of the generator and the comparator 4
Then, the difference signal is input to the amplifier 43.
The amplifier 43 outputs, for example, a signal A that is turned on at 640 kW or less, and operates the relay 65L of FIG. 3 to control the governor motor GM by this signal A, thereby switching the output of the generator G to 100% to 75%. .

Further, a signal B for turning on at 680 kW or more is output, and the relay 65R is operated to reduce the generator output by 75%.
And return to 100%. This switching does not respond to an instantaneous power fluctuation, but is confirmed for 3 to 5 minutes (180 to
300 seconds → About 1 of the response time of the constant power control of 20 to 30 seconds
Switch).

The power information detected by the power detectors W _{1 to} W ₃ is not only calculated as described above, but also depending on the necessity of a response. May be switched.

[0026]

As described above, according to the present invention, a large number of specially required load information such as a load of a specific supply is continuously captured, their signals are collected, and fluctuations in the average value and instantaneous value are grasped to output the generator. Is controlled continuously or stepwise, so that reverse power prevention control can be performed while receiving power constant control is performed.

In the case where the fluctuation of the load of the specific supply or the like is grasped in a time-series manner by the recorded data, it can be realized by incorporating it into the schedule setting of the central monitoring panel.

[Brief description of the drawings]

FIG. 1 is a wiring diagram of one embodiment of the present invention.

FIG. 2 is a flowchart illustrating the present invention.

FIG. 3 is an explanatory view of a main part of FIG. 1;

FIG. 4 is an explanatory diagram of power generation output switching according to one embodiment of the present invention.

FIG. 5 is an explanatory diagram for studying a minimum value of received power.

[Explanation of symbols]

40 ... adder, 41 ... setter, 42 ... comparator, 43 ... The amplifier, AG1, AG2 ... generator, DE ... diesel engine, GM ... governor motor, P ₁ to P ₄ ... power detector, MP
C1: Received power constant control device, MPC2: Generated power constant control device, 52R: Received power circuit breaker, 52G1, 52
G2: generator power circuit breaker, 53B: communication bus circuit breaker, CB: circuit breaker, 52F2-52Fn: feeder,
1A to NA, 1B to 3B, 1AG to NAG ... Load, W ₁
To _W-3 ... power detector for the generator output switching due to specific supply power.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02J 3/38 H02J 3/00

Claims (1)

(57) [Claims] (1) Individual loads which fluctuate rapidly or change substantially simultaneously.
Identification of multiple moving loads gathering and fluctuating beyond a certain width
A plurality of loads, including loads, perform parallel operation of the system connected to the commercial power supply and the generator, and basically set the received power constant control, and when the generator output reaches the rated value, set the generator output to constant control In a cogeneration system, the power of a plurality of loads of a specific supply is continuously detected, respectively, introduced into an adder and detected as a signal of an average value or an instantaneous value. detecting a deviation signal between the set value, continuously or stepwise issued in response to the deviation signal
The reverse of the combined heat and power generation system characterized in that the output is output to the governor motor for the generator so as to switch the electric machine output, the generator is controlled via the governor motor, and the reverse power prevention control is performed while performing the constant received power control. Power prevention method.