Point Of Common Interconnection Research Articles

CAPSA Based Control for Power Quality Correction in PV Array Integrated EVCS Operating in Standalone and Grid Connected Modes

In this article, a solar photo voltaic (PV) array and a storage battery integrated three phase electric vehicle charging station (EVCS) is presented, which uses a convex combined affine projection sign algorithm (APSA) for improving the power quality at the grid. This algorithm convexly combines the output of two APSA with large step size and small step size. Therefore, this algorithm achieves fast convergence and low steady-state error in abruptly changing input conditions. Therefore, this algorithm is suitable for an EVCS, where the charging current of EV changes frequently. The EVCS provides both ac and dc charging to EVs. In the daytime, the CS operates in standalone mode to charge the EV connected at the point of common interconnection (PCI). However, the EV requiring dc power can take power from the dc link through a bidirectional dc-dc converter. Whereas, in the absence of PV array generation, the CS takes power from the grid. Moreover, while connecting the CS to the grid, the PCI voltage is synchronized to the grid voltage for achieving the seamless mode transition. Various steady-state and dynamic condition results have been taken on the experimental prototype developed in the laboratory for demonstrating its satisfactory behavior.

Improved Widrow–Hoff Based Adaptive Control of Multiobjective PV-DSTATCOM System

This article presents an adaptive control algorithm for a multiobjective grid-tied solar photovoltaic (PV)-distribution static compensator. The multiobjective system extracts the maximum energy available across the solar PV array and delivers it to the load and the grid connected at the common point of interconnection (PIC). In addition to this, the system reduces the losses on the distribution network and improves the quality of the voltage at the PIC by maintaining the grid currents balanced with THD value less than 5%. The perturb and observe-based maximum power point tracking method is used to extract the maximum energy, while the voltage source converter (VSC) is controlled by the presented improved Widrow-Hoff algorithm. This control algorithm improves the grid current power quality by estimating the fundamental component of the load current. It uses two weight to track the desired signal as compared to the other existing similar algorithms, which improves its tracking accuracy, reduces the steady-state error, and oscillation form the desired output signal. The same algorithm is used for synchronization of the VSC with the distribution network. Hence, it eliminates the need for another algorithm for the synchronization, which further improves its performance in dynamic conditions. An additional feed-forward term corresponding to the solar PV array (IPVFF) power is added in the VSC control to improve its dynamic response in the severe atmospheric conditions. The performance of the system is validated through simulated and test results in various dynamic conditions.

ANOVA Kernel Kalman Filter for Multi-Objective Grid Integrated Solar Photovoltaic-Distribution Static Compensator

In this paper, a novel ANOVA Kernel Kalman Filter (AKKF)-based adaptive control algorithm is introduced which is used for accurate harmonics support during operation of grid-integrated solar energy conversion system (SECS). For grid integrated SECS, a single-phase two-stage topology is considered, where local loads are attached on common point of interconnection (CPI), and a battery is attached on DC link. The AKKF is the improved form of Kalman Filter (KF), where the ANOVA Kernel (AK) trick is hybridized to improve the estimation accuracy of the KF. The objective of proposed control technique is to use this solar power to fulfil the load requirement. After satisfying the load requirement, the rest of solar power is fed to the grid. However, when the solar power is not available (in nighttime), then the system operates as Distribution Static Compensator (DSTATCOM), which provides reactive power support to the grid. The performance of the developed control technique is validated through experimentation on a developed prototype. During testing, adverse grid conditions, solar insolation variation, and load unbalance conditions are considered for satisfying the motive of the developed control technique.

Solar PV Energy Generation System Interfaced to Three Phase Grid With Improved Power Quality

This paper deals with a multipurpose distributed sparse (DS) control approach for a single stage solar photovoltaic (PV) energy generation system (SPEGS). This SPEGS is interfaced here to the three phase grid at varying solar irradiance and compensating the nonlinear load tied at point of common interconnection. The SPEGS performs multitasks. It feeds the generated solar PV power to the local three phase grid. It reduces the harmonics of loads and furnished balanced currents of local three-phase grid. The SPEGS uses a solar PV array, a voltage source converter (VSC), a nonlinear load, a three phase grid, and a dc-link capacitance. In case, when the solar irradiance is not available, the proposed system works as distribution static compensator by utilizing same VSC. For extracting maximum power from the PV source, the traditional perturb and observe (P&O) scheme is utilized here. The tracking performance and efficiency of P&O technique are also examined here at rapid changing climatic conditions to show the behavior of the P&O scheme. The DS control approach is capable to estimate required fundamental component to find out reference grid currents. The proposed control approach is validated on a developed prototype in the laboratory.

Power management in PV‐battery‐hydro based standalone microgrid

This work deals with the frequency regulation, voltage regulation, power management and load levelling of solar photovoltaic (PV)-battery-hydro based microgrid (MG). In this MG, the battery capacity is reduced as compared to a system, where the battery is directly connected to the DC bus of the voltage source converter (VSC). A bidirectional DC-DC converter connects the battery to the DC bus and it controls the charging and discharging current of the battery. It also regulates the DC bus voltage of VSC, frequency and voltage of MG. The proposed system manages the power flow of different sources like hydro and solar PV array. However, the load levelling is managed through the battery. The battery with VSC absorbs the sudden load changes, resulting in rapid regulation of DC link voltage, frequency and voltage of MG. Therefore, the system voltage and frequency regulation allows the active power balance along with the auxiliary services such as reactive power support, source current harmonics mitigation and voltage harmonics reduction at the point of common interconnection. The experimental results under various steady state and dynamic conditions, exhibit the excellent performance of the proposed system and validate the design and control of proposed MG.

A Decoupled Adaptive Noise Detection Based Control Approach for a Grid Supportive SPV System

A grid supportive two-stage three-phase four-wire solar photovoltaic (SPV) system is presented in this paper, wherein a boost converter is used as a first stage to serve the function of maximum power point tracking (MPPT) and a four-leg voltage source converter (VSC) is used to feed the extracted SPV energy, along with supporting distribution system for improvement in the power quality. Unlike conventional SPV inverters, the proposed solar energy conversion system provides extra functionalities such as balancing of grid currents, reactive power compensation, mitigation of harmonics, and neutral current elimination in grid side neutral conductor. An extra feed-forward term is added in the control loop to provide fast dynamic responses. The PV array voltage is continuously adjusted using a boost converter to achieve MPPT. A control approach employing decoupled adaptive noise detection (DAND) algorithm is used for controlling the four-leg grid-tied VSC. The DAND algorithm is a simple approach using two multipliers, one integrator, and one summer per phase for detection of useful component of load current. The proposed control algorithm gives features such as simple structure, fast convergence, frequency adaptive detection, and good steady-state performance. The grid currents are found adhering to an IEEE-519 standard, even under nonlinear and unbalanced loads at common point of interconnection.

A Three-Phase Grid Tied SPV System With Adaptive DC Link Voltage for CPI Voltage Variations

This paper deals with a three-phase two-stage grid tied SPV (solar photo-voltaic) system. The first stage is a boost converter, which serves the purpose of MPPT (maximum power point tracking) and feeding the extracted solar energy to the DC link of the PV inverter, whereas the second stage is a two-level VSC (voltage source converter) serving as PV inverter which feeds power from a boost converter into the grid. The proposed system uses an adaptive DC link voltage which is made adaptive by adjusting reference DC link voltage according to CPI (common point of interconnection) voltage. The adaptive DC link voltage control helps in the reduction of switching power losses. A feed forward term for solar contribution is used to improve the dynamic response. The system is tested considering realistic grid voltage variations for under voltage and over voltage. The performance improvement is verified experimentally. The proposed system is advantageous not only in cases of frequent and sustained under voltage (as in the cases of far radial ends of Indian grid) but also in case of normal voltages at CPI. The THD (total harmonics distortion) of grid current has been found well under the limit of an IEEE-519 standard.