• Journal of Electrical Engineering and Technology
• /
• v.12 no.3
• /
• pp.1007-1015
• /
• 2017

This paper proposes a new control technique of energy storage system (ESS) for smoothing the active power of renewable energy sources (RES) such as photovoltaic and wind turbine generation. As the penetration of RES into grid increases, it is difficult to maintain the permissible level of power quality, that is, voltage and frequency fluctuation in power systems. To solve this problem, ESS control methods using low pass filter (LPF) have been proposed for mitigating the fluctuation of RES output. However, those have a lot of drawbacks which need to be supplemented. Hence, this paper presents the improved active power control with additional reactive power control for maintaining power quality properly. The proposed method minimizes the capacity of ESS to be required for smoothing RES output fluctuation through mitigation of phase delay problem in LPF. In addition, the voltage regulation improves by using additional reactive power control. The proposed method was verified through simulation analysis using PSCAD/EMTDC.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.2
• /
• pp.92-99
• /
• 2022

Due to space and geographical constraints, the power source may be located outside the island area, resulting in the considerable length of transmission line. In these cases, when an active power is transmitted, unexpected reactive power is generated at a point of common coupling (PCC). Unlike the power transmitted from the power generation source, the reactive power adversely affects the system. This study proposes a new algorithm that controls reactive power at PCC. Causes of reactive power errors are separated into parallel and series components, which allows the algorithm to compensate the reactive current of the inverter output and control reactive power at the PCC through calculations from the impedance, voltage, and current. The proposed algorithm has economic advantages by controlling the reactive power with the inverter of the power source itself, and can flexibly control power against voltage and output variations. Through the simulation, the algorithm was verified by implementing a power source of 3 [kVA] capacity connected to the low voltage system and of 5 [MVA] capacity connected to the extra-high voltage system. Furthermore, a power source of 3 [kVA] capacity inverter is configured and connected to a mock grid, then confirmed through experiments.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.1
• /
• pp.8-20
• /
• 2013

This paper deals with the concept design of HVDC system for controlling AC network reactive power. HVDC system can control active power and reactive power and the control concept of reactive power is similar to SVC(Static Var Compensator). Reactive power is controlled by adjusting firing angle of HVDC system under the condition that AC filters are switched. Reactive power depends on AC voltage condition, considering the steady-state and transient state to maintain the stable operation of AC network in the viewpoint of voltage stability. Therefore, in the design stage of HVDC, the reactive power required in the AC network must be considered. For the calculation of operation angle in HVDC system, the expected reactive power demand and supply status is examined at each AC system bus. The required reactive power affects the determination of the operation angle of HVDC. That is, the range of "control deadband" of operation angle should have the capability supplying the required reactive power. Finally, the reactive power control concepts is applied to 1GW BTB Pyeongtaek-Dangjin HVDC system.

• Journal of Power Electronics
• /
• v.13 no.4
• /
• pp.719-728
• /
• 2013

A novel hybrid active power filter (NHAPF) that can be adopted in high-voltage systems is proposed in this paper. The topological structure and filtering principle of the compensating system is provided and analyzed, respectively. Different controlling strategies are also presented to select the suitable strategy for the compensation system. Based on the selected strategy, the harmonic suppression function is used to analyze the influence of system parameters on the compensating system with MATLAB. Moreover, parameters in the injection branch are designed and analyzed. The performance of the proposed NHAPF in harmonic suppression and reactive power compensation is simulated with PSim. Thereafter, the overall control method is proposed. Simulation analysis and real experiments show that the proposed NHAPF exhibits good harmonic suppression and reactive power compensation. The proposed compensated system is based on the three-phase four-switch inverter, which is inexpensive, and the control method is verified for validity and effectiveness.

• Proceedings of the KIEE Conference
• /
• 2003.07b
• /
• pp.1072-1074
• /
• 2003

In this paper, a new control strategy of a series active power filter using direct compensating voltage extraction method is proposed. This control algorithm compensates harmonics, reactive power and neutral line currents which are generated by balanced or unbalanced nonlinear loads. The advantage of this method is that the compensating voltage of the series active power filter can be extracted without phase transformation. Therefore, calculation time is shorten and the control method is simple compared with conventional method as the p-q theory In addition, this control strategy was applied for the series active power filter in 3-phase 4-wire system which is widely employed in distributing electric energy to several office building and manufacturing plants. Some results obtained from the experimental model using the proposed method are presented to demonstrate and confirm its validity.

• Journal of IKEEE
• /
• v.25 no.3
• /
• pp.462-466
• /
• 2021

DVR is a device that compensates for voltage fluctuations in distribution lines and is generally used in combination with a device that compensates reactive power and improve power factor. Such a coupling compensator has the disadvantage of being relatively difficult to control and bulky. In this paper, mathematical analysis of the maximum magnitude of the compensation voltage, phase angle, compensable reactive power and active power was performed in order to simultaneously compensate the reactive power and voltage fluctuation of the distribution line by applying the power angle control method of the DVR. A control algorithm for charging active power to the battery and supplying stored energy when the voltage is changed was developed and the results were confirmed through Matlab simulation.

• Proceedings of the KIEE Conference
• /
• 1997.07f
• /
• pp.2082-2084
• /
• 1997

This paper proposes a new control strategy of bidirectional uninterruptible power supply(UPS) with the performance of active power filter which compensate the harmonics and reactive power. To improve the transient response for the effective compensation in active power filter mode, it is considered that a simple and precise calculation method of the compensation reference current for the harmonics and reactive power compensation. So a novel closed-loop control strategy is used to calculate the reference current. And the current regulated instantaneous voltage control scheme is used in back-up power mode. The system model and control algorithm are described and analyzed, and the system Performance is verified by the simulation and experimental results.

• Proceedings of the KIEE Conference
• /
• 1999.07f
• /
• pp.2481-2483
• /
• 1999

This paper proposed the p-q-r coordinate system where the instantaneous active power p, and the two instantaneous reactive powers $q_{q}$, $q_{r}$ were defined. The three power components are linearly independent, so the compensation for the two instantaneous reactive powers leads to control the two components of the current space vector. With the theory, the neutral current of a three-phase four-wire system can be eliminated by only compensating the instantaneous reactive power using no energy storage element.

• Proceedings of the KIEE Conference
• /
• 2000.07b
• /
• pp.1174-1176
• /
• 2000

This paper presents a new control strategy of the active power filter to compensate the fundamental and high order reactive power. Using the proposed control strategy, the calculation of active and reactive power of the load is not required. So the system configurations and the controller can be constructed very simply. To decrease the load of active power filter, the LC passive filter bank can be used without any additional strategy. In this paper, the algorithm of the proposed new control strategy is discussed and the experimental results are shown.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.41 no.3
• /
• pp.244-252
• /
• 1992

This paper describes a reactive power compensator using current-source delta modulation converter, which compensates the reactive power in the ac sides of 3-phase rectifier. In the conventional current control methods for the current-type reactive power compensators, it is usual to compare the reactive reference current signal with the triangular wave and hence to generate the ON-OFF signals for the reactive power compensator. To improve the response as well as the control capability, the delta modulated current control technique is used in this paper. As a result, the input power factor is improved close to unity and both simulation and experimental results show good compensating performances.